Lassa fever

Lassa fever is an acute viral disease from the group of zoonoses with natural foci. It is characterized by a severe course, high mortality, hemorrhagic syndrome, ulcerative pharyngitis, damage to the respiratory system, kidneys, central nervous system, myocarditis.

Etiology, pathogenesis of Lassa fever 

 

The causative agent belongs to adenoviruses. The reservoir of infection in nature is the polynipple rat, which is widespread in West Africa. Infection can occur by alimentary and airborne droplets, through microtraumas of the skin, and also by airborne dust. The causative agent of Lassa fever is one of the most dangerous viruses for humans, working with it requires the strictest precautions. The virus is quite stable in the external environment. At the site of the infection gate, no changes are detected. Characterized by hematogenous dissemination of the virus and the defeat of many organs and systems. The fragility of blood vessels increases, deep disorders of hemostasis appear and the syndrome of disseminated intravascular coagulation develops. Hemorrhages are most pronounced in the intestines, liver, myocardium, lungs, and brain.

Lassa fever symptoms

The incubation period lasts 3-17 days. There are no prodromal symptoms. The disease begins relatively gradually. Every day the severity of fever and symptoms of general intoxication increases. In the first days, patients report general weakness, weakness, general malaise, moderate muscle and headache. Body temperature rises and after 3-5 days reaches 39-40 C. Fever may last 2-3 weeks. The symptoms of general intoxication (asthenization, muscle pain, disorders of consciousness) also increase. The face and neck are hyperemic, sometimes pasty, the vessels of the sclera are injected. In the initial period, most ball patients (80%) develop a characteristic lesion of the pharynx – on the arches of the tonsils and the soft palate, foci of necrotic-ulcerative changes of a yellowish-grayish color, surrounded by a zone of bright hyperemia, are noted. Their number then increases they can merge, raids can resemble fibrinous. On the 5th day of the disease, pain in the epigastric region, nausea, vomiting, profuse liquid, watery stools may appear. Sometimes dehydration develops. In severe forms of the disease on the 2nd week, the symptoms of intoxication sharply increase, pneumonia, pulmonary edema, myocarditis, swelling of the face and neck, and hemorrhagic syndrome join. During this period, death is possible.

Generalized lymphadenopathy is detected early, at the end of the 1st week, exanthema appears (roseola, papules, spots). Clinically and radiographically revealed pneumonia, rarely pleural effusion. Pain in the epigastric region, copious watery stools are noted. The liver is enlarged. Sometimes ascites develops. In the blood, leukopenia, thrombocytopenia, increased activity of aminotransferases.

Diagnosis . Of great importance are epidemiological data (stay in an epidemic area no more than 17 days before the development of the disease). It will be necessary to differentiate from many diseases – tonsillitis, diphtheria, severe pneumonia, yellow fever, malaria, etc. Specific confirmation of the diagnosis is the isolation of the virus (in special laboratories) and serological studies (RSK, RIF).

Lassa fever treatment

All patients are subject to isolation. There are no etiotropic agents. The basis is pathogenetic therapy. Rehydration is carried out (see Cholera}, 60-80 mg of prednisolone, 400-800 ml of reopoliglyukin are injected intravenously. Oxygen therapy, a complex of vitamins. The prognosis is serious, mortality is 36-67%.

Prevention of Lassa fever

It is necessary to strictly carry out preventive measures, taking into account the airborne and contact routes of transmission. The patient is isolated in a box, and most likely in special plastic or glass-metal cabins with autonomous life support. Personnel must work in protective clothing (coats, respirators, goggles). Carry out thorough current and final disinfection. The danger is blood and urine, therefore, not only bacteriological, but also conventional clinical and biochemical studies are carried out in compliance with all safety measures. The duration of isolation of the diseased is not less than 30 days from the onset of the disease. Persons in contact with patients with Lassa fever are monitored for 17 days (maximum incubation period). If it is necessary to transport sick people, strict measures to prevent the spread of infection are observed. Specific prophylaxis has not been developed.

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