The Ugandan government recently reported an outbreak of Marburg virus disease in the east of the country. All three people found to have the disease have since died. More than 100 people are now being monitored and the country’s health authorities are holding their breath, waiting for the 21-day incubation period of the virus to pass – hopefully, without further cases being reported.
On average, half of those infected with the Marburg virus will die, however, mortality rates as high as 88% have previously been reported. Thankfully, Uganda has a good track record of handling outbreaks of viruses, including Marburg and its close cousin, Ebola.
The latest Marburg outbreak, in the Kween district bordering Kenya, was declared when the first case was confirmed by laboratory tests. The patient subsequently died, but, unfortunately, she had been in contact with family members, including one who travelled to Kenya. It turned out that the patient (the so-called “index case”) was, in fact, not the first case in the current outbreak.
The index case was a family member who was a game hunter who lived near a cave in which bats that harbour Marburg virus dwell. He was found with symptoms fitting with Marburg virus disease in September 2017, which however, was not confirmed through lab tests. He later died.
This has sparked a rapid and large response from the Ugandan Ministry of Health and international groups such as the World Health Organisation, UNICEF and Médecins Sans Frontières. The outbreak is being handled by monitoring and isolating close contacts of the victims and minimising the chances of further transmission of the virus. These measures have proved highly effective at controlling outbreaks of Ebola and Marburg in the past, so they should work this time as the outbreak was identified quickly by the Uganda Virus Research Institute.
Although Marburg virus is less well known than its relative, Ebola, scientists found Marburg virus almost a decade before the Ebola virus.
In 1967, three seemingly independent outbreaks of the same disease occurred in lab workers across Europe – including the German city of Marburg, from where the virus derives its name. The lab workers, who were doing polio research with apparently healthy vervet monkeys imported from Uganda, became infected with the virus and, without realising it, spread the infection to family members and healthcare workers. Seven people died before the outbreaks were finally controlled.
Since then, there have been 12 more outbreaks, mostly across sub-Saharan Africa, causing nearly 400 deaths.
The Marburg virus is similar to the Ebola virus and they are both grouped in a family of viruses called filoviruses – so called because of their filamentous structure. The virus is found in cave-dwelling Egyptian fruit bats. These animals don’t show signs of disease, but can spread the infection to any humans or monkeys that come into contact with their bodily fluids.
For humans and other monkeys, filoviruses are particularly nasty, and Marburg and Ebola viruses can kill. Patients develop high fever accompanied with diarrhoea, vomiting and extreme tiredness. Many later develop a rash or “haemmorhagic” symptoms involving bleeding from multiple sites in the body.
Filoviruses are highly infectious and spread by contact with bodily fluids, including blood. As with the Ebola virus, Marburg can also spread via sexual contact and can persist for a long time in humans.
There are no specific treatments for filoviruses and, although an effective Ebola vaccine has been used to control the spread of Ebola virus disease in humans, none are approved for the Marburg virus yet. Even though they’re closely related, Marburg virus infection is not likely to be preventable by vaccination against Ebola virus. It will need a completely new vaccine.
Will Uganda cope?
In the past decade, Uganda has faced and effectively controlled a number of Marburg virus outbreaks without specific treatments or vaccines. The early and rapid response to this Marburg outbreak suggests that the same factors that hampered an effective response in West Africa during the beginning of the 2014 Ebola epidemic are not being repeated here.
Although Uganda is experienced and well-equipped for controlling filovirus outbreaks, these viruses often spread quickly and unpredictably, are highly lethal and lack effective treatments. They are a drain on human and economic resources for any country – no matter how prepared or well equipped they are – and a very serious challenge for global health.