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Plague

Plague. Dr Navya N Assistant Professor Department Of Community Medicine. SPECIFIC LEARNING OBJECTIVES. To understand the epidemiology of plague disease To understand the clinical features of plague To understand the prevention and control of plague. INTRODUCTION. Zoonotic disease

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Plague

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  1. Plague Dr Navya N Assistant Professor Department Of Community Medicine

  2. SPECIFIC LEARNING OBJECTIVES • To understand the epidemiology of plague disease • To understand the clinical features of plague • To understand the prevention and control of plague

  3. INTRODUCTION • Zoonotic disease • Causative organism – Yersinia Pestis • One of the oldest diseases known to man • Exits in natural foci – transmitted- infected flea bites

  4. INTRODUCTION • Many forms - enzootically, epizootically, sporadically and in epidemics • Endemic in many parts of the world • Widely distributed in the tropics and subtropics • In SEAR, natural foci of plague- India, Indonesia, Myanmar and possibly in Nepal

  5. PLAGUE PANDEMICS • Justinian plague: Sixth century-100 million victims • Black Death: 14th century - 50 million deaths. • 3rd pandemic: Hong Kong in 1894 • This pandemic resulted in 13 million deaths in India

  6. PROBLEM STATEMENT • Plague outbreaks continued to occur- decreasing frequency • Globally in 2013 – 783 cases- human plague – 126 deaths • In India – 2004- localized outbreaks – bubonic plague – 8 cases, 3 deaths- Dangud village- Uttarkashi

  7. AGENT FACTORS • Gram - negative , non motile, coccobacillus • Bipolar staining with special stains – Wayson’s stain • Reclassified as Enterobacteriaceae • Non sporulating, non - lactose fermenting

  8. AGENT: YERSINIA PESTIS

  9. RESERVOIR OF INFECTION • Wild rat (Tatera Indica) • Field mice • Gerbils • Disease -Maintained and spread by resistant species of wild rodents (Rodents immune to plague)

  10. SOURCE OF INFECTION • Infected rodents and flea • Case of pneumonic plague

  11. PLAGUE VECTORS • Xenopsyllacheopis(Oriental rat flea; worldwide) • Oropsyllamontanus(United States) • Nosopsyllusfasciatus(Nearly worldwide) • Xenopsyllabrasiliensis(Africa & India) • Xenopsyllaastia(Indonesia and Southeast Asia) • Xenopsyllavexabilis(Pacific Islands)

  12. TRANSMISSION • Flea bite (78%) • Direct animal contact (20%) − Tissues, body fluids, scratches, bites − Enters through break in skin • Aerosol (2%) • Human cases − April-November (93%) − Increased activity of fleas and hosts

  13. LIFE CYCLE

  14. BLOCKED FLEA • Flea- ingest upto 0.5 cu.mm of blood- 5000 plague bacilli. • Plague bacilli multiply enormously- gut of rat flea- may block the proventriculus- no food - blocked flea • Blocked flea- eventually faces starvation and dies as it is unable to obtain blood meal. • A blocked flea is an efficient transmitter of plague • A partially blocked flea is more dangerous then a completely blocked flea because it can live longer

  15. HOST FACTORS • AGE and SEX : all ages and both sexes • HUMAN ACTIVITIES : activities – increases flea-man contact • MOVEMENT OF PEOPLE : cargo, sea or land • IMMUNITY : no natural immunity

  16. ENVIRONMENTAL FACTORS • SEASON : north india – September – may South- no definite plague season • TEMPERATURE AND HUMIDITY : 20-25 deg C humidity – 60% • RAINFALL : heavy rainfall – flood the burrows – protective factor • URBAN and RURAL AREAS • HUMAN DWELLINGS

  17. PLAGUE IN RODENTS • Primarily a disease of rodents • Infection is maintained- natural foci of the disease in wild rodent colonies • Enzootic (maintenance) hosts • Epizootic (amplification) hosts

