Plague

Description

Plague is a zoonosis involving rodents and their fleas. The causative agent of plague is a bacterium, Yersinia pestis. Humans are incidental hosts and are usually infected by the bite of rodent fleas. Plague can also be acquired by direct contact with infectious materials or by inhalation of infective respiratory droplets. Initial signs and symptoms of plague can be nonspecific, with fever, chills, malaise, myalgia, nausea, prostration, sore throat, and headache. Bubonic plague, the most common form, usually presents with painful, swollen lymph nodes (buboes) that develop in the afferent lymphatic chain draining the site of the flea bite.

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Plague continues to be enzootic in wild rodent populations over large rural areas of the Americas, Africa, and Asia, with occasional outbreaks among commensal rodents in villages and small towns. Wild rodent plague poses a real, though limited, risk to people. When infection spreads to rats in urban or populated areas, people are at markedly increased risk of exposure. In the past several decades, however, urban outbreaks have been rare and limited in size.

Occurrence

Wild rodent plague exists in the western third of the United States, in widely scattered areas of South America; in north-central, eastern, and southern Africa; in Madagascar; in Iranian Kurdistan; along the frontier between Yemen and Saudi Arabia; in central and southeast Asia (Burma [Myanmar], China, India, Indonesia, Kazakhstan, Mongolia, and Vietnam); and in portions of Russia. In recent years, human plague has been reported in Africa from Angola, Botswana, Democratic Republic of the Congo (Zaire), Kenya, Libya, Madagascar, Malawi, Mozambique, South Africa, Tanzania, Uganda, Zambia, and Zimbabwe; in Asia from Burma [Myanmar], China, India, Kazakhstan, Laos, Mongolia, and Vietnam; and in the Americas from Bolivia, Brazil, Ecuador, Peru, and the United States.

Risk for Travelers

Risk to travelers in any of these areas is small.

Preventive Measures

Vaccine

Plague vaccine is no longer commercially available. Vaccination against plague is not required by any country as a condition for entry. In the past, vaccine was recommended only for people who were at a particularly high risk of exposure because they worked with plague routinely in the laboratory or because of field exposures to rodents and their fleas in epizootic areas. In most of the countries of Africa, Asia, and the Americas where plague is reported, the risk of infection exists primarily in rural mountainous or upland areas. People who travel to plague-infected areas should follow the preventive measures described in the following section.

Other

Travelers considered to be at high risk for plague because of unavoidable exposures in active epizootic or epidemic areas should be advised to consider antibiotic chemoprophylaxis with tetracycline or doxycycline during periods of exposure. Trimethoprim-sulfamethoxazole is an acceptable substitute for use in infants and in children younger than 8 years of age. Personal protective measures should also be recommended, including the use of insect repellents containing N,N-diethylmetatoluamide (DEET) on skin and clothing. Clothing also can be treated with insecticidal sprays containing permethrin. Travelers should be advised to avoid sick or dead animals or rodent nests and burrows. Whenever possible, travelers should also avoid visiting areas that have experienced recent plague epidemics or epizootics. Travelers are unlikely to be at high risk for plague while staying in modern accommodations.

Credits: National Center of Infectious Diseases