Emerging & re emerging diseases


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Lecture given to 3rd year medical students.

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Emerging & re emerging diseases

  1. 1. EMERGING & RE-EMERGING [parasitic] INFECTIONSINIMMUNOCOMPETENT & IMMUNOCOMPROMISED HOSTS<br />Rumala Morel<br />Department of Parasitology<br />Faculty of Medicine<br />Peradeniya<br />Year 3 2005/06 Batch<br />
  2. 2. Mad cow disease<br />H5N1 avian influenza<br />Severe Acute Respiratory Syndrome (SARS) <br />Ebola virus<br />Hantavirus<br />Monkeypox<br />Swine flu<br />New Diseases Emerge<br />Old Diseases Re-emerge<br />
  3. 3. Objectives<br />Define emerging & re-emerging infections<br />List the emerging & re-emerging parasitic infections which are important globally & in SL<br />Briefly describe the factors which predispose to emergence & re-emergence of infections in immunocompetent & immunocompromised hosts<br />Recognize the current handicaps when dealing with the risks of these infections<br />Briefly describe the preventive aspects of these infections<br />
  4. 4. "emerging," "re-emerging," or "endemic"<br />Re-emerging<br />= diseases that once were major health problems globally or in a particular country, and then declined dramatically, but are again becoming health problems for a significant proportion of the population.<br />Diseases thought to be adequately controlled making a “comeback” are “re-emerging” <br />Emerging = diseases <br />that have not occurred<br />in humans before<br /> or<br />that occurred only<br />in small numbers<br />in isolated places.<br />"endemic"<br />a long term problem.<br />Never significantly declining<br />Eg. pneumonia<br />
  5. 5. New Diseases Emerge<br />Emerging diseases = new infections that arise from changes in existing organisms <br />or <br />known infections that spread to new geographic areas or populations<br />Incidence of such a disease in people increases over 20 years or threatens to increase<br />WHAT ARE EMERGING DISEASE <br />‘HOT SPOTS’?<br /><ul><li>Regions where new emerging infectious diseases are most likely to originate.
  6. 6. Usually tropical – developing countries
  7. 7. ill equipped to cope</li></li></ul><li>Old Diseases Re-Emerge<br />(A) EVOLUTION OF THE INFECTIOUS AGENT<br />Mutations in bacterial genes that confer resistance to antibiotics – 20% <br />Multidrug-resistant & extremely drug-resistant TB <br />Multi drug resistant P.falciparum<br />(B) REDUCED HUMAN IMMUNITY<br />Immunization failure <br /> (breakdowns in public health measures)<br /> a greater proportion of susceptible individuals in a population and an increased reservoir of the infectious agent. <br />Increased number of immunocompromised hosts - due to the stress of famine, war, or disease<br />
  8. 8. WHY EMERGE? FACTORS PREDISPOSING TO EMERGENCE<br />1st step <br />Introduction of an infection for the first time into the<br />human population<br />ZOONOSES <br />In most cases (60%) that’s an infection that’s already out there in nature – may be a virus that’s naturally infecting some other species.<br />Ecological changes - puts humans in contact with the virus. Usually due to human activities <br />
  9. 9. WHY EMERGE? FACTORS PREDISPOSING TO EMERGENCE<br />ENVIRONMENTAL CHANGE <br /> tropical forests are cleared to make way for new roads, displacing disease-carrying animals and insects and increased human traffic through previously isolated areas <br />URBANIZATION - person-to-person transmission <br />POOR PRIMARY HEALTH CARE <br /> public health services may not be equipped to deal with some infectious outbreaks<br />
  10. 10. Globally important Emerging & Re-emerging Infectious Diseases<br />EMERGING<br />AIDS <br />cholera <br />CJD<br />Ebola hemorrhagic fever<br />influenza<br />Legionnaire disease Lyme disease<br />RE-EMERGING<br />tuberculosis<br />malaria<br />schistosomiasis<br />
