Louis Pasteur was born on September 18, 1822 in the small French town of Doyle. His father, a veteran of the Napoleonic Wars, made a living by running a small leather workshop. The head of the family never finished school and could barely read and write, but he wanted a different future for his son. The tanner spared no expense, and after leaving school, young Louis was sent to college, where he continued his education. They say that a more diligent student was difficult to find in all of France. Pasteur showed unprecedented stubbornness, and in his letters to his sisters he talked about how much success in the sciences depends on "desire and work." No one was surprised when, after graduating from college, Louis decided to take the examination at the Higher Normal School in Paris.
Having successfully passed the entrance tests, Pasteur became a student. The money that the tannery brought in was not enough for education, so the young man had to earn money as a teacher. But neither work nor passion for painting (Pasteur received a bachelor of arts degree, painted many portraits that were highly appreciated by the artists of that time) could distract the young man from his passion for natural sciences.
Vaccination of a boy bitten by a rabid dog. Photo: www.globallookpress.com
Already at the age of 26, Louis Pasteur received the title of professor of physics for his discoveries in the field of the structure of tartaric acid crystals. However, in the process of studying organic substances, the young scientist realized that his vocation was not physics at all, but chemistry and biology.
In 1826, Louis Pasteur received an invitation to work at the University of Strasbourg. While visiting rector Laurent, Pasteur met his daughter Marie. And a week after they met, the rector received a letter in which the young professor asked for the hand of his daughter. Pasteur saw Marie only once, but he was completely sure of his choice. In the letter, he honestly informed the bride's father that “apart from good health and a kind heart,” he had nothing to offer Marie. However, Monsieur Laurent for some reason believed in the happy future of his daughter and gave permission for the wedding. Intuition did not disappoint - the Pasteur spouses lived in harmony for many years, and in the person of Marie, the scientist found not only his beloved wife, but also a faithful assistant.
Wine and chickens
One of the first works that brought Pasteur fame was a work on fermentation processes. In 1854, Louis Pasteur was appointed Dean of the Faculty of Natural Sciences at the University of Lille. There he continued the study of tartaric acids, begun at the Higher Normal School. One day, a rich wine merchant knocked on the door of Pasteur's house and asked the scientist to help him. Local winemakers could not understand why wine and beer were spoiled. Pasteur enthusiastically set about solving an unusual problem. Having examined the wort under a microscope, Pasteur discovered that in addition to yeast fungi, microorganisms in the form of sticks are also present in wine. In the vessels where the sticks were present, the wine turned sour. And if the fungi were responsible for the very process of alcoholic fermentation, then the sticks were the culprit for the spoilage of wine and beer. This is how one of the greatest discoveries was made - Pasteur explained not only the nature of fermentation, but also made the assumption that microbes do not arise by themselves, but enter the body from the outside. The solution to the problem of wine spoilage Pasteur began by creating an environment free of bacteria. The scientist heated the wort to a temperature of 60 degrees to kill all microorganisms, and already on the basis of this wort, wine and beer were prepared. This technique is still used in industry today and is called pasteurization in honor of its creator.
Louis Pasteur in his laboratory. Photo: www.globallookpress.com
Despite the fact that this discovery brought Pasteur recognition, those times were difficult for the scientist - three of Pasteur's five daughters died of typhoid fever. This tragedy prompted the professor to study infectious diseases. Examining the contents of abscesses, wounds and ulcers, Pasteur discovered many infectious agents, including staphylococcus and streptococcus.
Pasteur's laboratory at that time resembled a chicken farm - the scientist identified the causative agent of chicken cholera and tried to find a way to counteract this disease. The professor was helped by an accident. The culture with cholera microbes was forgotten in the thermostat. After the dried virus was introduced to the chickens, they, to the scientist's surprise, did not die, but suffered only a mild form of the disease. And when the scientist infected them again with fresh culture, the chickens did not show a single symptom of cholera. Pasteur realized that introducing weakened microbes into the body could prevent further infection. This is how vaccination was born. Pasteur named his discovery in memory of the scientist Edward Jenner, who, in order to prevent smallpox, injected patients with the blood of cows infected with a form of this disease that is safe for humans (the word "vaccine" comes from the Latin vacca - "cow").
After a successful experiment with chickens, Pasteur developed an anthrax vaccine. The prevention of this disease in livestock has saved the French government huge sums of money. Pasteur was given a life pension and was elected to the French Academy of Sciences.
Mad Dogs
In 1881, a scientist witnessed the death of a five-year-old girl, bitten by a rabid dog. What he saw so amazed Pasteur that he set about creating a vaccine against this disease with great zeal. Unlike most microorganisms that the scientist had to deal with before, the rabies virus could not exist on its own - the pathogen lived only in brain cells. How to get a weakened form of the virus - this question worried the scientist. Pasteur spent days and nights in the laboratory, infecting rabbits with rabies and then dissecting their brains. He personally collected the saliva of sick animals directly from the mouth.
The professor personally collected the saliva of rabid animals directly from the mouth Photo: www.globallookpress.com
Relatives seriously feared for the professor's health - it left much to be desired even without unbearable loads. Thirteen years earlier, when Pasteur was only 45, he suffered a severe stroke, which turned the scientist into an invalid. He never recovered from his illness - his hand remained paralyzed, and his leg dragged. But this did not stop Pasteur from making the greatest discovery in his life. From the dried brain of a rabbit, he created a rabies vaccine.
The scientist did not dare to conduct tests on humans until the mother of a boy who had been badly bitten by a rabid dog turned to him. The child did not have a chance to survive, and then the scientist decided to inject him with a vaccine. The child has recovered. Then, thanks to Pasteur's vaccine, 16 peasants were saved, bitten by a rabid wolf. Since then, the effectiveness of rabies vaccinations has not been questioned.
Pasteur died in 1895 at the age of 72. For his services, he received about 200 orders. Pasteur had awards from almost every country in the world.
In 2012, according to WHO, 35,412 people die from rabies worldwide. The picture does not change - the difference in the numbers of deaths for 2010 and 2012 is 1 (one) case, which indicates a constant, long-lasting, circulating infection, leading to painful death in one hundred percent of cases. Fleming understood the history of the oldest known infectious disease.
The first virus on earth
Rabies is an infectious disease that has been known since antiquity. People knew that it was transmitted from animals to humans. The first mention of deaths from dog bites dates back to 2300 BC. Then dog owners in the Babylonian city of Eshnunna were fined for carelessness in relation to pets. In 800 BC. in the Iliad, Homer describes the son of the Trojan king Priam as a "rabid warrior", which indicates that the ancient Greeks were already aware of the clinical picture of this disease.
