Fatal case of pneumonic plague in USA

Health officials in Coconino County, Arizona, have recently confirmed a fatal case of pneumonic plague. According to the report this is the first death in the county since 2007.

Plague statistics in the USA

Deaths are quite rare in the USA with only 15 reported between 2000 and 2023.

A total of 502 cases were notified during this period with the highest numbers in New Mexico, Colorado, Arizona and California.

Where does plague occur in the USA?

According to CDC most cases occur in two locations in the rural west of the United States:

• Northern New Mexico, northern Arizona and southern Colorado
• California, southern Oregon and far western Nevada.

For more information, see CDC's guide on plague prevention in the USA.

What is plague and how is it transmitted?

Plague is an infectious disease caused by a bacterium called Yersinia Pestis

It is transmitted to humans by the bite of an infected flea. The animal reservoir is usually a rodent.

In Europe during the Middle Ages, the plague was responsible for more than 200 million deaths in three major pandemics. The name still conjures fears despite the fact we now have modern antibiotics to successfully treat the disease if recognised early.

Types, symptoms and presence of plague

Human disease is mostly bubonic plague where the infected individual presents with swollen lymph nodes (often in the groin). Gastrointestinal symptoms are common. Pneumonia plague may follow respiratory exposure to droplets from an infected person. This form is much less common but has a higher mortality (> 50%) versus 5% for bubonic plague.

The last reported occurrence of human-to-human transmission was reported in 1924.

Plague exists in nature in wild rodents in Asia, Africa and the Americas. Domesticated dogs and cats may carry infected fleas into the home.

Historical plague in the UK and Australia

The last recorded outbreak of plague in the UK was reported in 1918 and no cases, either local or imported, have been reported since then.

Australia experienced two periods of plague. The first between 1900 and 1910 and the second after 1920 for another five years. More than 1,200 cases were notified in the first period with most cases occurring in NSW. The outbreaks were coastal and mostly related to port areas. More than 500 deaths were recorded.

Endemic regions

Over 1500 cases are reported to the World Health Organisation annually with mortality rates less than 10%. Very few cases are reported in major cities. Most occur in small rural villages in agricultural areas where rodents and farm produce co-exist.

According to the WHO, the three most endemic countries globally are the Democratic Republic of Congo, Madagascar and Peru. Australia does not have endemic plague.

Risk to travellers and expats

The risk of exposure to plague is very low for both travellers and expatriate workers. Rural activities such as camping, trekking or hunting might increase your risk. Protection measures used for insects (clothing and repellents) can help to reduce bites.