What is the Marburg virus? WHO confirms outbreak of the deadly viral disease in Equatorial Guinea and Tanzania

• The CDC is warning doctors to be on the lookout for Marburg virus amid outbreaks in two African countries
• The highly contagious virus causes fever, fatigue, and blood-stained vomit.

The Centers for Disease Control and Prevention this week issued a health advisory warning to US doctors regarding an outbreak of the deadly Marburg virus in two African nations.

The World Health Organization confirmed an outbreak of the virus in Equatorial Guinea and Tanzania earlier this year. Authorities first issued a warning for Equatorial Guinea in February following a series of deaths in early January. The Ministry of Health of Tanzania then announced its own outbreak in late March.

There have been 14 confirmed cases in Equatorial Guinea since the epidemic began, with 10 of those patients dying, according to the CDC An outbreak among a group of fisherman in Tanzania produced eight confirmed cases of the viral fever, five of which were fatal, the CDC said.

The CDC on Thursday warned doctors to watch for possible imported cases and patients exhibiting symptoms that include fever, fatigue, and blood-strained vomit and diarrhea. There have not been any reported cases of Marburg virus thus far in the US and the CDC said the risk of imported cases is relatively low.

The virus' presence in both Equatorial Guinea and Tanzania mark the first outbreak of the disease in either country. It comes approximately six months after an outbreak of cases was reported in Ghana in July 2022.

Marburg virus is rare among people but it is highly infectious once it finds a human host, and the disease can be fatal, with an average fatality rate of around 50%, according to the WHO. During a 2005 outbreak of the virus in Angola, the death rate among Marburg patients was as high as 88%, the agency said.

What are the symptoms of the Marburg virus?

Common symptoms of the Marburg virus include hemorrhagic fever, fatigue, blood-stained vomit, and diarrhea.

Illness from the disease often begins abruptly, according to the WHO, starting with a high fever, a bad headache, and malaise. Muscle aches and cramps can accompany the onset, as well as jaundice, nausea, and pain in the abdomen.

The CDC said a non-itchy rash can also appear around the fifth day of the disease, striking the patient's chest, back, or stomach.

Patients can appear "ghost-like" around day three, with deep-set eyes, expressionless faces, and extreme lethargy, according to the WHO.

In fatal cases, death often occurs between eight and nine days after the onset, usually preceded by blood loss and shock, the agency said.

The virus is highly contagious and bodies can remain contagious even after death.

What is the treatment for Marburg?

There are no known vaccines or antiviral treatments currently approved for the virus, according to the WHO, but supportive care, including rehydration efforts and treatment of specific symptoms, can improve patients' chances of survival.

The WHO convened an emergency meeting on Tuesday to discuss whether to test one of the multiple Marburg virus vaccines and treatments that are currently in the development process.

Marburg virus can be difficult to diagnose given its similar presentation to several other infectious diseases, including malaria, typhoid fever, meningitis, and Ebola.

Marburg originates from the same family of viruses that cause Ebola, according to the WHO, a group called filoviruses.

The Marburg virus is transmitted to humans via fruit bats, which are a natural host of the virus, according to the WHO.

The virus is not respiratory. Once a human is infected, the virus spreads through direct contact with the bodily fluids of infected people, as well as via contaminated surfaces and materials.

The virus was first recognized in 1967 among lab workers conducting research in Marburg and Frankfurt, Germany, and in Belgrade, Serbia.

How is the WHO responding to the outbreak?

The UN health agency said in a February that it had deployed health emergency experts in epidemiology, case management, and infection prevention to Equatorial Guinea to try and control the outbreak.

The organization also sent advance teams to the impacted area to trace contacts, isolate people showing symptoms of the disease, and provide medical care.

02/16/2023: This story has been updated to clarify that Marburg virus is caused by a filovirus in the same family as Ebola, and not the same virus.

04/07/2023: This story has been updated to include the CDC's April health advisory warning.