Emerging pathogens

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Emerging pathogens

  1. 1. EMERGING PATHOGENS
  2. 2. DEFINITION <ul><li>Incidence of infection increased during last 2 decades or threaten to increase in near future or increase incidence of epidemic outbreak e.g. Cryptosporidiosis, E.coli O157:H7, Hantavirus, HIV, SARS, MRSA etc. Also refers to newly appearing infectious diseases or disease spreading to new geographical area e.g. Cholera in South America, Yellow fever in Kenya. </li></ul>
  3. 3. RE-EMERIGING PATHOGENS: def <ul><li>Diseases which are previously easily controlled by chemotherapy & antibiotics but now deve antimicrobial resistance & often appear in epidemics </li></ul>
  4. 4. <ul><li>In 2001, a review of the scientific literature identified </li></ul><ul><li>1415 species of infectious organisms known to be pathogenic to humans, including </li></ul><ul><li>217 viruses and prions, </li></ul><ul><li>538 bacteria and rickettsiae, </li></ul><ul><li>307 fungi, </li></ul><ul><li>66 protozoa and </li></ul><ul><li>287 helminths. </li></ul><ul><li>Of these, 61% were zoonotic and 12% were associated with diseases considered to be emerging. </li></ul>
  5. 5. Major etiological agents of infectious diseases identified since 1972 <ul><li>Year Agent Disease </li></ul><ul><li>1972 Small round structured viruses </li></ul><ul><li>Diarrhoea (caliciviruses) </li></ul><ul><li>1973 Rotaviruses Infantile diarrhoea </li></ul><ul><li>1975 Astroviruses Diarrhoea </li></ul><ul><li>1975 Parvovirus B19 Aplastic crisis in </li></ul><ul><li>chronic haemolytic anaemia </li></ul><ul><li>1976 Cryptosporidium parvum Acute </li></ul><ul><li>enterocolitis </li></ul>
  6. 6. <ul><li>1977 Ebola virus Ebola haemorrhagic </li></ul><ul><li>fever </li></ul><ul><li>1977 Legionella pneumophila </li></ul><ul><li>Legionnaires’ disease </li></ul><ul><li>1977 Hantaan virus Haemorrhagic fever </li></ul><ul><li>with renal syndrome </li></ul><ul><li>1977 Campylobacter spp. Diarrhoea </li></ul><ul><li>1980 Human T-cell lymphotropic virus-1(HTLV-1) Adult T-cell leukaemia/ HTLV-1 associated myelopathy </li></ul><ul><li>1982 HTLV-2 Hairy T-cell leukaemia </li></ul>
  7. 7. <ul><li>1982 Borrelia burgdorferi Lyme disease </li></ul><ul><li>1983 HIV-1, HIV-2 Acquired </li></ul><ul><li>immunodeficiency syndrome </li></ul><ul><li>1983 Escherichia coli O157:H7 </li></ul><ul><li>Haemorrhagic colitis; haemolytic </li></ul><ul><li>uremic syndrome </li></ul><ul><li>1983 Helicobacter pylori gastritis, gastric </li></ul><ul><li>ulcers, increased risk of gastric cancer </li></ul><ul><li>1988 Human herpesvirus-6 Exanthema </li></ul><ul><li>subitum </li></ul><ul><li>1989 Ehrlichia spp . Human ehrlichiosis </li></ul>
  8. 8. <ul><li>1989 Hepatitis C virus Parenterally </li></ul><ul><li>transmitted non-A, non-B hepatitis </li></ul><ul><li>1990 Human herpesvirus-7 </li></ul><ul><li>1990 Hepatitis E virus Enterically </li></ul><ul><li>transmitted non-A, non-B hepatitis </li></ul><ul><li>1991 Hepatitis F virus Severe non-A, </li></ul><ul><li>non-B hepatitis </li></ul><ul><li>1992 Vibrio cholerae O139:H7 New </li></ul><ul><li>strain associated with epidemic cholera </li></ul><ul><li>1992 Bartonella henselae CAT-scratch </li></ul><ul><li>disease, bacillary angiomatosis </li></ul>
  9. 9. <ul><li>1993 Sin nombre virus Hantavirus </li></ul><ul><li>pulmonary syndrome </li></ul><ul><li>1993 Hepatitis G virus Non A-C hepatitis </li></ul><ul><li>1994 Sabia virus Brazilian hemorrhagic </li></ul><ul><li>fever </li></ul><ul><li>1994 Human herpesvirus-8 Kaposi’s </li></ul><ul><li>sarcoma </li></ul><ul><li>1995 Hendra virus Castleman’s disease </li></ul><ul><li>1996 Prion (BSE) Meningitis, encephalitis </li></ul><ul><li>1997 Influenza A virus New variant </li></ul><ul><li>Creutzfeldt-Jakob disease </li></ul>
  10. 10. <ul><li>1997 Transfusion-transmitted virus </li></ul><ul><li>1997 Enterovirus 71 Epidemic </li></ul><ul><li>encephalitis </li></ul><ul><li>1998 Nipah virus Meningitis, encephalitis </li></ul><ul><li>1999 Influenza A virus Influenza </li></ul><ul><li>1999 West Nile-like virus Encephalitis </li></ul><ul><li>(New York) </li></ul><ul><li>2003 Corona virus (SARS) </li></ul><ul><li>(Most of the emerging pathogens are viruses.) </li></ul>