And Hector, boasting with terrible force,
Rampant violently, strong against Zeus; he imputes nothing
Mortals and gods themselves, possessed by a terrible frenzy
There are enough of them to saturate the unfulfilled Hector, the son of Priam, even if he were even stronger! It will not be easy for him, and with all his fury in battles
"Iliad" in the lane. N. I. Gnedich
In 400 BC. Aristotle writes about the disease: “Dogs seem to lose their minds. Anyone they bite also gets sick. " The Greeks worship two gods: Aristeus, the son of Apollo, who prevents disease, and Artemis, who is believed to cure rabies.
The disease continues to spread throughout the Mediterranean, in ancient Rome at the junction of the old and new eras, the pathogen is called for the first time a virus, which means "poison" in ancient Roman. The Romans approach the disease with a pragmatism - they begin to look for its causes and try to treat it. Pliny the elder notes that rabies is caused by a specific worm that lives in the language. The famous Roman physician Celsus refutes the theory, pointing out that the virus is contained only in the saliva of a sick animal. He offers treatment: to wash and cauterize the bite wound, thereby mechanically removing the pathogen from the body surface. This treatment will remain the only treatment for the next 18 centuries. By the year 900, Arab and Syrian doctors describe all the symptoms of the disease, including the most noticeable one - the fear of water, hydrophobia. The Syrians admit their powerlessness in the face of the disease, helping the sick to live their last days, singing them secretly, disguising the water as honey.
In medieval Europe, rage is raging. It spreads from country to country, falls on the British Isles, cases are recorded in Spain, in Germany in 1271 a whole village dies of rabies after being attacked by wolves. By 1600, cases of rabies were recorded everywhere: Turkey, Belgium, Austria, Bulgaria. Paris is in panic after the first cases of the disease. With the discovery of the New World, the disease spreads to a new continent: in 1703, the first case of rabies in a priest from Spain. The disease spreads in wild and domestic animals, while the symptoms in pets are different, the disease is not initially identified with rabies. In 1752-1762, the fear of the disease is so great that in Britain they issue a permit for uncontrolled shooting of all dogs and wolves, the government pays 2 shillings for the head of the killed animal. The situation is similar in France, Italy and Spain. More than 900 dogs are killed in Madrid in one day. The price of a dog's head goes up to five shillings. By the early 19th century, the disease spread to South America and was first documented in the Russian Empire. By the middle of the 19th century, the disease occurs in all regions of the planet, excluding Antarctica and Australia.
The path to healing
In 1881, Louis Pasteur and Emile Roux, an employee of his laboratory in Paris, began to study rabies. By 1883, Roux published an article describing the results: a rabies vaccine was created from the spinal column of infected animals.
When tested on animals, it showed its effectiveness: when an injection of a dried extract of the spinal canal of rabid animals was injected into an infected dog, five of the animals that received the vaccine did not develop the disease. Pasteur, in a report to the French Medical Academy, wrote: “The virus persists in the spinal canal. However, by air drying it, we reduce its virulence, thereby reducing its danger to the body. " On July 6, 1885, an opportunity presented itself to test Pasteur's assumptions in practice. Three residents of Alsace came to the scientist's house. One of them, a nine-year-old boy named Joseph Meister, was bitten by the rabid dog of his neighbor, a certain Theodore Vonn. Pasteur vaccinated despite the fact that he himself did not have the right to do so: Pasteur did not have a medical license. Subsequently, Pasteur described his decision as follows: “The boy's death was a foregone conclusion: the dog that bit him was sick. In view of his imminent death, I considered it necessary to apply a vaccine on him, which had previously consistently shown its effect on dogs. " The injections were repeated 12 times over the next 10 days.
Louis Pasteur
Joseph Meister did not fall ill with rabies, thus becoming the first person who managed to avoid certain death. Humanity has put the first barrier before the fatal disease, not yet knowing its nature and pathogenesis. Until recently, rabies vaccination was the only way to prevent disease.
Bodies of Negri
In 1913, physician Joseph Pivan became an assistant surgeon at the Colonial Hospital in Port of Spain in what is now Trinidad and Tobago. Educated in Europe, Pivan completed an internship in Paris at the University of Pasteur. In 1925, a rabies epidemic breaks out on the island, and Joseph, as the only doctor on the island with experience with infectious diseases, is studying the outbreak. He discovers that all primary infections have occurred in wild or domestic animals that have been bitten by the island's vampire bat. The peculiarity was that, unlike other animals, which, catching rabies, ultimately died from the disease, these bats did not die of rabies. For the first time, mankind has discovered the so-called natural focus of this infection: the place where the pathogen persists and circulates in the interval between outbreaks.
Hidden killer
The causative agent of rabies is an RNA-containing (i.e., storing its genetic information on RNA) virus, which belongs to the family of rhabdoviruses. The RNA of the virus is built in a modular way: each of the five modules encodes a specific part of the viral particle, from a special enzyme RNA-dependent-RNA polymerase, which is responsible for the synthesis of new viral genomes, to the external receptors of the virus. Any mammal can get rabies, the main place of replication (reproduction) of the virus is nerve cells, along the axons of which the virus eventually enters the brain. Most often, the infection is transmitted through the bite of a sick animal, as a result of which saliva, which contains a large amount of the virus, enters the muscle tissue. The virus immediately enters the cell by endocytosis, and most often it is a muscle cell. After the replication process, which is no different from the replication of other RNA-containing viruses, the virus rushes to the neuromuscular synapse, through which it enters the nerve cell, apparently, together with neurotransmitters absorbed back into the axon (this process has not yet been fully understood ). A virus entering a nerve cell begins active replication already there. After collecting the particle, it “hitchhikers”, along with other substances transported by the cell itself, moves along the neurons at a speed of about 3 mm / h. Once in the brain, the virus continues to spread throughout the body, using nerve fibers as pathways that lead to every organ in the human body. Thus, the virus enters the salivary glands, making the saliva of the sick animal dangerous.
The process of formation of new rabies viruses does not differ from that of other RNA viruses.
In the brain, the rabies virus causes atypical changes. Most neurotropic viruses cause hemorrhage or cell necrosis in the brain. However, the rabies virus causes impaired transmission of nerve impulses. This is due to the inhibition of the synthesis of proteins in neurons used as neurotransmitters, as a result of which the cell simply has nothing to transmit the signal. A number of studies in mice show that the virus hedges in case neurons do continue to synthesize neurotransmitters by blocking acetylcholine receptors in the brain. In addition, the number of ion channels for chlorine anions increases in the affected cells, which leads to a violation of the onset of excitation in the nerve cells. All these changes lead to the typical clinical picture of rabies.
The most dangerous places for the virus to enter are well-innervated organs: the face, hands, genitals. In the event of a bite in these places, the likelihood of the virus entering the nervous tissue is especially high. Nevertheless, as mentioned above, even when it enters a muscle cell, the virus does not stop, easily overcoming histological incompatibility.
