Photograph by Robert Montgomery
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A giraffe suffers from a skin disease that causes grayish lesions. The condition occurs in both wild and captive animals.

Photograph by Robert Montgomery

Mysterious Giraffe Disease Has Scientists Baffled

It's unknown whether the condition, which causes bloody lesions, is contributing to the decline of the world's tallest mammals.

When Arthur Muneza was about to start his master's at Michigan State University in 2014, he faced a pivotal question: What did he want to study?

He considered many rock stars of the African animal kingdom: elephants, lions, even hyenas.

But then the biologist heard that few were studying the little-understood giraffe skin disease, and he knew he was onto something.

"We said, let's just go for it. Let's look at giraffe skin disease and see what we can get out of it," he says.

The mysterious condition, which is widespread in sub-Saharan Africa, causes grayish, crusty lesions on giraffe necks and legs. It's unknown what, if any, environmental factors are to blame, or even if it's a compilation of several diseases that attack the skin of the world's tallest mammals.

But what scientists do know is that it's a possible threat to giraffes, which have declined by the thousands in the past 15 years, mostly due to habitat loss and poaching. (See "Inside the Fight to Stop Giraffes' 'Silent Extinction.'")

Compared with well-studied African herbivores like elephants, giraffes are "kind of the forgotten megafauna," says Jenna Stacy-Dawes, research coordinator for San Diego Zoo Global.

But as giraffe numbers fall, more scientists have shifted their attention to this "silent extinction"—and how to stop it, she says.

Building a Baseline

For Muneza, his first task was scouring previous giraffe studies for any reference to the telltale signs of the disease: those lesions that sometimes ooze blood or pus.

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Giraffe numbers are dwindling throughout their range due to habitat loss and poaching.

After digging into multiple online scientific databases, Muneza and colleagues found only eight sources mentioning the skin disease in wild populations going back to the 1990s.

The team also sent out questionnaires to researchers, conservationists, and veterinarians working with giraffes, asking if they had seen signs of the condition. (See 14 incredible pictures of giraffes.)

They received 63 responses, 48 of them from zoos. Of these, over 30 percent of respondents had seen skin disorders in captive giraffes, and, of these cases, 70 percent, or 14 cases, were giraffe skin disease.

In wild giraffes, scientists had detected the disease in seven sub-Saharan countries, with a wide range of occurrence depending on location.

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For example, while there were no cases of the disease recorded in three national parks or conservancy areas clustered in northwestern Tanzania, the more centrally located Ruaha National Park reported 79 percent of their Masai giraffe were infected. It's unknown whether the incidence of the disease has increased in recent years. (Read how there may actually be four species of giraffe.)

Armed with this baseline data, Muneza and his advisor, Robert Montgomery, are now working with zoos, universities, and African governments to collect samples of infected giraffes and determine causes and effects of the affliction.

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The skin disease could be a single condition or a combination of several, experts say.

For instance, it's possible the lesions can make giraffes less mobile and easier targets for predators in the wild, Montgomery notes.

Mysteries Remain

In the meantime, Fred Bercovitch, director of the Texas-based nonprofit Save the Giraffes, cautions giraffe skin disease should not yet play a role in wider conservation efforts. That's because it's not clear how the skin issues impact giraffe mortality or reproduction.

But such research is very valuable, he says: "If you understand more about GSD, it might lead to other questions, and those questions might lead to more insights into giraffe conservation efforts," said Bercovitch. (Related: "Giraffes, Zebras Face Surprising Top Threat: Hunting.")

For example, studying one population of giraffes with a high occurrence of the disease might show that the population is severely inbred, or that it has experienced detrimental environmental changes resulting in new soil composition.

Many questions remain, though, including how the disease spreads and if there's a cure. Muneza also wonders if other animal species can be infected.

"In the case of GSD," he says, "we think this is something that is particular for giraffes."