Washington — An international research team has identified a previously unknown virus that caused two deaths in the Democratic Republic of the Congo in 2009.
The unusual characteristics of the virus and its deadly consequences still puzzle the team, however, and research continues to better understand how the virus is transmitted and what might stop it.
This much is known: the virus induces acute hemorrhagic fever, a fast-moving viral disease that can kill in days. In the DRC, two teens, a boy and a girl, died. A third person, an adult male, developed the disease but recovered.
Acute hemorrhagic fever causes fever, dizziness, muscle aches and exhaustion. Patients with severe cases of hemorrhagic fever, which can be caused by a number of different pathogens, often show signs of bleeding under the skin, in internal organs or from body orifices such as the mouth, eyes or ears.
The new microbe is named Bas-Congo virus (BASV), after the province in the southwest corner of the DRC where the three people lived.
"Known viruses, such as Ebola, HIV and influenza, represent just the tip of the microbial iceberg," said Joseph Fair, a co-author of the research published in late September in PLoS Pathogens. Fair is vice president of Metabiota, a California-based company specializing in disease and pathogen detection, evaluation and response. "Identifying deadly unknown viruses, such as Bas-Congo virus, gives us a leg up in controlling future outbreaks," he said.
The two cases in 2009 occurred in a 15-year-old boy and, a week later, a 13-year-old girl who attended the same school. Both fell ill suddenly and declined rapidly. A week after the girl's death, a nurse who cared for her developed similar symptoms. He was transferred to a hospital and survived.
"These are the only three cases known to have occurred, although there could be additional outbreaks from this virus in the future," said Dr. Charles Chiu, an assistant professor of laboratory medicine at the University of California, San Francisco, who led the effort to identify the virus. Chiu and his team continue to work on new methods to detect the virus so health officials in the DRC and elsewhere can quickly identify it should it emerge again.
BASV belongs to a family of viruses known as rhabdoviruses, a large group of microbes that infect plants, insects and mammals, including humans. The most widely known disease from this group is rabies. But BASV is genetically distinct from other members of this family, and causes very different symptoms when it infects humans. No other rhabdoviruses are known to cause the acute, rapid and deadly hemorrhagic fever seen in the three cases in the DRC.
The scientific team was able to design an antibody test for the virus, which allowed positive identification of BASV in the third patient. Further screening of those who came in contact with this patient identified another nurse whose system had produced the antibodies after exposure to the virus, even though he did not fall ill.
"What this suggests is that the disease may be transmissible from person to person -- though it's most likely to have originated from some other source," said Nathan Wolfe, a co-author on the paper. "The fact that it belongs to a family of viruses known to infect a wide variety of mammals, insects and other animals means that it may perpetually exist in insect or other 'host' species and was accidentally passed to humans through insect bites or some other means."
Wolfe is also founder and chairman of Global Viral, a nonprofit organization based in California that supports research and collaboration to address global infectious disease threats.
Researchers from the United States, the DRC, France and Gabon collaborated on this work. Funding for the work came from France, Gabon and the United States. The Department of Defense Armed Forces Health Surveillance Center and the U.S. Agency for International Development (USAID) were among the sponsoring partners in their ongoing efforts to detect emerging health threats and the potential causes of pandemics.