The Bundibugyo virus, the cause of the current Ebola outbreak in the Democratic Republic of the Congo, has resulted in more than 1,250 cases and at least 362 deaths, with 254 deaths reported so far. This outbreak has largely gone unnoticed while attention focused on an Andes virus outbreak on a cruise ship.
Bundibugyo virus: a deadly pathogen
Bundibugyo virus is a highly fatal pathogen with sudden symptom onset including headaches, diarrhoea, kidney and liver malfunction, and less frequently internal and external bleeding. Contagiousness persists after death, exposing family members who wash and clothe the body for funerals.
Current priorities involve isolating patients and tracing contacts, as no proven vaccine is available. Once the outbreak is controlled, two critical questions remain: why did this outbreak occur, and where did the disease originate?
Limited knowledge of Ebola viruses in the wild
Bundibugyo virus is a relative of the Zaire Ebola virus, which caused a pandemic in West Africa from 2014 to 2016. Despite being ranked as a bioterror agent, little is known about these viruses in the wild. Marburg virus persists in large fruit bats, leading to the assumption that bats are reservoir hosts for Ebola viruses, but proof for Zaire Ebola virus remains elusive.
According to disease ecologist Dan Salkeld, "Fruit bats are widespread, abundant, large and conspicuous animals and are easily blamed as a source for each Ebola virus outbreak. Yet proof that bats are viable incubators of the Zaire Ebola virus remains frustratingly elusive."
Wildlife hosts and transmission challenges
Historically, first human cases in Ebola outbreaks were linked to exposure to forest antelopes, gorillas, and chimpanzees. Experimentally infected pigs can shed infectious Ebola viruses and infect primates. The virus may also hide in the same host for years before re-emerging, explaining long dormant periods.
Determining Bundibugyo virus transmission in tropical forests is challenging. Researchers must decide whether to capture monkeys, analyse faeces, target bush pigs, or giant fruit bats. Political unrest and funding cuts by the US and UK further complicate research.
Trend toward larger epidemics
Before 2010, the largest Ebola outbreaks rarely exceeded 300 cases. Since then, three outbreaks have involved thousands of cases, indicating a trend of larger epidemics. Understanding Ebola viruses could help mitigate human exposure through wildland buffers or discouraging consumption of wild animals.
Integrated surveillance programmes looking for disease spread among wildlife, livestock, and humans could be adopted. Without knowledge of the source, not only do humans remain at risk, but wildlife can suffer retaliations, such as bat-killing sprees after COVID-19 in Cuba, Rwanda, and other countries.
One health approach needed
Disturbing or culling wildlife populations can unintentionally exacerbate disease spread for Marburg virus, rabies, or bovine tuberculosis. If habitat destruction drives recurrent Ebola outbreaks, smarter approaches are needed. The "one health" approach recognizes connections between humans, wildlife, and environment, aiming to optimize health for all components.
Salkeld emphasizes that this concept is not limited to Bundibugyo and can be applied locally. The burning question is whether this outbreak will provide the incentive to prevent future epidemics.
