"New Outbreaks of Marburg Virus Disease in Equatorial Guinea and Tanzania: Updates, Risks and Treatment Options"

2023-05-23 14:22:39

Equatorial Guinea and Tanzania are facing several cases of Marburg virus disease (MVD), respectively since February and March 2023. This is the first time that outbreaks of MVD, already present in Africa, have been reported in these two countries. .

The World Health Organization (WHO) estimated in March 2023 that emerging epidemics of Marburg virus disease (MVD) in Equatorial Guinea and Tanzania posed a very high national public health risk. For the moment, if the risk is also considered high at the sub-regional level and moderate at the regional level, it remains assessed as low at the global level. This is the first time that the epidemic risk has been mentioned for these two countries regarding VDD. Other outbreaks have been reported previously in other African countries.

In Equatorial Guinea, 17 cases have been confirmed and 23 probable cases reported between February 13 and May 1, 2023. The last confirmed case was reported on April 20. Among these cases, 12 deaths have been recorded, representing a case fatality rate of 75%. Many cases are linked to gatherings, or geographical or social proximity. However, the presence of previous cases and/or clusters in several districts without clear epidemiological links could indicate undetected transmission of the virus.

In Tanzania, 9 cases, including 8 laboratory confirmed and one probable case, were reported between March 16 and April 30, 2023. The last confirmed case was reported on April 11. Six deaths were recorded, including one probable case and five confirmed cases, representing a case fatality rate of 66.7%.

A hemorrhagic fever of the Ebola family

Marburg virus disease causes hemorrhagic fever, with a mortality rate of up to 88%. The virus belongs to the same family as the Ebola virus. Once an individual is infected, the Marburg virus is transmitted by direct contact (through damaged skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected persons, as well as with surfaces and materials (eg, bedding, clothing) contaminated with these fluids. The incubation period varies from 2 to 21 days. The disease begins abruptly, with high fever, severe headaches and intense malaise. Severe hemorrhagic manifestations may appear between five and seven days after the onset of symptoms.

Geographical distribution of outbreaks of Marburg hemorrhagic fever and bats of the Pteropodidae
Source: OMS, 2022.

In 1967, two large epidemics occurred simultaneously in Germany (in Marburg and Frankfurt), and in Belgrade in Serbia, leading to the initial recognition of the disease. The outbreak of the epidemic is associated with laboratory work using African green monkeys imported from Uganda. Outbreaks and sporadic cases were subsequently reported in Angola, Democratic Republic of Congo, Kenya, South Africa (in a recent traveler to Zimbabwe) and Uganda. In 2008, two independent cases were reported in travelers who visited a cave inhabited by colonies of fruit bats Rousettus in Uganda.

No vaccine or treatment yet

While several treatments, mostly from research against Ebola, are being evaluated, no vaccine or antiviral treatment has been approved to prevent or treat the virus. Fortunately, research is accelerating: Six vaccines are being developed for MVD:

Sabin Vaccine Institute’s ChAd3-MARV, with a Phase 2 clinical trial of ChAd3-MARV in 125 patients in Uganda and Kenya, trial enrollment starting no later than 2023;
VSVΔG-MARV (Musoke) from the International AIDS Vaccine Initiative (IAVI), whose preclinical studies have been completed and in which the candidate induced strong immunity even at lower doses;
rVSVG-MARV-GP (Angola) from Public Health Vaccines (PHV), first-in-human phase 1 protocol approved by the US Food and Drug Administration (FDA);
rVSVN4CT1-AMARV GP1 (Angola) from Emergent BioSolutions/Auro Vaccines;
ChAdOx1 Marburg from the University of Oxford;
Ad26 vector multivalent ZEBOV, Sudan, Janssen MARV.

Remdesivir (which has shown signs of efficacy in animals) is used exceptionally and monitored in Equatorial Guinea. Other molecules are being tested or used in compassionate access in the event of accidental exposure: galidesivir, AVI-7288, favipiravir but also immunoglobulins or even a monoclonal antibody (MR-191-N).

According to the WHO, the health authorities of the two countries are mobilized in the face of these emergencies, and the organization continues to monitor the epidemiological situation.