INFECTIOUS DISEASES : RABIES (LYSSA, RABIES, HYDROPHOBIA) - etiology, pathogenesis, symptoms and course of, recognition, prediction and prevention
Etiology and epidemiology. The pathogen belongs to neurotrophic group filterable viruses. Located intracellular and the cytoplasm of the ganglion cells, the virus causes the cell reaction, deposited around it products degeneration of the nucleus, known under the name Taurus Negri. The virus is found predominantly in the Central nervous system, salivary and lacrimal glands and adrenal glands. There are street virus and passaged through a series of rabbits to the limit of virulence (virus fixe). Reservoirs of the virus, in addition to a sick person, are dogs, cats, wolves, rats, livestock. Infection occurs primarily through the bites of rabid animals, saliva which gets into the wound, but it is possible through abrasions of the skin, scratches, with clothing contaminated with saliva. Saliva animal becomes infectious in the incubation period for 8 - 10 days before illness. Contamination outside the direct contact does not occur.
The pathogenesis. Trapped in the wound fixed rabies virus in nerve endings and is propagated along the nerve trunks to the Central nervous system. In the brain develop local changes of degenerative or inflammatory nature, localized mainly in the brain stem. Lesions of the spinal cord in humans is variable, but in some cases can be expressed very redo. The autonomic nervous system also undergoes strong changes in the sympathetic ganglia. In connection with these changes appear first prodromal pain along the nerves from the site of the bite, the phenomena of psychic excitation, excitation motor areas, respiratory and vomiting centers and increased heart rate. For the period of excitation is followed by a period of oppression and paralysis, ending in paralysis of the respiratory centre. Animals paralysis of masticatory muscles and limbs are compared with a person is much sharper.
Symptoms. At the end of the incubation - pain along the nerves closest to the site of the bite, and tenderness of the scar. In the prodromal period of fever, bad soy and appetite, depression, and sometimes shortness of breath and palpitations. Beginning zapalenie manifested or sudden agitation, reaching sometimes to violence and sexual excesses, or spasm of the pharyngeal muscles when washing or eating. The hydrophobicity is expressed not in all cases; there is often aerophobia - sensitivity to the movement of air and blow. Strong salivation. When lesions localized in the spinal cord, tendon reflexes on one side sharply attenuated.
Course and complications.
Dog rabies. Incubation of 14 - 30 days, rarely up to 60 days. There are two forms: violent and paralytic. When the first form is clear three stages:
a) precursors (change in behavior, loss of appetite),
b) excitation (convulsions, salivation, the desire for movement, not eating edible items, attacks on people and animals),
C) paralysis (start with chewing and swallowing muscles). The paralytic form - early paralysis, the change in the sound of barking; the desire to bite there.
The rage of the people. Incubation of various lengths - from 15 to 90 days, depending on the localization of the bite, the nature and multiplicity of wounds. The onset of the disease is diverse (see Symptoms). Duration from 3 to 5 to 6 and occasionally up to 10 days. There are forms occurring during strong excitation with subsequent respiratory paralysis, paralytic form, in which the phenomena of excitation is very short and are followed by paresis and paralysis, starting with groups of muscles at the site of the bite, gradually spreading and turning on smooth muscles of internal organs (intestines, bladder).
Difficulty in diagnosis is possible in two directions:
1) rabies atypical flows and the overall picture makes the first impression hysterical seizure or acute psychosis; less patient similar to tetanus;
2) hysteria with a history of biting animals, simulate rabies.
For all the variety of the beginning of the rabies differencirovanie possible on set of symptoms of cramps pharyngeal muscles, dilated pupils, tremor of the upper extremities, increased or, conversely, the weakening of the skin and tendon reflexes, fever, cold sweats. In every suspicious case, a detailed history regarding bites, pokusavao animal and its future fate. At the opening of a fallen or dead animal in the presence of rabies (inedible objects in the stomach, black hemorrhages in the mucous membrane of the stomach) is the study of the brain on the calf Negri with subsequent infection of rabbits.
Systematic control of rabies among animals, particularly dogs; the prohibition of importation of dogs, quarantine for imported dogs for 6 months, destruction of stray dogs, the compulsory wearing of dog muzzles. Destruction mad and suspicious of rabies dogs with research on calf Negri and infected rabbits. Bitten by rabid animals dog shall be destroyed; valuable animals kept in quarantine for at least 3 months. Widespread use of vaccination dogs encounters practical difficulties, but it is quite possible concerning valuable species. Infected people are sent to mandatory vaccination in the Pasteur station or their affiliates.
1) bitten by a rabid or suspect animals directly or through clothing, even in the most insignificant injuries,
3) with the skin contaminated with saliva,
4) in contact with saliva in the eyes,
5) even with negligible damage to the skin while working with pathological material (autopsy, laboratory work).
Suspect rabies animals:
1) suddenly escaped from the house,
2) fallen during the time of observation,
3) killed when applying bites,
4) ikusawa many persons,
Individual prevention is carried out using a Pasteur vaccination.
Complications of vaccination:
1) local reaction anaphylactic nature,
2) mono - and paraplegia, developing suddenly on the 2nd and 3rd week after onset of rabies vaccination. The complication rate is about 0, 028%. Histologically detectable inflammatory infiltrates in the white matter of the brain and nerves.
The course is usually benign.
The treatment of the developed disease effect does not. It is desirable to soften the painful cramps lubricating throat 2% solution of novocaine or destination of the drugs (chloral hydrate in the enema).