Infectious disease research expands as concerns rise
Bats are increasingly under scrutiny as reservoirs for many zoonotic diseases including rabies and SARS.
December 6, 2007
West Nile's arrival created huge demand
In 1999, most Americans had their attention focused elsewhere when the crows started to die in New York City. At first, it was just the wild birds. But then the birds in the Bronx Zoo began to succumb to the mystery illness and concerned scientists took a closer look. At about the same time dead crows were noticed, a cluster of human encephalitis cases were reported. West Nile had arrived in the United States.
Disease carried westward by birds and mosquitoes
During the first outbreak, 62 people suffered serious illness and seven of those people died. Winter set in, but the disease was here to stay. As the disease was carried westward by birds and mosquitoes, the death toll rose.
"Our program here really ramped up when West Nile hit in 1999 and we jumped on in 2000 when a huge demand developed to do equine work with West Nile," said Dr. Richard Bowen, a Professor in the Department of Biomedical Sciences and Director of the Animal Models Core for the Regional Center of Excellence (RCE) for Biodefense and Emerging Infectious Diseases. "People were very concerned about the threat to humans, especially routes of infection, and we did a lot of vaccine efficacy testing."
Understanding host switching
Today, in addition to the development of animal models and vaccine testing, the overarching goal of Dr. Bowen's research laboratory is to better understand host switching. Host switching is the essential, defining characteristic of diseases that are known as zoonoses.
Zoonoses are diseases caused by pathogens that make the leap from a nonhuman animal into a person. West Nile virus is one such pathogen, as is monkeypox, toxoplasmosis, Dengue fever, Lyme disease, rabies, and Hanta virus. In fact, fully 60 percent of the infectious diseases that affect humans are shared between animals and people.
Alligators as one possible reservoir of West Nile virus
In the last several years, Dr. Bowen's research team has investigated alligators as one possible reservoir of West Nile virus, acting like living incubators that allow the virus to overwinter and reinfect mosquitoes which in turn transfer the virus to humans and other animals. In collaboration with the USDA and USGS, his team recently finished a large study on bat rabies and raccoon rabies.
Avian influenza - a pandemic in the making?
Another project that Dr. Bowen's team is working on is avian influenza, a zoonotic threat that scientists worry may represent a pandemic in the making. There are three components to the study including:
(1) how human and veterinary medicine need to work together to prevent and/or limit an outbreak of avian influenza including looking at how backyard poultry operations would contribute to the spread of the disease as birds move about the country;
(2) studies in Indonesia, considered ground zero for avian influenza, that focus on sampling bird populations; and
(3) evaluating different vaccines that are developing to protect against avian influenza, as well as determining if a vaccine would make the situation better or worse by keeping birds from getting ill but still allowing them to shed the virus.
How interactions between humans and birds lead to transmission of avian influenza
In addition, Dr. Bowen is the principal investigator on a three-year, $2.6 million grant awarded this year from the Centers for Disease Control to study how interactions between humans and birds may lead to more widespread transmission of avian influenza.
"The questions surrounding host switching when we are looking at zoonotic disease are complex and challenging," said Dr. Bowen. "But gaining a better understanding of how and why some diseases are able to mutate and adapt to new hosts is essential to helping us fight zoonotic disease. Why is it a particular virus can infect but not kill a host, like rabies infecting a bat population but only seeing a few die? Why do some viruses stay dormant for years, but then we'll see a terrible outbreak, like the Ebola virus? How come some pathogens are very host specific, and others very promiscuous with regards to the species they infect?
Collaborations seek to improve human and animal health
"We are working collaboratively with many other researchers to help answer these questions, including colleagues at the Centers for Disease Control, the U.S. Geological Survey, public health organizations in Mexico, bat specialists, and so many others. Emerging infectious disease and biodefense completely overlap so we are seeing an investment in this area that is helping to advance our studies and enabling us to bring greater understanding to all these areas so that we can improve human and animal health."
------------------------------
- Originally appeared in the College of Veterinary Medicine and Biomedical Sciences Biomedical Sciences Update, Fall 2007
Contact: Jayleen Heft
Email: Jayleen.Heft@colostate.edu
Phone Number: (970) 491-2655
