For most lay people, all knowledge of rabies virus ends with the fact that if a stray dog has bitten, they will make forty injections into the stomach. Is it really? How dangerous is this viral infection, and what are the modern methods of combating this disease? We will answer these questions in this article. And although the stability of the rabies virus in the external environment is small, its spread is dangerous and in many cases can be fatal.
About the relevance of the problem
How long does the rabies virus live in the environment and how can it enter the human body? There is a worldwide partnership, United Against Rabies ("Against Rabies"), which includes organizations of public health of people and animals of various countries. According to the program of this association, by 2030 it is planned to eliminate the mortality of people from rabies virus, whose annual figure in the world is tens of thousands of people. More than 40% of them are children under the age of 15 years.
More than fifteen million people are vaccinated annually 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 are dogs.
Vaccination of domestic animals and the prevention of bites are effective methods in the fight against this infection. Immediately washing the wound with soap and subsequent vaccination can save a person’s life.
Refusal of vaccination is a guaranteed fatal outcome.
History reference
Long before the discovery of viruses by Russian biologist Dmitry Iosifovich Ivanovsky (1892), people knew this disease. It was called hydrophobia or hydrophobia. Now we call this infection rabies. Mention of the disease can be found in the oldest evidence - the papyrus 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 she 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
Rabies virus belongs to the group of RNA-containing. The genus Lyssavirus is included in the Rhabdoviride family 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 human rabies virus is a dead end branch. In the absence of timely medical care for humans, this infection causes death.
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. Type 2 rabies virus is not pathogenic. It was first obtained by Louis Pasteur in 1885 by passage of the pathogen through the brain of rabbits.
Microbiology of rabies virus
The causative agent of this disease refers to myxoviruses containing a ribonucleic complex - single-stranded RNA and nucleoprotein. Its size is from 90 to 200 nanometers, and in shape it looks like a bullet from a rifle. The virus is protein coated with the inclusion of lipoproteins (capsid). After penetrating the cells through endocytosis, the rabies virus starts the replication of its hereditary material in the cytoplasm of the cell, forming Negri bodies (named after their discoverer Adelcha Negri), which are a 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 to most warm-blooded animals. In the environment it is sensitive to ultraviolet and direct sunlight. It is rapidly inactivated by lysol, carbolic acid and chloramine.
Under conditions of lyophilization, the pathogenicity of rabies virus is preserved for several years. Stability in the environment during drying will lead to inactivation in a few days. Man for this pathogen is a dead end.
How dogs get sick
The answer to the question “how long does the rabies virus live in the environment” is ambiguous and depends on many factors. The incubation period in dogs is 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, recurrent, and abortive forms of the disease.
With a violent form, 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 fond of people. At the second stage, aggression appears, the animal pounces on everything that can bite. At the same time, the movements of the jaws are so strong that they can damage the teeth or even the jaws of the animal. Laryngeal paralysis causes hoarse barking and salivation. Then comes the last stage - the animal simply lies, 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 returnable form is characterized by a change in typical clinical signs. With the abortive course of the disease, after typical signs, recovery occurs.
Effective rabies prophylaxis in dogs - vaccinations. The first is done at an early age (up to six months), then vaccinations are carried out annually. Vaccination of pets will prevent the disease in 98% of cases. There is no cure for rabies for animals. Infected individuals are destroyed, which is associated with an increased risk of infection of people when they are kept.
No vaccination anywhere
In the Russian Federation, all domestic dogs and cats are subject to mandatory prophylactic vaccination with rabies serum. Vaccination marks are entered in the veterinary passport of the animal and certified with the stamp of the veterinary institution. Unvaccinated dogs are not used in protection, hunting, breeding. They are forbidden to transport and take part in exhibitions or broods. Veterinary institutions use domestic and foreign vaccines, mono-vaccines and multiple-action vaccines. Vaccination of animals with domestic drugs is free.
By the way, rabies virus resistance to freezing and antibiotics has been proven.
How is infection?
A person can become infected with rabies by biting or salivating damaged skin or mucous membranes in sick animals. The severity and speed of the development of the disease depends on the location of the bite, bites in the head are especially dangerous. Infection of humans by humans is theoretically possible, but not confirmed. Inhalation of aerosols with the virus leads to the disease is extremely rare, as with transplantation of infected organs. Infection with raw meat or other animal tissues has not been confirmed.
