Arenaviruses and Filoviruses

Arenaviruses and Filoviruses are zoonotic viruses associated with one or more nonhuman host or vector species, mostly rodent and bats. Vascular leak, shock, and multi-organ dysfunction are prominent features and lead frequently to fatal hemorrhagic fever. However, confirming early clinical impressions requires further, specific virologic and serologic testing. A combination of several laboratory techniques should be used to confirm any clinical suspicion, keeping in mind that the manipulation of these dangerous viruses requires specific biosafety requirements. A correct understanding of the order of appearance of RNA, antigen, virus, antibodies in blood, secretions, tissues over the period of the infectious process, as well as accurate knowledge of a patient’s clinical status, is important to understand and interpret laboratory results. During the acute phase of the disease, the amplification and sequence of viral genome, PCR-based assays, are certainly the most sensitive assays, assuming that the primers match with an eventual new virus. The antigen capture ELISA seems to be less virus-specific and readily detects antigen during the obvious clinical phase of disease. Because of the time required for culture and the associated biohazard, virus isolation data for these viruses are usually available only retrospectively. A rising IgM or IgG ELISA titer constitutes a strong presumptive diagnosis. Early recognition of viral hemorrhagic fever infection is valuable, as it can trigger strict isolation procedures, thus preventing or limiting the spread of disease, and allowing specific treatment, when available, to be initiated early in the infectious process.