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Animals As Sentinels

Animal SentinelsWildlife can act as a barometer for human and environmental health by helping us gauge levels of risk from toxins, emerging diseases, or bioterrorism.


Five pairs of binoculars pivot in unison as they track two juvenile semipalmated plovers riding the crisp ocean breezes that waft over Gooseberry Neck Beach in southern Massachusetts. But suddenly their focus shifts to a great black-backed gull posed on the beach like a sentinel soldier as it eyes them from a distance.

Despite its regal appearance, there's something off-kilter about its contour - the soft down of feathers on its underbelly looking oddly distorted. As it takes flight, the little group of birders follow its path, concurring on what is becoming startlingly apparent: A large mass is dangling from its abdomen like an omen in the wind.

"Right there you see a bird that could end up [dead] on the beach, and that's data," says Jamie Bogart, a research assistant at the Lloyd Center for the Environment in South Dartmouth, Mass., a nonprofit organization involved in environmental education and research focusing on marine biology and coastal ecology.

Bogart is leading this sneaker-clad group on a three-mile bird identification walk along the rocky beaches of Gooseberry Neck as part of the Seabird Ecological Assessment Network (SEANET) project. In 2002, Tufts Veterinary School started the program in conjunction with the Lloyd Center to instruct volunteers on how to collect information for a database on coastal birds. Equipped with satchels containing data sheets, rubber gloves, rulers, calipers, scissors, cameras and plastic sacks, citizen scientists are instructed on how to identify live birds and gather information from bird carcasses. The information is then entered into a database that researchers at the Tufts Wildlife Clinic can use as indicators for human and environmental health.

"Seabirds are very good sentinels because they're high up on the food chain," explains Tufts' Dr. George Saperstein, department chair for Environmental and Population Health. "Since the seabirds are eating the fish, over time they're potentially bioaccumulating toxins. Or if there was an [infectious disease such as West Nile or a bioterrorist] event, we might see a die-off in the seabirds," he adds.

"Fish-eating birds are exposed to the same contaminants that we are through the fish that they eat. So you may get similar levels of bioaccumulation, which makes them good sentinels for human health in terms of seafood consumption," says Rebecca Harris, Ph.D., G01, a biologist at the clinic and the SEANET coordinator. "If you're interested in shellfish, you would monitor eiders [sea ducks], for example. Other species like gannets and terns are exclusively fish eaters," she notes.

"They also provide valuable geographic data on where contaminants are located. And there also are a lot of health risks and pathogens that we share in common, including those resulting from marine biotoxins [red tides]," she says.

After their successful launch with the Lloyd Center, Tufts started a second SEANET collaboration on Cape Cod in 2003 with the Mass Audubon/Wellfleet Bay Wildlife Sanctuary. From there, SEANET quickly proliferated into a network of 300 volunteers working with various environmental groups along the Atlantic from New Jersey to Canada. Tufts has started to talk with groups in Florida as well in an effort to extend the project down the entire east coast.

In addition to monitoring the impact of oil spills on coastal marine life, SEANET is acquiring data on the effects of oil-laced bilge waste and ballast water from boats. Some 70 percent of the birds collected from Atlantic Canadian beaches had oil on their feathers and died from oil pollution, Harris says. "We thought it would be a good idea to use the same methods and extend that kind of monitoring down the east coast of the U.S. because it hasn't regularly been done here."

Although she hopes the project will involve long-term monitoring, the information obtained over the last few years has already proved useful.

For example, researchers were able to determine from the data that so far there appears to be less chronic oiling of birds on the east coast of the U.S. than in Canada, probably due to stricter laws and larger fines, Harris says.

"What's unique about this is the recruitment of citizens as scientists," says Saperstein.

It's an indispensable ingredient to the program's success, agrees Harris. "SEANET gets the public involved in the monitoring, which I think is a very key piece of this because it's got the educational component as well."

Animal Sentinels

"We were completely unprepared for an introduction of a foreign virus which swept through [the U.S.] like wildfire. We're lucky that it was West Nile virus, essentially because there are far worse agents," says Tufts' Sam Telford.

"And it's a great opportunity for our veterinary students," adds Tufts' Dr. Flo Tseng, assistant professor in the Department of Environmental and Population Health. "Other beached-bird projects don't have the same level of analysis - they're only doing visual examinations. We're taking that one step further and doing x-rays and gross necropsies [internal exams], as well as saving tissue samples for other kinds of testing."