Pathogenesis of the disease
After getting through skin lesions, the rabies virus quickly spreads through the nerve trunks to the central nervous system. Then, in the same way, it returns to the periphery and affects the entire nervous system, falling into the salivary glands. Reproduction of the virus in the nervous tissue causes edema, hemorrhage, degeneration and necrosis of neurons. The medulla oblongata is most affected, but the destruction affects the cerebral cortex, cerebellum, midbrain, basal nuclei, and brain bridge. Slave nodules appear around the affected areas, and inclusions - Negri bodies - appear in the cytoplasm of the cells, where the virus accumulates.
Symptoms of the disease
The latent (incubation) period lasts from one to three months and depends on the place of penetration of the virus and its quantity. Cases of reduction of the incubation period to 1 week and its extension to 1 year have been noted. 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, and depression appear. A person becomes closed, loses his appetite, sleep is disturbed, nightmares appear in dreams. The stage lasts from 1 to 3 days.
- Raging rabies - a person is hyperactive, hydrophobia (fear of water and even its sounds) and aerophobia (fear of fresh air) appear. Attacks of convulsions are accompanied by violence, hallucinations with frightening scenarios. Death can occur quickly (several days) as a result of stopping heart rate drivers and respiratory centers.
- Paralytic rabies - occurs in a longer period. Cramps and bouts disappear. It is accompanied by a 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 reinfection with rabies.
Diagnosis of the disease
Modern methods for diagnosing the disease reveal infection after the first symptoms appear - hydrophobia and aerophobia. Intravital and posthumous diagnosis in humans is carried out by identifying the virus itself, antigens, nucleic acids of the virus in the brain, skin integument and fluids (urine, saliva). One of the latest techniques is the detection of virus antigens in the imprint 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 nervous system. It consists in the following:
- Excessive washing with soap wounds as soon as possible after a bite.
- Immunization with a vaccine that meets the WHO standard.
- The introduction of rabies immunoglobulins at appropriate rates.
Effective post-exposure prophylaxis can prevent the onset of rabies symptoms and the death of the disease.
Indications for vaccination
Vaccine prophylaxis is prescribed immediately with:
- Bites, scratches, saliva on exposed skin and mucous membranes in contact with a clearly rabid animal suspicious of rabies or unknown.
- When injured by objects that are contaminated with the saliva of sick or suspicious animals.
- When biting through clothing, if it is torn, knitted or thin.
- When bites or salivation of a healthy animal, if within 10 days it became sick, died or disappeared.
- When bitten by wild rodents.
When vaccination is not necessary
Rabies vaccinations should not be given:
- If the bite did not damage the dense multilayer clothing.
- When not injured by birds of prey.
- When bitten by domestic rodents, if rabies has not been reported in the area in the last two years.
- If a bitten animal remains healthy for 10 days.
Really forty injections?
The modern rabies vaccine is administered intramuscularly five times - on the day of infection, on days 3, 7, 14, 28. 6 injections are also recommended 90 days after infection. These vaccinations are carried out on an outpatient and inpatient basis. Only those injured with severe injuries, people with central nervous system diseases or allergies, pregnant and revaccinated are hospitalized. Along with rabies, the use of other vaccines is not recommended. Issuance of sick leave is not provided for in case of outpatient vaccination. At the time of vaccination and within six months after it, it is recommended to refrain from taking alcoholic beverages, to avoid hypothermia or overheating, not to overwork.
What is the vaccine market?
There are two domestic rabies vaccines on the Russian market - KAV or Rabivak-Vnukovo-32 (cultural rabies vaccine) and CoKAV (concentrated rabies vaccine). There is also the Verorab vaccine made in France and the Rabipur made in Germany. They contain inactivated rabies viruses. The French Imogam Razh vaccine is an immunoglobulin. It is administered once, simultaneously with the vaccine and is intended for people with suspected infection and in case of significant damage from bites.
Preventive vaccination
Today, medicine offers vaccines to prevent rabies before contact with an animal. They are intended for people who are involved in a particular type of activity associated with an increased risk of rabies infection. These are employees of those laboratories that work with live rabies viruses, professionals who come in contact with animal carriers of this pathogen (workers in circuses and zoos, huntsmen and hunters, dog handlers).
Such immunization is also recommended for people who intend to visit remote areas affected by the disease, cavers, climbers, hunters. It is advisable to immunize adults and children living in remote areas where access to the rabies vaccine is limited, and everyone who is going to visit areas with an unfavorable epidemiological situation for this disease.