Marburg Virus and Fruit Bats

Linkhttp://www.reuters.com/article/healthNews/idUSL1166433320080711, http://www.sciencedaily.com/releases/2009/08/090801185900.htm, http://news.bbc.co.uk/2/hi/africa/6958015.stm

Just over a year ago, on July 11th 2008, there was a report on the important ListServ Promed Ahead and some other news outlets that told the terrifying story of a Dutch tourist who had died in Holland after being in contact with fruit bats in Uganda. She had visited the Maragambo Forest in Queen Elizabeth National Park, like thousands of others before her. These thousands included me, my wife and at least fifty of my students. We had gone there because there is a cave there that is home to thousands,
if not tens of thousands of Egyptian Fruit bats (Rousettus aegyptiacus) and it is mesmerizing to watch them flit in and out of the roost, never mind to see them clinging to the rock in their serried ranks.

There was an added bonus of attraction at the cave. A pair of African Fish Eagles had taken up residence just outside the entrance – grub to go as it were. Furthermore there was a resident python. In fact the last group of students had seen two pythons. So it is probable that a little biology 101 had been taking place. No exercise need for their packed lunches!



As you can imagine, the park authorities have closed the cave to tourists. The last thing they need is another catastrophe.

The Dutch doctors who cared for the dying patient and identified the cause of her death could not be absolutely certain where the virus came from, but the evidence has now mounted and seems conclusive.

The first suggestion of the link between fruit bats and Marburg, which is closely related to the better known Ebola virus, seems to have been made in 2007, as this BBC report shows.

Then came the recent (Aug 2nd 2009) report in ScienceDaily titled
'Ebola Cousin' Marburg Virus Isolated From African Fruit Bats. To quote:- “A paper published in the open-access science journal PLoS Pathogens provides new insight into the identity of the natural host of this deadly disease.”

As the authors of the PLoS article state, this brings the identification of the natural host of Ebola one step closer, as fruit bats are also strongly suspected in this disease. The first indication of this may have been in a 2005 paper in the prestigious journal Nature that can be found here.

There is one more important part of this chain. Fruit bats are a major source of bushmeat in the forests of central Africa. They are also pretty easy to catch when they return to their roosts during the day.

How many human forest dwellers have died of one of these deadly diseases and not even been noticed?

Queen Elizabeth National Park bat caves and possible disease link

Interesting to see that a case of fatal Marburg Hemorrhagic Fever (MHF) has been linked to the Maramgambo bat cave in Queen Elizabeth National Park in Uganda. I picked this report up on the important listserv PRO/AH> ProMED-AHEAD Digest of 11th July, a service to which I have been subscribing for several years.

The report describes how one unfortunate Dutch tourist, visiting the cave that is the roosting site for thousands of Egyptian Fruit Bats went down with the disease not long after she returned home and died soon afterwards despite heroic care. Genetic analysis of samples showed that her condition was indeed caused by a previously unreported type of this virus. Marburg HF has been seen before in Uganda and the DRC. One of the list’s moderators wrote, “The involvement of cave-dwelling bats in transmission of the disease is compelling, but still circumstantial.” In the last case of Marburg disease reported in Uganda the death of one man was established as being linked to his skinning of a colobus monkey.

My interest is more than merely academic. I have been to the cave several times, each time with up to a dozen students, both Canadians and Ugandans, as we have studied the human x wildlife x livestock interface. Our students, seen here at the cave entrance, not only see a seething mass of bats, but there is at least one cave-dwelling python. Packed lunches, as it were.

An African Fish eagle seems to have taken up residence nearby, abandoning his more normal diet for a guaranteed lunch-on-the–wing . At least when I have visited one of these magnificent birds is usually hanging out with 15 metres of the cave entrance. The one shown here had just taken a fish in the Okavango swamp.

In other parts of Africa Egyptian Fruit bats are known to harbour filoviruses, the group to which MHF belongs. (Marburgvirus, fruit bats - W. Africa 23 Aug 2007: ProMED-mail.

If the Marburg and Maragambo bat link is clearly established the cave might fall off our list of places to visit.

The list reports very frequently, sometimes as much as three times a week, on infectious diseases of animals (including humans) from around the world. Avian ‘flu is a hot one right now, anthrax features with great regularity, but the moderators play no favourites, and anything is up for report, with pithy comments where needed. Subscribers are invited to add comments when they feel inclined

For another way to find out what ProMED can do, especially for those who enjoy a good read, I can recommend The Eleventh Plague by Dr. John S. Marr and John Baldwin. This novel is based on the efforts of a mass murderer to terrorize with the threat of a new plague, an eleventh, as he causes havoc by killing off people with horrifying ease in ways that mimic the Biblical plagues of Egypt. The authors show the world-wide power of ProMED and its subscribers as they race to solve the riddle before it is too late. Any more and I’ll be giving away too much of the story, but the dedication is important. It reads, in part, “This book is dedicated to (these) scientists (several groups are named) and to ProMED-mail.”

Ryan commented on this posting and I have replied in the comments box, but I think it may be worth adding here as well, in case a reader does not want to go to comments.

I should have added, in the original, that Marburg virus is in the same family as the better-known Ebola virus, and produces about the same effects. Ebola has not only been linked to many deaths in people, but has caused wide-spread epidemics in great apes. Dr. Jane Goodall told me how an acquaintance of hers who studies gorillas has lost her entire study group to this scourge, not once, not twice, but three times!