For most people, all knowledge about the rabies virus ends with the fact that if bitten by a stray dog, they will make forty injections in the stomach. Is it really? How dangerous is this viral infection, and what are the modern methods of dealing with this disease? We will answer these questions in this article. And although the resistance of the rabies virus in the external environment is small, its spread is dangerous and in many cases can be fatal.
On the urgency of the problem
How long does the rabies virus live in the external environment and how can it enter the human body? There is a worldwide partnership United Against Rabies ("United Against Rabies"), which includes human and animal he alth organizations in various countries. According to the program of this association, by 2030 it is planned to eliminate the death rate of people from the rabies virus, the annual rate of which in the world is tens ofthousands of people. More than 40% of them are children under the age of 15.
More than fifteen million people are vaccinated every year after being bitten.
The disease occurs on all continents of the planet. The only exception is Antarctica.
Up to 99% of all cases of rabies virus in humans were dogs.
Vaccination of pets and bite prevention are effective methods in the fight against this infection. Immediate washing of the bite wound with soap and subsequent vaccination can save a person's life.
Failure to vaccinate is a guaranteed death.
Historical background
Long before the discovery of viruses by Russian biologist Dmitry Iosifovich Ivanovsky (1892), people were aware of this disease. It was called hydrophobia or hydrophobia. We now call this infection rabies. Mention of the disease can be found in the oldest evidence - the papyri of ancient Egypt, Greek and Roman records, in the Bible. A man bitten by a rabid animal was doomed, no means could save him. The first rabies vaccine was invented and applied by the great biologist Louis Pasteur in 1885. And the first person saved was a shepherd boy who was bitten by an infected dog. From that moment on, the rabies virus and the diseases associated with it ceased to be a death sentence for people.
Brief description of the pathogen
The rabies virus belongs to the group of RNA-containing. The genus Lyssavirus is included in the familyRhabdoviride and has six species isolated from different animals that are a natural reservoir for the virus (dogs, cats, wild animals of the canine family, bats, less often cows and horses, birds). The rabies virus in humans is a dead end branch. In the absence of timely medical care for a person, this infection causes a fatal outcome.
How many rabies viruses are there? Microbiologists distinguish two variants of the virus - wild, which circulates in nature, and attenuated, synthesized in the laboratory. The first is dangerous and causes disease in humans. The second type of rabies virus is not pathogenic. It was first obtained by Louis Pasteur in 1885 by passage of the pathogen through the brains of rabbits.
Microbiology of rabies virus
The causative agent of this disease belongs to myxoviruses containing the ribonucleic complex - single-stranded RNA and nucleoprotein. Its size is from 90 to 200 nanometers, and its shape is similar to a rifle bullet. The virus is covered with a protein shell with the inclusion of lipoproteins (capsid). After entering the cells by endocytosis, the rabies virus starts replicating its hereditary material in the cytoplasm of the cell, forming Negri bodies (named after their discoverer Adelci Negri), which are the histological indicator of infection.
Resistance and pathogenicity
The described rabies virus dies when boiled for 2 minutes, is destroyed by acids and alkalis, and is pathogenic for most warm-blooded animals. In the external environment is sensitive toultraviolet and direct sunlight. It is rapidly inactivated by Lysol, carbolic acid and chloramine.
Under the conditions of lyophilization, the pathogenicity of the rabies virus remains for several years. Stability in the external environment when dried will lead to inactivation in a few days. A person for this pathogen is a dead end link.
How dogs get sick
The answer to the question "how long does the rabies virus live in the external environment" is ambiguous and depends on many factors. The incubation period in dogs ranges from 14 days to three months. In saliva, the virus appears 8-10 days before the onset of the first clinical symptoms. And during this period the animal is already dangerous. Dogs have violent, paralytic, relapsing, and abortive forms of the disease.
When the violent form of the disease goes through three stages and lasts from 6 to 11 days. At the initial stage, the animal either hides from people, or is active and caresses people. At the second stage, aggression appears, the animal pounces on everything that can bite. In this case, the movements of the jaws are so strong that they can damage the teeth or even the jaws of the animal. Paralysis of the larynx causes hoarse barking and salivation. Then comes the last stage - the animal just lies down, developing paralysis leads to coma and death.
The paralytic form lasts from 2 to 4 days, aggressive behavior is not observed, progressive paralysis develops, which leads to death. The return form is characterized by a change in typicalclinical signs. With an abortive course of the disease, after typical signs, recovery occurs.
Effective prevention of rabies in dogs - vaccinations. The first is done at an early age (up to six months), then vaccinations are carried out annually. Vaccinating pets will prevent the disease in 98% of cases. There is no cure for rabies in animals. Infected individuals are destroyed, which is associated with an increased risk of infection of people when they are kept.
Without vaccination anywhere
In the Russian Federation, all domestic dogs and cats are subject to mandatory preventive vaccination with anti-rabies serum. Vaccination marks are entered in the animal's veterinary passport and certified with a stamp of a veterinary institution. Unvaccinated dogs are not used in protection, hunting, breeding. They are forbidden to transport and take part in exhibitions or broods. In veterinary institutions, domestic and foreign vaccines, monovaccines and multiple-action vaccines are used. Vaccination of animals with domestic drugs is free of charge.
By the way, the resistance of the rabies virus to freezing and antibiotics has been proven.
