Parasites represent new opportunity for University of Utah Biologist 

By Javan Rivera

Peromyscus maniculatus, more commonly known as the Deer Mouse

Parasites are beautiful. They are amazing and interesting.

Those are not the words that the average person associates with the worms and parasitic creatures that reside within the intestines of various mammals. However, graduate student Craig Gritzen of the University Of Utah Department Of Biology is not the average person.

For Gritzen, the various parasites that reside within the intestines of the local deer mouse and their possible connections to the Sin Nombre Virus (SNV) represent the sum of his entire graduate career and research.

“It is cool and important because these parasites are [possibly] important, immunologically, to these mice,” said Gritzen. “It’s a very complex field of immunology.”

While Gritzen feels confident that there is a link between the parasites and the immune system of the mice, he stressed the fact that no link has yet been identified or proven.

Gritzen is currently pursuing a Master of Science in biology at the U, but his interest in mice and the parasites that infect them began during his undergraduate career at Penn State University.

As an undergraduate, Gritzen chose to focus his studies on infectious diseases. He said that for the most part he was interested in the diseases that could infect humans, but that through those studies he became interested in diseases that could jump from animals to humans.

“Those core classes sparked my interest in studying diseases in wildlife,” Gritzen said of his time at Penn State.

He first began studying parasites that infected the white-footed mouse in Pennsylvania during his junior year. During that year, he began working with Professor Peter Hudson doing fieldwork, including setting the traps for the mice and collecting samples for the research.

It was through this work that he secured a spot in Hudson’s lab studying the complex lifecycle of the parasites that infected the white-footed mice. His work mostly consisted of studying crickets that acted as a secondary host for the parasites that infected the mice.

“My tasks there consisted mostly of field work,” Gritzen said. “We’d collect the crickets and dissect them to verify that they had the parasites in them.”

His work with the labs at Penn State went on for two years before he finally graduated with a Bachelor of Science and applied for graduate school at the University of Utah.

According to Gritzen, he was drawn to the parasite studies that were going on at the U. It provided him an opportunity to continue to apply his knowledge from his undergraduate career into his graduate work.

“The research experience [at Penn State] prepared me to conduct the research I’m doing today,” Gritzen said.

Gritzen currently works in the Dearing Lab at the U. The goal of his research is to see if a connection exists between the various intestinal parasites that infect the deer mice of Utah and the deadly virus the mice carry.

Sin Nombre Virus, Spanish for the “No Name” virus, first came into public awareness when a deadly outbreak of the virus killed a number of people in the four corners region in the early 90s. The virus, which is a type of Hantavirus, is spread to humans through the inhalation of airborne fecal particles, when people attempt to clean up deer mice droppings that they find.

“Understanding what parasites are infecting these mice and identifying the effects of these parasites on the mice, will allow researchers to understand whether the parasites will increase or decrease the likelihood of the mice becoming infected by the virus, which in turn can determine the likelihood of humans getting infected due to close proximity to the mice,” Gritzen said.

Gritzen believes that discovering a connection between the parasites and SNV could allow future researchers to predict SNV outbreaks in mice populations in the future, thereby, increase preventative care taken by humans who live in close proximity to the mice.

In his time researching at the Dearing Lab, Gritzen has found eight species of intestinal parasites that infect the deer mice he is studying, and has been able to conduct various tests ranging from dissection of infected mice to fecal floats that allow him to search for parasite eggs in deer mice droppings.

For Gritzen, however, the work not only represents an opportunity to further scientific knowledge of the subject for human protection, but also an opportunity for him to continue to pursue his love of science.

“Becoming a researcher here at the U has been a really enjoyable experience because I really love science,” Gritzen said. “Going in and asking a question and then trying to discover an answer through science feels really good. It helps me to apply my experience. It’s amazing.”

Gritzen will be defending his thesis for his masters in May, and with his schooling coming to an end, he is looking forward to a future where he can continue to apply his scientific knowledge to beneficial causes. For him, those opportunities lie in the Utah Division of Wildlife Resources.

“As a scientist I’d like to continue studying wildlife,” Gritzen said. “I’d be interested in looking at and researching parasites of other mammal species.”

He also hopes that his work can act as a catalyst for future study in the field of parasites.

“I really hope that the work I’m doing can inspire other scientists to look into these parasites,” Gritzen said, “It’s sad that we discovered some of these [deer mice] parasites over 100 years ago and we still don’t know what they do [to the mice].”

Protospirura numidica is just one of the many parasites that can infect the digestive tract of Deer Mice.

Craig Gritzen doing fieldwork in the Great Basin Desert, in Juab County Utah, 2009. Working with the "Sin Nombre Virus" requires the use of specialized headgear to prevent human infection.