Friday, October 18, 2013

Penguin-killing avian malaria surprises Calgary Zoo

Penguin-killing avian malaria surprises Calgary Zoo
 Doug Whiteside, senior staff veterinarian at the Calgary Zoo, points to a spot of infection on an X-ray that caused the death of Humboldt penguin Eduardo at the Zoo’s Animal Health Centre on Tuesday. A second Gentoo named Akemi also died of avian malaria on the weekend. Photograph by: Ted Rhodes , Calgary Herald
The Calgary Zoo is reconsidering how it treats its birds for avian malaria after recording Alberta’s first-ever penguin fatality from the disease this week.

Akemi, a three-year-old female Gentoo, was one of two penguins to die at the zoo over Thanksgiving weekend. The other — a three-and-a-half-year-old Humboldt named Eduardo — died of a respiratory infection common to penguins in captivity and the wild. Akemi, though, died Monday of avian malaria.

The zoo is awaiting test results on two other Humboldt penguins that died in August. Malaria is suspected in both cases.

Senior staff veterinarian Doug Whiteside said Akemi’s was the first confirmed case of the disease in a penguin in Alberta, and all other outdoor-based penguins were being screened for malaria.

The colony was also tested after the two August deaths, but came back clear.

They were given a malaria drug for 30 days as a precaution, Whiteside said, but the zoo had no preventive treatment program in place because there had been no sign of the disease.
“We’ve never had an index of suspicion.”

“We’ve never diagnosed it in the past; we’ve never seen it on a blood smear and we’ve never seen it in previous penguin deaths.”

The two types of mosquito that carried the malaria strains that most affected penguins were not found in Alberta, Whiteside said.

“We may either have a different species affecting the penguin, which is a possibility, or the vector is starting to move north.”

The zoo will likely increase blood testing for malaria and is now considering preventive treatment, he said.

It will consult with U.S. zoos that have had experience with the disease and look at alternative treatments such as treating affected birds but exposing others to build a natural immunity.

San Francisco State University associate professor in biology Ravinder Sehgal said he was surprised to learn the zoo did not already have preventive measures in place.

“It sounds like they weren’t aware they would get malaria up there, but it’s very reasonable that they would.

“Malaria will be common in birds that are migratory. You’ll find a lot of birds in Calgary that migrate south for the winter. It’s quite common that you’ll find birds with malaria in Calgary.”

Avian malaria was found as far north as Alaska, Sehgal said. Malaria mosquitoes can transmit the disease in temperatures above 13 C.

All penguins were being given preventive treatment for aspergillosis — the respiratory infection that claimed Eduardo.

Six penguins are believed to have died since the popular Penguin Plunge exhibit opened at the zoo but Whiteside said the fatality rate did not jeopardize the future of the attraction.

Penguin deaths:

December, 2012: Fiona, a gentoo, dies following surgery after swallowing a foot-long stick
February, 2012: Asa, a king penguin, dies of Aspergillosis, a respiratory infection
August, 2012: Guillermo and Juntos, Humboldt penguins, die within days of each other. Zoo staff first looked at whether bacterium Chlamydia psittacine or parasitic disease Toxoplasmosis was to blame. However, new lab tests are still in the works and zoo officials now believe the deaths may be linked to avian malaria.
October, 2013: Eduardo, a Humboldt penguin, dies of Aspergillosis. Akemi, a gentoo, dies from heart failure due to avian malar


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