A different perspective on parasites

UND researcher Vasyl Tkach finds parasites fascinating, not terrifying

Vasyl Tkach, professor in the UND Department of Biology and president-elect of the American Society of Parasitologists, sees parasites as an interesting life form that’s part of the natural ecosystem. Photo by Patrick C. Miller/UND Today.

To most people, a parasite is an organism that creates feelings of fear and revulsion, a creature that exists to feed off a living host to sustain itself.

But as a parasitologist, Vasyl Tkach, a professor in the University of North Dakota Department of Biology and president-elect of the American Society of Parasitologists, doesn’t share this view.

“In general, not every parasite is linked to a disease, but that’s partly because we don’t know enough about them,” said Tkach (pronounced T-Catch). “Those parasites that are known to cause detectable harm are a very, very small proportion of parasites. Others are just really interesting animals from evolutionary viewpoint.

“It’s a biodiversity that is hidden and not easily observed even by experts, but nevertheless, it’s there,” Tkach continued. “It’s potentially the most common way of life in animals because about half of all animals on earth are parasitic.”

Throughout a career spanning more than 30 years, Tkach – a native of Ukraine – has described about a hundred new species of parasites, published 250 peer-reviewed articles and book chapters, and been honored as one of the top parasitologists in the field. Some of his UND graduate students have also become leading researchers in parasitology.

Zoology to parasitology

UND professor Vasyl Tkach works in a makeshift laboratory in a field camp on Mount Kenya, the second highest mountain in Africa. His study of parasites has taken him every continent except Antarctica. He has also collaborated with more than 300 researchers in 30 countries. Photo courtesy of Vasyl Tkach.

In the early 1980s, Tkach entered Uzhgorod State University in Ukraine thinking his goal was to become a zoologist. But sharing a dorm room with two roommates who studied parasitology changed his mind and the course of his education.

“The first time I saw a living creature inside another living creature, I got immediately attracted to that,” he recalled. “Maybe it’s kind of scary for the general public, but it’s an amazing way of life.”

The research conducted by Tkach and other parasitologists is changing our understanding of parasites. For example, parasites might even be beneficial in helping humans strengthen their immune systems.

“There are serious studies going on now using parasitic round worms to deal with autoimmune diseases and immune disorders,” Tkach said. “If your body is not exposed to potential pathogens and alien organisms, your immune system is not well enough trained. Wild animals don’t have this problem. Essentially, every wild animal has a parasite of some sort, but not all of them get sick.”

While many people are repelled at the idea of having something living inside them that can cause physical harm, serious diseases and even death, Tkach believes playing the public’s fears by portraying parasites in a sensational manner isn’t helpful. As an example, he points to Animal Planet’s “Monsters Inside Me,” a TV show the network describes as telling “the real-life harrowing dramas of people infected by deadly parasites.”

“Unfortunately, the media mostly tries to scare people and shock them instead of educating them,” he noted. “The point often missed is that a very high percentage of the animals on the planet are parasitic. They are underestimated and often overlooked. They’re part of natural ecosystems. A shift in the balance of the ecosystem causes changes in parasites, as well as in animals, that we otherwise can’t see.”

Problem parasites

The study of parasites assists the medical and veterinary communities in helping to identify unexplained illnesses and develop potential cures, Tkach said, further illustrating the value of parasitology.

“I receive requests to help identify parasites from zoos and veterinary professionals when they encounter unusual parasites,” Tkach said. “It’s very difficult to know what it is because there are thousands of these species. They don’t teach about all of them in regular university courses because it’s impossible.”

His primary research interest is in phylogenetics, the study of how organisms evolve and how they are related to each other. Tkach last month co-authored a paper in Scientific Data, one of the peer-reviewed research journals published by Nature. The paper discussed the genome of a tapeworm used as a model species around the world. He is also a part of the research team that recently published a series of works in high-profile ecological journals on global avian malaria, with an emphasis on South and North America.

