- David Wolking
The caves were interesting, full of bats. At this chamber you could just hear all the bats surrounding you and when the guide point to the inside of the chamber you could see hundreds of bats just flying around. - Melvin (a tourist in Tanzania at the Amboni Caves, Tanga Region)
Cave tourism sounds like a great time. You shimmy down through a limestone tunnel into a large cavern in the dark, headlamps shining sporadically on stalactites and casting eery shadows, the echo of your voice and of dripping water, and the chirping of cave bats. Cave tourism also means big business. Mammoth Cave National Park generates an estimated $64 million for the south central Kentucky area each year.
But cave tourism also presents certain risks. Beyond the fear of headlamps dying out leaving you in the dark bowels of the earth without Batman's utility belt and his famous nightvision Bat-goggles, there is the risk of disease both to you and to those happily chirping and roosting bats.
If you somehow missed the plethora of news reports, White-nose Syndrome (WNS), a fungus infecting bats and causing them to awake more often during hibernation, has been associated with the deaths of 5-6 million North American bats. The rapid spread of WNS and uncertainty about its spread and transmission has lead the US Fish and Wildlife Service to declare a moratorium on caving activities in affected regions, as it is suspected that the fungus is transported through soil via clothing and boots of cavers.
But bats are not the only ones that can get sick when hanging out with people in caves. We know bats harbor a lot of disease causing organisms, including viruses like rabies, Marburg, and coronaviruses like SARS, and people visiting caves have been infected and in some cases even died from these viruses.
Caves are fascinating ecosystems, and cave-dwelling bats live in amazingly social, interesting colonies. A recent article in PLOS Pathogens describes the behavioral characteristics of Egytian fruit bats in Python Cave, Uganda, a popular cave tourist destination associated with recent Marburg virus outbreaks. In Python, the fruit bats compete for roosting space in the cave, with juvenile sub-adult bats dwelling in less secure locations in tight clusters near the floors and cave entrance, locations with higher risk of predation (it is after all Python Cave), and where they get shit on. Literally. Roosting near the floor of the cave means all your relatives and elders above urinate and defecate on your head, a risk factor for viral exposure the researchers speculate is linked to seasonal pulses of Marburg virus circulation in this sub-adult demographic. So, to make a long story short, all that guano cave tourists are trudging through could be infectious, it could make you sick.
I stress that it could make you sick because in a lot of cases we don't really know. Even in the Python Cave study, the researchers were unable to detect Marburg virus in the bat guano. But we do know people visiting caves, or working in mines or abandoned mine shafts have gotten sick from viruses linked to bats in the past, and have died. The risk is there. Cave tourists beware.
What does this have to do with HALI?
Our PREDICT project field team is in northern Tanzania this month capturing bats and rodents at high-risk human-wildlife contact interfaces, like the cave tourism context, where people might get sick from wild animals. One of the places they are visiting is the Amboni Caves, where our friend Melvin (quoted above) saw so many bats. Amboni is a popular tourist destination and the largest cave system in East Africa. Lonely Planet even advises cave visitors to "wear closed toed shoes to avoid picking bat droppings off your feet." Nice - some inadvertent disease risk prevention advice from the travel gurus!
We hope to capture and sample some of the Amboni cave bats and investigate them for viruses that may be harmful to people. By looking at bat feces (and other samples), we can determine if there are infectious disease risks to cave visitors and other high-risk groups like the cave guides. If Zika brought his utility belt, we may even get some good pictures from Amboni to share, so tune in soon, "same bat-time, same bat-channel..."