28 January 2013

Uganda: Why Are Hippos Dying of Anthrax?

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Celsus Sente is just beginning his work as a RISE student, but he brings to it a wealth of diverse experiences in several fields and a fervent curiosity about nature.

As a Ugandan born in the remote western district of Rubirizi, he grew up near the Queen Elizabeth National Park, which is 764 square miles of rich, diverse terrain that spans both Uganda and part of the adjacent Democratic Republic of Congo.

When he was studying Veterinary Medicine as an undergraduate at Makerere University, he met Ludwig Siefert, a lecturer and lion researcher at the university who has worked for three decades towards the conservation of lions, leopards, and other large carnivores which have suffered massive and indiscriminate poisoning and poaching. Celsus began to tag along as his mentee, learning much about the park from him.

After earning his bachelor's in Veterinary Medicine, he immediately enrolled for a master's degree in Wildlife Health and Management, also at Makerere. While studying he got involved in small projects here and there, including a study on community attitudes toward rhino conservation in Uganda.

Celsus was later involved in mass vaccination and treatment of various diseases in domestic animals at the human-livestock-wildlife interface at the Bogoria Game Reserve in Kenya; he notes that this was one way of involving rural communities in wildlife conservation.

In the winter of 2006, he went on a brief sojourn to United Kingdom, where he took a short course in Poultry Health at the Pirbright Institute (formerly the Institute for Animal Health) and participated in a barn owl workshop at Monks Wood Experimental Station in the East Midlands. In 2007 and 2008 he lived and worked in Norway as a wildlife biologist and veterinarian, developing his skills in wildlife handling and restraint.

Returning to Uganda in 2009, he secured a post at Makerere as an assistant lecturer, where he became interested in wildlife diseases, especially anthrax, on which his PhD study is based. Celsus heard about RISE from professors and colleagues at Makerere who had been participating in the program from the outset. "They were looking for someone to conduct water-related research," he recalled, "and I had already become interested in water and anthrax."

Anthrax, a highly infectious bacterial disease, is familiar to many people for its virulence and occasional use as a sensation-getting tool of bioterror. In the U.S., for example, much of the country was riveted by the anthrax attacks of 2001, when letters containing anthrax spores were mailed to the offices of several news media offices and two U.S. senators, killing five people and infecting 22 more. During the 1970s, the Soviet Union produced hundreds of tons of weapons-grade anthrax, though it was never deployed.

In its natural environment, anthrax most commonly infects wild or domesticated herbivorous mammals, such as sheep, cattle, and goats. These animals may ingest or inhale the bacterial spores while grazing, and in turn may pass the disease to humans. People most at risk include farm workers, veterinarians, and woolworkers.

Disease begins when the bacterial spores "germinate" or sprout, releasing toxic substances that cause internal bleeding, swelling, and tissue death. Once the spores reach the bloodstream, anthrax is usually fatal. Another menacing feature of anthrax is that the spores may remain viable for decades and even centuries. The disease once killed hundreds of thousands of people and animals annually before Louis Pasteur developed the first effective vaccine in 1881.

Anthrax is a perennial problem in the Queen Elizabeth National Park. In 2004 to 2005 and in 2010 a number of hippos were reported dead in the Kyambura River and Kazinga Channel, which supplies water to fishing communities and to wild and domestic animals.

Kyambura Gorge harbors a diversity of wild animals that are easily exposed to anthrax outbreaks, making it a possible hub for anthrax spillover into livestock and humans. But little is known of the cycles that allow anthrax to persist in the hippos' environment.

"We know the hippos die," said Celsus, "and we know they die of anthrax. We know that the soil is the reservoir for the bacteria, but probably, without water collecting, concentrating and distributing the spores, there would be no anthrax. And that is all we know.

The outbreaks in the hippos mostly occur right after the rainy season, so the water plays a crucial part in the anthrax cycle. I want to see how it collects and disperses anthrax spores, and learn to model future outbreaks." It is important to relate stagnant water and free flowing water with the physico-chemical nature of the landscape, water flow pattern, presence/absence of anthrax spores in the environment, and geospatial distribution of ecological risk determinants.

Another dimension of his project is the place of humans in the anthrax cycle. In this rural region of Africa, hippo meat is revered, and the local people cannot resist an easy meal of fresh dead hippo meat. As a consequence, many people die of anthrax from eating the hippos.

The number of deaths is unknown, but Celsus is determined to explore this ongoing mystery. "The people won't talk about how many people die, because they know that eating hippos is illegal. But they will often talk about it at drinking joints or during any other casual talk session, as long as they trust the people they are talking with."

Many of the large animals of the park were killed during the Uganda-Tanzania War of 1978-79, which led to the overthrow of Idi Amin. Since then these populations have largely recovered, but anthrax remains a continuing menace.

Celsus' work through RISE will include collection of soil and water samples in the dry and rainy seasons to capture the seasonal variation in anthrax. In addition, he will review scientific reports and literature and hold Focus Group Discussions (FGDs) to capture the views of communities.

The reports and FGDs will give insight into the temporal trend of anthrax in QEPA. Through transect walks, boat rides, and observation facilitated by GPS, the spatial dynamics of anthrax and landscape features will be determined.

The laboratory phase will involve analysis of soil and water samples for physico-chemical properties, presence/absence of anthrax bacillus and isolation of DNA. The title of his proposal is "Ecohydrological Risk Determinants for the Prediction of Anthrax Outbreaks in Queen Elizabeth Protected Area."

Among the chief mysteries is whether animals can catch anthrax directly from water, and Celsus Sente hopes to break new ground on this question. When the rainy season begins, the water accumulates in low-lying spots, valleys, dams, pools, and drainage channels where the hippos congregate and begin to die. Celsus will begin his studies here.

His long-time collaboration with Dr. Siefert will be invaluable, both for Dr. Siefert's long experience and for his access to remote regions. "I will help him in his work," said Celsus, "and he will help me. He has a vehicle, which I don't have, and I will depend on our friendship for my RISE project."

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