  18. PLAGUE IN RODENTS • Enzootic hosts: • Relatively mild illness and low mortality rates. • Voles and mice • Epizootic hosts: • High susceptibility and high mortality. • Mice, rats, voles, gerbils, ground squirrels and marmots • Rats have historically been a primary carrier

  19. URBAN PLAGUE • Infected fleas or rodents move to urban area • Commensal (domestic) rodents infected • Rapid die off • Fleas seek new host − Domestic cats or humans • Poverty, filth, homelessness

  20. HUMAN PLAGUE -CLINICAL FEATURES • Bubonic Plague • Septicaemic Plague • Pneumonic Plague

  21. BUBONIC PLAGUE • Mode of entry: Flea bite • IP: 2-6 days • Infection spreads to the regional lymph nodes • Headache, chills, fever, malaise and pain in the affected regional lymph nodes • Buboes: Inflammation and swelling in one or several nodes (Axillary and supraclavicular) • Mortality – untreated – 50-60% and treated - <5%

  22. Bubonic plague

  23. SEPTICAEMIC PLAGUE • Invades and continues to multiply in the bloodstream. • Secondary to bubonic plague or without detectable lymphadenopathy. • DIC, multiple organ failure and ARDS • Complications : Plague pneumonia, plague meningitis and hepatic or splenic abscesses • Mortality – untreated 100%

  24. SEPTICAEMIC PLAGUE

  25. PNEUMONIC PLAGUE • IP: 1-3 days • Least common-most dangerous and fatal form • Primary – Inhalation of infected droplets – Y Pestis • Secondary complication of septicaemic plague • Chills, fever, headache, body pains, weakness and chest discomfort. • Person to person spread possible • Death if specific antibiotic therapy is not begun within 18 - 24 hours of onset

  26. Plague

  27. PREVENTION & CONTROL • Early diagnosis & Treatment • Chemoprophylaxis • Control of fleas • Control of rodents • Vaccination • Surveillance • Health education

  28. DIAGNOSIS • Demonstrate the bacilli • Blood, sputum & aspirates from suspected buboes • Gram, Giemsa, Wright, or Wayson stain • Supportive but not confirmatory

  29. DIAGNOSIS • Cultures: Specific phage lysis • 4 fold in titre to the Yersiniapestis F1 antigen by passive haemagglutination test • Dipstick PHTs • ELISAs for detecting IgM and IgG antibodies

  30. PREVENTION AND CONTROL • Early diagnosis and treatment • Notification: • Antibiotics: Streptomycin drug of choice – IM -2 divided doses – 7-10 days ( 30mg/kg/BW) • Others - Tetracycline, gentamycin • cephalosporins are NOT effective • Isolation • Disinfection

  31. Plague Prophylaxis • Close contacts of cases- pneumonic plague • Persons suspected to have had direct contact with body fluids or tissues of - infected mammal in previous six days • Tetracycline and Chloramphenicol

  32. FLEA INDICES (Multiplication of this index by 100 gives the percentage index)

  33. FLEA INDICES

  34. RODENT AND FLEA CONTROL • Isolate infected animals −Limit number of people in contact, Personal protection- Surgical mask, gloves, eye protection • Flea control−Most effective method to break the chain of transmission (Rodent-flea-man) −Insecticidal spraying (DDT and BHC), malathion −Indoor spraying, Rat burrows- insufflated- insecticidal dusts

  35. VACCINATION • For prevention, not the control of the human plague • Formalin killed vaccine is used. • 1 week prior to anticipated outbreak • 2 doses- SC - interval of 7-14 days • Immunity develops within 7 days • Booster dose to given every 6 months

  36. PREVENTION AND CONTROL • Public health education −Notification of dead rats and suspected plague case • Surveillance • Epidemiological investigation −To determine source of infection −Distribution −Prevalence −Potential spread to human population

  37. SUMMARY ???

  38. Thank you!

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