U maps genes of diarrhea parasite

The parasite is one of the most common causes of water-borne diseases in humans in the U.S.

by Geoffrey Ziezulewicz

University researchers announced this week that they have mapped out the gene sequence of a parasite that causes diarrhea in animals and humans.

The parasite, formally known as Cryptosporidium Parvum, lives in the intestines of humans and animals, and is passed via the feces of an infected person or animal, according to the Minnesota Department of Health.

It affects between 100 and 200 Minnesotans a year.

University researchers said they hope the gene sequencing will potentially lead to medicines that can combat the parasite.

Dr. Mitch Abrahamsen, a professor of veterinary medicine at the University, began sequencing the gene in 2000 with funds from the National Institutes of Health.

The parasite, also known as “crypto,” is found throughout the world and is generally acknowledged as one of the most common causes of water-based diseases in humans in the United States, according to the health department.

Symptoms include diarrhea, loose or watery stool, cramps and a low-grade fever. Symptoms last between three and 10 days and usually appear a few days after infection.

“You have to come into contact with fecal material, or the fecal material has to be in food and water and you have to ingest it,” Abrahamsen said.

The parasite is a bigger problem for people with AIDS and weakened immune systems because the body cannot fight off the parasite and the symptoms can last longer and become more problematic, he said.

“There is a lot of interest in why these parasites cause these problems,” Abrahamsen said.

People who contract the parasite can usually recover by taking it easy and rehydrating themselves, he said.

The parasite has an outer shell that allows it to survive outside a host body for long periods of time, he said. It is also very resistant to normal chlorine disinfection used to clean water.

“Apples could get sprayed with contaminated irrigation water and get contaminated,” he said of one of the ways people ingest the parasite.

The Minnesota Zoo saw a human outbreak of the parasite in 1997, according to the U.S. Centers for Disease Control and Prevention.

More than 360 children reported symptoms after playing in a fountain at the zoo. The CDC believes children in the pool ingested a child’s fecal matter, causing the outbreak.

The parasite is so microscopic that ingestion in that kind of situation is not difficult, Abrahamsen said.

To prevent animal to animal or animal to human transmission of the parasite, the Minnesota Zoo isolates young calves and other farm animals when they are most likely to ingest the parasite, said Dr. Jim Rasmussen, senior veterinarian at the zoo.

“We don’t let patrons bottle feed our calves anymore because it’s the younger animals that usually shed it,” Rasmussen said. “As their immune system is developing, they go through a period of infection.”

He said quarantines treat outbreaks, which have not been severe.

Despite the low level of fatality from the parasite, developing ways to combat it could prevent sickness for many people and animals, Abrahamsen said.

“It’s nasty for everybody. But if you’re a normal individual, you won’t die,” he said. “But you’ll wish you were dead for about three days. If you want to get one of your friends good, put some (of the parasite) in their water.”