McGill. Canada: Research on whipworms has implications for human health and animal conservation. About 600 million people around the world live with whipworms. Most are
children in the developing world, whose physical and mental development
is stunted by these gastrointestinal parasites.
The whipworms affect
their ability to learn and therefore have a long-term impact on the
social and economic situations of some of the world’s poorest people.
Although the whipworm species Trichuris trichiura is known to
inhabit both non-human primates and humans, little is known about the
parasite. Indeed, until a recent study by Ria Ghai, a doctoral student
in biology at McGill, it was widely assumed that a single species was
capable of infecting both primates and humans. But Ghai has discovered
that there are three genetically distinct groups of whipworms – and only
one of the three appears to be transmissible between humans and
non-human primates. It is important information for public health
officers around the world.
Ghai’s research, published recently in PLoS Neglected Tropical Diseases,
was done in the rainforest of Kibale National Park in southwestern
Uganda, which has one of the largest concentrations of primates in the
world. The trees are alive with monkeys, and include endangered species
such as the red colobus monkey, the eastern chimpanzee, and the rare
l’hoest’s monkey as well as more common species, like baboons. In all,
there are 13 different species of primates within the park. But the
park is an island of forest within one of the most densely populated
agricultural regions in East Africa, with a population of 300-600 people
per square km. And there is increasing human pressure on limited land
and growing interaction between the two groups.
“The park has been a protected space since 1993, but for a very long
time people have been going into the forest to gather wood to burn and
banana leaves and grasses to weave with, as well as to hunt bush meat,
and it’s hard to change habits when people are in such need,” says Ghai.
“The monkeys also come out of the park to raid the fields for maize and
sweet potatoes. So in a place where there is little running water to
wash either food or hands and where people walk barefoot wherever they
go, it is not surprising that there is an exchange of fecal matter
between humans and primates that has led to the transmission of
whipworms.”
Although researchers and medical people have known about whipworms
for a long time, people have paid little attention to the transmission
of the parasite between primates and humans until now. Ria Ghai’s
molecular analysis of the fecal matter from various species, including
humans, suggests that there is one strain of whipworms t found only in
humans, another strain which is only found in either black-and-white or
red colobus monkeys, and a final strain found in both humans and
primates.
“What this shows us is that we have been underestimating
biodiversity,” says co-author Prof. Colin Chapman, from McGill’s
Department of Anthropology and School of the Environment who has been
working in the area for many years. “There are far more species of
parasites around than we had expected, and we hope this new information
will be useful both for conservationists and for people working in
health policy.”
To read the full article in PLoS Neglected Tropical Diseases: http://www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd.0003256