SOUTH AMERICAN HEMORRHAGIC FEVERS

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The SOUTH AMERICAN HEMORRHAGIC FEVERS -

the infectious diseases which are characterized by an acute current, fever and the expressed hemorrhagic syndrome. The Argentina and Bolivian hemorrhagic fevers similar among themselves on an etiology, epidemiology, a pathogeny and a clinical current concern to them.

The Argentina hemorrhagic fever (febris haemorrhagica argen-tinica) is endemic for the central provinces of Argentina where annually there are 100 — 3500 cases of a disease. The disease is revealed in 1943 in the province Buenos Aires. In 1955 Arribalsaga (R. And. Ag-ribalzaga) in detail described the outbreak of a disease in sowing. - zap. parts of the province Buenos Aires. After 1958 diseases are registered in provinces Cordoba and Santa Fe.

The disease-producing factor — the Junin virus (according to the name of the city, in Krom there was one of the outbreaks of a disease), belongs to the sort Arenavirus this. Arenaviridae (see Arenovirusa); A. Parodi with sotr is allocated. in 1958 from blood of the patient. Newborn white mice, young hamsters, Guinea pigs, chicken embryos, the intertwined cells of Vero and HeLa are susceptible to a virus.

A source of a contagium in the natural centers are wild rodents of Calomys laucha and Calomys musculinus; the virus is allocated also from the rodents belonging to the sort Mus, Akodon and Oryzomys. The person catches, inhaling dust or using the foodstuff or water contaminated by the excrements of rodents containing activators. Infection through the injured skin is possible.

The men at the age of 20 — 50 years living in rural areas get sick generally. The outbreaks of diseases usually begin in February (the end of summer at the latitude of Argentina), reach peak in May and come to an end in June — July. Developing of diseases matches a season of harvesting of corn and increase in population of wild rodents — sources of a contagium.

The virus reaches the next limf, nodes where there is its reproduction. Generalization of an infection is carried out in the hematogenous way. The virus causes damages of walls of capillaries that causes development of the hemorrhagic phenomena. Heavy disease is caused by deep dysfunctions of cells and fabrics as a result of direct impact of a virus on cells. Characteristic morfol. display of a disease is the generalized lymph a denopatiya, regarding cases the hemorrhagic necrosis limf, nodes is found. In kidneys the picture of a nephrosis is noted, vessels of marrow and capillaries of renal balls are full-blooded.

Immunity is studied insufficiently.

The incubation interval makes usually 8 — 12 days. Beginning of a disease gradual: the fever, an indisposition, weakness, head and muscular pains which are most expressed in costovertebral joints are noted. Loss of appetite, nausea, vomiting, diarrhea are quite often observed. In typical cases temperature to 3 — to the 4th day of a disease increases to 39 — 40 °, the hyperemia of conjunctivas develops, there are petechias on face skin, a neck and an upper part of a breast; rare petechias on skin of axillary hollows are characteristic. Dehydration of an organism is possible, and also the oliguria, edges can pass into an anury. In hard cases the hemorrhagic syndrome develops: nasal bleeding, bleeding of gums, hematemesis, bloody chair, hamaturia. Psychosensorial and psychomotor frustration are described. Duration of fever is 9 — 16 days. At recovery temperature decreases lytically, the diuresis is considerably increased, the general fortune improves within several days, the absolute recovery comes in several weeks and even months.

The diagnosis is made on the basis by a wedge, pictures, data epidemiol. anamnesis (place and time of possible infection) and results of laboratory researches. In blood the leukopenia (to 2000 — 1000 cells in 1 mkl) and thrombocytopenia is observed (to 100 000 — 50 000 cells in 1 mkl).

Laboratory diagnosis is based on allocation of a virus, detection of specific antibodies and increase of their caption in the course of a disease and reconvalescence (see. Virologic researches). The virus can be allocated from the blood taken from the patient on 3 — the 10th day of a disease; blood is entered into a brain to newborn white mice or intraperitoneally Guinea pigs. Paralyzes and death of mice, death of Guinea pigs against the background of the hemorrhagic phenomena indicate an infection by a virus Junin. Specific antibodies reveal by means of reaction of binding complement or an immunofluorescence (see. Serological researches). For a research use the pair blood sera taken in the first days of a disease and in 3 — 4 weeks.

Treatment pathogenetic and symptomatic (administration of solutions of glucose, salts, ascorbic acid, Vikasolum). The available results of use of serum of convalescents do not allow to give a final assessment of its therapeutic effect.

