Rabies (hydrophobia)

Rabies (hydrophobia, hydrophobia, Latin - rabies, Greek - lyssa) is a viral zoonotic natural focal and anthropurgic infectious disease with a contact mechanism of transmission of the pathogen through the saliva of an infected animal with a fatal death.

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What causes rabies?

Rabies is a viral-type disease that occurs after being bitten by an infected animal, characterized by severe damage to the nervous system and resulting, as a rule, in death. The rabies virus causes specific encephalitis, manifested in the initial stage by increased body temperature, depression, alternated by agitation, aggression, increased salivation and vigilance. The diagnosis is confirmed by the results of serological studies and biopsy. Persons at risk are shown to vaccinate against rabies. Rabies prevention consists of locally treating a wound and taking measures for passive and active immunoprophylaxis. After the onset of symptoms, the disease inevitably leads to death. Symptomatic rabies treatment.

Annually in the world 50,000 people die from the disease rabies, mostly in Latin America, Africa and Asia, where it is still preserved in endemic areas of the city (canine) rabies type. In the United States, vaccination of domestic animals has reduced the incidence of rabies in humans to less than 6 cases per year; The main carriers of the disease in the United States are infected bats, but infection of rabies from the bite of a sick raccoon, skunk or fox (a natural type of rabies) is not excluded.

Infection of a person occurs when a bite is caused by a “rabid” animal, as well as when the sick animal’s saliva hits the damaged skin or mucous membrane of the eyes, nose or mouth. After penetration into the body, the rabies virus spreads through the nerve fibers to the spinal cord and brain, affecting almost the entire nervous system, as well as other organs and tissues. The closer the bite is from the head, the faster the virus enters the CNS. The virus in the salivary glands and mucous membranes of the oral cavity increases the likelihood of infection with the rabies virus through the saliva of a sick person.

What are the symptoms of rabies?

Discomfort, pain, or paresthesias bother the bite site. The rate of development of the disease depends on the amount of penetrated virus and the location of the bite, i.e. Its distance from the head. The incubation period of rabies lasts from 1 to 2 months, sometimes more than 1 year. Rabies disease begins with general malaise, headache, a small increase in body temperature. A few days later develops encephalitis, typical symptoms of rabies, "violent" rabies (80%) or "quiet" rabies (paralysis - 20%). In the period of violent rabies, the patient becomes irritable, excitable, very aggressive; characterized by increased saliva and sweating, attacks of hydrophobia due to muscle spasm of the pharynx and larynx at the sight and sound of flowing water, causing the patient a sense of horror. The patient notes symptoms of rabies such as: insomnia, nightmares, and hallucinations. At the stage of "quiet" rabies, the patient calms down, and against this background he develops paralysis of the limbs and cranial nerves, impaired consciousness and convulsions. Death comes from respiratory paralysis or cardiac arrest.

How is rabies diagnosed?

Rabies may be suspected based on the clinical picture of encephalitis or ascending paralysis in combination with an animal bite (or contact with bats - their bites may not be seen by humans) in history. Diagnostic evidence of rabies is a positive immunofluorescence test for the presence of antibodies to the rabies virus in a sample of the skin from the back of the head. An additional method is the detection of viral antigen by PCR in samples of CSF, saliva or tissues or the detection in these materials by serological methods of antibodies against the rabies virus. CT, MRI and EEG remain normal, or the identified changes are non-specific.

An intravital diagnosis of rabies can be confirmed by determining the viral antigen in the first days of the disease using the fluorescent antibody method in cornea prints or in skin biopsy specimens of the occiput, as well as by detecting antibodies after the 7-10th day of PH disease. In unvaccinated patients, the diagnosis of rabies confirms a fourfold increase in antibody titer in the study of paired sera. In vaccinated patients, when making a diagnosis, they rely on the absolute level of neutralizing antibodies in serum, as well as on the presence of these antibodies in the cerebrospinal fluid. After post-exposure prophylaxis, neutralizing antibodies in the cerebrospinal fluid are usually absent or their titer is low (less than 1:64), while in rabies the titer of neutralizing antibodies in the cerebrospinal fluid ranges from 1: 200 to 1: 160,000. PCR is also used for diagnostic purposes to detect rabies virus RNA in brain biopsy specimens.

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How is rabies treated?

Death usually occurs within 3-10 days from the onset of the disease. Cases of recovery after the onset of symptoms of rabies are rare, in all cases the patients underwent immunoprophylaxis before the onset of symptoms. Rabies is treated only symptomatically, - sedation and rest.

