Bugged: Susan Paskewitz shares why ticks, mosquitoes matter to global health

Entomology professor and chair Susan Paskewitz, right, and a graduate student check a mosquito trap as part of field research. Paskewitz, an expert on ticks and mosquitoes, is keynote speaker for the 2018 Global Health Symposium. (Photo by Jeff Miller.)

For most of us, bugs are an irritation. Mosquitoes are to be swatted. Ticks avoided. Spiders … well, let’s not go there.

For Susan Paskewitz, keynote speaker at the April 10 Global Health Symposium, insects are cool – and gorgeous – and understanding them is a way to contribute to health in Wisconsin and around the world.

Susan Paskewitz

“I am at heart a biologist who really values biodiversity,” says Paskewitz, professor and chair of the University of Wisconsin-Madison Department of Entomology, co-director of the new Midwest Center of Excellence for Vector-Borne Disease and an Advisory Committee member at the Global Health Institute (GHI). “The marquee element for me is thinking about all the wonderful life that’s out there, what it does, how it makes a living, how it enriches and supports us. At the same time, I’ve found a way to take that appreciation for nature and biology and turn it into something that has the potential to generate impacts on people’s well-being.”

This year’s Global Health Symposium, Advancing Health in Uncertain Times, is again free and open to the public. Registration is requested and check in begins at 4 p.m. at Union South on the UW-Madison campus.

Hosted by GHI, the symposium also includes a panel discussion: “Medications: Abuse, Misuse, What’s Next,” with panelists from pharmacy, public health and veterinary and human medicine. Fifteen speakers will present concurrent oral sessions on topics ranging from domestic violence to quality improvement to rural health, and posters will be on display. (Learn more details here.)

A video of Pakewitz’s talk can be found here, and a video of the panel discussion can be found here.

A safari in the backyard

When Paskewitz talks about insects and their arthropod cousins—which include eight-legged ticks—she sees diversity and talks about taking a safari in her backyard. She looks through a microscope and sees colors, patterns and a variety of body shapes that are interesting and, yes, sometimes very beautiful. Unfortunately, the adaptability that generates so much diversity also produces tiny pests that are capable of causing a great deal of harm.

“Most insects are not causing a lot of trouble and are really important to the stability of our environments, and some of them fill important roles,” she says.  “Some of them, of course, cause a lot of difficulty. Those are the ones entomologists are most focused on. … For me, because of my interest in health, that’s why insects that transmit disease became the focus of my career.”

Those insects, including mosquitoes and ticks, are called vectors, which means they can transmit viruses and other organisms that cause disease from one animal to another. With malaria, for example, mosquitoes transmit parasites from one human to another. With Lyme Disease, ticks spread bacteria that they pick up from mice or birds to humans. With Zika Virus, mosquitoes carry the disease from monkeys to humans and humans to humans.

Paskewitz started her career researching mosquitoes and malaria. When she moved to Wisconsin in 1991, her work expanded to ticks, another blood-sucking organism common here. As an expert on the biology and control of mosquitoes and ticks that transmit disease, Paskewitz also works with public health and the general public to control the pests and teaches courses in medical entomology, insect pest suppression and global health.

UW-Madison graduate student Xia Lee hunts for ticks. (Photo by Susan Paskewitz.)

The Midwest Center of Excellence for Vector-Borne Disease, which Paskewitz co-leads with Lyric Bartholomay from the School of Veterinary Medicine, was funded with a $10 million grant from the U.S. Centers for Disease Control and Prevention. It helps partners from Wisconsin, Minnesota, Michigan, Iowa and Illinois train more public health entomologists, share information on vector-borne disease and conduct research on the mosquitoes and ticks in the region. Paskewitz believes that even if she never solves the problems of Lyme Disease or West Nile virus, she can help people and communities protect themselves and respond to changes.

As she learns more about mosquitoes and ticks, Paskewitz’s fascination continues to grow. She studies their ecology, the way they make their living and how they function. “If you were to dissect a mosquito or tick, they have their own tiny little organ systems that do the same things (as humans),” she says. “They have to breathe, they have to digest food. I find that comparative aspect really fascinating.”

With her unique insight into the critters, Paskewitz also agreed to share five facts about ticks and mosquitoes that you might not know:


Out of all the thousands of insects, mosquitoes are the most important to human health because of their role in transmitting many different viruses and parasites that make a lot of people sick around the world.


Ticks are the most important for animal health because they transmit a lot of different pathogens to animals, and animals have a harder time removing them.


Both evolved to suck blood–they had to find food somewhere – usually from mammals but also birds and sometimes reptiles and amphibians. Ticks feed on blood and only blood through every life stage. Mosquitoes begin their lives in water, but adult females usually require blood to produce eggs. The blood they suck carries the pathogens that can make us sick.


Both are ectotherms or cold-blooded organisms whose bodies mimic the outside temperature. Many have physiologies that allow them to create antifreeze molecules so they don’t die in the winter. The seemingly dead mosquito on the cold garage wall is only waiting for spring to warm up again. Mosquito eggs can survive in icy water. Ticks go dormant in leaf mulch that’s a cozy retreat with a few inches of snow on top of it.


If you wait and let a mosquito finish its meal, it’ll double its body weight in five minutes – and still manage to fly away. A deer tick can swell to the size of a grape as it feeds.

Paskewitz will share how these ubiquitous– sometimes beautiful – bugs affect health during her keynote address, “Deadly Foes: Why Mosquitoes and Ticks Matter to Global Health,” at the 14th annual Global Health Symposium on Tuesday, April 10, at Union South.

By Ann Grauvogl/March 19, 2018