AUDIE CORNISH, HOST:
Sixty thousand people a year die of rabies, mostly in Asia and Africa. NPR's Eyder Peralta traveled to Tanzania to learn about a large-scale scientific experiment trying to keep humans and wildlife safe from the disease.
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EYDER PERALTA, BYLINE: Out here along the edges of Serengeti National Park, domestic dogs are not really pets. They're used for work as security dogs or as hunting partners. Dr. Imam Mzimbiri, who vaccinates dogs every day at pop-up clinics like these, says owners are just not used to touching them. So they're not friendly, and they will bite.
IMAM MZIMBIRI: Some of the dogs are not calm. They are very harsh, so you have to use your common sense. Otherwise, you'll be bitten several times.
PERALTA: Then he shows me what common sense looks like. With a needle in one hand, he stalks around a little tan dog who knows something is about to go down.
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PERALTA: But the vet is too fast, and all the dog can do is yelp.
PERALTA: That's one of the tricky ones.
MZIMBIRI: Yes, that's the technique. Otherwise, things would be very bad.
PERALTA: This vaccination program started in the late '90s after two outbreaks - a rabies one that almost wiped out the entire wild dog population and a distemper one that killed a third of the lions. Now, Dr. Mzimbiri spends almost every weekday vaccinating dogs around the Serengeti.
MZIMBIRI: All the villages in the radius of 10 kilometers - we are creating a disease-free zone so that rabies will not go inside the park. And also it doesn't affect the people surrounding these areas.
PERALTA: Dr. Felix Lankester, a vet at Washington State University, says the program has not only saved lives, but it's also taught them a lot about rabies. When the program started, scientists didn't know what animal was the main carrier in Africa. They thought the so-called reservoir hosts were jackals or hyenas.
FELIX LANKESTER: But our work has shown - certainly in the areas that we work that when you vaccinate dogs, you eliminate the disease rabies from the domestic dogs. But you also eliminate it from all the secondary hosts, such as wild carnivores and humans.
PERALTA: There's still a lot more to learn. For example, why dogs make such good hosts. But in the field, there are lots of practical hurdles. The biggest is that this is labor-intensive. It takes a whole year to vaccinate about 45,000 dogs just to keep a tiny part of Tanzania disease free. Machende Bigambo, a project manager, is registering a long line of dogs, getting their names and sex.
MACHENDE BIGAMBO: (Speaking Swahili).
PERALTA: He points at most of the owners in line with their dogs. They're kids. Most have never seen a case of rabies.
BIGAMBO: In the past, they were so many rabies cases. Now, no rabies cases. So some people - they relax. They think, OK, now it's gone.
PERALTA: But that's also their biggest challenge. It may mean that people won't take a very deadly disease seriously. Eyder Peralta, NPR News, on the outskirts of Serengeti National Park.
(SOUNDBITE OF NOBODY'S "WAKE UP AND SMELL THE MILLENNIUM") Transcript provided by NPR, Copyright NPR.