The mode is determined by the indication for hospitalization. Patients with hydrophobia are hospitalized in the ICU. The development of hydrophobia is accompanied by a violation of swallowing, which requires the installation of a nasogastric tube and a tube feeding.

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How is rabies prevented?

Rabies can be prevented if rabies is controlled in animals: vaccination (domestic, homeless and wild animals), quarantine, etc. It is important to recognize a sick animal: attention should be paid to the oddities of behavior - agitated state and anger, muscular weakness or paralysis, lack of fear of people, the appearance of nocturnal animals (bats, skunks, raccoons) during the daytime.

Sick bats can make unusual sounds and fly uncertainly. At the slightest suspicion of rabies to the animal should not approach. It is necessary to notify the sanitary authorities so that the sick animal is isolated.

By contact is meant any bite with a violation of the integrity of the skin or the ingress of animal saliva on damaged skin or mucous membranes. Timely and thorough prevention almost always prevents rabies in humans after contact with a sick animal. The wound should be immediately and thoroughly washed with soap and water or with a solution of benzalkonium chloride; deep wounds should be washed under moderate pressure. The bandage is not imposed.

vaccine and rabies immunoglobulin - postexposure prophylaxis (PEP) - is performed depending on the type of animal and the specific circumstances. Simultaneously with the PCP, a sick animal is examined for the presence of rdovirus. This is usually done by local or state health departments or by disease control and prevention centers, who also advise on all matters of prevention and treatment.

Preventing rabies after contact with an animal

Kind of animal	Evaluation and quarantine activities	Prevention after contact with animals 1
Skunks, raccoons, bats, foxes and most other predators	Consider it sick until the opposite is proved by negative laboratory test results.	Immediate Vaccination
Dogs, cats and ferrets	Healthy animals can be monitored for 10 days.	Do not start immunization if the animal does not develop symptoms of rabies.
	Unknown (escaped)	Consult the sanitary and epidemiological service
	Sick or supposedly sick with rabies	Immediate Vaccination
Livestock, small rodents (eg, squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, mice), hares (rabbits and hares), large rodents (North American woodchucks and beavers) and other mammals.	Individually	Consult the sanitary and epidemiological service; Immunoprophylaxis is almost never required for bites of squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, mice, other small rodents or hares

¹ Wash all bite areas immediately with soap and water.

Due to the difficulty in recognizing bat bites, vaccination is indicated by the assumption of a bite, i.e. A person wakes up and finds a bat in the room or parents find a bat in the child’s hands.

The animal must be put down and investigated as soon as possible. Keeping an animal for observation is not recommended. Vaccine administration is discontinued to produce negative results from an immunofluorescence study.

If the animal remains healthy during the 10-day observation period, it was not infected during the bite. Despite this, treatment of rabies with the use of a rabies immunoglobulin (ARIG) and human diploid cell vaccine (PDSCV) or a rabies vaccine is started at the first sign of rabies in a dog, cat or ferret that bit the person. An animal with suspected rabies is immediately put to sleep and sent to the study.

If it is impossible to consult a specialist on the spot and there is the slightest chance of infection with rabies, immediate vaccination is indicated.

In the framework of the control panel, the bite is cut off with a solution of anti-rabies immunoglobulin (ARIG), 20 IU / kg, for the purpose of passive immunization. If the calculated volume of ARIG is too large to be introduced into the area of the bite (for example, fingers, nose), part of the solution can be injected intramuscularly. Next, the patient is injected with a rabies human diploid cell vaccine (PDCV) for active immunization. PDSCV is administered 5 times as an intramuscular injection of 1 ml (preferably in the region of the deltoid muscle), starting from the day of the bite (day 0); the vaccine is injected into a healthy limb, if ARIG was injected into the affected. The following portions of the vaccine are administered on the 3rd, 7th, 14th and 28th day. WHO recommends administering the 6th batch of vaccine on the 90th day. Possible complications in the form of severe systemic or neuroparalytic reactions; during their development, an assessment is carried out of the risks associated with the completion of vaccination against the risk of developing rabies. For a more accurate assessment of the risks associated with the termination of vaccination, determine the titer of rabies antibodies.

Conducting PCP to persons previously vaccinated against rabies consists of intramuscular administration of PCPV, 1 ml per day of the bite and on day 3, ARIG is not administered.

To prevent rabies, PDCVs are administered to pre-prevent people in the risk group, including veterinarians, animal trainers, cavers, medical workers who come in contact with the virus, as well as people traveling to endemic areas.

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