What is the Marburg virus?
It is a filovirus, to which the Ebola virus also belongs. As such, it can cause outbreaks and epidemics with a high mortality of up to 88%. The incubation period varies between two and 21 days. Symptoms begin abruptly with high fever, severe headache and severe malaise. Other symptoms include severe watery diarrhoea, abdominal pain, cramps, nausea and vomiting.
Contrary to the collective imagination, not all cases show haemorrhagic signs, although fatal cases usually do.
There is currently no treatment or vaccine, although there are some candidates in development.
What is happening in Africa?
On 27 September 2024, the Rwandan Ministry of Health announced the confirmation of a case of Marburg virus disease. This was the first time the virus had been detected in the country. As of 3 October, according to ECDC data, 25 cases and 11 deaths have been reported, spread across seven of the country's 30 districts, as reported by the Africa CDC. More than 70 % of the infections have occurred in health workers in two health centres in Kigali and contact tracing of 300 contacts is ongoing.
How did the outbreak start?
The origin of the outbreak in Rwanda is unknown, but outbreaks usually start when a person comes into contact with an infected bat of the genus Rousettus.
How does it spread?
Once the virus enters a human population by jumping from an infected bat, it spreads from person to person through direct contact with blood, secretions, organs and other body fluids. Surfaces and materials, such as clothing and bedding, can also be a source of infection.
This is in addition to the risk for health workers treating patients, as well as the danger posed by funeral ceremonies involving direct contact with bodies. For their part, Rwandan authorities have reduced the size of funerals to prevent the outbreak from spreading, as reported by the BBC.
Could it affect more countries inside and outside the African continent?
According to the WHO, the risk of the outbreak is ‘very high’ at the national level, ‘high’ at the regional level and ‘low’ at the global level. In other words, there is concern about its spread in Rwanda and neighbouring countries, but there is no fear of the virus reaching distant countries.
The risk of spread to neighbouring countries is particularly high, given that the affected areas of Rwanda border the Democratic Republic of Congo, Tanzania and Uganda.
The possible importation of cases from Rwanda to Belgium and Germany has been in the media this week, but both alerts have been false alarms, as reported by the ECDC.
How serious have the Marburg outbreaks been so far?
Unlike Ebola, whose outbreaks and epidemics have claimed the lives of more than 15,000 people, Marburg has never caused a major crisis so far. Most situations end with very few cases and deaths. Only the 1998-2000 and 2004-2005 outbreaks exceeded 100 detected infections and deaths.
This makes the current outbreak in Rwanda, which exceeds 30 cases, already the third largest known outbreak.
Is there cause for concern?
Film and literature have painted a terrifying picture of filoviruses through films such as Outbreak - based on the controversial book The Hot Zone. This has led to fears about the spread of these pathogens to the West when outbreaks and epidemics occur in Africa. One example was during the Ebola epidemic of 2013-2016, when there were a few cases outside the continent - the best known in Spain, that of the nurse who cared for a deceased missionary.
The reality is that the biological characteristics of these viruses, with a very high mortality rate but a very poor capacity for human-to-human transmission, explain why there has never been an outbreak outside Africa beyond isolated cases, mostly imported or related to laboratory incidents. What can happen is that protocols may be triggered by travellers with symptoms from affected countries.
