Image: Emergency Preparedness
History of Machupo
A new hemorrhagic fever began appearing in rural Bolivia in 1959. By 1962, machupo, or Bolivian hemorrhagic fever (BHF), was identified as the new disease terrorizing Bolivian communities (Kilgore et al., 1995). Today, the threat of machupo rises and falls according to rodent populations in the surrounding areas, but is endemic to areas vulnerable to the rodents.
Image: International Notes Bolivian Hemorrhagic Fever -- El Beni Department, Bolivia, 1994
Machupo is in the Arenaviridae family of viruses and takes about 7-15 days to incubate. Symptoms include hemorrhage, fever, headache, aches, fatigue, and shock. (Kilgore et al., 1995). Anywhere from 25-35% of cases result in death (Patterson, Grant, & Paessler, 2014). Ribavirin therapy is often administered intravenously as a treatment (Bolivian Hemorrhagic Fever, 1994).
Image: Emergency Preparedness, n.d.
What Environmental Factors Stimulated the Outbreak of Machupo?
Around the time of the first known outbreak of machupo, Bolivia was facing dangerous political instability. Many residents began subsistence farming near the forests in order to survive, leading them to have more contact with wild animals such as rodents living in the forest. DDT was introduced to Bolivia around the same time and was sprayed generously; a lack of rainfall also occurred. DDT decreased the cat population, making it possible for rodents such as Calomys callosus to grow in population and thrive. As such, rodents began to invade farm houses and subsequently villages (Burrell, Howard, & Murphy, 2017)
How is Machupo Spread?
Machupo is spread through aerosolized rodent excretions (most often those of the rodent species Calomys callosus) (LeDuc, 1989). Community transmission is also possible, but typically only happens within family units or hospital settings where there is constant close contact. Person-to-person transmission is uncommon (Enría, Mills, Bausch, Shieh, & Peters, n.d.)
Local wild rodent populations chronically transmit Bolivian hemorrhagic fever. The wild rodents have a constantly maintained population and constantly reintroduce machupo into society (Bolivian Hemorrhagic Fever Reservoir, 1964). Machupo-carrying rodents like Calomys callosus thrive near humans and villages, making Bolivian hemorrhagic fever very difficult to prevent at times. Machupo is usually seasonal; during the dry season, more farmers are out and about, leading to increased contact with machupo-carrying rodents. (Enría et al., n.d.)
Image: Vesper Mouse, n.d.
In response to chronic machupo infections, authorities attempted to control the rodent population. By exterminating Calomys callosus, the risk of contracting machupo has decreased (Bolivian Hemorrhagic Fever Reservoir, 1964). In 1964, an epidemic of machupo emerged. When rodent control was implemented, the epidemic was over within 2 weeks, further illustrating the impact of rodent population on machupo prevalence (Kilgore et al., 1995). Today, machupo outbreaks occur when rodent populations explode and they begin leaking into surrounding communities (Enría et al., n.d.).
Image: Victor®, n.d.