  11. 11. Factors responsible for emergence <ul><li>i) increase use of antimicrobial agents </li></ul><ul><li>ii) subtherapeautic doses </li></ul><ul><li>iii) medical practices: dialysis in renal failure, multiple bl transfusions increases risk of hepatitis inf, HIV inf. </li></ul><ul><li>Relaxation in immunization: quick resurgence of ds e.g. diphtheria in Russia. </li></ul><ul><li>New animal ds: Mad Cow Ds (bovine spongiform encephalitis). </li></ul>
  12. 12. Factors responsible for emergence: <ul><li>Unplanned / under planned urbanization. </li></ul><ul><li>Overcrowding, rapid population growth. </li></ul><ul><li>Poor sanitation. </li></ul><ul><li>Inadequate public health infrastructures. </li></ul><ul><li>Resistance to antibiotics. </li></ul><ul><li>Increase exposure to vectors & reservoir of inf in nature. </li></ul><ul><li>Rapid & intense international traveling. </li></ul>
  13. 13. WHY DO PATHOGENS EMERGE? Other factors <ul><li>New environments : new technologies like dams & irrigation systems, leads to spread of malaria, schistosomiasis, J E, AC systems: legionella inf. etc. Filtration of water, agricultural and wastewater management practices. </li></ul><ul><li>sewage and sewage treatment </li></ul><ul><li>alternatives </li></ul>
  14. 14. <ul><li>Scientific advances: inappropriate & excessive use of antibiotics & antiparasitic drugs. ■ Improved methods of detection and analysis </li></ul><ul><li>■ Inappropriate use of new generation insecticides. </li></ul>
  15. 15. <ul><li>Changes in human behaviour and vulnerability: Human circulation and the accessibility and rapidity of transport worldwide. ■ Deliberate and accidental release of pathogens to water. * Individual’s level of nutrition and fitness, stress, excessive exposure to ultraviolet irradiation, and pregnancy. </li></ul>
  16. 16. <ul><li>Demographic : increase size of high risk population. Overcrowding, increasing population. </li></ul><ul><li>Socio-economic factors: Poor sanitation. </li></ul>
  17. 17. List of emerging pathogens <ul><li>Human infection: caused by </li></ul><ul><li>bacteria, viruses, fungi & parasites. Sources of these infections are different like water borne, inhalation, ingestion etc. </li></ul><ul><li>Plant pathogens: may cause inf in humans. </li></ul><ul><li>Animal pathogens: zoonotic diseases. </li></ul>
  18. 18. Bacterial infections <ul><li>EHEC, VTEC, O 157: H 7 E.coli </li></ul><ul><li>Legionella pneumophila </li></ul><ul><li>Burkholderia (cystic fibrosis) / Stenotrophomonas </li></ul><ul><li>H.pylori </li></ul><ul><li>Chlamydia spp. </li></ul><ul><li>Borrelia burgdorferi : Lyme ds </li></ul><ul><li>Streptococcus pyogenes </li></ul><ul><li>Mycobacteria spp </li></ul><ul><li>Brucella </li></ul><ul><li>Anthrax ( B.anthrasis ) </li></ul>
  19. 19. <ul><li>Staphylococcus aureus & staph epidermidis : nosocomial inf. </li></ul><ul><li>Enterococci </li></ul><ul><li>Bordetella pertussis </li></ul><ul><li>Tropheryma whippelii (whipple’s ds) </li></ul><ul><li>Compylobacter jejuni </li></ul><ul><li>Mycoplasma </li></ul><ul><li>Ehrlichia spp.& other rickettsial spp. </li></ul><ul><li>Y.pestis (plague) </li></ul>
  20. 20. viruses <ul><li>West-Nile virus </li></ul><ul><li>Arboviruses causing J E, Yellow fever, Dengue etc. </li></ul><ul><li>Norwalk virus </li></ul><ul><li>HIV </li></ul><ul><li>Rota V </li></ul><ul><li>Avian flue H5:N1 </li></ul><ul><li>Nipah V </li></ul><ul><li>Influenza V </li></ul><ul><li>HTLV </li></ul><ul><li>Hanta V </li></ul><ul><li>Hepatitis C V, E V G V. </li></ul><ul><li>Corona V </li></ul>
  21. 21. Fungi : <ul><li>black moulds found in environment (in immunocompromised person inf occurs): </li></ul><ul><li>a) skin inf (warts & cauliflower like lesions). Redness, swelling, discharge, pain at the inf site. b) Pneumonia most common inf. c) Sinusitis </li></ul><ul><li>MOI: inhalation of spores </li></ul><ul><li>Treatment: antifungal agents, surgical excision </li></ul><ul><li>No vaccine available. </li></ul><ul><li>Zygomycetes (eg, Mucor and Rhizopus  ), Fusarium , Trichosporon , Pseudallescheria , and Scedosporium . </li></ul>