This image of a parasite shows hooks on the head of a Taenia tapeworm, found in humans, domestic animals and wildlife. Parasites use the hooks to anchor themselves in the intestine of their hosts. Photo courtesy Vasyl Tkach.

“Malaria is the most important human parasitic disease,” Tkach said. “However, humans have only four or five species of malaria, while birds have hundreds.”

Tkach has traveled to every continent except Antarctica to study parasites in animals from fish to birds to reptiles and humans, while engaging in international collaborations with more than 300 scientists from 30 countries.

“For instance, parasites of crocodilians give us insight into what was happening before the supercontinents broke up into smaller pieces,” he said. “Crocodiles floated their way to these new pieces of land. They already had the parasites inside them over 100 million years ago. We can track that now using molecular genetic methods.”

Tracking climate change

Tkach, whose work has been primarily funded by the National Science Foundation (NSF) during his 17 years at UND, recently submitted a proposal for review to the organization to study parasites in the Arctic as a way to measure their response to climate change.

“Parasites are very sensitive to that,” he said. “They reflect the changes, sometimes better, because they have complex lifecycles that require vertebrates – like small mammals – and invertebrate animals.”

Tkach said the ability to easily transport people, animals and materials around the world has led to the introduction of parasites into regions where they weren’t previously known – another reason for studying parasites through international collaborations.

“Parasitic worms called helminth – roundworms, tapeworms and flukes – can cause direct harm,” he said. “The harm from the parasite side is because they consume resources and cause physical damage. Usually, much or most of the harm is caused by our own reaction to the infections these parasites cause. The host’s organism can underreact or overreact to it – both are bad.”

Parasites in paradise

The larval stage of the Trichobilharzia parasitic flatworm is the most common cause of swimmer’s itch or cercarial dermatitis in the Northern Plains region. The black eye spots and large glands produce secretions that help the parasite penetrate skin. Image courtesy of Vasyl Tkach.

While Americans might think of parasites as being found primarily in poor countries or in remote tropical locations, Tkach said they are quite common in the United States – including the Northern Plains. Anyone who’s experienced “swimmer’s itch” (cercarial dermatitis) after swimming or wading in the warm water of a lake or pond has had a parasitic encounter with blood flukes that caused an allergic reaction.

In addition, introduced parasites can have a profound effect on wildlife.

“An alien snail was introduced to Minnesota not long ago,” he said. “We really don’t know how. It was a suitable host for a fluke and that resulted in huge mortalities of ducks in some Minnesota lakes. Thousands and thousands of ducks died from these invasive parasites.”

Rather than fearing parasites, Tkach believes the best approach is to become educated about them and understand how to avoid getting them. When planning a visit to an exotic vacation spot, he encourages travelers to do research and learn whether there are any parasitic diseases found in the area. He recommends a visit to the Centers for Disease Control and Prevention website.

“There are parasites in paradise,” Tkach wryly observed. “It might look idyllic with white sand and blue skies and blue ocean and all that, but you still have to remember what’s under your feet and what you eat. What you eat is a big part of it.”

Sometimes breaking the cycle that enables parasites to enter a host is as simple as wearing flip flops, using bug repellent, staying out of stagnant water, eating properly cooked food or employing mosquito netting around a bed at night.

“I’ve been to the Philippines, Vietnam, Thailand, Laos, Kenya, Malawi, Central and South America, and I have never gotten any parasitic tropical diseases because I’m educated about them,” Tkach said.

During his world travels, Tkach often organizes educational workshop on parasites for students. There’s never a shortage of interest or participants. The American Society of Parasitologists’ Facebook page features a new parasite each week, leading to interesting discussions among Tkach and his colleagues, sometimes about new discoveries and current events involving parasites in the news.

“Education may help fight diseases, sometimes more than drugs,” Tkach said. “On one of my recent trips to Peru, I gave workshops at five different local universities a week. I can’t say ‘No’ because that’s how you educate people and popularize the science.”

To learn more about Tkach’s work, visit his website.