Chapare Hemorrhagic Fever Can Be Transmitted From Person to Person

At a tropical medicine conference, CDC scientists shared their findings on the transmission of an enigmatic virus, the Chapare virus, from person to person. In a Bolivian hospital, it killed three people suffering from Ebola-like symptoms.

Chapare Hemorrhagic Fever virus

Pygmy Rice Rat. Image Courtesy of Yamil Hussein E.

At a hospital in La Paz, Bolivia, several people were treated for hemorrhagic fever. It was not Ebola that afflicted these patients, but another virus that causes similar symptoms: the Chapare virus. Five people who came in contact with these patients were also infected, including a medical assistant, an ambulance driver, and a gastroenterologist from the hospital. Two of them died as a result of this infection.

This happened in 2019 and was the first description of person-to-person transmission of the Chapare virus. This case was the subject of a conference of scientists from the CDC (Centers for Disease Control and Prevention) at the last congress of the American Society of Tropical Medicine and Hygiene. Scientists are particularly concerned about the spread of this virus, which is still poorly understood.

Return of a virus observed in 2004

The first confirmed case of infection by the Chapare virus dates back to 2004 in a community in the province of Chapare, east of La Paz, which gave the virus its name. It belongs to the Arenavirus genus, a group of RNA viruses that are involved in hemorrhagic fever, such as Lhasa fever. The Ebola virus does not belong to this genus, it is an Ebola virus from the Filoviridae family. Diseases caused by Arenaviruses are sometimes called New World Fever. Infected patients experienced fever, abdominal pain, vomiting, and bleeding gums. There is no specific treatment so far for this condition.

The Chapare virus is transmitted by contaminated biological fluids (blood, urine, saliva, and semen). It appears that the medical assistant became infected by the saliva of an infected patient. The presence of viral RNA in the semen of an infected patient who survived 168 days after infection raises the question of sexual transmission. All routes of transmission of the Chapare virus are still unclear.

An emerging infectious disease under surveillance

Caitlin Cossaboom, an epidemiologist at the CDC, has conducted an investigation to identify the natural reservoir of the Chapare virus. Its genome has been isolated from small rodents, the pygmy rice rats (genus Oligoryzomys). They were found near the home of the first infected patient during the 2019 outbreak. Therefore, we cannot be sure that humans have been infected by contact with these animals, because the presence of the virus genome does not attest to its ability to be contagious, but it is a valuable clue.

Scientists are now working on diagnostic tests since the disease is not well known and can easily be confused with others. Since this case in 2019, more Chapare virus infections have been reported, including one involving a child. Scientists are closely monitoring the development of this emerging infectious disease.