Machupo Virus: What Is Bolivian Hemorrhagic Fever?

The Machupo viral infection, known as Bolivian Hemorrhagic Fever (BHF), was first discovered in 1959. The virus was identified by a team of researchers led by Dr. Karl Johnson, an American virologist working with the United States Centers for Disease Control and Prevention (CDC) at the time.

This virus was eventually named the Machupo virus after the Machupo River near San Joaquin, Bolivia, where the outbreaks were discovered.

Further studies by Dr. Johnson and his colleagues led to the understanding that the virus was transmitted to humans from rodents, specifically the Calomys callosus, a type of vesper mouse common in the area.

The discovery of the Machupo virus was a major breakthrough in the study of viruses and disease control. It helped control the outbreak in Bolivia and improved knowledge about hemorrhagic fevers caused by arenaviruses.

Notable outbreaks

• 1959-1963: Bolivia in the city of San Joaquin, with 500 cases reported and 90 deaths. After 1963, rodent control measures were implemented, and no outbreaks were reported for a while.
• 1990s: A few cases reported.
• 2007 – 2008: Bolivia: 220 cases and 14 deaths reported.  

The highest death rates are reported in children under five and adults over 55 years of age.

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Other dangerous arenaviruses are Lassa virus, Chapare virus, and Lujo virus. Bolivian Hemorrhagic Fever is also known as Black Typhus and Machupo Hemorrhagic Fever.

Calomys collosus, a kind of rodent, is the main vector, and the disease can be passed from animals to humans.

The virus can spread in different ways: through tiny droplets in the air, by eating food contaminated by rodent urine or feces, or by directly touching the virus. Person-to-person transmission is rare.

The Machupo virus is not without controversy. 

In 2023, false information about Machupo went viral on WhatsApp, the popular messaging app, and caused a stir in India. Readers were told to avoid using a new white and shiny Paracetamol pill with ‘P/500’ written on it because it “contains Machupo virus.” However, this content had no truth to it and was eventually debunked. 

Arenaviruses, like the Machupo virus, are known to cause severe illness in humans and silent infections in rodents and other vectors. These types of viruses enter the human body through the respiratory or gastrointestinal tract, depending on the mode of transmission. 

Once in the body, the virus replicates in the endothelial cells lining the throat or gut. Eventually, the virus enters the bloodstream and causes severe bleeding (hemorrhaging). 

Unfortunately, because opportunities for research are limited, there is a lot more we need to learn about the effect of the Machupo virus on humans. Most available information is from animal models.

• Incubation period: 5-19 days.
• Early symptoms of Machupo include fever, headache, tiredness, muscle pain, and joint pain. Patients might start showing signs of bleeding from the mouth, nose, lungs, stomach, and urinary tract within a week. It is very similar to the Argentine hemorrhagic fever.
• Case fatality rates range from 25% to 35%.

Laboratory testing of blood samples is the usual way to diagnose viral hemorrhagic fevers. 

However, given that the virus is highly infectious and dangerous, the tests need to be performed only in specific high-security labs with strict protocols to be followed.

There is no cure for the Bolivian Hemorrhagic Fever, so treatment is usually supportive care. Despite the Machupo virus being dangerous and a potential agent of bioterror, there is no FDA-approved vaccine.

The best prevention of BHF is to control the rodent population in the affected area. In fact, eradicating the Calomys callosus rodent population in Bolivia significantly reduced the case count of infected individuals and helped minimize the spread of the Machupo virus.

There is a live, attenuated vaccine called Candid–1 that has been used in Bolivia and other affected countries to inoculate at-risk demographics, particularly workers who are at risk of getting infected. 

Bolivian Hemorrhagic Fever, while relatively rare, presents significant challenges in regions where it is found. The journey from the virus’s discovery in the 1960s to our current understanding underscores the importance of ongoing research and vigilance in the face of infectious diseases. 

Bolivian Hemorrhagic Fever, caused by the Machupo virus, may not be a global threat yet, but it is a stark reminder of the potential dangers of zoonosis, where illnesses can jump from animals to humans, and viral mutations that may be more deadly.

Prevention and control remain key. Simple measures like rodent control, awareness, and education in affected areas can go a long way in preventing outbreaks. Meanwhile, the scientific community continues to work on understanding this virus better, aiming to improve treatment and develop a vaccine approved to protect the general population against Machupo.

While Bolivian Hemorrhagic Fever remains a localized health concern, its study contributes to the global understanding of viral infections and helps prepare us for future challenges in public health.

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