On the occasion of the current outbreaks of the Marburg virus in Africa, the Internet is showing itself from its best side again: The virus is a lab leak. You can find out where the misinformation came from here.
Two African countries are currently struggling with outbreaks of the virus Marburgfiebers. Already on February 25, the World Health Organization (WHO) made the first outbreak in Equatorial Guinea public. As of March 21, 9 laboratory-confirmed cases and 20 other probable cases have been reported there. Mortality is high: all of the probable and 7 of the 9 confirmed cases have been fatal so far. March 21 was the outbreak in Tanzania by the WHO confirmed; So far, 8 cases have been registered there, 5 of which ended fatally (as of March 22). Although occurring at the same time, there is no evidence to date that the two outbreaks are epidemiologically linked.
Refresher: What is Marburg fever?
Marburg fever is triggered by Marburg-Virus – a close relative of the better known Ebola-Virus. Both belong to the family Filoviren at; the courses of the disease in the case of an infection are very similar. The virus is transmitted through direct contact with the infected person’s blood, feces, and other body fluids.
The incubation period of Marburg fever is variable and ranges from 2 to 21 days. The disease begins with a sudden high fever, headache and general malaise. After a few days, heavy ones join in diarrhea, pain and cramps of the abdomen, as well as nausea and vomiting among these symptoms. Bleeding symptoms may continue for 5 to 7 days after symptom onset. In the case of a fatal course, the patient dies about 8 to 9 days after the appearance of the first symptoms.
Marburg fever mortality is high and highly dependent on the medical care available. With optimal intensive care treatment, it is around 25% – in reality it is unfortunately significantly higher at up to 90%. Targeted virostatic treatment of the Marburg virus has not yet been possible, and no vaccine is yet available. The treatment is therefore limited to symptom-specific therapies and the compensation of water and electrolyte losses.
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And the lab leak theory greets you every day…
As is so often the case, the Marburg virus is a zoonotic virus: natural reservoir hosts are flying foxes of the species Rousettus aegupticus. Transmission to humans often occurs by entering mines or caves in which fruit bats have settled. But as already from SARS-CoV-2 known, this is not enough as an explanation for some people: On Twitter, individual users describe the Marburg virus as a “lab leak”.
The reason for this is the fact that the Marburg virus was named after the city of Marburg, where the first documented outbreak took place in 1967 – among laboratory employees of the local pharmaceutical company Behringwerke. So a cultivated super virus that got from the laboratory to humans after all? A very clear no, as the virologist Dr. Angela Rasmussen unraveled on Twitter.
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In fact, the virus had simply not yet been discovered at that point in time – rather, the virus was identified for the first time at this event. How did that happen? The pathogens were brought in unnoticed from Uganda via vervet monkeys, which the affected laboratory technicians worked with. Tissue samples were taken from these infected animals, which the employees worked with largely without protection.
Example of spillover, not ruthless research
As Rasmussen explains, however, the circumstances at that time cannot be compared with today’s laboratory work. In 1967 there were no modern cell cultures, so research often had to use primary cells that came directly from the tissue of experimental animals. But it wasn’t just cell-based vaccine research that was still in its infancy at the time – safety concepts such as personal protective equipment and biosafety cabinets did not yet exist either. At that time, it was simply not known that disease transmission from non-human primates was possible in this way.
In this respect, the outbreak in Marburg was also an important experience for laboratory safety and the safe handling of biological samples. And while transmission occurred in the lab rather than in the wild, the outbreak is an example of human-animal interaction spillover. However, the whole story has nothing to do with a “Lab Lea” in which human-modified or engineered viruses are circulating.
Image source: generated with Midjourney