“Cancer at Sea”
by Elizabeth Preston
BioGraphic, August 23, 2016
[greeting blah blah blah]
As many as one-fifth of human cancers are linked to viral infections. Cancer-causing viruses are common in other animals too, ranging from belugas to frogs to Atlantic salmon, but opportunities to study these diseases in nature are rare. That’s why scientists are taking advantage of a unique opportunity on the California coast.
When marine mammals strand here, teams rush to rescue and rehabilitate them. But some animals can’t be saved. The unluckiest California sea lions, although rescuers are sad to lose them, become fortuitous material for cancer research. This species has been stricken in recent decades with an aggressive, and increasingly common, genital cancer. It’s caused by a sexually transmitted herpesvirus.
Veterinarian Alissa Deming and others are studying this cancer not just to save the sea lions, but to better understand viral cancers in human. For example, Rolf Renne at the University of Florida studies the herpesvirus that causes Kaposi’s sarcoma in AIDS patients. There’s no lab animal model of the virus, but it turns out the sea lions are an excellent natural model. Recently, Deming’s work to sequence the sea lion virus’s genome revealed striking similarities to cancer-causing herpesviruses in humans.
I’d like to take readers from the drama of seashore animal rescues and necropsies to the potential of lab research for human cancer sufferers, finally leading to a larger idea doctors call “One Health.” It’s the concept that human health is inextricable from the health of animals and the environment. The factors that may be helping this cancer spread in sea lions are affecting humans too. Climate change, for example, causes warmer waters that make it harder for sea lions to find enough food. Malnutrition and other stressors may help the herpesvirus take hold, just as a stressed human is more likely to get a cold sore. Marine mammals also have to deal with pollution and parasites; in Africa, AIDS patients with Kaposi’s sarcoma often carry a lot of parasites too. Human health is part of the whole world’s health, which means that animals we can’t save might help save human lives.
Ideally, I’d love to travel to the Marine Mammal Center in Sausalito, CA, within the next month or so to report the first part of the story. It’s their busy season for strandings, so there would be a good chance of seeing a sea lion with cancer. (And they’re getting an especially high number of strandings this year.) If not, I would still be able to see necropsies and other on-the-ground action in handling these animals. Besides Deming and Renne, I’d like to talk to Frances Gulland. She’s a vet at the MMC who’s been studying the sea lion cancer since it appeared in the late 1990s. I’d also talk to Jim Wellehan at the University of Florida; he’s a zoo vet who specializes in exotic animals and hunts for the viruses behind disease outbreaks. He would have a great perspective to add, and could lead me to other scientists and examples of the broader One Health principle in action.
A little about me: I live in Boston and write the blog Inkfish, hosted by Discover. Here are some recent pieces I wrote for the Atlantic about ocean debris and eating invasive animals, and longer pieces about archaeology and climate change and invasive water chestnuts for Hakai. (I’d also point you to my piece in the latest Discover on pocket-sized glacial ecosystems, but it’s paywalled and I don’t have a copy yet.)
Please let me know if you’d like any other information. Thanks so much for reading!