Bundibugyo Ebola Virus: The looming threat with no approved vaccine or specific treatment

The World Health Organisation’s designation of the Bundibugyo Ebola virus outbreak as a Public Health Emergency of International Concern (PHEIC) is a stark reminder that Ebola remains a persistent global health threat rather than a disease of the past.

Bundibugyo Ebola virus was first identified in Uganda in 2007 during a viral haemorrhagic fever outbreak in the Bundibugyo District in western Uganda.

The strain has since emerged as a significant public health concern in East Africa, particularly in Uganda and the Democratic Republic of the Congo (DRC), where repeated outbreaks have been documented.

Geographic origin and distribution

Since its discovery, the Bundibugyo ebolavirus has remained largely confined to Central and East Africa, with subsequent outbreaks recorded mainly in Uganda and neighbouring areas of the DRC.

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Unlike the Zaire strain, which has demonstrated the capacity for rapid urban spread and international transmission, the Bundibugyo strain has largely remained contained within specific geographic regions.

Case fatality rates and clinical severity

During the first documented outbreak in 2007, there were 149 confirmed human cases and 37 deaths, representing a case fatality rate of 35%.

Transmission mechanisms

Like other Ebola viruses, Bundibugyo follows the same transmission pattern as other Ebola species. Ebola viruses are transmitted to humans from wild animals including:

• Fruit bats
• Porcupines
• Non-human primates

The virus spreads in the human population through direct contact with:

• Blood
• Secretions,
• Organs or other bodily fluids of infected people
• Surfaces and materials contaminated with these fluids.

The incubation period for Bundibugyo infection typically ranges from two to 21 days, during which an infected individual may not display symptoms but may still be infectious.

Here is a simple, easy‑to‑understand version:

Symptoms of Bundibugyo Ebola virus

The illness usually starts suddenly and worsens in stages.

At first, people may feel like they have the flu, with:

• Fever
• Tiredness
• Muscle pain
• Headache
• Sore throat

As the disease progresses, symptoms can become more severe, including:

• Vomiting
• Diarrhoea
• Skin rash
• Kidney and liver problems

In severe cases, patients may also experience internal and external bleeding.

Doctors often describe the illness in two phases:

1. Early (“dry”) phase - General symptoms like fever, aches and headache
2. Later (“wet”) phase - More severe symptoms such as vomiting, diarrhoea, and sometimes bleeding.

 Vaccines and treatment 

There is currently no approved vaccine or specific treatment for the Bundibugyo strain of Ebola.

While vaccines and medicines exist for other forms of Ebola, they are not yet effective against this strain. Researchers are continuing work on potential vaccines, although they remain in the early stages of testing.

Because there is no direct cure, treatment focuses on managing symptoms and keeping patients stable. This includes:

• Maintaining hydration
• Controlling fever and pain
• Reducing vomiting and diarrhoea
• Maintaining blood pressure

Doctors aim to support the body while it fights the infection rather than treating the virus directly.

Overview of other major strains

Four species of Ebola virus are known to cause disease in humans:

1. Ebola virus disease (EVD) caused by the Ebola (Zaire) virus
2. Sudan virus disease (SVD) caused by the Sudan virus
3. Bundibugyo virus disease (BVD) caused by the Bundibugyo virus
4. Taï Forest virus disease, caused by Taï Forest virus

There are six recognised species within the genus Ebolavirus, three of which - Bundibugyo, Sudan and Zaire - have previously caused major outbreaks.

Zaire Ebolavirus (EBOV):

Zaire ebolavirus (EBOV) was identified in 1976 during an outbreak in Zaire, now the Democratic Republic of the Congo.

This strain is regarded as the most serious global public health threat among Ebola viruses. World Health Organisation data collected before 2015 showed a case fatality rate of 76% for EBOV.

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The West African Ebola epidemic was the largest in history. It began in the forested rural region of south-eastern Guinea in March 2014 and was declared over in June 2016 after causing nearly 29,000 cases.

Sudan Ebolavirus (SUDV): The second major strain

Sudan ebolavirus (SUDV) was identified in 1976 during an outbreak in Sudan. World Health Organisation data collected before 2015 showed a case fatality rate of 55% for SUDV.

The Sudan virus is clinically indistinguishable from the Zaire strain of ebolavirus, although it is considered less transmissible. Unlike the Zaire virus, Sudan virus outbreaks have generally remained smaller and geographically contained.

Taï Forest Ebolavirus (TAFV)

Taï Forest ebolavirus (TAFV) was first identified in Côte d’Ivoire in 1994.

TAFV has been linked to only one non-fatal human case, making it the least documented Ebola strain known to infect humans and one with minimal outbreak potential.

Reston Virus

Reston virus was first detected in 1989 in Reston, Virginia, in the U.S. It was traced to a colony of monkeys imported from the Philippines.

Although Reston virus can infect animals, it is not considered pathogenic in humans and therefore represents a significantly lower public health threat than other Ebola species.

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ebola outbreak DRC Ebola outbreak Bundibugyo Ebola Uganda DRC