NCJ Number
191807
Journal
Morbidity and Mortality Weekly Report Volume: 45 Issue: RR-14 Dated: December 13, 1996 Pages: 1-15
Date Published
1996
Length
16 pages
Annotation
This report contains revised recommendations by the Advisory Committee on Immunization Practices concerning prevention of plague.
Abstract
Plague is an acute, often fatal, and potentially epidemic disease caused by infection with Yersinia pestis. This report included information and recommendations on vaccination, public health practices, and medical treatment to prevent plague among humans. Plague exists in natural enzootic and epizootic transmission cycles involving wild rodents and their fleas in certain regions of Asia, Africa, the Americas, and extreme southeastern Europe near the Caspian Sea. Y. pestis is a gram-negative coccobacillus belonging to the Enterobacteriaceae. This bacterium has several chromosomal and plasmid-associated factors that are essential to its virulence in mammalian hosts and flea vectors. The most common mode of transmission of Y. pestis to humans is by the bite of infectious fleas. Other modes of transmission were also described in this report. The three principal clinical presentations of plague are bubonic, septicemic, and pneumonic. Risk for plague in humans is greatest when epizootics cause high mortality in commensal rate populations, thereby forcing infected rat fleas to seek alternative hosts, including humans. During 1984-1994, a total of 18,739 cases of plague in humans were reported to the World Health Organization (WHO) from 20 countries. In the United States, most cases of plague in humans occur in the summer months, when the risk for exposure to infected fleas is greatest. Killed bacteria have been used in plague vaccines since 1896. However, only one vaccine--a formalin-inactivated preparation--is currently licensed for use in the United States. The efficacy of the inactivated plague vaccine in humans has not been measured in controlled studies. Persons should be vaccinated only if they are at high risk for exposure. Adverse reactions following injection of the first dose of plague vaccine generally are mild, but the frequency and severity of such events can increase with repeated doses. Precautions to prevent adverse reactions should include review of the vaccine’s history of hypersentivity to plague vaccine and its components. Vaccination is usually unnecessary when appropriate preventive measures are taken. Vaccinated persons should follow the preventive measures discussed in this report because of uncertainties about the efficacy of plague vaccine. In most instances, plague can be prevented by using an appropriate combination of: (a) personal protective measures; (b) applications of insecticides to home, recreational, and work environments when plague has been detected in local animal flea populations; (c) insecticidal treatment of pets; (d) avoidance of sick or dead animals; (e) environmental modifications to reduce the amount of food and shelter available to rodents; and (f) prophylactic antibiotic therapy for persons who are presumed to have been exposed to infection. References