The incubation period, which takes about 7 days in humans, is the time it takes for the virus to enter the brain. The smaller the distance from the site of the bite to the head, the shorter this period. After the spread of the virus and its penetration into the brain, clinical manifestations of the disease begin. There are two forms of the disease: one is characterized by a person's disorientation in space, active motor stereotypes, aggressive behavior, and hydrophobia, which progresses from the fear of drinking a sip of water to panic attacks at the sight of liquid. Death from cardiac arrest occurs after 2 to 3 days. Another form, paralytic, is less common (in about 30% of cases), manifests itself in progressive muscle paralysis with subsequent attenuation of consciousness and the development of terminal coma.
A feature of the virus is its phenomenal escape from the body's immune system. Before the onset of clinical symptoms, i.e. before the virus enters the brain, no antibodies are detected in human blood. The body does not identify the virus, it cannot recognize it, because the latter skillfully hides inside neurons, not providing the body with its antigen for the production of antibodies. As a result, when the body's immune system begins to struggle, it is too late to do anything. Since the time of Pasteur, the rabies vaccine contains a weakened strain of the virus that, when administered, causes a strain on the immune system, i.e. activates natural defense mechanisms with the production of antibodies. Thus, when infected with a "street" strain of the virus, the immune system quickly attacks the cells into which the pathogen enters, and causes their apoptosis. Such a system is effective as long as the virus did not enter the central nervous system, and until recently it was believed that it was impossible to cure a patient with a detailed picture of rabies.
last hope
Gianna Geezy, a 15-year-old girl from Wisconsin, was bitten by a bat on her index finger. For a whole month, the girl's parents did not go to doctors, only treating the wound with hydrogen peroxide. The girl went to school and led a normal life. A month after the bite, Gianna noted the occurrence of discomfort in her left hand and general weakness. Two days later, she began to have double vision and lost the ability to walk normally. A day later, nausea and vomiting appeared. The girl was shown to a neurologist, who could not make an unambiguous diagnosis: MRI and angiography of the brain showed nothing remarkable. On the fourth day after the onset of the first symptoms, the left leg ceased to obey. Finally, on the fifth day, Gianna's speech became incomprehensible, there is a tremor in the muscles of the left arm. Only then the girl's parents remember about the bat bite of a month ago, after which the girl is hospitalized in a pediatric hospital in the city of Milwaukee.
By this time, the young patient had already developed a fever, she followed only the simplest commands. The neurological symptoms intensified, increased salivation began, and the girl was intubated to prevent fluid from entering the airways. On the second day, doctors receive a positive cerebrospinal fluid test for rabies. Doctor Rodney Willoughby talks with the girl's parents, explaining the futility of treatment and warning about the imminent death of their child. He offers two options for further treatment tactics. The first is symptomatic therapy, which will result in Gianna dying in the next few days, and the second is an aggressive treatment that has never been used before. The parents agree to the experimental method. Gianna is immersed in a drug-induced coma, blood transfusions are given to ensure normal oxygenation of tissues and organs. Brain activity is monitored, blood gas composition is monitored. After consultation with the state's Centers for Disease Control, antiviral therapy is initiated with ribavirin, a drug that has been shown to be effective in animal trials; in addition, it can cross the blood-brain barrier. From the next day, amantadine is prescribed, another antiviral drug. On the fifth day of hospitalization, the girl shows signs of erythrocyte hemolysis and a decrease in blood pH (acidosis) due to side effects of ribavirin. This forced doctors to reduce the doses of antiviral drugs. On the tenth day, a fever broke out. The temperature could not be brought down by any medicine. They were able to lower the temperature only by lowering the temperature in the room by 5.5 degrees Celsius.
In parallel with this, tests of cerebrospinal fluid were regularly taken: on the eighth day, an increase in the number of antibodies was found. Doctors began to reduce the doses of drugs that keep the girl in a coma. On the 12th day, tendon reflexes began to appear, on the 14th day, Gianna began to blink, on the 16th day, she raised her eyebrows in surprise in response to the doctors' questions. After 3 days, she fulfills the commands of the doctors, fixes her gaze and wiggles her fingers.
Gianna is now 26 years old.
On the 23rd day, she sits down by herself, and 27 days after hospitalization she was extubated (disconnected from the artificial respiration apparatus). On the 32nd day, the tests did not identify the virus, 76 days after being admitted to the hospital with a fatal diagnosis, 15-year-old Gianna Gizi is discharged after a rehabilitation course, becoming the first person to completely recover from rabies.
The treatment tactics are called the Milwaukee Protocol. Later, 6 people were cured using a similar method. Despite a number of positive results, Dr. Rodney Willoughby himself, who was the first to apply the technique, says that the treatment of the disease was carried out by groping rather than according to a prepared scheme. Nevertheless, at the moment, the Milwaukee Medical College has already prepared the second version of the protocol, and this gives hope that the incurable disease will sooner or later be defeated.
The importance of viruses in medicine can be compared to a mass destructive factor. Once in the human body, they reduce its protective capabilities, destroy blood cells, and penetrate into the nervous system, which is fraught with dangerous consequences. But there are special types of viruses that leave no chance of survival. Rabies is one of those.
What is rabies and how dangerous is it for humans? How does infection occur in humans and are there outbreaks of infection in our time? How does the disease manifest itself and how does it end? Can this disease be treated and what kind of prevention is needed? Let's find out everything about this dangerous infection.
Description
Where the rabies virus came from is unknown. Since ancient times, it has been called hydrophobia, because one of the frequent signs of an advanced infection is the fear of water.
The first scientific works appeared in 332 BC. NS. Even Aristotle suggested that a person becomes infected with rabies from sick wild animals. The name itself comes from the word demon, since long before the viral nature of the infection was discovered, a sick person was considered possessed by evil spirits. Aulus Cornelius Celsus (ancient Roman philosopher and physician) called the infection hydrophobia and proved that wild wolves, dogs and foxes are carriers of the disease.
The foundations of the prevention and treatment of the rabies virus in humans were laid by the French microbiologist Louis Pasteur in the 19th century, who, as a result of many years of research, developed an anti-rabies serum that saved thousands of lives.
At the very beginning of the last century, scientists managed to establish the viral nature of the disease. And exactly 100 years later, they found out that rabies can be cured even at the stage of the appearance of the first signs of the disease, which was not the case before. Therefore, this, as everyone previously believed, a fatal disease, is now considered curable, but under certain circumstances.
What is rabies
Rabies is a neurotropic (affecting the nervous system) acute viral infection, which can be contracted by an animal and a person. After the virus enters the body, the symptoms quickly gain momentum, and the infection ends in most cases with a fatal outcome. This is due to the peculiarities of the microorganism.
Why is the rabies virus dangerous?
