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December 4, 2008

UW-WSU collaboration on animal-human health breaks new ground

By Bobbi Nodell
Global Health Department

The infectious disease plagues of our time — HIV, SARS and avian flu — have mutated and spread from animals to humans, yet getting the human and animal sectors together hasn’t been so easy. Animals are often passive reservoirs, so the disease may not affect them at all.

The U.S. Department of Agriculture may see the disease as a human problem, while the U.S. National Institutes of Health may classify the disease as an animal problem, said Dr. Guy Palmer, director of Washington State University’s new School for Global Animal Health.

“Government agencies just aren’t always that nimble,” he said.

But researchers at the University of Washington and Washington State University have been collaborating on animal and human health since the mid-1990s.

At a packed lecture at the UW Nov. 6, “Teaming up for Global Health: Frontiers of Research on Infectious Diseases,” more than 540 people signed up to hear Palmer and the UW’s Dr. Sam Miller discuss their collaboration. The lecture was part of Life Sciences Research Week, presented by the Northwest Association for Biomedical Research and the Washington Biotechnology & Biomedical Association and was moderated by Steve Davis, CEO of the Infectious Disease Research Institute.

UW President Mark Emmert, speaking at a regional global health conference in October, called the collaboration between the two schools “groundbreaking,” marking the first of its kind in academia.

He said one university president told him, “I can’t even get my own veterinary school and medical school to talk to each other.”

E.coli outbreak

The collaboration started after November 1992 when 400 people in Washington, Idaho and Nevada were infected with Escherichia coli 0157:H7 and four children died. The bacteria were linked to undercooked hamburgers sold by Jack in the Box.

Dr. Phil Tarr, a physician then at the Seattle Children’s Medical Center and a UW faculty member, wanted to find a way to intervene before the E.coli infection spread to children.

Tarr called Dr. Thomas Besser with the Department of Veterinary Microbiology and Pathology at WSU and asked, “Do you know anything about the E.coli 0157 strain?”

Subsequent research by Besser and others revealed that just 5 percent of animals are responsible for more than 80 percent of the shedding related to E. coli.

Researchers at the two universities teamed up to conduct studies to see if they could isolate which cattle populations — bucolic, feed lot, dairy — would most likely have E.coli. What they discovered is that there is no easy way of identifying which animals are carrying the bacteria and, in fact, bucolic (pastured) cows are just as likely to be carrying E.coli as feed lot cattle.

Working on an animal vaccine

Today, UW and WSU are working on creating an animal vaccine, that like the rabies vaccine, will be given to animals with the goal of protecting humans. The vaccine would be given to all cattle to reduce shedding and contamination of both the environment and food supply. The vaccine could have huge results.

According to the CDC, last year there were nearly 33 million cases of microbial food-borne diseases recorded just in the United States and more than 9,000 related deaths, according to the National Center for Health Statistics. The bacteria salmonella and E. coli are the most common causes of food-borne illnesses.

Salmonella outbreaks

During the recent salmonella outbreak in spinach, the CDC tracked down the origins of the outbreak — a field in California. In the field, cattle and wild pigs wandered around the spinach plants, and soil, plants and animals were all colonized with the E.coli 0157 strain.

Miller said the outbreak was much worse than past outbreaks, causing 16 percent of adults who contracted the disease to develop hemolytic uremic syndrome, the most common cause of acute kidney failure in children. Miller’s team worked with the organism to determine why it might be more virulent, as well as able to colonize plants, and they discovered some important clues using the DNA sequence.

“Infectious diseases can evolve to be worse for humans,” he said.

Recent salmonella outbreaks have also been linked to salsa, packaged breakfast cereal, cantaloupe, frozen prepared meals, snack food, peanut butter and tomatoes. Most of our food is now centrally located in large lots, Miller said — even fish caught in the Northwest can be shipped to Tokyo in a large lot and then shipped back. So when there is contamination in one of these lots, such as the salmonella outbreak related to alfalfa sprouts sold through a lot in Amsterdam in 1995-1996, then the outbreak goes worldwide.

Arms race

Miller said the world is now in an arms race between pathogens and antibiotics, but we need to learn how to better co-exist. This may be through developing drugs that block the disease-causing properties of diarrheal bacterial pathogens rather than killing the microbes — hence sparing the beneficial microbes that normally live in our intestinal, genital and oral cavities.

“I’d like to see us as a society learn more about the microbial world,” he said. “There are more microbes than humans out there and we need them to promote our health as beneficial microbes. We also now have the genomic technology to begin to define how pathogens spread and evolve to become more virulent.”

Palmer said “species’ jump” happens in many ways. He said a pathogen like the Chikingunya virus (with symptoms similar to dengue fever) underwent three mutations to be able to go into different mosquito vectors and transmit to humans with no prior exposure to the disease. Like measles, the Chikingunya virus seeks a population that is susceptible — a basic principle of evolution.

Palmer said the researchers’ mission is understanding these mutations and evolution’s role.

To find out about more upcoming global health events, visit UW’s Department of Global Health Calendar of Events at http://depts.washington.edu/deptgh/.