1.Epidemiology andPrevention Of PLAGUE Prepared by: Stacy Arvinna JamarunGroup 3,6th Year 2nd Semester 2013

2. History & Significance14th Century: Black Death responsible for >20 million deaths in EuropeUsed as a BW agent by Japan in WW IIStudied by Soviet and, to a smaller extent, U.S. BW programs1995: Larry Wayne Harris arrested for illicit procurement of culture via mail 3. Epidemiology Caused by Yersinia pestis Gram negative, non-motile, non-spore-forming bacillus Resistant to freezing temperature and drying, killed byheat and sunlight Zoonotic infection; Humans are accidental hosts Human plague occurs from bite of an infected flea(bubonic) Outbreaks are cyclical corresponding to rodent reservoirand arthropod vector populations Only pneumonic form of plague is spread person-to-personLast case of person-to-person transmission in U.S.occurred in 1924 4. Epidemiology Transmission Historically, rat-borne urban epidemics Now mostly endemic sylvatic plague with sporadicoutbreaks Pneumonic is only form capable of person to personspread Higher risk in overcrowding, indoorcontacts, cold/wet weather 5. Epidemiology Risk Factors Close contact with case Contact with infected animal Living or recent travel in endemic area Peridomestic animals running loose Residing in crowded conditions Cool, wet weather Exposure to a known intentional release 6. History of Plague Plague recorded more than 2000 years ago Three pandemics 1st 542AD; 100million dead in 60 years; from N.Africa 2nd 14th century; Black Death; 25million dead in Europe alone (>1/4 of entire population); from central Asia; disease became endemic in urban rat population and smaller epidemics occurred through 17th century 3rd ended in 1990s; Burma to China (1894) & Hong Kong to other continents including N. America via rat-infected ships; 20million dead in India alone; foci of infection firmly established in wild rodents in rural areas About 10-15 cases/year U.S. 7. Epidemiology cycles Sylvatic (wild) Cycle of PlagueReservoir (foci) = wild rodents (prairiedogs, rabbits, mice, dogs)Vector = wild rodent flea Urban (domestic) Cycle of PlagueReservoir = domestic (urban) black ratOver 8 million in NYC = human populationVector = oriental rat flea (Xenopsylla cheopis) Human Cycle of PlagueBubonic plague acquired from contact with eithersylvatic or urban reservoirs or arthropod vector biteand further transmitted in human population byspread of pneumonic plague 8. EpidemiologicalCycles of Plague 9. PlagueCase Definition Characterized byfever, chills, headache, malaise, prostration,& leukocytosis that manifests in one or moreof the following clinical forms: Regional lymphadenitis (bubonic) Septicemia w/o evident bubo (septicemic) Plague pneumonia Pharyngitis & cervical lymphadenitis (pharyngeal) 10. PlagueCase Definition, cont.Laboratory criteria for diagnosis:Presumptive Elevated serum antibody titers to Y. pestis F1 antigen (w/odocumented 4-fold change) in a patient with no history of plaguevaccination OR Detection of F1 antigen in a clinical specimen by fluorescent assayConfirmatory Isolation of Y. pestis from a clinical specimen OR 4-fold or greater change in serum antibody titer to Y. pestis F1antigen 11. Plague: Case ClassificationSuspected: Clinically compatible case w/o presumptive or confirmatory lab resultsProbable: Clinically compatible case with presumptive lab resultsConfirmed: Clinically compatible case with confirmatory lab results 12. PlagueClinical Forms Bubonic plagueMost common naturally-occurring formMortality 60% untreated,