- It is resistant to low temperatures and does not react to phenol, lysol solution, mercuric chloride and chloramine.
- It cannot be killed with a potent antibacterial drug, even viral drugs are powerless.
- At the same time, the rabies virus is unstable in the external environment - it dies after boiling in 2 minutes, and under the influence of a temperature of more than 50 ºC - in just 15. Ultraviolet light also quickly inactivates it.
- The virus travels to the nerve cells of the brain, causing inflammation.
- The microorganism exists on almost all continents and, according to WHO estimates, more than 50 thousand people die from it every year.
The rabies virus can be found not only in Africa and Asia, but also in the post-Soviet space, as it is spread by wild animals.
Causes of human infection
How is rabies transmitted to humans? This is a typical zoonotic infection, that is, people get infected from a sick animal. Carnivores are the natural habitat of the virus.
- The carriers of the infection are foxes and wolves in our forests. Moreover, the main role in the spread of the rabies virus belongs to foxes.
- In the countries of America, raccoon dogs, skunks, and jackals play an important role in the infection of people.
- In India, bats are involved in the spread of infection.
- Pets - cats and dogs - can also infect a person.
What are the routes of transmission of the rabies virus? - through the wound surfaces or mucous membranes, where the virus in the saliva of the animal gets.
How does the infection take place? The virus is active in the last days of the incubation period and during the development of the manifestations of the disease, it is then that it is already present in the saliva of a sick animal. When a rabies pathogen enters the mucous membranes or a wound, it enters the human body and begins to multiply.
How can you get rabies from a dog if there was no bite? Contact with the saliva of an infected pet is sufficient. It is almost impossible to suspect a disease during the incubation period, but the virus is already present and actively multiplying inside. This is another dangerous moment in the spread of infection. What are the signs of rabies in humans from a dog bite? - they are no different from those when infected with other animals. The only thing that matters is the size of the animal. The larger the dog - the more significant harm it can cause and the faster the infection will develop.
There is an assumption about where the virus comes from - scientists have come to the conclusion that there is a reservoir in nature - these are rodents with rabies that did not die immediately after infection.
Nowadays, foci of infection can be found absolutely everywhere, in any country in the world. But outbreaks of the disease were not recorded in those regions where rabies serum is actively used (Japan or on the islands of Malta, Cyprus).
Susceptibility to infection is general, but children are more likely to get sick in the summer-autumn period due to visiting the forest. Can you get rabies from humans? Throughout the history of the study of the disease, doctors feared that a sick person was dangerous to others. But this is almost impossible, because he is closely monitored, including his rigid fixation on the bed or complete isolation from others.
Is rabies transmitted by scratching? - yes, this is a possible way of contracting an infection, provided that a large amount of saliva gets into the wound. At the same time, the virus concentrates in the muscle mass, then reaches the nerve endings. Gradually, the microorganism captures an increasing number of nerve cells and affects all of their tissue. When the rabies virus multiplies, special inclusions are formed in the cells - Babesh-Negri's little bodies. They serve as an important diagnostic sign of the disease.
The infection reaches the central nervous system and affects important brain structures, followed by muscle cramps and paralysis. But not only the nervous system suffers, the virus gradually enters the adrenal glands, kidneys, lungs, skeletal muscles, heart, salivary glands, skin and liver.
The penetration of the rabies virus into the salivary glands and its multiplication causes the further spread of the disease. The infection spreads faster if a person is bitten by an animal in the upper half of the body. A head and neck bite will lead to a lightning-fast spread of the infection and a large number of complications.
Disease development periods
In total, there are several stages in the development of rabies:
- incubation or period without manifestations of the disease;
- the initial or prodromal period of rabies, when there are no visible typical signs of infection, but the person's well-being is significantly deteriorating;
- stage of heat or excitement;
- terminal stage or paralytic.
The most dangerous time is the onset of the disease. The incubation period for rabies in humans is 10 to 90 days. There are cases when the disease developed one year after the bite of an animal. What is the reason for such a large gap?
- As already noted, the bite site plays an important role in this. If an animal infected with the rabies virus has bitten a person in the upper half of the body, the time for the development of the disease is reduced. In the case of trauma to the foot or lower leg, infection develops more slowly.
- Depends on the age of the affected person. In children, the incubation period is much shorter than in adults.
- The type of infected animal also matters. The bite of small carriers of infection is less dangerous, a large animal will cause more damage and the disease will develop faster.
- Another important aspect is the size and depth of the wound, bite or scratch.
- The greater the amount of rabies pathogen trapped in the wound, the greater the chances of rapid disease progression.
- Plays a role and reactogenicity of the human body, or, in other words, to what extent its nervous system will be susceptible to this pathogen.
Human rabies symptoms
What are the first signs of rabies in humans?
But even at this time, it is almost impossible to suspect the onset of the disease, because such symptoms accompany many infectious diseases, not only rabies.
Symptoms during heat or excitement
After a short prodrome, another period follows - the peak. It does not last long, from one to four days.
In addition to the symptoms of the disease, pronounced attacks of aggression join:
- a person scratches, and sometimes even tries to bite himself and others, spits;
- the victim rushes about the room, trying to hurt himself or others;
- people infected with the rabies virus have an abnormal strength, it tries to break the surrounding furniture, bangs against the walls;
- there are attacks of disturbance of the mind - there are hallucinations, auditory and visual, delusional ideas.
Outside of seizures, a person is conscious and feels good, he is in a state of relative calm. During this period, a patient with rabies in paints describes his experiences and suffering during an attack.
Rabies Symptoms During Paralysis
How does the period of paralysis manifest with the development of rabies?
- Due to muscle paralysis, a person has constant salivation, while he cannot swallow and therefore constantly spits.
- Hand movements are weakened due to paralysis of the shoulder muscles and limbs.
- The jaw in such patients often hangs down due to the weakness of the facial muscles.
- In addition to paralysis, in patients with rabies at the last stage of the disease, the body temperature rises.
- Disturbances in the work of the cardiovascular and respiratory systems are increasing, so the next attack for a person can end in failure.
- Further, the symptoms of rabies in people fade away - a person's general calmness sets in, fear and anxiety disorders disappear, attacks are also not observed.
- Riot with rabies is replaced by apathy, lethargy.
The total duration of all periods of the disease is no more than 10 days, excluding incubation.
Atypical rabies course and prognosis
In addition to the familiar classic course of rabies, there are several more options uncharacteristic for this infection.
- The disease proceeds without fear of light or water, and begins immediately with a period of paralysis.
- Perhaps the course of the disease with mild symptoms, without special manifestations.
Doctors even suggest that one of the important factors in the spread of the disease is the latent or atypical course of the infection.
The prognosis of rabies is always difficult to predict. Here, perhaps, two main options are recovery or death from rabies. The later therapy is started, the more difficult it is to cure the patient. The last period of the disease is always unfavorable in terms of recovery, at this time a person no longer has a chance.