  11. 11. List of NIAID* Emerging and Re-emerging Diseases<br />Group I—Pathogens Newly Recognized in the Past Two Decades<br />Group II—Re-emerging Pathogens<br />Group III—Agents with Bioterrorism Potential<br />NIAID—Category A <br />NIAID—Category B <br />NIAID—Category C<br />* NIAID = National Institute of Allergy & Infectious Diseases - USA<br />
  12. 12. Emerging and Re-emerging Parasites<br />NIAID Group 1 - Pathogens newly recognized in past two decades<br /><ul><li>Acanthamoeba
  13. 13. Microsporidia</li></ul>Encephalitozoon cuniculi Encephalitozoon hellem Enterocytozoon bieneusi<br />NIAID Group 3 -<br />Category B<br />Food & Waterborne pathogens<br /><ul><li>Cryptosporidium parvum
  14. 14. Cyclospora cayatanensis
  15. 15. Giardia lamblia
  16. 16. Entamoeba histolytica
  17. 17. Toxoplasma gondii</li></li></ul><li>Encephalitozoon cuniculi<br />coiled polar filament,<br /> thin wall with <br />endospore,<br />and <br />exospore<br />extruded polar filament. <br />
  18. 18. What is a Pandemic? <br />????Panic & Epidemic??? <br />pandemic is a global disease outbreak<br />"The world is now at the start of the 2009 influenza pandemic 30,000 confirmed cases from 74 countries” 11th June 2009 <br />WHO increases pandemic alert level to phase 6 "community level outbreaks in at least one other country in a different WHO region in addition to the criteria defined in Phase 5.<br />" Phase 5 is characterized by human-to-human transmission of the virus into at least 2 countries in 1 WHO region.<br />H1N1 immunization campaign <br />
  19. 19.
  20. 20. Global Warming<br />A temperature change of several degrees may make temperate zones more hospitable to vectors of tropical diseases<br />Malaria, Dengue - mosquitoes<br />Schistosomiasis – snails<br /> At the same time, tropical areas may become less hospitable to some of the same diseases. <br />
  21. 21.
  22. 22. Schistosomiasis <br />? Spreading from<br />TROPICAL to<br />TEMPERATE regions<br />Due to spread <br />of snail vector<br />With <br />GLOBAL WARMING<br />
  23. 23. crayfish as a biocontrol agent for the<br /> snail vector of human schistosomiasis,<br /> a disease that has resurfaced <br />as a growing problem due to<br /> China's rapid land-use change. <br />
  24. 24. Transmission ofpathogens with reduced dependence on host mobility<br />water-borne –diarrhoeal agents<br />attendant-borne [eg. Escherichia coli]<br /> Emerging hospital-acquired pathogens<br />Humans create pathways for transmission <br /> eg. spreading HIV through needle sharing, blood transfusion, commercial sex trade. It is now pandemic in spite of its relatively inefficient transmission. <br />mosquito-transmitted diseases: water is the limiting step.<br /> So irrigation projects, building of dams, cause an increase<br />in the mosquito population, and suddenly you see an<br />increase in the diseases<br />
  25. 25. MALARIA<br />WHO Global Malaria Programme <br />aims not only to reduce<br /><ul><li>the burden of malaria in endemic areas, </li></ul>but also to <br /><ul><li>Limit the geographical extent of malaria in the world. </li></ul>Local Elimination<br />the complete interruption<br />of mosquito-borne malaria transmission <br />in a<br />defined geographical area<br />
  26. 26. Key interventions to control malaria include:<br /><ul><li>prompt and effective treatment with </li></ul>artemisinin-based combination therapies; <br /><ul><li>use of insecticidal nets by people at risk; </li></ul>And<br /><ul><li> indoor residual spraying </li></ul>to control the vector mosquitoes.<br />
  27. 27. Emerging Parasitic Diseases in Sri Lanka<br />Leishmaniasis<br />Cryptosporidiosis<br />Dirofilariasis<br />Toxocariasis<br />Cutaneous Larva Migrans<br />
  28. 28. Sand fly<br />Cutaneous leishmaniasis is established<br /> Visceral leishmaniasis is <br />Emerging in Sri Lanka<br />Promastigotes<br />Amastigotes<br />
  29. 29. Cutaneous leishmaniasis in Sri Lanka<br />
  30. 30.
  31. 31.
