Genetic analysis finds Ugandan whipworm parasite has three distinct
14 January 2015
A gastrointestinal worm that infects primates and humans in
Western Uganda and thought to be one species has been found to be
three distinct genetic groups.
Although whipworms have been known for a long time, little
attention has been paid to the transmission of the parasite between
primates and humans until now. The whipworm species Trichuris
trichiura is known to inhabit both non-human primates and
However, research by Ria Ghai, a doctoral student at McGill
University, and published in PLoS Neglected Tropical Diseases,
suggests that there is one strain of whipworms found only in humans,
another strain that is only found in either black-and-white or red
colobus monkeys, and a final strain found in both humans and
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.
Ghai's research was conducted in the rainforest of Kibale
National Park in southwestern Uganda, which has one of the largest
concentrations of primates in the world. These 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
An endangered Red Colobus monkey in forest near
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
"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."
"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."
Ghai RR et al. Hidden Population Structure and Cross-species
Transmission of Whipworms (Trichuris sp.) in Humans and Non-human
Primates in Uganda. PLOS Neglected Tropical Diseases. October 23,
2014. DOI: 10.1371/journal.pntd.0003256. Open acess.