Stepwise diagnosis of rabies
Diagnosis of the disease begins with a detailed history of the affected person.
At the initial stage of the development of the disease, the fundamental principle of diagnosing rabies in humans is the analysis of symptoms. For example, conclusions can be drawn based on seizures following exposure to water.
Treatment
Rabies therapy begins with an important stage - complete isolation of a person in a separate ward, in which there are no irritants so as not to provoke attacks.
Then, the treatment of rabies in humans is carried out taking into account the symptoms.
- First of all, they try to correct the work of the nervous system, because the main problems are due to inflammation of the centers of the brain. For this purpose, hypnotics, drugs to reduce pain, anticonvulsants are prescribed.
- Considering that patients with rabies are weakened, they are prescribed parenteral nutrition, that is, glucose is administered with the help of solutions, vitamins to maintain the functioning of the nervous system, plasma-substituting substances and just salt solutions.
- Can rabies in humans be treated with antiviral drugs or other methods? In the later stages, the disease is incurable and fatal. Even the most modern antiviral drugs are ineffective and therefore not used against rabies.
- In 2005, a girl was cured in the United States, who was put into an artificial coma during the height of the disease, and after a week of shutting off the brain, she woke up healthy. Therefore, now active development of modern methods of treatment of patients with rabies is underway.
- In addition, they are trying to treat the disease with immunoglobulin in case of rabies in combination with mechanical ventilation and other methods.
Prevention
Due to the lack of effective methods of treating rabies, prevention remains the most reliable today.
Nonspecific rabies prophylaxis begins with extermination of the vectors and detection and elimination of the source. In recent times, the so-called cleansing of wild animals was carried out, they were exterminated. Since in nature the fox and the wolf are in the first place in the spread of rabies, they were destroyed. Now such methods are not used, only in the case of a changed behavior they can be taken care of by special services.
Since animals can spread the rabies virus in a city, much attention is paid to preventive measures for domestic dogs and cats. To this end, they are given specific rabies prophylaxis - they are regularly vaccinated.
Non-specific methods of protection against rabies include burning the corpses of dead animals or people so that the virus does not circulate further in nature. In addition, doctors strongly recommend that in the event of a bite from an unfamiliar animal, immediately rinse the wound with large amounts of liquid and contact the nearest medical center for emergency assistance.
Specific rabies prophylaxis
Emergency prevention of rabies consists of administering rabies vaccine to the affected person. To begin with, the wound is actively washed and treated with antiseptic drugs. If a person is suspected of being infected with the rabies virus, excision of the edges of the wound and suturing it is contraindicated, as is done under normal conditions. It is important to follow these rules, because during the surgical treatment of the wound, the incubation period of rabies is significantly reduced.
Where are rabies injections given? - drugs for infection are administered intramuscularly. Each vaccine has its own characteristics in the appointment and administration. The dose of the drug can also vary depending on the conditions. For example, it depends on the site of the bite or on the age of the injury and contact with animals. Rabies is inoculated in the deltoid muscle or in the anterolateral thigh. There are vaccines that are injected into the subcutaneous tissue of the abdomen.
How many injections are given to a person for rabies? - it all depends on the conditions. It matters to whom the administration of the drug is prescribed - to the victim or to a person who, by the nature of his activity, may encounter infected animals. The creators recommend that different types of vaccines be administered according to their developed schedule. After the bite of an animal patient with rabies, the method of six-fold administration of the drug can be used.
When vaccinating, it is important to comply with several conditions:
- for some time after it and for the entire period when a person is vaccinated, it is impossible to introduce unusual foods into the diet, as allergies often develop;
- if it was possible to observe the dog, and it did not die of rabies within 10 days, the vaccination schedule is reduced and the latter no longer do;
- alcohol and rabies shots are incompatible, the consequences can be unpredictable, and the vaccine simply will not work.
During the entire period of administration of the rabies vaccine, a person should be under the supervision of doctors. Emergency immunoprophylaxis of rabies is most often carried out in an emergency room, which is equipped with everything necessary for this.
What side effects can a person have after rabies shots? Previously, vaccines prepared from animal nervous tissue were widely used. Therefore, brain diseases such as encephalitis and encephalomyelitis developed after the application of the rabies vaccination several years ago. Now the composition and methods of making preparations have changed slightly. Modern vaccines are much easier to tolerate, after their use only sometimes an allergic reaction occurs or an individual intolerance manifests itself.
They have not yet invented effective drugs for rabies, which could save a person's life at the time of a developing disease. Its most common complication is death. For this reason, rabies is one of the most dangerous infections. Therefore, after a bite of an animal, heroism is not needed - it is important to seek help from an emergency room in a timely manner.
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Rabies(hydrophobia) is an acute zoonotic viral infectious disease with a contact mechanism of transmission of the pathogen, characterized by damage to the central nervous system with bouts of hydrophobia and death.
History and distribution
Rabies was known to doctors in the East for 3000 BC. The first detailed description of the disease (hydrophobia) belongs to Celsus (1st century AD), who recommended cauterizing bite wounds. In 1801, the possibility of transmission of the disease with the saliva of a sick animal was proved. In 1885 L. Pasteur and his collaborators E. Ru and Chamberlain applied the vaccine against rabies developed by them to prevent the disease in a person bitten by a sick dog.
Already in 1886, for the first time in the world, II Mechnikov and NF Gamaleya organized a Pasteur station in Odessa. In 1892 V. Babes, and in 1903 A. Negri described specific intracellular inclusions in the neurocytes of animals that died from rabies (Babesh-Negri's little bodies), however, the morphology of the virus was described for the first time by F. Almeida in 1962.
Animal rabies has been reported all over the world, excluding the UK and some other island states. The incidence of human disease (always fatal) is several tens of thousands annually. On the territory of Russia, there are natural foci of rabies and cases of diseases of wild and domestic animals are recorded, as well as individual cases of rabies in humans every year.
Rabies etiology
The causative agent of the disease contains single-stranded RNA, belongs to the family Rhabdoviridae, genus Lyssavirus. In the environment, the virus is unstable, thermolabile, is inactivated during boiling within 2 minutes, and remains frozen and dried for a long time.
Epidemiology
The main reservoir of rabies in nature is wild mammals, different in different regions of the world (fox, arctic fox, wolf, jackal, raccoon and raccoon dog, mongoose, vampire bats), in whose population the virus circulates. Infection occurs when bitten by sick animals. In addition to natural foci, secondary anthropurgic foci are formed, in which the virus circulates between dogs, cats and farm animals. The source of rabies for humans in the Russian Federation is most often dogs (especially stray ones), foxes, cats, wolves, in the North - polar foxes. Although the saliva of a sick person may contain the virus, it does not pose an epidemiological hazard.
