Virus behind Ebola-like outbreak in Bolivia found to have human transmission

A virus behind a small outbreak in Bolivia has been found to include human-to-human transmission in healthcare settings, according to newly presented findings from the CDC and other disease experts. The Chapare virus has been linked to rodents, though the source of the infection ultimately remains a mystery at this time. A spat of surprise cases in healthcare workers first raised the alarm bells about human transmission.

An emerging threat

Chapare virus is behind an Ebola-like emerging hemorrhagic fever in Bolivia that, until relatively recently, was only seen in a single confirmed case. In 2019, the virus caused at least five infections that resulted in three deaths, spurring a rapid investigation by multiple authorities, including the CDC.

Researchers with the CDC's Division of High-Consequence Pathogens and Pathology recently presented their findings during the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH). The researchers confirmed that infections appeared in healthcare workers exposed to infected patients, including a paramedic, young medical resident, and a gastro specialist.

Human transmission

'We now believe many bodily fluids can potentially carry the virus,' according to CDC epidemiologist Caitlin Cossaboom. The researchers say that the virus, which is deadly based on the limited number of cases, may be transmitted through multiple bodily fluids, including saliva and blood. The medical resident, who tragically died from the disease, may have been exposed to the virus from saliva while caring for a patient, for example.

The researchers note that sexual transmission of the virus may be possible as one survivor of the disease was found to have viral RNA present in semen 168 days after becoming infected. However, the researchers note that there's still an investigation underway to understand the possible ways this virus may be transmitted.

Unlike SARS-CoV-2, which is a coronavirus, the Chapare virus belongs to the arenavirus group, which includes other deadly viruses like Machupo and Lassa. Someone infected with the Chapare virus may develop hemorrhagic fever similar to the kind seen in Ebola patients.

According to the new presentation, the individuals infected with the Chapare virus experienced symptoms that included pain behind the eyes, stomach pain, vomiting, fever, skin rash, and bleeding gums. Sadly, there is no specific treatment for this disease at this time, meaning the patients received supportive care and fluids.

Many questions remain

The findings include new evidence of the virus in rodents found near the home of the first patients who died from the 2019 outbreak. However, there's no proof at this time that rodents may be the source of this infection. This particular type of rodent is found in Bolivia and multiple nearby countries.

This virus may have been circulating for several years, the experts note, with patients potentially having been misdiagnosed as having dengue fever, not Chapare virus. The presentation describes the steps taken once it was realized that the 2019 outbreak wasn't dengue — samples from patients were sent off to a highly secure lab at the CDC for analysis.

The experts were able to identify the virus using data collected from the single confirmed case of the Chapare virus back in 2004. The experts were praised for their work, with ASTMH President Joel Breman stating:

While there is still much that remains unknown about Chapare virus, it's commendable how quickly this team was able to develop a diagnostic test, confirm human-to-human transmission and uncover preliminary evidence of the virus in rodents. It's a valuable lesson that international scientific teams, equipped with the latest tools and freely sharing their insights, are our best front-line defense against the disruptive threats of deadly infectious diseases.

The investigation into the virus remains underway, with multiple elements planned, including work into determining whether rodents are the source of the infection and if any other animals are involved.

The CDC expects to continue testing samples, including from suspected cases, and diagnostic tests will be used to monitor the public for other possible human infections. The experts caution that there's quite a bit that remains unknown about this virus, however, including how it infects humans.