Etiology

The causative agent of the disease is the RNA-containing rabies virus, belonging to the family Rhabdoviridae genus Lyssavirus. The virus is shaped like a rifle bullet (180 p 75 nm). When heated to 56°C, the rabies virus is inactivated within 15 minutes, when boiling - for 2 minutes; inactivated by sublimate (1:1000), Lysol (1-2%), carbolic acid (3-5%), chloramine (2-3%). There are two types of rabies virus: wild and fixed virus (table 1).

Table 1.

Wild (street) virus	Fixed virus (PV-11)
– pathogenic for humans and animals – pronounced neurotropism – in brain cells and salivary glands forms specific inclusions - Babes-Negri bodies – excreted from the body of animals with saliva	– retains high virulence during intracerebral infection – does not have virulence when administered subcutaneously – not excreted in saliva – retains the antigenic characteristics of the wild virus – used to produce a vaccine

Epidemiology

The rabies virus is widespread everywhere except Antarctica. Associated with rabies 40-70 thousand deaths annually, 95% in developing countries in Asia and Africa. The rabies virus is widespread in the animal world among mammals. Transmission of the virus in the vast majority of cases is associated with dogs, wolves, lisami, raccoons and bats. Other mammals, like a person, susceptible to the virus, but do not play a significant role in its spread. In the Republic of Belarus, the disease is most often transmitted through fox bites.

Transmission of the rabies virus occurs:

– when an animal bites or salivates on damaged skin or mucous membranes;

– by transplantation (when transplanting a cornea or internal organs from a donor with undiagnosed rabies);

– transplacentally;

– aerogenously (when visiting caves, habitat for bats – dust inhalation, containing particles of brains from dead bats).

Pathogenesis

Initial replication of the virus takes place in muscle cells at the site of the bite. The virus then invades the nerve endings, innervating this muscle, migrates via retrograde axonal transport to the central nervous system, from where it spreads along the peripheral nerves to all organs and tissues, including salivary glands. In the central nervous system, the virus is fixed and multiplies in the cells of the medulla oblongata, hippocampus, hypothalamic cells, gray matter of the spinal cord. Reproduction of the rabies virus in nerve cells is accompanied by the formation of specific inclusions - Babes-Negri bodies - round eosinophilic formations with a diameter of up to 7 µm, containing virus nucleocapsids.

Clinic

The incubation period lasts on average from 1 to 3 month (possible fluctuations from 12 days until 1 a year or more).The clinical picture of rabies is divided into three stages:

I – initial stage (depression)

– body temperature rises, often to low-grade fever (37,2-37.3°С);

-discomfort in the bite area (quickly, burning, moderate pain, involuntary short-term muscle contractions at the site of the bite);

– symptoms of mental disorder (inexplicable fear, yearning, alarm, depression).

II – stage of excitation.

Develops later 4-10 days from the onset of the first symptoms of the disease.

Possible 2 variant of the course of this stage of the disease:

1. Encephalitic (acute) rabies (80% cases).

– disturbance of consciousness, manifested by unmotivated attacks of aggression, psychomotor agitation with tonic and tonic-clonic convulsions, alternating with oppression, apathy;

– hydrophobicity (painful contractions of the muscles of the pharynx and larynx at the sight of water, her murmur, trying to drink, mention of water)

-profuse, painful sweating and drooling,

Attacks of psychomotor agitation can be provoked by air movement (aerophobia), bright light (photophobia), loud or sudden sound (acousticophobia).

2. Paralytic ("quiet") rabies (20% cases).

Occurs when the spinal cord and brain stem are damaged. Characterized by ascending paralysis of the Guillain-Barré syndrome type or symmetrical tetraparesis without an excitation phase. Possible development of meningeal symptoms, coordination problems.

III – stage of paralysis.

Develops through 2-14 days from the development of the arousal stage. Characterized by an imaginary improvement: mood improves, fear disappears, convulsions and attacks of hydrophobia stop. However, lethargy gradually increases, tachycardia, hypotonia, body temperature rises to 40–42°C, paralysis of various muscle groups occurs, dysfunction of the pelvic organs (urinary incontinence, remains), depression of consciousness gradually develops up to coma. Death occurs within 12–20 hours from paralysis of the heart or respiratory center.

Diagnostics

During the incubation period:

– epidemiological anamnesis (possibility of infection, conditions, nature of the bite);

– animal research (If possible, the animal is monitored 10 days. During this period of time, the rabid animal must die or show obvious signs of rabies. The brain of a deceased animal is subjected to histological examination to detect specific inclusions (calf Babesha-Negri).

After the virus enters the central nervous system:

– clinical picture of the disease;

– OAK: lymphocytic leukocytosis with aneosinophilia;

– detection of virus antigens using immunofluorescence reaction in a patient’s skin biopsy, taken from the back of the neck - the virus is localized in the hair follicles (positive result in 50% cases in the 1st week of illness);

– detection of virus antigens in biopsy specimens, cerebrospinal fluid or saliva using real-time PCR.

The final diagnosis is made posthumously by histological examination. (Babes Negri bodies) and immunofluorescence (virus antigens) brain research.

Treatment

There is no specific treatment. Carry out symptomatic therapy, aimed at alleviating the patient's suffering - anticonvulsants, sedatives, analgesics.

Prevention

Specific rabies prevention is divided into two types:

1) pre-exposure – carried out to persons, having a high risk of contracting rabies due to the performance of their professional duties (eg, faces, catching stray animals, foresters, etc.), and can also be recommended to tourists, traveling to countries with high levels of rabies among animals (rabies vaccine intramuscularly into the deltoid muscle of the shoulder 0, 7, 21 days; revaccination every 2-3 of the year).

2) post-exposure – carried out to persons after events or manipulations, which may result in transmission of the rabies virus.

Includes three stages:

but) local wound treatment: This is done as soon as possible after the bite and involves generously washing the wound surface with soap and water. (the virus is unstable in an alkaline environment), treating the edges and skin around the wound 70% alcohol or 5% tincture of iodine. Sutures are not placed on a wound if there is a suspicion of possible rabies infection..

b) introduction of rabies vaccine;

The Speda vaccine is currently used in the Republic of Belarus. (China): course – 5 injections (0, 3, 7, 14, 28 days) for persons previously unvaccinated as part of pre-exposure prophylaxis and 2 injections (0, 3 days) for those who received pre-exposure prophylaxis intramuscularly into the deltoid muscle of the shoulder, for children - intramuscularly in the thigh. Insertion into the buttock is strictly prohibited.

in) administration of rabies immunoglobulin.

Not later 3 days after contact, infiltration around the wound and wound tissue, if it is impossible to administer the full dose into the wound area - intramuscularly into the muscles of the buttock, upper thigh, shoulder (to an area other than the area where the vaccine was administered). In the case of using homologous rabies immunoglobulin - 20 ME/kg, heterologous – 40 ME/kg.

Indications for the administration of rabies vaccine and rabies immunoglobulin are given in the table 2.

Table 2

Clinical situation	Prevention
Multiple, deep bites, bites to the face, neck, hands and feet, genitals, wild animal bites	A vaccine + immunoglobulin
Single, superficial bites, bites to other areas of the body, salivation of damaged skin	A vaccine
Salivation of intact skin, feeding, petting animals	No risk - no prevention

Nonspecific rabies prevention involves shooting wild animals with signs of the disease., catching stray animals, Vaccination of pets against rabies.