Q&A: The new Ebola outbreak

Growing global alarm surrounds the Ebola outbreak in Central Africa, which has now been declared a public health emergency of international concern by the World Health Organization. The current outbreak is centered in the Democratic Republic of the Congo and neighboring Uganda, where health officials have reported hundreds of suspected cases and dozens of deaths linked to the rare Bundibugyo strain of the virus.

Scott Pegan, a professor of biomedical sciences in the UC Riverside School of Medicine, answers questions on the outbreak in the Q&A below. Pegan's research focuses on emerging infectious diseases, viral-host immune interactions, and the development of antiviral therapies and vaccines, particularly for coronaviruses and Crimean-Congo hemorrhagic fever virus.

Q: How dangerous is Ebola?

Ebola represents a collection of viruses. Three of these have been observed to often infect humans: Zaire virus, Sudan virus, and, as demonstrated by the recent outbreak, the Bundibugyo virus. All three are often fatal, but they vary in terms of mortality. The Zaire and Sudan viruses have mortality rates of up to 90% and 50%, respectively. The Bundibugyo virus tends to have a lower fatality rate of around 35%.

The Bundibugyo virus first emerged in Uganda with an outbreak from August 2007 to February 2008. Due to the Bundibugyo virus's lower mortality rate and the fact that this is only the third major documented outbreak, prior research and therapeutic efforts have mostly focused on the Zaire and Sudan viruses, with no approved countermeasures for the Bundibugyo virus.

Q: How does the virus spread?

Like the Zaire and Sudan viruses, this form of Ebola is not transmitted through the air. The Bundibugyo virus primarily spreads through contact with infected bodily fluids.

The origin of this outbreak is likely what is considered a spillover event. The Ebola viruses are zoonotic in nature, with their primary hosts considered to be fruit bats. Spillover events of human infectious diseases occur when humans encounter infected animal feces or process bushmeat from infected animals.

Q: How can people protect themselves?

Individual chances of contracting Ebola are low, given what is currently known about the outbreak.

For individuals outside the DRC and Uganda, being responsive to contact tracing efforts will play a major role in protecting the community. The virus has an incubation period of 2 to 21 days. Symptoms are initially flu-like, including fever and other non-specific symptoms such as lethargy and fatigue. As the disease progresses, nausea, diarrhea, vomiting, and other gastrointestinal symptoms occur. Much like the recent concern around the hantavirus outbreak, the best approach is to be aware of who you have been in contact with and whether those individuals have recently visited the affected region.

Q: Could Ebola spread in the U.S.?

Effective spread of Ebola within the U.S. would be challenging for the virus. Many of the drivers for the large outbreaks seen in the DRC and neighboring regions are proximity to the primary animal reservoirs (e.g., fruit bats) and the interplay between public health guidance and local customs. Prior to the outbreak, and continuing today in the affected areas, traditional burial practices involved family members playing a role in preparing deceased individuals for burial. This provided an excellent opportunity for the virus to spread. These practices would likely not be a major factor in the U.S., particularly as awareness of the outbreak has grown and proper personal protective equipment (PPE) would be used in any suspected cases.

This doesn't necessarily mean that an infected individual coming into the U.S. could not spread the virus to others. However, the infection dynamics and capabilities of the virus suggest that such an event could be contained. Recent Centers for Disease Control and Prevention (CDC) efforts to quarantine U.S. citizens and raise awareness at U.S. ports of entry are effective, preventative first steps to ensure infected individuals are identified and quarantined rapidly. There are diagnostics for this form of Ebola, and they are likely being made readily available to those in need.

Q: What makes the current Ebola outbreaks in Democratic Republic of the Congo and Uganda concerning?

There is no approved vaccine for the Bundibugyo virus, whereas there is a highly effective one for the Zaire virus and vaccines for the Sudan virus are currently in clinical trials. This leaves only supportive care for infected individuals and a race to contain the outbreak before it becomes widespread. For context, a prior Zaire virus outbreak led to over 10,000 cases.

Q: What long-term public health strategies could reduce the risk of future Ebola outbreaks?

Another reason that containing the current outbreak of Bundibugyo virus is critical is that the more the virus interfaces with humans, the greater the chance for it to move from a spillover event to a crossover one. Much like with COVID-19, public health officials and scientists will continue to sequence the virus to detect any changes of consequence as this outbreak continues. Renewed public health efforts both inside the affected region and outside of it will be necessary to navigate this outbreak. This outbreak and the attention to it also stress the need to follow foundational public health practices and support global viral surveillance and therapeutic development efforts for the Bundibugyo virus and other often-fatal viruses that stand at the animal-human interface.

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