Arenaviruses, of the family Arenaviridae, include 29 spherical, enveloped RNA viruses that have T-shaped glycoprotein spikes 7 to 10 nm long surrounding the surface membrane of the virion (Table 1). The viruses can readily infect a variety of mammalian species, especially rodents and bats, often resulting in a deleterious effect on the reservoir rodent host. Human transmission usually occurs through inhalation of aerosols of infected rodent excrement (urine, saliva, feces, nasal secretions) or by direct contact with infected rodents. Disease in humans clinically displays a broad range of symptoms, from asymptomatic (no symptoms) to fever, prostration, head ache and vomiting, to the more severe cases of meningitis and hemorrhagic fever.
The arenaviruses capable of causing disease in humans include lymphocytic choriomeningitis (LCM) virus and Lassa fever virus (first detected in Lassa, Nigeria). LCM has been identified in cases of aseptic meningitis in Europe and the Americas. Lassa has been associated with hemorrhagic fever, shock, and death in 5% to 15% of symptomatic patients (80% of cases are asymptomatic). Lassa fever virus is a significant cause of morbidity and mortality in West Africa, where economic resources are limited. Capillary leak and widespread organ involvement, accompanied by shock, respiratory distress, and/ or hemorrhage, are responsible for most deaths from Lassa fever. Other, less commonly reported arenaviruses may also cause hemorrhagic fever.
Arenavirus infection is diagnosed using serologic tests or reverse transcriptase polymerase chain reaction (RT-PCR) to detect viral nucleic acid. Viral isolation using cell culture is not routinely recommended. Cell culture for viral isolation has proven to be unreliable because of inconsistent sensitivity. In addition, handling cultures and specimens puts laboratory personnel at high risk. Samples and cultures containing LCM virus require Biosafety Level (BSL) 3 facilities, and Lassa fever virus requires a BSL 4 laboratory. Serologic diagnosis is also difficult because the immunologic antibody response is delayed for several days and often weeks following symptomatic illness. An RT-PCR assay has been developed to detect arenaviruses, but it is not widely available in the acute care setting.
Table1. Arenaviruses