Infection is possible not only when bitten by sick animals, but also when the skin and mucous membranes are salivated, since the virus can penetrate through microtrauma. It is important to emphasize that the pathogen is detected in the saliva of animals 3-10 days before the appearance of obvious signs of the disease (aggressiveness, salivation, eating inedible objects). Latent carrier of viruses is possible in bats.
In cases of a bite from a known sick animal, the probability of developing the disease is about 30-40% and depends on the location and extent of the bite. It is more when bitten in the head, neck, less - in the distal extremities; more with extensive (wolf bite), less with minor damage. Cases of rabies are more often recorded among rural residents, especially in the summer-autumn period.
Pathogenesis
After the virus penetrates through damage to the skin or mucous membranes, its primary replication occurs in myocytes, then the virus moves centripetally along the afferent nerve fibers and enters the central nervous system, causing damage and death of nerve cells in the brain and spinal cord. From the central nervous system, the pathogen spreads centrifugally along the efferent fibers to almost all organs, including the salivary glands, which explains the presence of the virus in saliva already at the end of the incubation period. The defeat of neurocytes is accompanied by an inflammatory reaction.
Thus, the basis of the clinical manifestations of the disease is encephalomyelitis. Clinical manifestations of rabies are associated with the predominant localization of the process in the cerebral cortex and cerebellum, in the thalamus and hypothalamus, subcortical ganglia, cranial nerve nuclei, the pons of the brain (pons pons), midbrain, in the centers of life support in the area of the bottom of the IV ventricle. Along with the neurological symptoms caused by these lesions, an important place is occupied by the development of dehydration due to hypersalivation, sweating, an increase in perspiration losses, while a decrease in fluid intake as a result of hydrophobia and inability to swallow. All these processes, as well as hyperthermia and hypoxemia, contribute to the development of edema-swelling of the brain.
Rabies pathology
At postmortem examination, attention is drawn to the swelling and plethora of the brain substance, the smoothness of the convolutions. Microscopically detect perivascular lymphoid infiltrates, focal proliferation of glial elements, dystrophic changes and necrosis of neurocytes. The pathognomonic sign of rabies is the presence of Babesh-Negri bodies - oxyphilic cytoplasmic inclusions consisting of a fibrillar matrix and viral particles.
Rabies is a fatal disease. Death occurs as a result of damage to vital centers - respiratory and vasomotor, as well as paralysis of the respiratory muscles.
Clinical picture
The incubation period is from 10 days to 1 year, usually 1-2 months. Its duration depends on the location and extent of the bites: with bites to the head and neck (especially extensive ones), it is shorter than with single bites to the distal extremities. The disease is cyclical. There is a prodromal period, a period of excitement (encephalitis) and a paralytic period, each of which lasts 1-3 days. The total duration of the disease is 6-8 days, with resuscitation measures - sometimes up to 20 days.
The disease begins with the appearance of discomfort and pain at the site of the bite. The scar after the bite becomes inflamed, becomes painful. At the same time, irritability, depressed mood, a feeling of fear, melancholy appear. Sleep is disturbed, headache, malaise, subfebrile condition occur, sensitivity to visual and auditory stimuli increases, skin hyperesthesia is noted. Then a feeling of tightness in the chest, lack of air, sweating join. Body temperature reaches febrile levels.
Against this background, suddenly, under the influence of an external stimulus, the first pronounced attack of the disease("Paroxysm of rabies"), caused by painful cramps of the muscles of the pharynx, larynx, diaphragm. It is accompanied by impaired breathing and swallowing, severe psychomotor agitation and aggression. Most often, seizures are triggered by an attempt to drink (hydrophobia), air movement (aerophobia), bright light (photophobia), or loud sound (acoustic phobia).
The frequency of seizures that last for a few seconds is increasing. Confusion of consciousness, delirium, hallucinations appear. Patients scream, try to run, tear clothes, break surrounding objects. During this period, salivation and sweating increases sharply, vomiting is often noted, which is accompanied by dehydration, a rapid decrease in body weight. The body temperature rises to 30-40 ° C, there is a pronounced tachycardia up to 150-160 beats per minute. Perhaps the development of paresis of the cranial nerves, muscles of the extremities. In this period, there may come death from respiratory arrest or the disease goes into a paralytic period.
Paralytic period characterized by the cessation of convulsive seizures and excitement, relief of breathing, clarification of consciousness. This imaginary improvement is accompanied by an increase in lethargy, adynamia, hyperthermia, and hemodynamic instability. At the same time, paralysis of various muscle groups appears and progresses. Death occurs suddenly from paralysis of the respiratory or vasomotor centers.
Various variants of the course of the disease are possible. So, prodromal period may be absent and attacks of rabies appear suddenly, possibly "silent" rabies, especially after bites of bats, in which the disease is characterized by a rapid increase in paralysis.
Diagnosis and differential diagnosis
Rabies is diagnosed based on clinical and epidemiological data. To confirm the diagnosis, use is made of the detection of the virus antigen by the IF method in corneal prints, biopsies of the skin and brain, isolation of the virus culture from saliva, cerebrospinal and lacrimal fluid using a bioassay on newborn mice. Postmortem diagnosis is confirmed histologically by the detection of Babesh-Negri bodies, most often in the cells of the ammonic horn or hippocampus, as well as by the detection of the antigen of the virus by the method indicated above.
Differential diagnosis is carried out with encephalitis, poliomyelitis, tetanus, botulism, polyradiculoneuritis, atropine poisoning, hysteria ("lissophobia").
Rabies treatment
Patients are hospitalized, as a rule, in individual boxes. Attempts to use specific immunoglobulin, antiviral drugs, resuscitation methods have so far been ineffective, therefore, treatment is mainly aimed at reducing the patient's suffering. Sleeping pills, sedatives and anticonvulsants, antipyretics and analgesics are used. Correction of water-electrolyte balance, oxygen therapy, mechanical ventilation are performed.
Forecast... Lethality is 100%. The described isolated cases of recovery are not well documented.
Prevention aims to combat rabies in animals by regulating the population of foxes, wolves and other animals that are the reservoir of the virus, registering and vaccinating dogs, using muzzles, and trapping stray dogs and cats. Persons professionally associated with the risk of infection (dog catchers, hunters) must be vaccinated. Persons bitten or salivated by unknown patients or animals suspected of having rabies are treated with wound treatment and anti-rabies vaccination, and a specific immunoglobulin is administered.
A conditional course of vaccine prophylaxis (2-4 injections of rabies vaccine) is carried out for bitten healthy animals, and a 10-day observation is established for the animals. If during these periods they show signs of rabies, the animals are slaughtered, a histological examination of the brain is carried out for the presence of Babesh-Negri bodies, and the bitten ones are given a full course of vaccine prophylaxis. Antirabies drugs are administered in trauma centers or surgery rooms. The effectiveness of specific prophylaxis is 96-99%, side reactions, including post-vaccination encephalitis, are observed in 0.02-0.03% of cases.
