A known species of parasite that affects about 600 million people worldwide is not just one worm.
New research finds there are actually three genetically distinct groups of the Trichuris trichiura whipworm. But only one appears to be transmissible between humans and other primates.
The findings are important for public health officers around the world, researchers say.
The gastrointestinal parasite mostly affects children in developing countries. It can stunt the physical and mental development of these children, affecting their ability to learn.
The research, published in the journal, PLOS Neglected Tropical Diseases, was conducted in the rainforest of Kibale National Park in southwestern Uganda, which has one of the largest concentrations of primates in the world.
Monkeys that live there 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 that lies within one of the most densely populated agricultural regions in East Africa, with a population of 300-600 people per square km.
Researchers say 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 Ria Ghai, doctoral student in biology at McGill University.
“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.
The new molecular analysis of the fecal matter from various species, including humans, suggests that there is one strain of whipworms found only in humans, another strain which is only found in either black-and-white or red colobus monkeys, and a third strain found in both humans and primates.
“What this shows us is that we have been underestimating biodiversity,” says coauthor Colin Chapman, professor of anthropology.
“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.”
*Images of “Wild Red Colobus monkey” via Shutterstock and “Whipworm” via AJC1/Flickr