Connecting the dots: the emerging science of conservation medicine links human and animal health with the environment

E: The Environmental Magazine, Nov-Dec, 2004 by Jim Motavalli

"The grandiose optimism rested on two false assumptions," Garrett wrote in the journal Foreign Affairs, "that microbes were biologically stationary targets, and that diseases could be geographically sequestered." Scientists, she said, "have witnessed an alarming mechanism of microbial adaptation and change ... Anything but stationary, microbes and the insects, rodents and other animals that transmit them are in a constant state of biological flux and evolution."

Conservation medicine is a realization that modern science is fighting a new kind of war, one that we're ill equipped to wage. Conservation medicine is still a very small field, but it is increasingly gaining recognition from mainstream funding sources, such as the National Science Foundation, the World Bank, the National Institutes of Health, and private grantmaking foundations. Ongoing studies are both uncovering new disease pathways (from animals to humans, and vice versa) and helping devise effective treatment. Here are some examples:

* RWANDA: The Volcano Veterinary Center was created in 1986 at the request of renowned mountain gorilla researcher Dian Fossey to provide emergency care to Rwanda's sick or injured gorilla population. One possible explanation for a high death rate among mountain gorillas noted in the late 1980s is an outbreak of measles. Mountain gorillas share 97 percent of their genetic makeup with humans, and are very susceptible to human diseases. Contact with them has increased exponentially as their fame has grown. Without question, their lives have been disrupted by human contact. Ecotourism is one avenue of contact, and the standards for tourists visiting the great apes are more relaxed than those for visitors to zoos or primate centers. The increasing human population (with a growth rate of 3.7 percent annually) in the region is also a threat. Gorillas have close encounters with trackers, guides, researchers and veterinarians, not to mention poachers and farmers. Bacteriological studies have shown the presence of salmonella, Cryptosporidium parvum, the parasite giardia and campylobacter among gorilla populations. Gorillas have become habituated to human presence, and "there is a concern that the habituation is enhancing transmission of pathogens infectious to both people and the gorillas," says parasitologist Thaddeus Graczyk of the Johns Hopkins Bloomberg School of Public Health, who also works with penguins that have been infected with avian malaria from North America.

* NEW ENGLAND: The alarming declines in common loon populations in New England are being studied by Dr. Mark Pokras of the Tufts Center for Conservation Medicine (CCM). Mercury poisoning is believed to be a cause. "The common loon serves as an important environmental sentinel for mercury because, like humans, it feeds on freshwater fish," Tufts CCM reports. The center has documented weight loss and death in common loons resulting from mercury poisoning, which comes from local sources and arrives via aerial transportation. The Wildlife Conservation Society reports that pending Bush administration proposals to relax standards on mercury emissions from coal-fired power plants could further adversely affect common loon populations (already declining precipitously) in the Adirondacks. "Models indicate that, partly due to mercury contamination, reproductive rates of loons may already be too low to maintain their populations in portions of Maine and eastern Canada," says David Evers of the Adirondack Cooperative Loon Program. Another result of human interaction is lead poisoning resulting from ingestion of fishing sinkers. Dr. Pokras has successfully influenced the Massachusetts Fish and Wildlife Agency to regulate lead sinkers in the Quabbin and Wachusett reservoirs, and they've been banned in New Hampshire and Maine.