by Marcia Hill Gossard ’99, ’04 Ph.D. | Photos by Henry Moore Jr.
Last month the Hollywood movie Contagion showed the fear, devastation, and social chaos caused by a fast-spreading, airborne virus for which there is no cure. While the pandemic in the film is fictional, the newly emerging disease—Nipah virus—is not.
“Nipah is the most deadly virus in the Paramyxoviridae family,” said Dr. Hector Aguilar-Carreno, assistant professor and one of the newest scientists in the Paul G. Allen School for Global Animal Health. “There is about a 40–75 percent death rate in humans from encephalitis within 9 to 14 days after exposure to the virus.”
Nipah virus was first discovered in 1999 in Malaysia and Singapore, where it spread rapidly to animals and humans. In that first outbreak alone, more than one million pigs died. It is estimated to have killed over 200 people to date.
“The virus is transmitted through saliva or airborne though a cough,” said Dr. Aguilar-Carreno. “Pigs, for example, who often survive the virus, can cough and spread the virus to humans.”
“Disease doesn’t recognize borders.”
—Dr. Guy Palmer, director of the Paul G. Allen School for Global Animal Health
Fruit bats are the virus’s main natural host—they carry the virus, but do not become ill. And, because they migrate long distances, infected fruit bats can spread the virus globally.
With such a nasty disease, Dr. Aguilar-Carreno is quick to explain that at WSU they do not work with the live virus. “At WSU we try to understand the individual proteins in the virus,” said Dr. Aguilar-Carreno. “Our goal is to find a way to block the virus from entering the cells to reduce transmission and increase chances of survival.”
While Dr. Aguilar-Carreno studies newly emerging viruses, Dr. Viveka Vadyvaloo, assistant professor in the Allen School, studies an infectious disease that is centuries old. In 14th century Europe, millions of people died from an unknown disease for which there was no cure. And no one knew how it was spreading. The Plague, sometimes called the Black Death, could decimate an entire village, and it changed the social and economic structure of the continent. While the plague may seem like a disease of the distant past, it continues to be a public health issue even in the United States, particularly in the rural southwest.
“We’ve actually seen an increase in the number of cases of plague worldwide over the last 50 years,” said Dr. Vadyvaloo. “Madagascar, for instance, has an active plague focus and many human plague infection cases. Overall there is an increasing incidence of human plague cases in parts of Africa consistent with re-emergence of the disease.”
Spread by fleas, the bacterium Yersinia pestis is responsible for millions of deaths worldwide spanning centuries. The Oriental rat flea is the prototype carrier, or vector, and learning how the bacteria survive in the flea and is transmitted is what Dr. Vadyvaloo and her team are studying.
“The bacteria form a biofilm in the flea’s gut,” explains Dr. Vadyvaloo. The biofilm, a thick, sticky mass, fills the flea’s stomach and blocks the blood from passing into the flea’s gut. The blocked, starving flea will repeatedly bite its rodent or human host, creating more opportunities for infection by regurgitating blood containing bacteria dislodged from the biofilm into the bite site.
“You only need five bacteria to enter your body to result in death within 48 hours,” said Dr. Vadyvaloo.
By understanding the basic science of how the bacteria form the biofilm in the flea, researchers will be able to apply that work to creating solutions to reduce transmission.
“Our work could possibly lead to something as seemingly simple as a cream applied like a repellant that would prevent the biofilm from being created in the flea’s stomach,” said Dr. Vadyvaloo.
Diseases such as Nipah virus and the plague are a critical threat to global health and economies, yet some of the most devastating illnesses are those that families in developing countries live with everyday.
According to the World Health Organization, diarrheal disease is the leading cause of malnutrition and the second leading cause of death in children under 5 years old. Although it is preventable and treatable, it kills 1.5 million children every year.
Dr. Margaret Davis, assistant professor hired in the Allen School this past summer, studies disease from bacteria, such as Salmonella, that cause diarrhea. She identifies antibiotic-resistant salmonella strains that have the same genetic fingerprint, or profile, and are shared between humans and cattle. She has found that people who carry certain strains are also more likely to have come in direct contact with livestock, such as those working on a dairy farm.
“So different ways people interact with animals may explain how bacteria are transmitted, and not just transmission through food,” said Dr. Davis. “How people interact with their animals impacts human health.”
Although to date most of her research has been in the United States, she plans to collaborate with researchers in developing countries where there are often fewer restrictions on antibiotic use.
“Knowledge is a protective factor,” said Dr. Davis. “If we can demonstrate how animals transmit disease, it can lead to better health education and changes in animal management to reduce transmission.”
In the upcoming year, a clinical microbiologist with an appointment in the Allen School will be hired to expand the clinical laboratory training program, including quality management training. The ultimate goal is to provide lab quality training to scientists in developing countries, who can then take that knowledge back and train others.
“The first thing a lab needs is a good quality management system,” said Dr. Terry McElwain, professor and executive director of the Washington Animal Disease Diagnostic Laboratory at WSU. “Adequate laboratory infrastructure is critical for disease surveillance so outbreaks can be detected early.”
“Disease doesn’t recognize borders,” said Dr. Guy Palmer, director of the Allen School. “Dr. McElwain will be taking his expertise and making it global.”