Virus World

Africa is grappling with not one, but two outbreaks of Marburg fever, a disease that causes symptoms and a death rate comparable to Ebola, its viral cousin.  Health officials in Tanzania announced Tuesday that they had confirmed the country’s first-ever Marburg outbreak, involving at least eight people so far, five of whom have died. One of the people who died is a health care worker. Across the continent, Equatorial Guinea has been combating its first-ever Marburg outbreak for several weeks now, though in an unusual turn of events for a viral hemorrhagic fever outbreak, scant information has been shared with the international community. The last update from the World Health Organization on that outbreak was issued nearly a month ago, on Feb. 25. Tanzanian Health Minister Ummy Mwalimu announced that the country’s national public health laboratory had confirmed that Marburg was the cause of an outbreak that was first reported last week. Five members of a single family are among the cases. At least 161 people who have been in contact with the cases have been identified and are being monitored. “We are working with the government to rapidly scale up control measures to halt the spread of the virus and end the outbreak as soon as possible,” Matshidiso Moeti, the WHO’s regional director for Africa, said in a statement.

Moeti noted that while Tanzania has not previously battled Marburg, it has coped with a number of health emergencies in recent years, including Covid-19, cholera, and dengue fever. “The lessons learnt, and progress made during other recent outbreaks should stand the country in good stead as it confronts this latest challenge,” she said.But Gary Kobinger, a veteran of numerous Ebola and Marburg responses, questioned that line of thinking, and urged the two countries to both be transparent and to accept outside help. “Managing a filovirus outbreak is completely different than a typical emergence of let’s say cholera or measles or even Rift Valley fever,” said Kobinger, who is director of the Galveston National Laboratory at the University of Texas Medical Branch. Marburg and Ebola viruses are both filoviruses. Kobinger said that even countries that have experience with these viruses struggle sometimes to contain outbreaks. “You need to act very fast. The first two weeks, three weeks are extremely important. And this is where you’re going to define the evolution of the outbreak,” he told STAT. “If you lose control of a SARS-CoV-2 outbreak, which happens, that’s one thing. If you lose control of an Ebola outbreak or a Marburg outbreak, you have a different problem on your hands.” Viral hemorrhagic fever outbreaks pose significant and unique challenges, because of their death rates, which are generally in the high double digits. These diseases spark panic in the communities in which they spread at the very time when community cooperation is essential to stop transmission.

“People are scared. One case in one village will shut down the place. And people will not want to go there and people that come out of there will be treated as if they are infected, potentially,” Kobinger said. “So it’s very difficult in terms of trade, in terms of social movement, in terms of social acceptance. It’s much more traumatic than Covid or something else.”bHistorically Marburg outbreaks have been smaller than Ebola outbreaks; there have been none that involved thousands of cases, like the Ebola outbreaks in West Africa (2014-2016) or in the Democratic Republic of the Congo (2018-2020). But in 2004-2005, 252 people were infected in an outbreak in Angola, with 227 or 90% of them dying. There are no licensed vaccines to protect against Marburg and no approved drugs. A WHO-led meeting in mid-February convened to explore whether there were supplies of experimental vaccines or drugs that could be tested in the Equatorial Guinea outbreak found there are few doses available to test. The outbreak in Equatorial Guinea dates back to at least early January; by late February, nine cases — one confirmed, four probable and four suspected — had been identified. It is not unusual to see probable and suspected cases in a viral hemorrhagic fever outbreak, especially in the early days. People die and are buried without a diagnosis. Even after authorities realize what they are dealing with and testing protocols are established, some families hide their dead so as to be able to perform burial rituals which, while important culturally, serve to spread the virus further. It is believed additional cases have been identified in Equatorial Guinea, but the country’s leadership has been unwilling to disclose the information.

Equatorial Guinea has just confirmed its first outbreak of deadly Marburg virus, a hemorrhagic fever related to Ebola. Equatorial Guinea has just confirmed its first outbreak of Marburg virus, one of the families of hemorrhagic fevers related to Ebola. As with last year’s outbreak in Ghana, patient specimens had to be sent to the Institut Pasteur in Senegal for confirmation, as it requires specialized testing. One of eight samples has been confirmed thus far. There have been 16 suspected cases and 9 deaths so far. Symptoms of Marburg are nonspecific and include (the often abrupt onset of) fever, headache, nausea, vomiting and diarrhea, so it might be confused with many other infections. When there is blood in the emesis or stool, the diagnosis of a hemorrhagic fever becomes much clearer. The incubation period is from 2-21 days. Like Ebola, Marburg can be quite deadly, with an 88% fatality rate.

Unlike Ebola, we have no vaccines to protect people yet, or other specific treatments. Monoclonal antibodies have been used to successfully treat some people ill with Ebola, with a moderate reduction in death, from 49.4% to 35.1% for Ebanga (Ansuvimab-zykl) treatment. The vaccine for Ebola offered a 97.5% protection rate in the 2018-20 outbreak in the Democratic Republic of Congo, which was due to the Ebola Zaire strain. The most recent outbreak of Ebola in Africa occurred in Uganda in September 2022. It was due to a different strain, Ebola Sudan, for which we have no vaccines or specific treatment. For Marburg, Ebola Sudan, and other hemorrhagic fevers, treatment is supportive by providing fluids and electrolytes to avoid shock. The primary focus now will be controlling the spread of the infection, which occurs through these infected secretions or contaminated surfaces, and by quarantine. Patients who are symptomatic need to be carefully isolated. The WHO and local officials will provide education on infection control and supplies of gowns and gloves (PPE). Contact with bodies is common in many cultures and has previously been a source of transmission.

Marburg has now been seen in Ghana, Angola, Uganda, the Democratic Republic of the Congo, Kenya, and South Africa. The first outbreak was seen in 1967 in Germany and Serbia. It came from the importation of green monkeys from Angola. A quarter of the 31 people infected died. Subsequently, there were larger outbreaks in the DRC in 1998-2000, with 152 people and 83% mortality. The largest outbreak was in 2005 in Angola. There were 252 cases and a 90% death rate. This was thought to be caused by reusing contaminated transfusion equipment between patients. Egyptian Rousette bats, which live in caves and mines, are reservoirs for the Marburg virus. There have been infections among Uganda miners in 2007 from the Python Cave in Uganda. Subsequently, two tourists became infected from the same site, where they had gone caving. Bat guano or infected aerosols were the likely sources of transmission. One of the problems with Marburg, as with other animal-related infections (zoonosis), is that there is limited surveillance and diagnostic tests; until there is an outbreak, early cases are likely to be missed. Many of these events—called spillover events—occur because we encroach on wildlife. As we do this more—be it in mining, deforestation for cattle, or other disruptions of the environment, we can expect to see more such outbreaks.