Yushchuk N.D., Vengerov Yu.Ya.
Even 150 years ago, a man bitten by a rabid animal was doomed. Today, scientists are improving weapons in the war against an ancient and extremely dangerous enemy - the rabies virus.
Pasteur's legacy On the plaque of the house in which Pasteur's first laboratory was located, his discoveries are listed: the enzymatic nature of fermentation, refutation of the hypothesis of spontaneous generation of microorganisms, the development of ideas about artificial immunity, the creation of vaccines against chicken cholera, anthrax and rabies. Pasteurization and other "little things" were not included in this list
The first, but extremely important step towards the fight against rabies was taken by the brilliant French chemist and microbiologist Louis Pasteur. He began developing a vaccine against this disease in 1880, after witnessing the agony of a five-year-old girl bitten by a rabid dog.
Rabbits and dogs
Although rabies was first described in the 1st century BC. Roman Cornelius Celsus, after almost 2000 years, very little was known about this disease. Only in 1903, eight years after Pasteur's death, the French physician Pierre Remlenger established that rabies is caused by a submicroscopic form of life - a filterable virus.
Pasteur, not having this information, nevertheless was not going to give up: to create a vaccine, he chose a roundabout way - to find a repository of "poison" and turn it into an antidote. It was reliably known that something transmitted from a sick animal to another animal or person, along with infected saliva, affects the nervous system. During the experiments, it was found that the disease has a very long incubation period, but this only spurred Pasteur and his colleagues, since it meant that doctors had the opportunity to influence the slowly developing pathological process - the “poison” had to get to the spinal cord along the peripheral nerves. , and then the brain.
Then began experiments on rabbits in order to obtain the most lethal "poison" of rabies in large quantities. After dozens of transfers of brain tissue from a sick animal to the brain of a healthy one, from it to the next, etc., scientists managed to achieve that a standard extract from the brain killed a rabbit in exactly seven days instead of the usual 16-21. Now it was necessary to find a way to weaken the pathogen of rabies (the method of creating vaccines - weakening the pathogen - is also a discovery of Pasteur). And they found a way: two weeks of drying the virus-soaked rabbit brain tissue over a moisture-absorbing alkali.
After the introduction of the suspension from the obtained preparation, the dog infected with rabies not only recovered, but also became absolutely immune to rabies, no matter how much "poison" was injected into it.
Finally convinced that the same seven-day laboratory "poison" does not affect the vaccinated dogs, the researchers conducted a cruel experiment: vaccinated dogs were sent to their relatives suffering from rabies. The bitten mongrels didn't get sick!
40 injections in the stomach
Then it was the turn of the people. But where to find volunteers? Driven to despair, Pasteur was ready to sacrifice himself for the sake of science, but, fortunately, His Majesty Chance intervened.
On July 6, 1885, a tear-stained woman appeared on the threshold of Pasteur's Paris laboratory, holding the hand of her nine-year-old son, Joseph Meister. Three days before, the boy had been bitten by a mad dog, inflicting 14 open wounds on him. The consequences were quite predictable: at that time it was already known that death in such cases was almost inevitable. However, the boy's father had heard about Pasteur's works and insisted on bringing the child from Alsace to Paris. After serious hesitation, Pasteur injected the little patient with an experimental drug, and Joseph became the first person in history to be saved from rabies.
Know the enemy by sight
The causative agent of rabies (Rabies virus) belongs to the family of Rhabdoviridae containing a single-stranded linear RNA molecule, genus Lyssavirus. In shape, it resembles a bullet about 180 nm long and 75 nm in diameter. Currently, 7 genotypes are known.
The rabies virus has a tropism (affinity) for the nervous tissue, just like influenza viruses for the epithelium of the respiratory tract. It penetrates the peripheral nerves and moves at a speed of about 3 mm / h to the central parts of the nervous system. Then it spreads neurogenically to other organs, mainly to the salivary glands.
The likelihood of the disease depends on the place and severity of the bites: with bites by rabid animals in the face and neck, rabies develops on average in 90% of cases, in the hands - in 63%, and in the thighs and arms above the elbow - only in 23% of cases.
The main wild animals - sources of infection - are wolves, foxes, jackals, raccoon dogs, badgers, skunks, bats. Among domestic animals, cats and dogs are dangerous, and it is the latter that accounts for the maximum confirmed cases of rabies transmission to humans. Most of the sick animals die within 7-10 days, the only described exception is the yellow, aka fox-shaped mongoose Cynictis penicillata, capable of carrying a virus in itself without developing a clinical picture of infection for several years.
The most characteristic and reliable sign of the presence of a virus in the human or animal body is the detection of the so-called Negri bodies, specific inclusions in the cytoplasm of neurons with a diameter of about 10 nm. However, in 20% of patients, Negri's little bodies cannot be found, so their absence does not exclude the diagnosis of rabies.
The photo shows the rabies virus under an electron microscope.
People from all over the world flocked to Paris - Algerians, Australians, Americans, Russians, and often in French they knew only one word: "Pasteur". Despite this success, the discoverer of the vaccine against a deadly disease had to hear the word "killer" in his address. The fact is that not all those bitten survived after vaccination. In vain Pasteur tried to explain that they had applied too late - some two weeks after the animal's attack, and some a month and a half later. In 1887, at a meeting of the Academy of Medicine, colleagues directly accused Pasteur of simply killing people with pieces of rabbit brain. The scientist, who gave all his strength to science, could not stand it - on October 23, he developed a second stroke, from which he never recovered until his death in 1895.
But ordinary people supported him. By subscription, in a year and a half, residents of many countries of the world collected 2.5 million francs, for which the Pasteur Institute was created, officially opened on November 14, 1888. On its territory there is a museum and the tomb of a researcher who saved humanity from a deadly infection. Pasteur's death date, 28 September, has been selected by the World Health Organization (WHO) to celebrate the annual World Rabies Day.
For a long time, the vaccine was injected under the skin of the anterior abdominal wall, and the full course required up to 40 injections. A modern immunopreparation is injected intramuscularly, into the shoulder, six visits to the emergency room are enough.
Miracle Milwaukee
During the 20th century, the situation with rabies was unambiguous: if the victim was not vaccinated on time or did not receive the vaccine at all, the case ended tragically. According to WHO estimates, 50-55 thousand people die every year in the world after an attack by rabid animals, 95% of them are in Africa and Asia.
