21:10 14 July 2008
Marburg, a deadly haemorrhagic fever closely related to Ebola, is back in Europe, after a four-decade absence.
On Friday, 11 July, a 40-year old Dutch woman died in a quarantined ward of a hospital in Leiden, the Netherlands, less than two weeks after she returned from Uganda.
She had visited caves where she may have contracted the virus on 16 and 19 June, but she developed a fever and chills – early symptoms of Marburg – only after her return, on 2 July. More severe symptoms – such as liver failure and bleeding from multiple sites – struck two days after she was admitted to the hospital on 5 July.
New Scientist takes a closer look at this mysterious and deadly virus.
Where does Marburg come from?
The first reported cases occurred in the German city of Marburg in 1967 and originated in living monkeys at a monkey research facility. In total, 31 people in Marburg and Frankfurt in Germany and in Belgrade, now the capital of Serbia, contracted the disease and seven died.
After that, Marburg disappeared from Europe but has since flared up in South Africa, the Democratic Republic of Congo and Angola, where a 2004-2005 outbreak killed 355 of 399 people who contracted Marburg.
The virus’s reservoir remained a mystery for a long time, but new research has pointed the finger squarely on cave-dwelling fruit bats. In 2007, a team of virus hunters found fragments of the virus’s genome in a species called Rousettus aegyptiacus. The species also showed signs of an immune response against Marburg, which is unlikely to cause symptoms in the bats.
But the virus may be spread via other bats that don’t stick to caves, according to Peter Walsh of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Genetic sequences show similarities between viruses from Gabon and Angola, suggesting that some cave-to-cave transmissions occur.
How deadly is the virus?
That depends, according to the World Health Organization (WHO), which tracks outbreaks of the virus. The first human cases in Germany felled just a quarter of those infected, while more recent outbreaks in the Democratic Republic of Congo and Angola have killed 80 to 90% of those infected. There is no cure, and patients often die of haemorrhaging and massive organ failure.
Is there a vaccine for Marburg?
Not yet, but several research teams have made significant progress. In 2005, a team at Canada’s National Microbiology Laboratory in Winnipeg genetically engineered an unrelated virus to produce a key Marburg protein. Macaques that received a single shot of this virus were immune to Marburg virus administered a month later.
US researchers at the National Institute of Health and in the Army took a similar approach against Ebola, stitching one of its proteins into a weakened cold virus. They say the same could be done with Marburg. Alternatively, a virus-free vaccine – made up of the proteins that coat Marburg’s shell – might work, and one such vaccine has protected guinea pigs from Marburg infection.
So far, however, no vaccines against Marburg virus have been proven effective in humans.
What should people do to protect against Marburg?
Stay out of bat caves in countries known to have Marburg, such as Uganda, says the WHO and the Dutch government.
Human-to-human spread requires close contact with an infected person while they are showing symptoms. Because the most recent victim didn’t show any symptoms while in Africa or on her flight home, only the people she came into contact with after 2 July are at risk. No one else has yet come down with Marburg.