On June 28, 2019, the Bolivian Ministry of Health received notice of three cases of hemorrhagic fever syndrome. Two additional cases have since been reported. Current evidence suggests that the etiologic agent is Chapare virus or a similar virus, according to the US CDC. In this week’s Outbreak Thursday post, we will be discussing what we know about Chapare virus and the recent cases in Bolivia. 

What is Chapare Virus?

In 2003, a cluster of hemorrhagic fever cases occurred near the Chapare River in Bolivia. Clinical samples were collected from one of the cases but diagnostic testing failed to identify the pathogen responsible for the illness. Specimens were passed on to the Special Pathogens Branch of the US CDC who identified the pathogen as a novel virus of the New World Clade B arenaviruses - now known as Chapare virus. Since the 2003 cases, there have not been any cases of Chapare Hemorrhagic Fever (CHHF). 

Only one CHHF case has every been clinically described, so very little is known about the disease. Symptoms mimic other South American hemorrhagic fevers, inducing fever, headache, vomiting and joint and muscle pain. The patient described in 2003 died 14 days after symptom presentation. The incubation period is unknown, but the incubation period for Argentine hemorrhagic fever, a similar disease, is 6 to 16 days. Transmission for all arenaviruses, including Chapare virus, occurs through a rodent reservoir via direct contact with the rodent or through inhalation of aerosolized urine or feces of infected rodents. If person-to-person transmission is possible with CHHF, it most likely only occurs via direct contact with an infected person. 

Details on the Recent Bolivia Outbreak

All five cases had symptom onset between April 29 and May 29, 2019. The first case was a man from Caranavi Province. His healthcare provider subsequently became ill. Three additional cases followed - two were healthcare providers and the other was a family member of the first patient and a fellow agricultural worker. Three of the cases have died. The two surviving cases and one of the case fatalities tested positive for the same arenavirus, which was partially sequenced and appears to be similar to the Chapare virus. Currently, it is suspected that the agricultural workers were exposed during the rice harvest in the Guanay Municipality of the La Paz department, and the health care workers were exposed in the hospital setting where they had direct contact with blood and other secretions during invasive procedures of one of the cases. The Pan American Health Organization has released recommendations regarding how Member States should confront the disease, which can be found here

In response to the outbreak, particularly the deaths of two physicians and the hospitalization of another, the Medical Association of Bolivia is planning a 48 hour strike demanding better working conditions and biosafety in public hospitals. The US CDC has released a watch for Bolivia, urging travelers to avoid contact with sick people, rodents and their excreta and, if medical personnel, to wear full personal protective equipment when treating suspected hemorrhagic fever cases. 

Conclusion

While the Bolivia outbreak remains small, it will be important to remain vigilant, particularly as the etiology of the outbreak is still being parsed out. While this is the first outbreak of CHHF in 16 years, it will be interesting to see if increased awareness uncovers additional cases. Outbreak Observatory will continue to follow the situation and provide updates as it unfolds. 

Photo courtesy of the US CDC/Charles Humphrey.

Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly to allow others to learn from these experiences in order to improve global outbreak response capabilities.