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Overview of Arbovirus, Arenavirus, and Filovirus Infections
Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes) and arachnids (ticks). Arbovirus is not part of the current viral classification system, which is based on the nature and structure of the viral genome. Families in the current classification system that have some arbovirus members include
Most viruses associated with hemorrhagic fevers are classified in the families Arenaviridae and Filoviridae. However, some flaviviruses (yellow fever, dengue viruses), some Bunyaviridae (Rift Valley fever virus, Crimean-Congo hemorrhagic fever virus, and the hantaviruses) may be associated with hemorrhagic symptoms.
Arboviruses number > 250 and are distributed worldwide; at least 80 cause human disease. Birds are often reservoirs for arboviruses, which are transmitted by mosquitoes to horses, other domestic animals, and humans. Most arboviral diseases are not transmissible by humans, perhaps because the typical viremia is inadequate to infect the arthropod vector; exceptions include dengue fever, yellow fever, and chikungunya disease, which can be transmitted from person to person via mosquitoes. Some infections (eg, West Nile virus, Colorado tick fever, dengue) have been spread by blood transfusion or organ donation. Reservoirs for bunyaviruses include insects and vertebrates, often rodents. These viruses spread to humans directly from their reservoirs, but human-to-human transmission may occur.
The Arenaviridae includes lymphocytic choriomeningitis virus, Lassa fever virus, Mopeia virus, Tacaribe virus, Junin virus, Lujo virus, and Guaroa virus; all are transmitted by rodents and thus are not arboviruses. Lassa fever can be transmitted from person to person.
The Filoviridae consists of 2 genera: Ebolavirus (consisting of 5 species) and Marburgvirus (consisting of 2 species). The specific vectors of these viruses have not been confirmed, but fruit bats are the prime candidates; thus, Filoviridae are not arboviruses. Human-to-human transmission of Ebola virus and Marburg virus occurs readily.
Many of these infections are asymptomatic. When symptomatic, they generally begin with a minor nonspecific flu-like illness that may evolve to one of a few syndromes (see Table: Arbovirus, Arenavirus, and Filovirus Diseases). These syndromes include lymphadenopathy, rashes, aseptic meningitis, encephalitis, arthralgias, arthritis, and noncardiogenic pulmonary edema. Many cause fever and bleeding tendencies (hemorrhagic fever). Decreased synthesis of vitamin K–dependent coagulation factors, disseminated intravascular coagulation, and altered platelet function contribute to bleeding.
Laboratory diagnosis often involves viral cultures, PCR, electron microscopy, and antigen and antibody detection methods where available.
Arbovirus, Arenavirus, and Filovirus Diseases
Treatment for most of these infections is supportive. In hemorrhagic fevers, bleeding may require phytonadione (vitamin K1—see Treatment under Vitamin K Deficiency). Transfusion of packed RBCs or fresh frozen plasma may also be necessary. Aspirin and other NSAIDs are contraindicated because of antiplatelet activity.
Ribavirin 30 mg/kg IV (maximum, 2 g) loading dose followed by 16 mg/kg IV (maximum, 1 g/dose) q 6 h for 4 days, then 8 mg/kg IV (maximum, 500 mg/dose) q 8 h for 6 days is recommended for hemorrhagic fever caused by arenaviruses or bunyaviruses including Lassa fever, Rift Valley fever, and Crimean-Congo hemorrhagic fever. For dosage in hemorrhagic fever with renal syndrome, see Hemorrhagic Fever With Renal Syndrome (HFRS) : Treatment. Antiviral treatment for other syndromes has not been adequately studied. Ribavirin has not been effective in animal models of filovirus and flavivirus infections.
The abundance and diversity of arboviruses means that it is often easier and cheaper to control arbovirus infections by destroying their arthropod vectors, preventing bites, and eliminating their breeding habitats than by developing specific vaccines or drug treatments. At present, there are effective vaccines only for Yellow fever virus and Japanese encephalitis virus. Vaccines for tick-borne encephalitis are available in Europe, Russia and China but are not available in the US.
Diseases transmitted by mosquitoes or ticks can often be prevented by wearing clothing that covers as much of the body as possible, using insect repellants (eg, DEET [diethyltoluamide]) and minimizing the likelihood of exposure to the insect (eg, for mosquitoes, limiting time outdoors in wet areas; for ticks, see Tick Bite Prevention).
Diseases transmitted by rodent excreta can be prevented by sealing sites of potential rodent entry into homes and nearby buildings, preventing rodent access to food, and eliminating potential nesting sites around the home. Guidelines for cleaning up after rodents and working in areas with potential rodent excreta are available through the Centers for Disease Control and Prevention (CDC).
Because transmission of the filoviruses Ebola virus and Marburg virus is predominantly from person to person, prevention of spread requires strict quarantine measures.
Drug NameSelect Brand Names
AspirinNo US brand name
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