In a poetic confluence of events, I recently found myself reading Geraldine Brooks’s book “Year of Wonders, A Novel of the Plague” during the same week I was preparing for our Passover seder, collecting items to represent the ten plagues enumerated in the book of Exodus.
You remember the story. Moses says “Let my people go!” Pharaoh says no. God sends ten plagues. We keep the kids entertained during the traditional telling of the lengthy tale by tossing around pretend plagues. Rubber frogs. Wind-up flies. Styrofoam hail. You get the picture.
So I had plague on my mind when, during some research, I happened upon the 2007 case of the wildlife biologist working in Grand Canyon National Park. The biologist found a deceased mountain lion and, noting some wounds and blood-tinged discharge coming from the cat’s nostrils, suspected it had been attacked by another lion. He slung the heavy animal over his shoulders to carry it the kilometer to his vehicle, then to his garage, where he performed a post-mortem. A few days later, the biologist fell ill. A local medical clinic attributed the fever, chills, and bad cough to a presumptive viral infection. Three days later, he was found dead at home.
Plague. Caused by the nasty bacillus Yersinia pestis, the most common form in people is a swollen, painful lymph node, called a “bubo” (hence the name “bubonic plague”) accompanied by fever, chills, headache, and extreme fatigue. It also has a respiratory form (pneumonic plague) characterized by high fever, coughing, bloody sputum, and trouble breathing, and a septicemic form with nausea, vomiting, diarrhea, and abdominal pain.
Carried by wild rodents and rabbits, plague is transmitted to people in one of three ways: the bite of an infected rodent flea, direct contact with contaminated tissues, or, rarely, inhalation of respiratory secretions from infected people or animals. In the southwestern United States, plague also affects cats, both wild and domestic, presenting with the same three forms as in humans, i.e., bubonic, septicemic, and pneumonic. In the case of the mountain lion and biologist, it was later confirmed that they both died of plague.
Last year, there were two cases of human plague in the United States. The people involved shared a house with a few dogs. One of the people let one of the dogs sleep on his bed. C’mon. Admit it. We all do it sometimes. The dog wasn’t sick, but the Center for Disease Control later found it tested positive for exposure to Yersinia pestis. Was the dog exposed by the human, or the human by the dog? Well, neither. At least not directly.
In rat-infested environments, infected fleas may have easy access to humans, but just because you don’t have rats in the house, doesn’t eliminate the risk of rodent fleas. In cases like this one, the fleas hitched a ride from rat to dog to human. Dogs, and other canids such as coyotes and fox, appear fairly resistant to plague. This dog was not actually infected, but did mechanically transport infected fleas to the owner’s bed.
Now please, don’t panic. You’re not going to get plague from letting Bubo, the Bichon, sleep with you. At least, not if you’re sleeping on Martha’s Vineyard. We do not have plague in the eastern United States. So why am I even writing about this?
“Year of Wonders” is a book of historical fiction based on the true story of a small English village named Eyam. In 1666, when the town was beset by plague, the people voluntarily decided to quarantine themselves and remain within the village boundaries. Although back then no one understood what caused plague, or how it was transmitted, they recognized some essential principles about contagion.
Nowadays, we know so much more about infectious disease. We can treat with antibiotics. We know the importance of rat and flea control. But we are also more mobile than ever before in history. People and pets travel. The Vineyard routinely welcomes animals from all over the country. If you winter in Wyoming, or go camping in Colorado, if you’re arriving from Arizona or were just touring Texas, you should be aware that, although rare, plague is endemic to these areas.
The take-home lesson is that if you’ve been traveling with a pet who later becomes ill, tell your veterinarian where you’ve been. It changes the differential diagnosis. For example, a cat with high fever, swollen lymph nodes, and trouble breathing on the Vineyard, I’m thinking tularemia. The same cat in Colorado? It could be plague. Both are uncommon, but both can be deadly and present significant human health hazard.
Which brings us to zoonosis, i.e., infectious disease transmitted from animals to humans. There are several theories how the infection passed from the mountain lion to our ill-fated biologist. Not suspecting plague, he performed the necropsy bare handed, resulting in prolonged contact with infected tissue. He may have used power tools to dissect the lion, aerosolizing bacteria that he then inhaled. Or it may simply have been the act of carrying the body draped around his neck, the cat’s head in such close proximity to his own, as they hiked out of the Park.
The lesson here is to always take basic precautions when dealing with sick or deceased animals. We may not have mountain lions or plague here, but you can get just as sick if you get tularemia from handling an infected rabbit carcass bare handed or if you run it over with your lawn mower.
Finally, if you want to let Bubo share your pillow, that’s fine with me, but please use good flea and tick control products on all your pets. We may not have plague here, but our fleas and ticks can carry and transmit other diseases.
Now I have to go make matzoh ball soup for 20 and make sure I have enough toy frogs and vermin.