  22. 22. <ul><li>Parasites: </li></ul><ul><li>cryptosporidium parvum </li></ul><ul><li>Isospora belli </li></ul><ul><li>Giardia </li></ul><ul><li>Malarial inf </li></ul><ul><li>Cyclospora spp. </li></ul>Cyclospora oocyst Isospora oocyst
  23. 23. TRANSMISSION OF INFECTION (diff modes) <ul><li>Water borne infections: include </li></ul><ul><li>Cryptosporidium, Giardia </li></ul><ul><li>Legionella, Escherichia coli O157 ( E. coli O157), Cholera O139, </li></ul><ul><li>rotavirus, hepatitis E virus </li></ul><ul><li>norovirus (formerly Norwalk virus). </li></ul><ul><li>Helicobacter pylori (H. pylori) </li></ul>
  24. 24. <ul><li>Corona virus responsible for </li></ul><ul><li>Severe Acute Respiratory Syndrome (SARS) : transmitted through ‘faecal droplets’. </li></ul><ul><li>Mycobacterium Avium Complex (MAC): leading cause of death in HIV pts. Drinking water plays an imp role in the spread of inf. </li></ul>
  25. 25. <ul><li>Cyclospora cayetanensis: outbreaks in Dec 2000, southwest Germany, oocysts transmit thr’ local contact & thr’ water. </li></ul><ul><li>Schistosomiasis : S.mansoni </li></ul><ul><li>Severe illness due to dermal contact with toxic cyanobacteria has been reported from tropical marine bathing sites </li></ul>
  26. 26. <ul><li>Zoonotic infections : </li></ul><ul><li>Vector borne: </li></ul><ul><li>A) Mosquito : J E, dengue, Yellow fever, chikungunya, West-Nile fever (Arboviruses). </li></ul><ul><li>B) Tick : KFD, Colorado tick fever, Russian spring summer encephalitis, Rickettsial diseases: Tick typhus. </li></ul>
  27. 27. <ul><li>C) Rat flea : Y.pestis, Endemic typhus </li></ul><ul><li>D) Rat : Borrelia burgdorferi, Leptospira inf. Lassa fever V. sewer rat: reservoir of T.gondii </li></ul><ul><li>Nosocomial infection: </li></ul><ul><li>MRSA, Multidrug resistant E.coli, Ps.aeureginosa, Clostridium difficile, Serratia spp., Enterococcus infections. </li></ul>
  28. 28. <ul><li>Inhalation: </li></ul><ul><li>Fungal infections: inhalation of spores (black moulds, opportunistic fungi etc.) </li></ul><ul><li>Influenza virus: Avian flu strain: higher mortality. H5N1 strain outbreak in Hong-Kong ,2008 (in birds). </li></ul><ul><li>B.anthrasis inf. </li></ul>
  29. 29. Food-related diseases <ul><li>hepatitis E virus inf, Hep AV </li></ul><ul><li>intestinal spirochetosis caused by Brachyspira pilosicoli , gnathostomiasis caused by nematodes and anisakidosis caused by fish nematodes. </li></ul><ul><li>non-gastric Helicobacter spp., Enterobacter sakazakii , non- jejuni /coli species of Campylobacter , and non-O157 Shiga toxin-producing Escherichia coli . , Y.enterocolitica, M.paratuberculosis (Crohn's ds). </li></ul>
  30. 30. Plant pathogens likely to cause inf in human B.cepacia found in soil responsible for rot of onion. Erwinia amylovora , affects apples. Cynobacterium : blue green alge.
  31. 31. Control of emerging infectious diseases <ul><li>difficult because of the large number of disease-causing organisms that are emerging or could emerge and the great diversity of geographic areas in which emergence can occur. </li></ul><ul><li>Early Identification of organisms, Diagnosis & prompt Rx: </li></ul><ul><li>effective method of amplifying very specific regions of an organism's genetic material by Polymerase Chain Reaction (PCR). </li></ul>
  32. 32. <ul><li>Flow cytometery is a powerful technique using laser light to quantify particles or to recognize structural features of cells. By measuring the scatter and wavelength of light as a particle intercepts the beam, information can be gained that allows the rapid quantification of the organisms. </li></ul>
  33. 33. <ul><li>use of fluorescent monoclonal antibodies that are specific for a particular pathogen. </li></ul><ul><li>Detection of faecal contamination of drinking water. </li></ul><ul><li>Control of vectors. </li></ul>
  34. 34. THANK YOU

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