According to reports over the weekend, fleas in two Arizona counties tested positive for the plague.
Here are 10 things you should know about the infamous disease, how it is found, and what the danger level really is in the United States.
1. What is it?
Plague is known for killing millions in Europe during the Middle Ages, but that was before the invention of antibiotics.
The plague bacterium (Yersinia pestis) is transmitted by fleas and is regularly seen in wild rodents.
2. Where is it seen now?
It occurs naturally in the western United States, including Arizona, California, Colorado and New Mexico. Plague bacteria survive for prolonged periods in the soil, where burrowing rodents might directly acquire it.
3. What are the forms?
Bubonic plague is the most common form – it usually occurs after the bite of an infected flea. The key symptom is a swollen, painful lymph node, usually in the groin, armpit or neck. If it goes untreated, it can spread to the rest of the body as septicemic plague or pneumonic plague.
Septicemic plague happens when plague bacteria multiply in the bloodstream. It can quickly cause shock and organ failure, leading to death.
If the bacteria reach the lungs, it causes pneumonic plague, which is also almost always fatal if not treated properly.
4. How would you get it?
People get it through the bites of infected fleas, by touching or skinning infected animals (such as prairie dogs, squirrels, rats and rabbits), or inhaling droplets from the cough of an infected person or animal (particularly sick cats).
5. What are the symptoms?
High fevers, aches and pains, chills, swollen and painful lymph nodes and weakness are some of the common symptoms.
Septicemic plague can include abdominal pain, while pneumonic plague victims often cough up bloody mucus.
6. How many people does it affect?
Plague usually affects only a handful of people in the United States annually. According to the American Society of Tropical Medicine and Hygiene, only 57 cases were reported between 2000 and 2009.
Worldwide, 21,725 cases were reported, with more than 10,000 in the Congo and 7,000 in Madagascar.
7. Why is there plague now?
Studies suggest that outbreaks of the plague occasionally occur in southwestern U.S. states like Arizona during cooler summers that follow wet winters. Those weather patterns often create epizootics – outbreaks in which large numbers of susceptible rodents die. When this happens, hungry infected fleas leave the dead rodents and seek blood from other hosts, including humans and domestic pets.
8. How can it be prevented?
If you own pets and live in an area susceptible to plague, you should prevent food sources from accumulating outside their homes as these invite wild animals. Keep clutter and undergrowth out from under decks and porches and out of yards, where animals can hide. Avoid picking up dead animals – instead, report them to local law enforcement or health officials.
9. How can I protect my pets?
Use flea control medications on your pets regularly. Keep your pet food in rodent-proof containers. Don’t let them hunt or road in rodent habitats, such as prairie dog colonies.
10. What’s being done?
Reports say that a vaccine is expected in the next decade for soldiers, first responders, lab workers and travelers.
Until then, it’s important to remain vigilant. Plague can resurface after decades of being absent – notably it returned in Algeria after 57 years without a reported case.