They started talking about the possibility of a full-fledged treatment of infection only in the 21st century. This was due to the case of the American Gina Gis, who for the first time in the history of medicine did not receive a vaccine, but survived after the onset of symptoms of rabies. On September 12, 2004, 15-year-old Gina caught a bat that bit her on the finger. The parents did not go to the doctor, considering the wound to be trifling, but after 37 days the girl developed a clinical picture of infection: a rise in temperature to 39 ° C, tremor, double vision, difficulty speaking - all signs of damage to the central nervous system. Gina was admitted to the Wisconsin Children's Hospital, and rabies was confirmed at the Centers for Disease Control and Prevention (CDC) labs in Atlanta.
Viruses and bacteria
Humanity is fighting bacterial infections relatively successfully. Antibiotics and vaccines are doing their job, and sanitation and epidemiology are at their best. With viruses, everything is much more complicated. Suffice it to recall the flu, which the world's population suffers with enviable regularity, despite all the advances in science and the availability of vaccines and antiviral drugs.
This is primarily due to the ability of viruses to change in the most unpredictable way. Some, like pathogens of influenza, change the proteins of their shell, like gloves, so it is still impossible to develop high-precision weapons against them.
In the fight against disease, success came when a virus was found to have a weak double that did not kill a person, but left behind a powerful cross-immunity. Deliberate infection with a weaker strain made it possible to defend against a deadly one. The classic case that started the history of vaccination is smallpox and smallpox, then a similar story was repeated with polio. In the summer of 2012, there was hope that a similar scenario would be able to cope with rabies.
The parents were offered to try an experimental method of treatment on the girl. Having received consent, the doctors, using ketamine and midazolam, introduced the patient into an artificial coma, effectively turning off her brain. She also received antiviral therapy with a combination of ribavirin and amantadine. In this state, doctors kept her until the immune system began to produce enough antibodies to cope with the virus. It took six days.
A month later, the tests confirmed that there was no virus in the girl's body. Moreover, the brain functions were minimally impaired - she graduated from high school, and a year later she received a driver's license. Currently, Gina graduated from college and intends to continue her studies at the university. It is not surprising that she sees biology or veterinary medicine as her future profession, and plans to specialize in the field of rabies.
To get into the cell, the rabies virus uses the endosomal transport system: the cell itself must capture it and draw the vesicle formed from the cell membrane - the endosome, the “inner body” - into the cytoplasm. This process is activated after the virus binds to special receptor proteins on the cell membrane. The resulting endosome disintegrates over time, the viral particle releases RNA, then everything goes according to the standard scenario.
The treatment protocol that was applied to the girl was called "Milwaukee" or "Wisconsin". They have repeatedly tried to reproduce it in other medical institutions ... but, alas, without much success. The first version of the protocol was tested on 25 patients, of which only two survived. The second version, from which ribavirin was excluded, but drugs were added to prevent vascular spasm, was applied to ten patients and prevented the death of two of them.
Epidemiological investigations revealed that patients who were treated using the Milwaukee Protocol were bitten by bats. It was this fact that allowed some scientists to assume that, in fact, the treatment method has nothing to do with it, but the point is in these mammals, or rather, in the fact that they are infected with another strain of the virus, less dangerous for humans.
The Riddle of the Bat
In 2012, this assumption was first confirmed. An article appeared in the American Journal of Tropical Medicine and Hygiene by a group of CDC experts, US military virologists and epidemiologists from the Peruvian Ministry of Health. The results of their research had the effect of a bomb exploding: in the Peruvian jungle, they managed to find people who have antibodies to the rabies virus in their blood. These people have never been injected with any vaccines, moreover, they do not even remember being sick with anything serious. This means that rabies is not 100% fatal!
“This area of the Peruvian Amazonian jungle has had numerous reports of exposure to vampire bats and cases of rabies in humans and pets over the past 20 years,” explains PM lead author Dr. Amy Gilbert of the CDC's Rabies Research Program. ... “The villages and farms that we surveyed are located in very remote places from civilization - for example, two days' journey to the nearest hospital, and in some areas movement is possible only by boats on water.”
In a survey of residents, 63 out of 92 people reported bat bites to scientists. Blood samples were taken from these people, as well as from local flying vampires. The test results were unexpected: in seven samples, antibodies that neutralize the rabies virus were found.
The presence of antibodies could be explained by the introduction of an anti-rabies (Latin rabies - rabies) vaccine, but, as it turned out, only one in seven people received such a vaccine. The rest were ill with rabies, not only without death, but even without any serious symptoms. In two Peruvian villages, there are more survivors of this infection than described in all the medical literature! Unsurprisingly, Gilbert's group double-checked the findings for two years before deciding to publish them.
“This is most likely a unique set of circumstances in which the local population is regularly exposed to a specific non-lethal strain of the rabies virus,” says Dr. Gilbert. - In this case, natural vaccination occurs, which is confirmed by sufficiently high antibody titers. However, this still requires additional confirmation and clarification. "
From a laboratory diary, 1885
“The death of this child seemed inevitable, so I decided, not without serious doubt and anxiety, which is understandable, to test on Joseph Meister a method that I found successful in treating dogs. As a result, 60 hours after the bites, in the presence of Doctors Vilpo and Gransche, the young Meister was vaccinated with half a syringe of an extract from the spinal cord of a rabbit that had died of rabies, which had been previously treated with dry air for 15 days. In total, I gave 13 injections, one every next day, gradually injecting an increasingly lethal dose. Three months later I examined the boy and found him completely healthy. "
Her point of view is also shared by her Russian colleagues. Virologist Alexander Ivanov from the Laboratory of the Molecular Basics of the Action of Physiologically Active Compounds of the Institute of Molecular Biology. V.A. Engelhardt, who was asked by "PM" to comment on the discovery of CDC experts, stressed that these strange at first glance results may have a completely scientific explanation: “Based on the available data, it can be assumed that local residents were infected with variants of the virus, activity (ability to reproduce) and low pathogenicity ("toxicity"). In my opinion, this may be due to several factors. First, each virus has a huge number of variants due to its relatively high variability. Infectionists speculate that even for a successful transition from bats to other species, the rabies virus must undergo several specific mutations. If this is the case, then many strains of the virus carried by bats may be of little danger to humans. Second, mutations in the genome of the virus affect its recognition by the immune system, as well as the ability of the virus to block the immune response to infection. At the same time, it is precisely those variants of the rabies virus that are capable of eluding the innate immune system that have increased pathogenicity. Thus, these facts really allow us to assume the existence of such strains of the rabies virus in the bat population, which are recognized and destroyed by the human immune system in time, without causing fatal consequences. "
But in no case - this is emphasized by all experts, including the authors of the study - you can not refuse the introduction of the rabies vaccine for bites of wild animals. First, it may indeed be that bats have a different, weaker virus, and the luck of the Peruvian peasants does not extend to strains transmitted by dog or raccoon bites. Second, the results and conclusions of this study may turn out to be erroneous, so there is no point in putting yourself at risk.
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