A scanning electron micrograph depicting a mass of Yersinia pestis bacteria

Pneumonic plague, a severe type of lung infection, is one of three main forms of plague, all of which are caused by the bacterium Yersinia pestis. It is more virulent and rare than bubonic plague. The difference between the versions of plague is simply the location of the infection in the body; the bubonic plague is an infection of the lymphatic system, the pneumonic plague is an infection of the respiratory system, and the septicemic plague is an infection in the blood stream.

Typically, pneumonic form is due to a spread from infection of an initial bubonic form. Primary pneumonic plague results from inhalation of fine infective droplets and can be transmitted from human to human without involvement of fleas or animals. Untreated pneumonic plague has a very high fatality rate.

Epidemiology[link]

Since 2002, the World Health Organization (WHO) has reported seven plague outbreaks, though some may go unreported because they often happen in remote areas. Between 1998 and 2009, nearly 24,000 cases have been reported, including about 2,000 deaths, in Africa, Asia, the Americas and Eastern Europe. 98 percent of the world's cases occur in Africa.

Pathology and transmission[link]

Pneumonic plague can be caused in two ways: primary, which results from the inhalation of aerosolised plague bacteria, or secondary, when septicemic plague spreads into lung tissue from the bloodstream. Pneumonic plague is not exclusively vector-borne like bubonic plague; instead it can be spread from person to person. There have been cases of pneumonic plague resulting from the dissection or handling of contaminated animal tissue. This is one type of the formerly known Black Death.^[1] It could kill 90%–95% of a population if the victims coughed and passed on the bacteria.

Symptoms[link]

The most apparent symptom of pneumonic plague is coughing, often with hemoptysis (coughing up blood). With pneumonic plague, the first signs of illness are fever, headache, weakness, and rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery sputum.^[2] The pneumonia progresses for two to four days and may cause respiratory failure and shock. Patients will die without early treatment, some within 36 hours.

Initial pneumonic plague symptoms can often include:

• Fever
• Weakness
• Headache
• Nausea

Rapidly developing pneumonia with:

• Shortness of breath
• Chest pain
• Cough
• Bloody or watery sputum (saliva and discharge from respiratory passages).

Prognosis and treatment[link]

Pneumonic plague is a very aggressive infection requiring early treatment. Antibiotics must be given within 24 hours of first symptoms to reduce the risk of death,.^[2] Streptomycin, gentamicin, tetracyclines, and chloramphenicol are all effective against pneumonic plague.

Antibiotic treatment for 7 days will protect people who have had direct, close contact with infected patients. Wearing a close-fitting surgical mask also protects against infection.^[2]

The mortality rate from untreated pneumonic plague approaches 100%.^[3]

China[link]

The People's Republic of China has eradicated the pneumonic plague from most parts of the country, but still reports occasional cases in remote Western areas where the disease is carried by rats and the marmots that live across the Himalayan plateau. Outbreaks can be caused when a person eats an infected marmot or comes into contact with fleas carried by rats. A 2006 WHO report from an international meeting on plague cited a Chinese government disease expert as saying that most cases of the plague in China's northwest occur when hunters are contaminated while skinning infected animals.^[4] The expert said at the time that due to the region's remoteness, the disease killed more than half the infected people. The report also said that since the 1990s, there was a rise in plague cases in humans—from fewer than 10 in the 1980s to nearly 100 cases in 1996 and 254 in 2000.^[5] Official statistics posted on the Chinese Health Ministry's Web site showed no cases of plague in 2007 and 2008.^{[citation needed]} In September 2008, two persons in east Tibet died of pneumonic plague.^[6]

A recent outbreak of the disease in China began in August 2009 in Ziketan Town located in Qinghai Province. The town was sealed off and several people died as a result of the disease.^[4][7] According to spokesperson Vivian Tan of the WHO office in Beijing, "In cases like this [in August 2009], we encourage the authorities to identify cases, to investigate any suspicious symptoms among close contacts, and to treat confirmed cases as soon as possible. So far, they have done exactly that. There have been sporadic cases reported around the country in the last few years so the authorities do have the experience to deal with this."^[8]

In September 2010, there were 5 reported cases of pneumonic plague in Tibe.^[where?]

Peru[link]

Peru's health minister says an outbreak of plague has killed a 14-year-old boy and infected at least 31 people in a northern coastal province.^[when?]

Health Minister Oscar Ugarte says authorities are screening sugar and fish meal exports from Ascope province, located about 325 miles (520 km) northwest of Lima. Popular Chicama beach isn't far away.

Ugarte says the boy, who had Down syndrome, died of bubonic plague July 26, 2010.

He said August 1 that most of the infections are bubonic plague, with four cases of pneumonic plague. The former is transmitted by flea bites, the latter by airborne contagion. The disease is curable if treated early with antibiotics.

The first recorded plague outbreak in Peru was in 1903. The last, in 1994, killed 35 people.^{[9][unreliable source?]}

Recent notable cases[link]

On November 2, 2007, wildlife biologist Eric York died of pneumonic plague in Grand Canyon National Park. York was exposed to the bacteria while conducting a necropsy on a mountain lion carcass.^[10]

In popular culture[link]

Pneumonic plague has occasionally been depicted in popular culture. Elia Kazan's 1950 film Panic in the Streets, starring Richard Widmark and Jack Palance, concerns an attempt by New Orleans health authorities to suppress an outbreak of pneumonic plague.^[11][12] An episode of "NCIS", entitled "SWAK", depicts Special Agent Anthony DiNozzo becoming infected with the plague. In "Royal Pains", Divya and her fiancee Raj are quarantined for it when their tango instructor is diagnosed with the illness. The film Cassandra Crossing involves a terrorist who is accidentally infected with the illness and subsequently infects nearly everyone aboard a train. In an episode of S.W.A.T., a man hired to kill a U.S. senator contracts the disease in New Delhi.

See also[link]

• Bubonic plague
• Septicemic plague

References[link]

External links[link]

• Facts about Pneumonic Plague. Centers for Disease Control and Prevention.