The lethality, according to various researchers, fluctuates

from 1 to 10% and above. The uremic coma and hypovolemic shock are a cause of death of patients.

For the purpose of prevention of diseases attempts of development of vaccines from a virus Junin were made (inactivated and live). The researches conducted with a live vaccine from an attenuirovanny strain of XJCL3 specify on its considerable immunol. and epidemiol. efficiency. The measures interfering penetration of rodents into dwellings, their contact with foodstuff are applied; hold events for destruction of rodents.

The Bolivian hemorrhagic fever (febris haemorrhagica boli-viana) was for the first time registered in 1959 when in two rural districts of the province of Beni (sowing. - vost. a part of Bolivia) cases of the diseases which are followed by a hemorrhagic syndrome, a part were noted to-rykh ended letalno. Disease outbreaks periodically are registered in the province of Beni, in small settlements around the cities of San Joaquin (province Manora) and Orobayaya (province Itenes).

The disease-producing factor — Ma-chupo virus (according to the name of the river in the center of an infection), belongs to the sort Arenavirus this. Arenaviridae (see Arenoviru-sa); it is allocated in 1963 by Johnson (To. Johnson) with sotr. from tissue of a spleen of the died patient. The virus patogenen for newborn white mice and young hamsters, well breeds in the intertwined cultures of cells of Vero.

A source of a contagium are wild rodents of Calomus callosus. Infection with their virus of Ma-chupo causes hron. the infection which is followed by a virusemia and allocation of a virus with urine. Infection of the person happens to the dust, water and foodstuff contaminated by the urine of rodents containing the activator and also at hit of a virus on the injured skin. Persons of different age get sick, adult men are slightly more often. Cases are registered during the whole year, a little ^учащаются in February — September.

A pathogeny of the Bolivian hemorrhagic fever and developing at it morfol. changes are close to those at the Argentina hemorrhagic fever.

Immunity is studied insufficiently.

The incubation interval makes, as a rule, 8 — 12 days. The beginning of a disease gradual, temperature raises to 39 — 40 °

and remains at this level several days with small daily fluctuations. Approximately in 1/3 cases of a disease the hemorrhagic syndrome is observed: petechias on

skin of an upper body and a mucous membrane of an oral cavity, quite often nasal, gastric, intestinal and uterine bleedings, and also bleeding of gums. Approximately at a half of patients it is possible to observe the expressed tremor of language and hands, and at a part of patients — and others nevrol. symptoms. The disease lasts 2 — 3 weeks, the period of recovery usually drags on and followed by sharply expressed weakness, the hair loss is often noted.

The diagnosis is established on the basis by a wedge, pictures, data epidemiol. the anamnesis (the place of infection, seasonality matter) and results of laboratory researches. Detection in blood of a leukopenia and thrombocytopenia also has diagnostic value.

The laboratory diagnosis is based on allocation of a virus and detection of the specific antibodies appearing in the course of a disease. For the purpose of allocation of a virus the whole blood or blood serum received from patients during development of fever are entered into a brain to newborn white mice or hamsters. Allocation of a virus of Machupo and other works with it should be carried out in the conditions ensuring the maximum safety of personnel of laboratory. The infected white mice and hamsters who are plentifully allocating a virus with urine are especially dangerous.

At a research of pair blood sera apply reactions of an immunofluorescence or fixation of the complement to detection of specific antibodies. Sample of blood serum is taken in the first days of a disease and in 40 — 60 days. Treatment is carried out by pathogenetic and symptomatic means.

Symptomatic treatment. As specific treatment it was offered to apply a blood plasma of had. Outcomes of a disease at administration of plasma were favorable, however the small number of observations does not allow to estimate its efficiency objectively. The lethality, according to various researchers, makes from 1 to 10% and above.

The most effective measures of prevention are extermination of rodents of S. of callosus in settlements where there are diseases, the prevention of penetration of rodents into dwellings and prevention of their contact with foodstuff. The vaccine from Machupo's virus is not developed.

See also Hemorrhagic fevers.



Bibliogrdrozdov S. G. and Sergiyev V. P. Protection of ecdemic territories against tropical viral hemorrhagic fevers, M., 1984; The International symposium on the arenavirusny infections which are of interest from the point of view of public health care Bulletin WHO, t. 52, page 377, 1976; The Management on a zoonosis, under the editorship of V. I. Pokrovsky, page 59, L., 1983; Viral infections of humans, Epidemiology and control, ed. by A. S. Evans, p. 103, N. Y. — L., 1976. S.G. Drozdov.

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