Tufts is increasing its alliance with state and federal agencies on several fronts to create databases and coordinate information on public-health issues. For example, Tufts Wildlife Clinic will soon be monitoring wildlife populations for emerging diseases in a joint program with the Massachusetts Department of Public Health.

The clinic also is developing a system to necropsy animals and transport them to state biosecure labs that can handle select agents in the event of a bioterrorist attack that shows up first in wildlife.

"What we are trying to do is get a handle on the background rate of zoonotic diseases in Massachusetts and identify any potential early-warning signs of changes that could affect human health," says Dr. Fredric Cantor, V84, the state public health veterinarian for the Massachusetts Department of Public Health. "We're looking at the frequency of appearance and also the geographical hot spots, when it occurs and how often it occurs" with emerging diseases such as West Nile virus, Eastern equine encephalomyelitis, tularemia and tick-borne illnesses, he adds.

In addition to working with the state, Tufts received $23 million in grant money and contracts several years ago from a range of federal government agencies to do research on emerging diseases. And last year, the National Institutes of Health awarded Tufts $25 million for a seven-year research program on food- and water-borne pathogens and to create a Botulinum Therapies Research and Development Center, the first of its kind in the United States. The CDC has identified the botulinum toxin as the second-most serious potential bioterrorist agent, next to smallpox.

Of the emerging infectious diseases in the world, 75 percent are zoonotic, meaning that humans can contract them from animals. And 90 percent of the agents most likely to be used by bioterrorists are animal diseases, Saperstein says.

"It's only smallpox that's strictly human. So the human and public health infrastructure needs to be working closely with veterinarians, and in particular veterinary schools. Because most of these diseases are zoonotic, we may be the ones that detect it first," he adds.

"What better place to work on these diseases than at the veterinary school - a school whose faculty, staff and students have a deep and sincere collective respect for animals. Since most of these diseases occur naturally in animals, we understand them and are used to working with their causative agents," he points out.

Maxene Armour, bioterrorism education coordinator for Massachusetts, agrees that animals are important indicators for disease. Armour offers workshops to the public "to help animal caregivers recognize when something is out of the ordinary with their animal. We ask them to look at a group of clinical signs that may alert us that a bioterrorist agent or pathogen has been released," she says.

Cats can show signs of plague; dogs can be indicators of tick-borne diseases that are spreading in an area. And chickens are excellent sentinels for emerging diseases such as West Nile virus and Eastern equine encephalomyelitis.

Public-health officials received early warning signs of West Nile virus when exotic birds started dying at a New York City zoo, points out Sam Telford, Ph.D., a researcher and associate professor in the veterinary school's Division of Infectious Diseases in the Department of Biomedical Sciences. "Emerging diseases and biodefense really should be one and the same. They're identical, and in fact anyone who has followed the West Nile epidemic can see the lessons that it has for biodefense," he says.

"We were completely unprepared for an introduction of a foreign virus which swept through [the U.S.] like wildfire. We're lucky that it was West Nile virus, essentially because there are far worse agents," he notes. "For example, Rift Valley fever - not only does it have human public-health implications, but it would devastate our agricultural industry because it affects sheep and cattle and goats."

Carried by the same mosquitoes that transmit West Nile virus, Rift Valley fever appears to be following in the footsteps of its predecessor - it's creeping up from central Africa into the Middle East and Mediterranean. Scientists can only speculate on how West Nile virus leapt across the Atlantic - perhaps intentionally, or more likely accidentally, via hitchhiking mosquitoes in an airplane cargo bay.

"The issue with diseases like Ebola and West Nile and Rift Valley fever has to do with how we're moving plants and animals around the globe - more and more and faster and faster," says Dr. Mark Pokras, director of the Tufts Wildlife Clinic and Tufts Center for Conservation Medicine. "In the olden days of horseback and ship travel, somebody got on a ship to sail to the new world and if they were sick, they either got better or they died before they got here. It was relatively unlikely that they'd be carrying the disease across with them.

"But now with instantaneous transport you can get on a plane in South Africa in the morning and get off the plane anywhere in the world in the evening. And transporting any of these diseases - and I'm not even talking about bioterrorism, I'm talking about accidental transport - is a real serious possibility," he says.

Pokras then offers a startling example: The U.S. recently introduced equine infectious anemia from North America to South Africa, marking the first time the serious horse disease ever appeared on the African continent. "We just introduced it by shipping racehorses over there," he says emphatically.


Profile written by Cynthia B. Hanson.

This story originally appeared in the Winter issue of Tufts Veterinary Medicine. Photos by Andrew Cunningham

This story originally ran on Feb. 14, 2005