Marburg virus, bird flu and the bats out of hell

Pandemic influenza gets its share of headlines but there are other viruses out there that also are good tabloid fodder, most notably Ebola virus which causes Ebola hemorrhagic fever, whose gruesome effects were depicted in Richard Preston's book, The Hot Zone. Ebola has some close relatives in the filovirus family, among them Marburg virus. Like Ebola it can cause a gruesome demise. Marburg has cause several outbreaks in Africa, one of the largest in Angola at the end of 2004, early 2005 (see the Wikipedia article on Marburg for more details). One of the enduring mysteries is where the virus is found in nature, that is, what animal or animals are the reservoir for Marburg? A recent report in PLoS ONE, provides one clue:

Scientists have found the deadly Marburg virus in one type of African fruit bat, the first time it's been detected in an animal other than a monkey. The bats were collected in the West Africa countries of Gabon and the Republic of Congo, but the test results support a theory that bats caused two recent human Marburg cases in nearby Uganda, health officials said.

Scientists are not sure how Marburg is transmitted to humans, but for years they have suspected that bats might be helping to spread the disease.

[snip]

In the new paper, published in PLoS ONE, an online journal, Towner and other scientists say they tested more than 1,100 bats representing 10 species. They found Marburg in only one species, Rousettus aegyptiacus, a common type of fruit bat that lives in caves. Four bats tested positive for the virus, and 21 tested positive for at least low levels of antibodies to the virus, suggesting they had been infected by the virus, Towner said. (Boston Globe)

Bats were suspected because of recent evidence they were also one reservoir for Ebola virus.

So this brings up another question: how many species of animals besides birds have been tested as reservoirs for influenza A/H5N1? We've seen reports of feral cats, large cats in zoos and dogs and pigs, among other animals and we know it can infect mice and ferrets. Most of these are probably dead end or incidental hosts (although we don't know this for sure), but wouldn't it be important to know if there were some large reservoir besides birds out there for this virus? Is anyone conducting a large scale survey like the Marburg bat study?

Just asking.

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I remember a Hanta virus in fruit bats infected pigs in, where was it, Malaisia? Anyway, the pigs got infected by eating the remains of the fruits the bats had eaten from an overhanging tree. Shit happens.

By christian (not verified) on 24 Aug 2007 #permalink

I think you're thinking "Hendra virus," not "hanta virus". Nipah and Hendra are related viruses discovered in outbreaks like you mention, and yes, are thought to have bat reservoirs.

And yes, a study like that for H5N1 would be great--as would better studies of bat immunology, so we can figure out just how the heck they carry so many viruses which are deadly to humans, but rarely seem to harm the bats.

Hi Tara and Christian. Is it Hanta or Hendra? (the link doesn't seem to work) I am looking at a colonial disease in Mexico known as 'Cocolitzli'. It was the most devastating epidemic of the colonial period and was what brought the indigenous population to its low point. Interestingly it was not recognized either by Spanish or Indian doctors, so was not just an 'Old World' disease like smallpox to which Indians had no immunity. It also affected Spaniards, though apparently was not as deadly to them. But it seems to have been an 'emerging infectious disease' at the end of the 16th century.

I suspect that newly introduced domestic animals may have had something to do with this disease, but since we haven't identified the organism its hard to speculate. The most common proposal today is Hanta virus. The link between fruit bats and pigs could be important in this context.

Ron. Hanta virus, I believe is the one carried by the Deer Mice first from observed in the Southern USA and Mexico...and I believe now has moved north into Canada.

That is correct. Hantavirus is spread by deer mice and though they are asymtomatic, their feces contaminate areas of human occupation. But the deer mouse is native; what we are trying to explain is why Hantavirus Pulmanary Syndrome (if that is cocolitzli) became so virulent. For example, were other strains introduced from the Old World allowing recombination etc, ie the old familiar old story of highly pathogenic viral outbreaks?

Hendra virus (formerly called equine morbillivirus) is a member of the family Paramyxoviridae. The virus was first isolated in 1994 from specimens obtained during an outbreak of respiratory and neurologic disease in horses and humans in Hendra, a suburb of Brisbane, Australia.

Nipah virus, also a member of the family Paramyxoviridae, is related but not identical to Hendra virus. Nipah virus was initially isolated in 1999 upon examining samples from an outbreak of encephalitis and respiratory illness among adult men in Malaysia and Singapore.

CDC website......

By M. Randolph Kruger (not verified) on 24 Aug 2007 #permalink

There are several different species in the Genus Hantavirus. The one primarily responsible for Hantavirus Pulmonary Syndrome (HPS) in the Southwestern US is the so-called Sin Nombre virus. It is different than the "old world" species that primarily cause hemoragic fever with renal syndrome (HFRS - formerly Korean hemorragic fever), a syndrome first recognized during the Korean war, and coming from the area around the Hantan river (hence the name Hanta virus). A quick overview is available on Wikipedia here:

http://en.wikipedia.org/wiki/Hantavirus

Not sure who has done any wildlife studies on bats looking specifically for AI. But it's not out of the realms of possibility. Those things are super-reservoirs (see the brand spanking new reovirus they found in July)...makes me cringe everytime I go past the flying fox colony...

http://www.pnas.org/cgi/content/full/104/27/11424

By Jon Herington (not verified) on 25 Aug 2007 #permalink