The Plague: Why This Medieval Madness is Still a 21st Century Problem and How Your Cat May Play a Role

" .They would swell beneath the armpits and in the groin, and fall over while talking. Father abandoned child, wife husband, one brother another; for this illness seemed to strike through breath and sight. And so they died. None could be found to bury the dead for money or friendship. Members of a household brought their dead to a ditch as best they could, without priest, without divine offices.And they died by the hundreds, both day and night, and all were thrown in those ditches and covered with earth... And so many died that all believed it was the end of the world."

-Agnolo di Tura of Siena, description of the Black Death (after 1347)

The pandemic of the 1300s, commonly known as the Black Death, is one of the most significant outbreaks of the Plague to date, killing a quarter of the entire population of Europe; today that would be like wiping out everyone in the state of Texas. Those who just think of the Plague as a medieval epidemic might be surprised to know that the Plague has probably been around since early humans first began hunting small animals. More surprising still is that it currently infects roughly 2,500 people a year worldwide, 180 of whom die an agonizing death.

How does this affect your dear sweet kitty, you ask? Cats (and other small animals, such as dogs and rodents) can transmit the Plague to humans after being bitten by an infected flea. A typical cycle, for example, could involve an infected flea feeding on the blood of a rodent, which is later eaten during a backyard hunting adventure by your feline friend, who then later accidentally scratches your hand as you pull a string along the carpet in a playful game.

Figure 1. Cat recovering from the Plague and a submandibular bubo.  Image Courtesy:  Centers for Disease Control and Prevention.

Figure 1. Cat recovering from the Plague and a submandibular bubo. Image Courtesy: Centers for Disease Control and Prevention.

Cats were even a significant factor during the Black Death in Europe. People at that time had only vague ideas of how the disease was spread, and sometimes looked to superstitions, namely the bad luck of cats and their association with the devil. Even the Pope supposedly declared that cats were in league with the devil. Scared citizens began slaughtering cats everywhere in hopes of stopping the ever-increasing deaths of their loved ones. What probably happened, however, is that by killing all the cats, they allowed the population of rodents to increase, and the outbreak got worse, not better.

Figure 2. The Plague seems to be endemic to the western half of the United States. ".You go east, the rodent diversity stops; you don't see as many burrowing animals like you do in the West," says Ken Gage, CDC.  Rodents share space with each other in the burrows, spreading the disease to the whole colony.

Figure 2. The Plague seems to be endemic to the western half of the United States. ".You go east, the rodent diversity stops; you don't see as many burrowing animals like you do in the West," says Ken Gage, CDC. Rodents share space with each other in the burrows, spreading the disease to the whole colony.

Fast-forward to modern times, and you can still find isolated outbreaks of the Plague in parts of the United States. Charles Gregg, in his book Plague: An Ancient Disease in the Twentieth Century calls 1980 "the Year of the Cat, despite what the Chinese calendar said." Indeed, in New Mexico alone five cases of Plague in felines were reported that year, not including two found in other states. This is significant, considering that between 1940 and 1980, the Centers for Disease Control had recorded a mere eight cases of feline Plague. Since 1980, there have been over 250 cases of Plague reported in the United States, with an average of 13 cases occurring each year, indicating that this disease continues to be a modern dilemma. This summer, the CDC has already diagnosed four Wyoming cats with the Plague.

"Getting four of them in southern Wyoming in a short period of time is unusual," says Ken Gage, head of the Plague division at the Centers for Disease Control and Prevention in Fort Collins, Colorado "It's not cause for panic, or anything, but it is cause for some concern."

The owners of one of the cats had been gone for a week on vacation, returning home to find their cat very sick. After being examined by a local veterinarian and given fluids and antibiotics, the cat died. It was brought to the state's veterinary diagnostic lab, where Todd Cornish, a veterinary pathologist and assistant professor at Wyoming State, recognized the symptoms of pneumonia and large pus-filled lymph nodes to be consistent with the Plague, a diagnosis which was later confirmed by laboratory tests.

Donal O'Toole, the laboratory director, says Plague in cats "is relatively common, especially in the southwestern part of the United States. In Wyoming, it is less common, but we have seen previous cases in cats. Infected cats have been associated with 23 cases of human Plague in the U.S. in the last 20 years."

Outbreaks are somewhat common in rural areas and in areas where overcrowding, poor sanitation, and rat infestation are a problem.

Gus Lopez, director of the Cheyenne-Laramie County Health Department, is very uneasy about the recent events.

Figure 3. Yersinia pestis colonies on a culture plate following isolation from a cat with plague.  Colonies are characteristically sticky (arrow). Image Courtesy: Wyoming Animal Health and Disease Information Network.

Figure 3. Yersinia pestis colonies on a culture plate following isolation from a cat with plague. Colonies are characteristically sticky (arrow). Image Courtesy: Wyoming Animal Health and Disease Information Network.

"I think this is just going to be the tip of the iceberg," Lopez said. "And what really concerns me is these cases with cats right now really increase the risk of human exposure."

Very true: sick cats generally tug at our heartstrings more than rats, so we are more likely to handle them in our attempts to care for them. Also, cats increase our risk when they proudly leave their half-eaten-Plague-infested rat on our doorstep.

Since the disease is rare, its initial symptoms in humans of lethargy, swollen lymph nodes, fevers, and chills are often mistaken for other things, and proper treatment with antibiotics are often not started until it's too late. Such was the case for a forty-seven-year-old woman from Tahoe Paradise, California, who died after contracting pneumonic Plague (a type of Plague that primarily infects the lungs) from her pet cat in 1980. Her initial symptoms seemed to point to a urinary infection, since her urine contained bacteria and pus, so her doctor sent her home with tetracycline for her to take every six hours, though she also mentioned she had been having chest pains. Of course, the medicine was ineffective and she died two days later. Two days after that the hospital laboratory was able to identify the bacteria as Yersinia pestis (the bacteria that causes the Plague).

Luckily her sixteen-year-old daughter, who let the sick cat sleep on her chest, and the 150 children who stayed at the 24-hour daycare facility the woman ran, never came down with the Plague.

Diagnosing a cat with the disease can be just as tricky, putting veterinarians and their assistants at risk. In 1982, a veterinary assistant in her early twenties became ill from examining an infected cat named Jiggs, who had been in the clinic for a couple of days while they tried to figure out why he was sick. As she peered into the cat's throat, he coughed in her face, and died later that night. The woman was sick for a week and hospitalized for five days before she was adequately treated.

The instances of Plague in Wyoming seem to be under control, for now at least. However, knowing how difficult it is to properly diagnose the Plague in cats and humans, it is important to take some sensible precautions to prevent you or your pet from getting sick, especially since cat-associated Plague cases seem to occur year-round. Fleas and rodents, on the other hand, tend to be more active during periods of warm weather, causing more Plague outbreaks in the summer months. Obviously it would be wise to avoid handling rodents or animals that are not your own. And if you need yet another reason to keep your kitty flea-free and happy and warm in your home rather than on the loose outdoors, this would be an excellent one.

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