Giant Panda Was Infected With Scary Cat Parasite Toxoplasma

Just in case you needed more reasons to fear Toxoplasma, here's another. It infects that most adorable of charismatic critters, the giant panda.

Toxoplasma gondii is a brain parasite needs cat guts to survive. Here's Ed Yong's description of the nasty critter, from last year:

A mouse sniffs the air, catches the whiff of cat urine, and runs towards the source of the smell… and straight into the jaws of a cat. This bizarre suicidal streak is the work of a single-celled parasite called Toxoplasma gondii, which has commandeered the mouse's brain and turned it into a Trojan rodent—a vehicle for sneaking T.gondii into a cat.

T.gondii (or Toxo for short) infects a wide variety of mammals, but it only completes its life cycle in the guts of a cat. To get there, Toxo has ways of subverting the behaviour of dead-end hosts like mice. Its machinations are subtle, so subtle that it's normally hard to tell an infected mouse from an uninfected one. But the difference becomes obvious when there's cat pee in the air. Normal mice, even lab-born ones that have never met a cat, have an innate fear of cat smells. Those infected with Toxo do not. They (and their parasites) are more likely to end up in a cat.

Of course, Toxo isn't unique to mice and cats. It can infect people and change their behavior, it might be at least partially responsible for the wild antics of adolescent sea otters, and just last month researchers announced that it infects an estimated 10% of beluga whales off the Canadian coast in the Beaufort Sea.

Writing in Smithsonian SmartNews, Rachel Nuwer says,

Although the beluga whales appear to be unfazed by the infection, researchers are puzzling over how they acquired the parasite to begin with. It could be that more and more local people own cats, whose feces get washed into the water from the powdery Arctic soil. Or it could have something to do with climate change. As temperatures warm, perhaps the parasite is altering its ecological niche. While other marine animals have been shown to carry the infection before, this is the first time it has turned up in the Arctic.

In February, China's Zhengzhou Zoo suffered the loss of a 7-year-old female panda named Jin Yi. At the time, the public blamed the zoo for the death, alleging mistreatment and even torture. As CNN reported, her death was blamed on gastroenteritis which led to organ failure.

In a press event, the zoo told reporters the panda suddenly began refusing food on February 7. The next day, its physical and mental health "quickly deteriorated," and it died in the early morning of February 9.

Because giant pandas are so important in China, every deceased individual gets a necropsy. Samples from Jin Yi's body were sent to China's Veterinary Institute of the Academy of Military Medical Sciences. Now, the China Daily is reporting that Jin Yi was infected by everybody's favorite cat parasite, Toxoplasma gondii.

"This is also the first time we found toxoplasma in a giant panda, so we know very little about the infection and its pathology as it relates to this animal," said Wang Chengdong, head of the animal management department at the China Conservation and Research Center for the Giant Panda at Wolong Giant Panda Reserve, Sichuan province, where Jinyi was originally raised.

Before Jinyi was sent to Zhengzhou in 2011 together with male panda Longsheng, the center gave her a thorough physical examination. During the years the pair lived at Zhengzhou Zoo, veterinarians were sent from Sichuan to examine the pandas once or twice each year, Wang said.

But those routine veterinary examinations didn't include tests for Toxo, so it is unclear when Jin Yi became infected. Neither is it clear how, since the parasite can be carried by a wide range of mammals and birds. In any case, veterinarians will now include tests for the parasite in their panda check-ups.

Toxo, by itself, may not have been enough to kill the panda, but it may have contributed to her deterioration. As the China Daily reports,

They determined that Jinyi was infected by bacteria and suffered from toxoplasma, or parasites. Those conditions resulted in acute complications such as repeated vomiting and massive bleeding of the stomach and intestines. The panda eventually died of heart and lung failure.

Jin Yi, by the way, was a cousin to the National Zoo's famous panda-cam star, Bao Bao. The species is classified by the IUCN Red List as endangered, mainly due to habitat loss and population fragmentation.

Header image: Giant Panda at the San Diego Zoo, copyright Jason G. Goldman