Marburg, Monkeypox, And Other Viruses Emerging From Africa

Marburg virus is new to Ghana, with the first two cases reported last week. Samples were sent to the Institut Pasteur in Senegal for confirmation, which is still pending.

Marburg is but one of the diseases emerging from Africa. The World Health Organization (WHO) just reported a 63% increase in zoonotic outbreaks in the region from 2012-2022 compared to 2001-2011. Most of these (70%) were due to viruses that cause hemorrhagic fevers, like Ebola and Marburg. Monkeypox, anthrax, plague, dengue, and others make up the remainder. Marburg virus is similar to Ebola, and both are caused by filoviruses and transmitted initially by fruit bats. Lassa is another hemorrhagic fever in Africa, caused by an arenavirus but is transmitted by multimammate rats. Rodents likely transmit monkeypox.

For Marburg, early symptoms are non-specific and might be confused with malaria or typhoid. There is often an abrupt onset of fever, headache, diarrhea, nausea, and vomiting. Then bleeding can begin, as can shock, and the disease is often fatal, as it was for these two people.

The only other case in West Africa occurred last September 2021, in Guéckédou, Ghana, the same region that had an Ebola outbreak earlier in the year. The disease is seen in Angola, Uganda, the Democratic Republic of the Congo, Kenya, and South Africa.

With both Marburg and Ebola, transmission between people then occurs through infected fluids or contaminated surfaces. Contact with bodies during burials has been problematic, as it is difficult to change traditional practices.

Marburg epidemics have been the most limited. The first large outbreak was in 1967 with infections in Germany and Yugoslavia (now Serbia), originating from green monkeys imported from Angola. Thirty-one people were infected, and a quarter of them died. A large outbreak occurred in the Democratic Republic of the Congo (DRC) in 1998–2000, involving 152 people, with 128 of them dying (83%). The 2005 Angolan outbreak was the worst, with 252 infections and a 90% mortality. This outbreak was thought to have primarily spread through contaminated transfusion equipment reused between patients.

We now know that Egyptian Rousette bats, which live in caves and mines, are reservoirs for Marburg virus. There were infections among Uganda miners in 2007 and two female tourists (Dutch and American) who had gone caving at separate times in the Python Cave in Uganda. They are likely to have been infected either through aerosols or contact with guano.

Surveillance for zoonotic diseases is very limited, as are diagnostics. It may require a high- level suspicion unless there is an outbreak.

Treatment is solely supportive care for Marburg virus. While there are now specific treatments for Ebola, the mortality rate remains very high. Inmazeb, a combination of three monoclonal antibodies (atoltivimab, maftivimab, and odesivimab-ebgn), had a 33.8% death rate after 28 days, compared to 51% for a control group. For the single monoclonal antibody Ebanga (Ansuvimab-zykl), the mortality rate was 35.1% at 28 days, compared to 49.4% for those who received a control.

There is now a vaccine available for Ebola, Ervebo, which is used in a ring vaccination strategy, vaccinating contacts of patients with Ebola. It was given to more than 300,000 people in DRC 2018-20, with a 97.5% efficacy. There are other vaccines in development. There is no similar vaccine for Marburg.

Monkeypox

Monkeypox has been rising since ~2020 and has been noted primarily in the Democratic Republic of the Congo and Nigeria. Since Jan 2021, there have been 2087 cases. But it was only when cases were spotted in Europe and now in the US that the disease began to receive appropriate attention. Sadly, the public health response has been too little, too late, and cases are sky-rocketing. An added problem is that the rash might be confused with syphilis, which is also increasing.

Unlike Marburg, treatment is available for monkeypox. The antiviral Tecoviramat (TPOXX) is the most effective antiviral. As with Ebola, ring vaccination is also the strategy to protect people exposed to the virus, this time with the Jynneos vaccine. Both medicines are in short supply. As we’ve seen with Covid-19, wealthy countries are snatching up available supplies, and inequities are occurring.

Africa has the world’s fastest-growing population, according to WHO, resulting in rising urbanization. There’s also improved transportation linking remote areas with cities and different countries. As we encroach more on wildlife and invade their territory, such spillover events like Marburg, Ebola, and monkeypox will become more likely.