How infection occurs
A person can become infected with rabies by biting or saliva on damaged skin or mucous membranes of sick animals. The severity and rate of development of the disease depends on the site of the bite, bites to the head are especially dangerous. Infection of a person by a person is theoretically possible, but not confirmed. Inhalation of aerosols fromvirus leads to disease extremely rarely, as in transplants of infected organs. Infection through consumption of raw meat or other animal tissue has not been confirmed.
Pathogenesis of disease
After entering through skin lesions, the rabies virus quickly spreads along the nerve trunks to the central nervous system. Then, in the same way, it returns to the periphery and affects the entire nervous system, getting into the salivary glands. Reproduction of the virus in the nervous tissue causes swelling, hemorrhage, degeneration and necrosis of neurons. The medulla oblongata is most affected, but the destruction also affects the cerebral cortex, the cerebellum, the midbrain, the basal nuclei, and the brain bridge. Rabies nodules appear around the affected areas, and inclusions appear in the cytoplasm of cells - Negri bodies - where the virus accumulates.
Symptoms of the disease
Latent (incubation) period lasts from one to three months and depends on the place of entry of the virus and its amount. There have been cases of reduction of the incubation period to 1 week and its extension to 1 year. The first symptoms of infection are fever and pain, tingling and tingling at the site of the bite. The spread of the virus through the nervous system leads to progressive inflammation of the brain and spinal cord, which ends in death.
Stages of the disease
In humans, the disease proceeds through three stages:
- Depressive rabies - the bite site swells, causeless fear, anxiety appear,depression. A person becomes withdrawn, loses appetite, sleep is disturbed, nightmares appear in dreams. The stage lasts from 1 to 3 days.
- Violent rabies - a person shows hyperactivity, hydrophobia appears (fear of water and even its sounds) and aerophobia (fear of fresh air). Seizures are accompanied by violence, hallucinations with frightening scenarios. Death can occur quickly (several days) as a result of stopping the pacemakers and respiratory centers.
- Paralytic rabies - takes longer. Convulsions and seizures disappear. Accompanied by gradual paralysis of the muscles, starting from the site of the bite. This leads to a coma and death within 5 to 8 days.
The prognosis of the course of the disease is always unfavorable. There are also cases of re-infection with rabies.
Diagnosis of disease
Modern methods of diagnosing the disease reveal infection after the first symptoms appear - hydrophobia and aerophobia. In vivo and post-mortem diagnosis in humans is carried out by detecting the virus itself, antigens, nucleic acids of the virus in the brain, skin and fluids (urine, saliva). One of the latest techniques is the detection of virus antigens in a print from the outer shell of the eyeball.
If you are still bitten
Post-exposure treatment or prophylaxis (PEP) begins with immediate assistance to the victim, which will significantly reduce the entry of the virus into the central nervoussystem. It consists of the following:
- Copiously washing the wound with soap and water as soon as possible after the bite.
- Immunized with a vaccine that meets the WHO standard.
- Administration of anti-rabies immunoglobulins with appropriate indicators.
Effective post-exposure prophylaxis can prevent rabies symptoms and death.
Indications for vaccination
Vaccine prophylaxis is prescribed immediately when:
- Bite, scratch, saliva on exposed skin and mucous membranes in contact with an obviously rabid animal, suspected of rabies or unknown.
- When injured by objects that are contaminated with the saliva of sick or suspicious animals.
- When biting through clothing that is torn, knitted or thin.
- When bitten or salivated by a he althy animal, if within 10 days it fell ill, died or disappeared.
- When bitten by wild rodents.
When vaccinations are not needed
Rabies vaccinations should not be given:
- If the bite did not damage the thick layered clothing.
- When injured by non-birds of prey.
- When bitten by domestic rodents, if rabies has not been reported in the area in the last two years.
- If the bitten animal remains he althy within 10 days.
Really forty shots?
The modern anti-rabies vaccine is administered intramuscularly five times - on the day of infection, on the 3rd, 7th, 14th, 28th day. Recommended and 6 injections90 days after infection. These vaccinations are carried out on an outpatient and stationary basis. Only victims with severe injuries, people with diseases of the central nervous system or allergies, pregnant women and those who are vaccinated repeatedly are hospitalized. Simultaneously with anti-rabies, the use of other vaccines is not recommended. The issuance of a sick leave is not provided for in the case of outpatient vaccination. At the time of vaccination and for six months after it, it is recommended to refrain from taking alcoholic beverages, to avoid hypothermia or overheating, and not to overwork.
What is the market for vaccines
There are two domestic rabies vaccines on the Russian market - CAV or Rabivak-Vnukovo-32 (cultural rabies vaccine) and KoKAV (concentrated rabies vaccine). There is also the Verorab vaccine, produced in France, and Rabipur, produced in Germany. They contain inactivated rabies viruses. The French vaccine "Imogam Rage" is an immunoglobulin. It is given as a single dose, at the same time as the vaccine, and is intended for people with suspected infection and severe bite injuries.
Prophylactic vaccination
Today, medicine offers vaccines to prevent rabies before contact with an animal. They are intended for people who are engaged in certain activities associated with an increased risk of rabies infection. These are employees of those laboratories that work with live rabies viruses, professionals who are in contact withanimals carrying this pathogen (circus and zoo workers, gamekeepers and hunters, cynologists).
Such immunization is also recommended for people who intend to visit remote areas affected by the disease, speleotourists, climbers, hunters. It is advisable to immunize adults and children living in remote areas where access to rabies vaccine is limited, and anyone who is going to visit areas with an unfavorable epidemiological situation for this disease.
