Birds of a Feather
Parasitologist Thaddeus Graczyk's bond with creatures great and small at the Baltimore Zoo -- and with the zoo's top vet -- is guiding research at the intersection of animal and human health.
Thaddeus Graczyk leans forward to let Biscuit and Albert nip at his heavy gloves, an almost goofy grin on his usually solemn face. The two African black-footed penguins, glossy and stout, gaze up at Graczyk with what look like earnest stares.
Today is just a social call, but Graczyk, an associate research professor at Hopkins' Bloomberg School of Public Health, knows the inhabitants of the Baltimore Zoo's Rock Island well. With Mike Cranfield, director of animal management, research, and conservation at the zoo, Graczyk has worked to battle avian malaria, a disease North American birds are resistant to that can sicken and kill the non-native penguins. Cranfield stands nearby, laughing as more penguins come outside to crowd around his friend and research partner.
During a 10-year collaboration that has spawned more than 60 papers, the quiet but intense scientist from Poland and the energetic veterinarian have moved from testing penguins for malaria and saving snakes from cryptosporidiosis at the zoo to studying mountain gorillas in central Africa. For Cranfield, the thread in each project is animals, both captive and wild; for Graczyk, it's the parasites that move so freely between animals and humans. The two work at the intersection of animal and human diseases in the developing field of conservation medicine.
In a world of shrinking habitats for animal life, surging population growth among humans, dramatic climate change, and the diseases that accompany such shifts, conservation medicine makes sense because it combines the interests and methods of veterinary science, medicine, and public health. But the men's partnership didn't start out with such lofty underpinnings--it began with a request from Graczyk to collect snails from a pond on zoo property for his work on avian schistosomes, parasites carried by birds.
|Graczyk, left, and Mike Cranfield, head veterinarian at the Baltimore Zoo, hold a boa contrictor in the zoo hospital.||
Intrigued, Cranfield asked about Graczyk's work and
told him about the problems the zoo was having with avian
malaria among its colony of African black-footed penguins,
the largest in the United States. Young penguins going
outside for the first time were dying from the disease, at
rates of up to 70 percent. At the time, Graczyk was working
on the immunological response of children infected with
malaria, and he pondered whether a screening method used
for human malaria--a test that looks for antibodies to the
parasite in blood samples--would work for the penguins. It
did. Graczyk could tell in 100 percent of cases which birds
were getting malaria, enabling zookeepers to treat infected
birds in early stages of the disease.
The test was just a starting point. Graczyk also helped to develop a DNA-based malaria vaccine that is effective in the first year, when the birds are most at risk. But the vaccine doesn't confer a lasting immunity, so research continues.
From penguins, the researchers moved on to snakes infected with Cryptosporidium parvum. Being able to identify the sick snakes by testing fecal samples allows the zookeepers to remove them before they infect other snakes, and Graczyk has also been testing a treatment, hyperimmune bovine colostrum, which is loaded with protective antibodies and also nutrients that improve the health of the emaciated snakes. A vaccine is in the works as well; Graczyk calls it "very promising."
|Human diseases brought into the habitat of the mountain gorillas could devastate the endangered species, says Cranfield. "Measles could finish them."||
These days, Graczyk is studying the human health
effects of water-borne parasites and working on the
mountain gorilla project. The latter offers a textbook
example of the strengths of conservation medicine: With
support from the Morris Animal Foundation, Cranfield and
Graczyk are researching the extent to which humans and
livestock are affecting and are affected by the mountain
gorillas of Rwanda, Uganda, and the Democratic Republic of
Congo--the ones made famous by Dian Fossey.
Some of the gorillas have been "human-habituated"-- conditioned to be around humans--in an effort to develop ecotourism in the national park. "The [Ugandan] government realizes the gorillas are natural treasures," says Graczyk. "But there is a concern that the habituation is enhancing transmission of pathogens infectious to both people and the gorillas."
Cranfield, director of the Mountain Gorilla Veterinary Project, puts it simply: "We collect poop samples, and Thaddeus uses molecular biology techniques to test the samples for things like cryptosporidium, giardia, salmonella. From that, we know these cycles are going on between people and their cattle and the gorillas."
Graczyk explains that the parasites cycle through the groups via feces, contaminated water and soil, and, in the case of mange, clothing left behind by tourists. The researchers' work will help to determine what controls could be used to break the transmission cycles, such as building latrines and restricting cattle's grazing range.
"It's not so much of a worry about giardia [an intestinal parasite]--the gorillas throw that off," Cranfield says. "We have to worry about TB and measles" that could devastate the population, already on the brink of extinction. "Measles could finish them."
Cranfield travels often to Africa to collect samples and oversee the mountain gorilla project; Graczyk, asked whether he plans to go, replies, "Why would I? The samples come here."
Indeed, the habitat Graczyk prefers is the lab, home base for the detective work that helps him divine the mysteries of parasites. Evidence sits in three large jars near his desk: nematodes, trematodes, and tapeworms, all drawn from infected people. He seems charmingly unaware that the murky contents are unsettling for the uninitiated.
Cranfield tells of a lecture/slide show at a local restaurant: "Thaddeus starts out all warm and fuzzy with the penguins from the zoo, and all of the sudden, we're all eating and looking at parasites coming out of people!"
Reminded of the story, Graczyk allows himself a tiny smile. But then, as if to emphasize he doesn't mind getting out of the lab, he reaches down to pat Albert, a rather rotund resident of the Rock Island colony. "The penguins are very nice. Very nice," Graczyk says. "But the naughty ones, they're always trying to pinch me."
The Johns Hopkins Magazine | The Johns Hopkins University |
3003 North Charles Street |
Suite 100 | Baltimore, Maryland 21218 | Phone 410.516.7645 | Fax 410.516.5251