Bats and viruses, a continuing love affair

Bats continue to be an intriguing player in the field of wildlife disease. Beside the fact that they carry disease pathogens, they can carry human disease pathogens - and crazy fatal ones to boot! Most of us don't have to worry about this, but if you are a horse rancher in Australia  or a pig farmer in Malaysia or Singapore - be careful! Two of the most deadly and thus fascinating human diseases (in my opinion) to erupt in recent years have taken hold in these areas. Hendra and Nipah viruses are current examples of what disease researchers call spillover events. In short, this refers to the 'fuzziness' of the boundaries separating humans, domesticated animals, and wildlife. As our worlds come into more contact with each other, it makes sense that we all start swapping pathogens and start getting new diseases from them.

The tricky thing is, you can't just say, 'Oh this animal has no visible disease symptoms, I'll be safe, my contact with it won't result in me catching anything bad." We are becoming more aware that some pathogens, while living just fine in one type of animal , can inflict surprisingly detrimental harm as soon as it "spills over" into a new animal host. It's like seeing the mild-mannered Dr. Jekyll turn into a violent, inflammatory Mr. Hyde! The term researchers use for the animal host that physically tolerates and harbors the pathogen is reservoir species. A lake reservoir holds water much like a reservoir host stores (and transmits) the pathogen.
When the pathogen is transmitted to a new/different host, i.e. a host who has never encountered this pathogen in its evolutionary history, its body can basically flip out and go bananas. The new host will likely get sick from having this foreign invader and in the most dire scenario, might even die from it. The cascade of these events are varied and dependent on A LOT of things. Many people spend their whole research careers trying to tease apart this puzzle so I won't try to here. But what is it about bats that make them so special? There are plenty of ideas: http://cmr.asm.org/content/19/3/531.abstract, http://onlinelibrary.wiley.com/doi/10.1111/zph.12000/abstract (from my labmate, Paul Bradley). Bats hang out in large groups, are highly social, eat a variety of plant/animal/bug material, can fly (!), all the while being warm-blooded mammals like us! It will be interesting to see what comes of this line of disease research...

For now, you can read more on:
- this Wikipedia page [http://en.wikipedia.org/wiki/Henipavirus]
- this CDC website [http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/nipah.htm]
 - this Nature piece from 2006 [http://www.nature.com/nrmicro/journal/v4/n1/abs/nrmicro1323.html]


UPDATE Feb-16-2013:
I just found out a group of researchers have evidence pinpointing bats as being the reservoir host for the Ebola virus in Bangladesh [http://www.sciencedaily.com/releases/2013/01/130116163819.htm]

And this just came in the recent issue of Nature: Bats as disease reservoirs. Let me know if you are interested in this article :)