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South American haemorrhagic fevers
Last reviewed: 23.04.2024
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South American haemorrhagic fevers (Argentine, Bolivian, Venezuelan) are common only in these regions and pose a serious problem for local health authorities. In Argentina, 100 to 200 cases of hemorrhagic fevers are diagnosed every year. In recent years, the use of a specific vaccine for the prophylaxis of Argentine hemorrhagic fever has been started, and a rather high vaccination efficiency has been noted.
The morbidity rate of the Bolivian and Venezuelan hemorrhagic fevers is slightly less than the Argentine one, several dozens of cases are recorded every year. In 1990, the Sabia virus was identified, only a few cases of a disease caused by it, called Brazilian hemorrhagic fever, are described, the natural reservoir of the pathogen has not yet been fully studied. Infection of a person occurs in the same way as in the case of Lassa fever. The epidemiological characteristics of South American haemorrhagic fevers are fundamentally similar to the characteristics of the Lassa fever.
[What causes South American haemorrhagic fevers?
The pathogenesis of South American haemorrhagic fevers has been little studied. Its main features are very similar to the pathogenetic mechanisms of the Lassa fever (the role of IFG in the development of the disease, the primary viral damage of monocytes, the activation of cytokines, the formation of polyorganous lesions, impaired vascular permeability due to endothelial damage, development of DIC syndrome, toxic shock, collapse). The dependence of the severity of the infection on the level of interferon-alpha in the blood serum of patients was established: with its significant increase to 6-12 days of illness, the disease ended in a lethal outcome (at autopsy there was significant blood filling in the spleen, liver, red bone marrow).
Vascular damage in South American haemorrhagic fevers is less pronounced than with Lassa fever.
In most cases of South American haemorrhagic fevers, a secondary bacterial infection is associated with the development of bronchopneumonia.
Symptoms of South American hemorrhagic fever
The incubation period is from 5 to 19 days (usually 7-12 days), with parenteral transmission of infection, it is reduced to 2-6 days.
Symptoms of South American haemorrhagic fever are very similar.
The onset of the diseases is acute: body temperature rises rapidly to high figures, myalgia of different localization develops, especially the muscles of the back, general weakness. Patients often note symptoms of South American haemorrhagic fever: pain in the eyeballs, photophobia, epigastric pain, constipation. Often dizziness occurs, orthostatic collapse is possible.
When examining patients, hyperemia of the face and neck, conjunctivitis, and enlargement of the peripheral lymph nodes are noted. Characterized by exantheme in the form of petechiae and small vesicles on the skin (more often in the axillary regions) and on the mucous membranes. Hemorrhagic manifestations in the form of petechial rash and bleeding (nasal, stomach, etc.) may be early clinical signs in the early days of the disease. There is a depression or excitation of the central nervous system.
The course of the disease can be burdened by the development of convulsive syndrome (clonic convulsions) and coma, which greatly complicate the prognosis.
Especially hard all South American haemorrhagic fevers occur in pregnant women. Diseases lead to miscarriages (with high mortality), infection can be transmitted to the fetus.
In the blood often there is severe leukopenia, thrombocytopenia, hematocrit buildup, in the urine - protenuria.
The period of convalescence can be prolonged up to several weeks, astenovegetative syndrome (hypotension) is observed for a long time. There may be hair loss on the head.
Mortality is observed in 15-30% of cases, with Venezuelan hemorrhagic fever - up to 50%.
Diagnosis of South American hemorrhagic fever
Diagnosis of South American haemorrhagic fever uses ELISA (IgM), developed by PCR diagnostics. It is possible to isolate the virus from the blood from the first days of illness.
What tests are needed?
Treatment of South American hemorrhagic fever
Pathogenetic treatment of South American hemorrhagic fever aimed at correcting metabolic disorders (metabolic acidosis) and restoring the volume of circulating blood is carried out, haemostatic preparations are used. The appointment of antibacterial drugs for the attachment of a secondary bacterial infection is indicated.
The effectiveness of ribavirin in South American haemorrhagic fever has not been established, while the treatment uses convalescent plasma.
How is South American haemorrhagic fever prevented?
Activities for all fevers are aimed at limiting the populations of certain species of rodents; specific prevention of South American haemorrhagic fever is developed only with Argentine hemorrhagic fever (live vaccine).