Human Tuberculosis in wildlife

I picked up this interesting item on the Wildlife Disease Digest listserve (wdin@usgs.gov) of today's date. They run a blog (here) that covers many topics, and this one caught my eye. It concerns a recent article in the Times of South Africa has highlighted a problem that is likely to get worse as human populations expand and wild animals become more and more crowded and pressurized by people. The headline reads Human TB Strain Jumps To Animals and the key sentence reads “The human strain of the disease has been found in springbok, mongooses, baboons, chimpanzees and, most recently, a Maltese poodle." (Note the incorrect use of the plural mongooses, with the extra "s") The full story can be found here.

Of course this article builds upon scientific reports from authors working in other regions, most notably Botswana and South Africa, where the human form of the disease, caused by Mycobacterium tuberculosis has been found in both banded mongoose and meerkats (aka suricates).

An important journal article published in the journal Emerging Infectious Diseases by Kathleen Alexander and her co-investigators that describes the situation can be found here. Simply put, the animals had probably been exposed to the human form of tuberculosis at rubbish tips, or by investigating sputum that passers by had spat on to the ground. As Tb is the world’s most important infectious disease, and appears to manifest itself even more rapidly than before when a person is infected with HIV/AIDS, the risk to the animals is hugely increased.

We have seen examples of this self-same situation in Uganda, where, I had taken students from the Western College of Veterinary Medicine in 2003. The trip was the first in what has become an annual rotation for final year students enrolled in the college, and it is called the “African Wildlife Experience.” (you can find out more about at the 2007 and 2008 students blogs here.) Our goal is to link closely with students and faculty of the Makerere University Veterinary school, specifically the Department of Wildlife and Animal Resource Management (aka WARM).

In 2003 we saw a severely emaciated warthog (seen here) at Mweya, in Queen Elizabeth National park, and Ugandan faculty member Dr. Ludwig Siefert obtained permission to immobilize it and carry out a necropsy. We all saw lesions in liver and lung that looked very much like Tb, just like these small white spots in the liver, but to date we have had no confirmation of culture results.

The connections to human and other animal activity are interesting and convoluted. The warthogs in and around the lodge and backpacker’s hostel are totally habituated and can be found rooting in the garbage at any time – witness these two photos. Not only are they habituated to humans, but they have an amazing symbiotic relationship with banded mongoose, the same species that has been diagnosed with Tb in Botswana.

As this photo shows, the mongoose will clamber all over a warthog, appearing to search for food goodies that may range from ticks to skin scraps and who-knows-what else. Warthogs will lie down and solicit attention as soon as they see a mongoose.

Most alarming has been the recent finding in the park of an elephant that had lesions resembling Tb. We are going to Uganda again in February, and will hope to learn more. I wonder if the elephant is the bottle-raised Maria, seen here near the hostel and very near a group of warthogs, that has been a more-or-less permanent resident of the area. In 2003 she tried her damndest to get into our rooms, convinced that the bananas unwisely stored there were for her. The only problem was that she could not get her 40 inch wide frame through the 30 inch wide doors. She did manage to drink the wash water that one of our students had so carefully collected.