- Old World (Eastern hemisphere)
- New World (Western hemisphere)
The Old World Arenaviridae include Lassa virus (from West Africa) and lymphocytic choriomeningitis virus (found in Europe, Asia, and the Americas).
The New World Arenaviridae cause South American hemorrhagic fevers and share some common clinical features, but are found in very specific geographical locales. The individual fevers are sometimes referred to as Argentinian hemorrhagic fever, Bolivian hemorrhagic fever, Venezuelan hemorrhagic fever, and Brazilian hemorrhagic fever. The group known as the Tacaribe complex includes four common viruses:
Junin virus is from the pampas of Argentina. It is acquired from exposure to the corn mouse (Calomys masculinus), the grass field mouse (Akodon azarae), or the dark field mouse (Bolomys obscurus).
Machupo virus is from the savannas of the Beni province of Bolivia. It is acquired from exposure to Calomys callosus, the vesper mouse.
Guanarito virus is from Venezuela. It is acquired from exposure to Sigmodon alstoni, the cane mouse.
Sabia virus is from the southeast province of Brazil. It has not yet been associated with a rodent reservoir.
Less common New World Arenaviridae include the Tamiami virus reported in the United States in Florida. It is associated with the cotton rat, Sigmodon hispidus. The Whitewater Arroyo virus has been reported in the United States in California and New Mexico. It is associated with the white-throated wood rat, Neotoma albigula.
South American hemorrhagic fever infections have widely varied clinical presentations, but share some common presenting features. Most infections are asymptomatic.
Mildly symptomatic cases are difficult to distinguish from common respiratory or gastrointestinal infections. The incubation period is between 7-14 days. Initial symptoms include headache, body aches, cough, nausea, sore throat, and fever. The fever is usually high and may be intermittent or constant. Five days after the onset of fever, hemorrhagic phenomenon may be observed and are associated with dehydration, shock, and cardiovascular collapse. Edema of the face and neck is common. Encephalopathy and seizures are common. The mortality rate is 15% in hospitalized patients and fetal loss is common in infected pregnant patients. Hair loss and loss of coordination is seen during convalescence. Deafness is seen in 25% of survivors.