Machupo virus is a New World arenavirus responsible for Bolivian hemorrhagic fever. This enveloped virus has a bi-segmented, negative-sense RNA genome and is naturally maintained in Calomys callosus rodents. Humans acquire infection through contact with contaminated rodent excreta.
Explanation
Machupo virus (MACV) belongs to the genus Mammarenavirus. Its virions are enveloped and roughly 50–300 nm, containing two segments of negative-sense RNA. The small (S) segment encodes the nucleoprotein and glycoprotein precursor, while the large (L) segment encodes the RNA-dependent RNA polymerase and a zinc-binding protein; an ambisense coding strategy enables expression of viral genes. The virus circulates in the large vesper mouse Calomys callosus in the savannas and agricultural zones of Bolivia, where the animals shed virus in urine and feces. Humans become infected when they inhale aerosolized excreta or come into contact with contaminated grain or farm structures. After an incubation period of about one to two weeks, symptoms begin with fever, malaise and myalgia and can progress to mucosal bleeding, petechiae and neurological signs such as tremor or hearing loss. Case fatality rates during early outbreaks exceeded 20 %, reflecting the lack of specific treatments. Because the virus is transmitted by rodent excreta and can also spread in healthcare settings, strict infection control is essential.
Historical outbreaks and management
Bolivian hemorrhagic fever was first recognized in the early 1960s when clusters of severe febrile illness occurred in the Beni Department of Bolivia. Investigations identified Machupo virus as the causative agent, and rodent control measures helped curb the outbreaks. Unlike Junin virus, no licensed vaccine exists for Machupo virus; however, passive transfer of immune plasma and the antiviral ribavirin have been used with some success. Sporadic cases still occur when rodent populations expand and come into contact with humans. Healthcare workers should be aware of the potential for person‑to‑person transmission during the viremic phase and employ protective equipment. Machupo virus exemplifies New World arenaviruses that cause hemorrhagic fevers in South America. Awareness of the rodent reservoir and adherence to infection control practices are critical for preventing and managing Bolivian hemorrhagic fever. Related Terms: Junin virus, Guanarito virus, Sabia virus, Chapare virus, Lassa virus