  32. 32. Since 1981, HIV/AIDS has infected <br />60 million & killed half of them.<br />2 million die every year & <br />every 15 seconds a person is infected with HIV<br />
  33. 33. Control of HIV/AIDS<br />“test and treat”<br /> strategy of universal, <br />voluntary, annual HIV testing <br />and immediate treatment for<br /> those who test positive.<br />High-risk populations <br />In SL<br /> CSWs, Drug users, <br />Internal migrants<br />and transport workers<br />Global fund for AIDS/TB/Malaria ( GFATM)<br />Community-based outreach<br />strategies and new social-media<br />tools like mobile phones,<br />the Internet, Twitter, and Facebook<br />
  34. 34. Guidelines for Preventing Opportunistic Infections Among HIV-Infected Persons --- 2002Recommendations of the U.S. Public Health Service and the Infectious Diseases Society of America* <br />(A) preventing first episodes of disease by chemoprophylaxis or vaccination (primary prophylaxis), and preventing disease recurrence (secondary prophylaxis).<br />(B) PREVENTING EXPOSURE TO PATHOGENS<br />oral-anal contact - to reduce the risk for intestinal infections e.g., cryptosporidiosis, shigellosis, campylobacteriosis, amebiasis, giardiasis, and hepatitis <br />contact with animals - cryptosporidiosis, toxoplasmosis, salmonellosis, campylobacteriosis, or Bartonella infection. <br />
  35. 35. HIV infected - PREVENTING EXPOSURE TO PATHOGENS (contd)<br />New pet – avoid animals aged <6 months or <1 year for cats –toxoplasmosis,cryptosporidiosis, Bartonella infection (avoid cat bite/scratches, flea control), salmonellosis, and campylobacteriosis<br />Poultry and meat are safest when adequate cooking is confirmed with a thermometer (internal temperature of 180ºF for poultry and 165ºF for red meats). no trace of pink <br />Uncooked meats should not be allowed to come in contact with other foods; hands, cutting boards, counters, and knives and other utensils should be washed thoroughly after contact with uncooked foods (BIII). <br />
  36. 36. Cryptosporidium parvum: an emerging pathogen<br />six major outbreaks in the United States<br /> - contamination of drinking water<br /><ul><li>highly environmentally resistant cyst of </li></ul>C. parvum survives <br /><ul><li> drinking water filtrations
  37. 37. chlorination
  38. 38. oocysts do not survive cooking</li></ul>2 types of oocysts<br />thick-walled - excreted <br />thin-walled -autoinfection<br />
  39. 39. Cryptosporidium<br />
  40. 40. TRANSMISSION<br />CLINICAL FEATURES<br />feco-oral<br />water contaminated by livestock mammal feces <br />HIGH RISK GROUPS<br /><ul><li>infants and younger children in day-care centers -frequent diaper-changing
  41. 41. those whose drinking water is unfiltered and untreated
  42. 42. Farmers / veterinarians </li></ul>Watery diarrhea (up to 20 liters/day) <br />dehydration, weight loss, abdominal pain, fever, nausea and vomiting.  <br />In immunocompetent – self limited -1 to 2 wks<br />immunocompromised<br /> chronic and severe diarrhoea<br /> Disseminated - lungs<br />50% infective dose (ID50) of C. parvum<br />is only 132 oocysts for healthy persons<br />
  43. 43. CRYPTOSPORDIOSIS<br />Laboratory Diagnosis:Acid-fast staining <br />immunofluorescence microscopy <br /> method of choice - greatest sensitivity and specificity<br />enzyme immunoassays<br />Molecular methods - research tool.<br />
  45. 45. Cyclospora cayetanensis<br />
  46. 46. Life Cycle <br />of<br />Cyclospora<br />cayetanensis<br />
  47. 47. Acanthameoba spp.<br />Isolated from water, soil, air conditioning etc<br />In healthy -<br />Acanthamoeba<br /> keratitis<br />Immunosuppressed -<br />Granulomatous Amebic Encephalitis (GAE) <br />Disseminated infection <br />
  48. 48. Emerging & Re-emerging Infectious Diseases Surveillance & Control<br />Disease surveillance is concentrated not in developing countries, where emerging diseases are most likely to arise, but in developed countries that can afford laboratories <br />Global disease surveillance networks<br /> (1) U.S. Defense Department’s GEIS <br /> (2) WHO - Global Outbreak Alert and Response Network (GOARN)<br />Identify, confirm and respond to outbreaks of international importance.Emerging Pathogens Institute -prevent or contain new and re-emerging diseases <br />
  49. 49. References<br />“Global Trends in Emerging Infectious Diseases,” February 2008 in the journal Nature.<br />
  50. 50. SGD questions<br />