Could New Cases of “The Plague” Spread to Humans?

Plague is an ancient disease that still occurs in parts of Asia, Africa, South America, the Middle East, Eastern Europe, and in certain regions of the U.S.

According to the CDC, Division of Vector Borne Infectious Diseases, all present-day outbreaks of plague in this country can be traced specifically to infected fleas carried by wild rodents.

How the Plague is Transmitted

The plague is caused by Yersinia pestis, a bacteria transmitted by the rodent flea – a flea found not only on rats, but also other rodents, squirrels, prairie dogs, rabbits, cats and dogs.

Fleas carrying the bacteria can continue to transmit the plague for months. Risk to other animals and humans increases during outbreaks of plague in which large numbers of rodents die off from the disease, forcing infected fleas to find other hosts.

Your pet can catch the disease through a bite from an infected flea or by eating a rodent or other animal carrying infected fleas.

You or a family member can contract the plague several ways, including:

• Through flea bites
• During contact with an infected animal like the family pet
• By inhaling airborne droplets from an infected person or animal (especially cats)
• Exposure to the bacteria in a laboratory

Types of Plague

There are three forms of plague:

1. Bubonic plague, which infects the lymph glands
2. Septicemia plague, which is a blood infection
3. Pneumonic plague, an infection of the lungs and the most contagious because it can be transmitted through airborne droplets

Signs and Symptoms in Your Pet

Dogs have a high resistance to plague bacteria. If your dog does become infected, which is very unlikely, he’ll have fever, inflammation and pain associated with swollen lymph nodes. Rarely, the skin over the lymph nodes might break due to excessive swelling from fluid buildup. In the vast majority of cases, these symptoms clear up on their own without medical intervention.

Both feral and domestic cats can contract all three types of the disease. But unlike plague in dogs, in kitties it’s a life-threatening situation. Cats infected with plague bacteria have only a 50 percent survival rate.

Feline symptoms include:

• Painful, swollen lymph nodes that may abscess
• Fever and inflammation
• Vomiting, diarrhea and dehydration
• Anorexia and visible weight loss
• Enlarged tonsils, swelling in the head and neck area
• Coma

If your cat exhibits any of the above symptoms and you suspect she’s come in contact with a potential source of plague, get her to a veterinarian right away.

Cats that spend time outdoors are much more likely to be infected – another reason indoor kitties stay healthier and safer than cats who live or roam unsupervised outdoors.

Human Symptoms of the Disease

It takes from two to six days after exposure to plague bacteria for symptoms of infection to appear.

If you contract the plague, the bacteria will travel through your bloodstream and infect your lymph nodes, typically those in the groin, armpit and neck. Your lymph nodes will swell and the resulting painful lumps are a hallmark of bubonic plague.

You might also come down with a headache, fever, chills, fatigue, and perhaps gastrointestinal symptoms.

If left untreated, bubonic plague bacteria can multiply in your bloodstream and cause a second type of the disease – septicemia plague, which is a serious blood infection. Symptoms of septicemia include fever, chills, fatigue, abdominal pain, bleeding into the skin and other organs, and shock.

Septicemia plague can be fatal unless immediate treatment is initiated.

The third type of plague, pneumonic plague, occurs when bacteria infects the lungs. If you develop plague pneumonia, you’ll run a fever, experience chills, difficulty breathing, coughing and bloody sputum.

Like septicemia plague, untreated pneumonic plague is usually fatal.

This type of plague is classified as a public health emergency because the bacteria is quickly and easily transmitted through coughing. All suspected cases of plague are reported to the appropriate government health agencies.

If your doctor or other healthcare provider suspects you have the plague, you will very likely be hospitalized in an isolation unit, and treatment – typically antibiotics -- will begin immediately, even before the plague has been definitively diagnosed.

How Common is the Plague? Should I Be Worried?

Worldwide cases of the plague in humans run about 1,000 – 2,000 cases each year. The U.S. averages about 10 to 15 cases per year.

Most cases of the plague in people occur in the following regions:

• Northern New Mexico
• Northern Arizona
• Southern Colorado
• California
• Southern Oregon
• Far western Nevada

If you live in the southwest, you should be aware that fleas from rock squirrels are the most common cause of infection. If you’re on the coast in California or Oregon, infected ground squirrel fleas are the usual source.

You should take care to safeguard your pets and other family members, especially during the warm weather months, if you:

• Live in areas where plague is known to occur in wild rodents
• Camp or hike in areas where plague is known to exist
• Trap or hunt or for some other reason handle an infected animal
• Come in contact with people suffering from pneumonic plague

Preventive Measures

If you live or travel to areas known to have plague outbreaks, there are steps you can take to minimize your risk of being infected.

1. Avoid creating a rodent habitat. Make sure the exterior of your home or campsite is free of food and shelter sources for rodents. Get rid of brush, rock piles, trash and any food sources.
2. Steer clear of sick or dead animals and report them to the health department.
3. Use a non-toxic insect repellent wherever there is a risk of flea bites.
4. Keep your pet safe with regular natural flea and tick control treatments