Introduced diseases and their impact on people and wildlife

Ward Stone

Head of Wildlife Pathology, York State Department of Conservation

This is the recap of a talk given at the Jan 11, 2004 CDHS monthly meeting.

Ward Stone, head of the Wildlife Pathology Unit at the New York State Department of Conservation, spoke at the January meeting on "Introduced diseases and their impact on people and wildlife." His discussion included PCB pollution, infectious disease, the attitude of the DEC administration toward these threats, and what we face in the future.

As a state pathologist, Stone is responsible for the health of New York wildlife ranging from amphibians to the largest mammals. His work requires extensive knowledge in their anatomy, physiology, and diseases.

Stone's interest in the environment started at an early age. As a child, he began to question why the streams of Chatham he fished in were polluted. He was told the human activities responsible for this (paper mill, etc) were beneficial in so many ways that, by comparison, the effect on the environment was not important. Throughout Stone's career in wildlife pathology, he would find himself combating variations of this argument again and again.

PCBs: Having been influenced by Rachel Carson's "Silent Spring" while in college, Stone later found himself faced with the same issues she addressed in her book. Not only were there serious problems with DDT and PCB contamination in NY wildlife, but human obstacles were present as well. The attitudes in different levels of administration at the DEC often mirrored those of the polluting industries, rather than conservationists. By adopting the view that these chemicals were necessary for the economy and no feasible alternatives existed, the DEC was like the proverbial fox guarding the hen house. To prove that there are alternatives to PCBs, Stone only has to point to the Japanese response. Due to poisonings from contaminated rice oil, Japan banned PCBs in favor of ecologically sound alternatives. The situation with PCBs in now improved in NY, but there are many other threats including infectious disease.

Raccoon rabies epidemic of the 1990s: The original strain of the rabies now in New York State can be traced to the late 40s in Florida. Raccoons from the south were released in Virginia for hunting purposes. The epidemic reached New York in the 90s. Rabid raccoons viciously attacked other raccoons and animals regardless of their size: large dogs, cats, skunks, deer, grey foxes. (Opossums have some resistance to infection because they are marsupials. Coyotes seem to have natural resistance as well). Stone pointed out that, during this epidemic, the DEC really missed an opportunity to get close to the public. They had no system in place to monitor or collect the dead raccoons turning up on people's property. All they did was to refer people to the Health Department if there was human or pet exposure. Stone's Wildlife Pathology Dept, however, was able to provide a broader response. They would collect the dead animals and study them. The NYS Health Department has a very good laboratory in charge of vaccinations and post-exposure treatment. To this day, when the raccoon population increases, so does the incidence of rabies. People have died from raccoon and bat rabies (camping, working in barns, etc.) without ever knowing they were exposed. The DEC recommends that if there is a bat in your house, it should be destroyed and tested in case you were bitten while sleeping. (However, if you see a bat fly in the window and you know it hasn't bitten you, it is ok to let it fly out).

Duck Plague: Another example of an introduced disease. A resident in Long Island imported ducks from Europe which had a virus. There are still occasional outbreaks in wild waterfowl.

Prions: Prions are thought to be responsible for diseases like Bovine Spongiform Encephalopathy (Mad Cow). There is still debate on this theory because prions are a radically different form of infectious agent when compared with viruses. Prions are proteins that have become misshapen, whereas a virus is a genome-based organism. Prions are created when the proteins found in the nervous system of humans and animals form abnormal folds. These folds result in a disease structure which leads to the death of neurons. This causes holes in the brain. In order to "denature" a prion it has to be heated to temperatures in excess of 1600 degrees F. A prion is thought to be responsible for an encephalopathy disease (Kuru) affecting highlanders in New Guinea. In the 1950s, 21% of a population of 8,000 had the disease. It is believed that ritual ingestion of dead (and undercooked) relatives allowed the entry of the prion into the population. In Bovine Spongiform Encephalopathy, material from sheep with scrapie was fed to cattle. People were not susceptible to scrapie, but the prion, possibly through mutation, was able to infect the cattle that fed on it, causing Mad Cow Disease. Some humans were then infected with Creutzfeld-Jacob Disease when they ate the infected beef. There are other Spongiform Encephalopathy diseases that humans are susceptible to, including inheritable ones.

Chronic Wasting Disease: In the Colorado/Wyoming/Montana area, white-tail deer and elk developed a spongiform disease called CWD. A prion was found to be the cause. Because of the Elk farming industry (the meat is lean), animals with CWD were consequently moved from state to state. CWD might be found in other farm animals and could have a big effect on deer populations. Stone says we don't want it to reach NY. However, considering the funding and job cuts (in addition to the troubling philosophy present in the DEC administration), they would not be able to handle an epidemic. Staff and resources would have to be in place for a physically demanding program of destroying sick animals. This would involve shooting, bagging up, blood clean-up, high-temperature burning, etc. Yet staff and resources are continually shrinking. There is no evidence yet that CWD could make the jump to humans but that does not mean it is impossible. The bottom line, Stone says, is the DEC needs to change. Departments between states are working together and that is a positive step. But more is needed.

West Nile Virus: In August 1999 when crows started dying in the New York and Westchester area, Stone played an important role in the discovery of West Nile Virus. The main concern now is the lack of funding for continued monitoring of WNV and the bird population. His department has been told to cut back on monitoring but Stone has refused to do to so, citing the importance of this research. He has to rely on reportings from professors and graduate students and feeder counts in different locales to try to measure bird populations, which are well into decline. Squirrels, horses, sheep, dogs, cats have been infected, as well as people.

Botulism: Birds are dying of Botulism in Lake Erie. A type of fish, and the zebra mussels they feed on, were introduced to the area. This resulted in the mussel's defecation increasing the levels of botulism in the environment. The birds then get Botulism from the fish they eat. A DEC technician was responding to this threat by picking up the dead birds so that other creatures would not eat them and die. The DEC has laid off this technician, so now there is no one to pick up the dead birds.

Bio-terror: This is a likely occurrence in the future and we are not prepared for it.

In the face of all these threats, funding is cut, people are laid off and the money is sent to the wrong places by a DEC riddled with conflicts of interest. There seems to be a perception at the DEC that no further wildlife research is ever needed. And yet the present situation with infectious diseases cries out for it. The research arm of the DEC has been virtually destroyed, Stone says. Colleges need more support to study native species and there are fewer graduate students studying wildlife.

Stone reflected on the high environmental idealism of the 1960s; ideals that he continues to fight for in his position as wildlife pathologist. He faces continuous challenges from both nature and the DEC but is as committed as ever to preserving the environment. Currently Stone's department is working on producing an article about West Nile Virus in February and also addressing concerns they have with a diagnostic test for WNV which has a troubling 20% false positive/negative result.

Go to top of page

Send website comments to webmaster@humanistsociety.org

Return to CDHS Home