Nairobi — Anthrax has killed at least several wild chimpanzees in the tropical rainforest of the Ivory Coast - the first time the disease has been seen in these animals and in this type of habitat. As well as threatening great ape populations, the discovery raises fears that the disease could spread to humans through the illegal trade in bushmeat.

Researchers studying chimps (Pantroglodytes verus) in the Tai National Park saw eight animals disappear or die suddenly in the last few years. Healthy animals became weak, vomited and died within a few hours of symptoms appearing.

Post mortems revealed that the animals suffered massive internal bleeding, suggesting bacterial infection as a possible cause. Genetic analysis of six animals showed Bacillus anthracis, the bacterium that causes anthrax, to be the culprit.

"Finding anthrax was a big surprise," says Georg Pauli from the Robert Koch Institute in Berlin, Germany, who studied the primates. There have been no previous reports of anthrax in wild chimps, and the bacterium, which also infects humans and hooved animals, has not been found in Africa's tropical rainforests before.

"It's a serious problem for chimps," says conservationist Peter Walsh from Princeton University, New Jersey. Africa's 100,000 to 200,000 remaining wild chimps are already under threat from commercial hunting, habitat destruction and the Ebola virus. It is not clear whether the anthrax outbreak is a one-off, or if there are likely to be further incidents.

The disease could also spread to humans. The bacterium forms hardy spores that can be breathed in, consumed in contaminated food and water, or can infect the skin through human-to-animal contact.

Although illegal, the bushmeat trade continues to thrive, so hunters could catch anthrax when handling infected corpses.

It is unclear how the chimps became infected, making it hard for officials to instigate prevention and containment strategies.

One possibility is that the disease was imported from neighbouring countries, where anthrax is endemic. Deforestation means that cattle transport routes from Mali and Burkina Faso now pass close to the Tai National Park border, so the chimps may have caught the disease from passing livestock. "This is a reasonable suspicion," says Walsh.

Other suggestions are less likely, but still possible. The chimps may have ingested spores from contaminated water. But drinking sources are shared by many species, and no other animals have so far been diagnosed with the infection.

Or the chimps may have dined on contaminated antelope. But anthrax has never been confirmed in Ivory Coast antelope, and chimps have never been seen eating the animals.

Our lack of knowledge highlights the need for improved health surveillance of wild chimps, says Pauli. In response to the anthrax finding, he is helping to establish a survey to assess the disease status of the world's great apes.

The threat of the disease affecting humans is real with the current levels of illegal bushmeat trade. Although monkey and chimps are not delicacies in East Africa like they are in West Africa, now the proliferation of bushmeat trade in Kenya cannot rule out the presence of these meats in the local outlets.

An on-going analysis of meat sold in Nairobi markets indicates that over a third of samples analysed so far are not from beef, mutton or goat. They are from bushmeat.

In total, two million metric tons of illegal bushmeat are harvested each year in Africa, with an estimated 300,000 tons being consumed in Kenya.

Nigeria is the largest exporter of bush meat in Africa yet it has low wildlife population and thus may be obtaining the bushmeat from other countries.

The preliminary analysis so far only differentiates between bushmeat and the three mentioned but a further analysis that identifies the bushmeat up to the species level is underway and will be released soon.

The analysis, which is supported by the Kenya Wildlife Coalition, is bound to send shockwaves in Kenya's conservation circles, as well as to nyama choma enthusiasists. It also came at a time when major stakeholders in the conservation industry were meeting in Mombasa for a three-day conference to chart the way forward for wildlife utilization in this country.

The statistics indicate that after drugs, bushmeat trade is the second largest illegal trade in the world, worth in excess of 5.5 billion US dollars. Fifteen million animals are killed each year in the Brazilian Amazon alone.

Forty-four tons of bush meat is consumed in logging camps in Peru. Ghana trades in 140 million pounds per annum worth of bush meat.

Twenty one tons of bushmeat is sold in Ghana in one month at over 26,000 pounds.

In Ivory Coast, about $117 million is received from bushmeat trade per year. In total, two million metric tons of illegal bush meat is harvested each year in Africa, with an estimated 300,000 tons being consumed in Kenya. Nigeria is the largest exporter of bush meat in Africa yet it has low wildlife population and thus may be obtaining the bushmeat from other countries.

Last year, 82 people were caught with bushmeat while 22 have been caught this year. It is believed that this meat finds its way to outlets in Nairobi such as Burma Market, Rikana House as well as butcheries in other towns.

Wildlife experts now fear that the trade is getting out of the hands of poor people and is financed by fairly wealthy people. The bushmeat trade is now recognized as a major direct cause of wildlife decline in eastern and southern Africa.

"A DSRS survey shows that 58 per cent of Kenya's wildlife has been lost in the last 20 years and most of this is attributed to the bush meat trade," said a participant at the meeting.

There is also the danger of zoonotic diseases being passed from the animals to humans, especially viral diseases such as Ebola, Monkey Pox and Sars, which can jump from animals to humans.