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Emerging Disease

“ Emerging and Re-emerging humans disease Abdul Aziz Djamal Dept of Microbiology Andalas University. Emerging Disease. Newly identified and previously unknown infectious agent that cause public health problem locally or globally. Re-emerging Infectious Disease.

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Emerging Disease

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  1. “Emerging andRe-emerging humans diseaseAbdul Aziz DjamalDept of Microbiology Andalas University

  2. Emerging Disease Newly identified and previously unknown infectious agent that cause public health problem locally or globally

  3. Re-emerging Infectious Disease • Infectious disease that have been known for sometime and had fallen to such a low level and no longer consider as a public health problem and now showing upward trend in prevalence or incidence globally

  4. Examples of Emerging and Re-Emerging Infectious Disease: past 10 years A Fauci, NIAID/NIH, 2005

  5. 10,000-fold difference in impact Log 1 0 Major and minor killers: global impact viewed on a ‘Richter’ (logarithmic) scale 7 Tobacco HIV Infant/child ARI & diarrhoeal dis Malaria HBV + HCV 6 Road accidents Non- HIV tuberculosis Measles RSV, Rota virus Influenza 5 Dengue Viruses Hospital infection H Papilloma v 4 Suicide West Nile virus 3 SARS Ebola Polio 2 Hanta virus vCJD 1 Weiss & McMichael, 2004

  6. Outline of Talk • Microbes, infectious diseases: recent trends • Infectious diseases as result of major changes in human ecology and environmental – historical transitions; current conditions • Examples of infectious disease risks • Travel, trade • Land use, agriculture • Intensive animal husbandry • Climate variability, climate change • Needed: a more ecological perspective

  7. Receding – then Resurging? 1950s-60s: Infectious diseases apparently receding in developed countries • Antibiotics and vaccines • Pesticides to control mosquitoes • Improved surveillance and control measures – internationally coordinated Early 1970s: Authorities proclaimed end of infectious disease era. Premature! • >30 new or newly-discovered human IDs over past 30 yrs • We overlooked the ecological/evolutionary dimensions

  8. Choi Young-Soo/Associated Press - Yonhap South Korean health workers disinfecting a chicken farm north of Seoul last week. Though 140 million birds have died or been killed as a preventive measure in Asia, the risks of wide human infection are not known. Avian ’flu, H5N1 Mad Cow Disease (BSE)  vCJD Nipah viral encephalitis, Malaysia (1997-99) Previous ’flu epidemics (1918-19, ’57, ’68) South Korean health workers disinfecting a chicken farm in April, 2005. Though several hundred million birds have died or been killed as a preventive measure in Asia, the human epidemic risk remains unknown.

  9. Human-Microbe Transitions over the Millennia Pre-historic: hunter-gatherers disperse into distant new environments 1. Local agrarianism/herding: 5-10,000 yrs ago 2. Trans-continental: 1,000-3,000 yrs ago 3. Inter-continental: From c. 1500 AD 4. Today, global: Fourth historical transition Successive increases in SCALE

  10. Factors in Emerging/Re-emerging Infectious Diseases • Microbial adaptation and change • Human susceptibility to infection • ageing, HIV, IV drugs, transplantation, transfusion • Population growth and density • Urbanization, crowding – social and sexual relations • Globalization of travel and trade • Live animal markets • Intensified livestock production • Misuse of antibiotics (humans & domestic animals) • Changes to ecosystems (deforestation, biodiversity loss) • Global climate change

  11. Zoonotic Sources: Land-use, Livestock, Wild-life Clearing forests for agriculture Viral haemorrhagic fevers in South America: peasant-farmers Guanarito, Sabia, Kunjin, etc. Eating infected animals Newvariant Creutzfeldt Jacob disease (from BSE) Cultivation of infected animals Nipah viral encephalitis (pig farms in Malaysia) West Nile virus (goose “fois gras” farms in Ramala, Israel) Collection and trade of wild game HIV (bush meat: primates) Ebola (bush meat?) SARS (civet cat?)

  12. Incidence of BSE in UK, 1987-99 (c.180K cases) 1988/9 bans: Sale of nervous tissue and offal for human consumption Eating cattle >30 months old Mammalian products in ruminant feed BUT: no ban on feed for swine or poultry Human vCJD (end 2003) -- 125 cases: UK-117, France-6, Ireland-1, Italy-1

  13. Nipah Viral Encephalitis, in Malaysia 01/97 Farm worker hospitalized with viral encephalitis (VE). 10/97 First death (pig-farm worker) from VE. 02/98 3 farm workers develop VE. 11/98 Health Minister declares it ‘Japanese Encephalitis’  mosquito control and vaccine program. But outbreak spreads. 1-2/99 Pig farmers begin ‘fire sales’ of pigs. Outbreak recedes a little. 02/99 Laboratories receive first samples of infected human tissue. “New” virus? Mass pig culling begins. Villagers flee. 03/99 Virus isolated and identified with reagents used to characterize Hendra virus (a recently-identified horse virus, from Queensland). 04/99 ‘Nipah virus’ discovery announced. Culling continues. 05/99 WHO declares outbreak over (265 cases, 40% fatal). 02/00 Last death. Fruit bats (flying foxes) deemed the likely reservoir.

  14. Travel and Trade: examples Aedes albopictus mosquito eggs inshipments of used tyres  dengue fever Long-distance travel; wild animal trade • HIV/AIDS • West Nile Virus (New York City, 1999) • SARS, 2003

  15. SARS Severe Acute Respiratory Syndrome A genetic model for the Coronavirus family. (Photo: J Oxford, Retroscreen Virology Ltd)

  16. China Lao PDR Vietnam Cambodia Key wildlife trade routes in SE Asia and China

  17. Environmental Changes • Land use, forest clearance • Biodiversity losses, extinctions • Dams, irrigation • Climate change

  18. Village (deforested) Farm (deforested) Forest Secondary growth Density of An. darlingi (malaria vector) in Peruvian Amazon An. Darlingi abundance (log scale) No. of survey sites = 2433 Patz et al, 2003

  19. Lyme Disease: Influences of Habitat Fragmentation & Biodiversity Loss High Lyme Disease risk Woodland suburban housing (NE USA) High tick density and high tick infection prevalence  infected deer Complex life- cycle of tick Many competent reservoir species  less dilution by incompetent reservoir species Expanding mouse populations Less diversity of vertebrate predators and viral hosts Poor inter-species regulation Forest fragmentation, hunting (wolves, passenger pigeons) Adapted from: R. Ostfeld

  20. Climate Change and Infectious Disease Some recent changes in ID patterns may reflect the influence of climate change (debate continues) • Tick-borne encephalitis (north spread in Sweden) • Cholera in Bangladesh (strengthening relationship with El Niño events) • Malaria ascent in east African highlands • Time-trends in incidence of (reported) food poisoning, esp. Salmonellosis

  21. . . Darwin . Katherine . Cairns . . Broome Townsville . Port Headland . Mackay . Rockhampton Risk region under medium emissions scenario, 2050 Carnarvon . . Darwin . Katherine . Cairns . . Broome Townsville . Port Headland . Mackay . Rockhampton Carnarvon Risk region under high emissions scenario, 2050 Dengue Fever: Estimated geographic region suitable for maintenance of Ae. aegypti, under alternative climate scenarios for 2050 . Darwin . Katherine . . Cairns . Broome . Townsville . Port Headland Mackay . Current risk region for dengue Rockhampton . Brisbane NCEPH/CSIRO/BoM/UnivOtago, 2003

  22. MALARIA IN ZIMBABWE, UNDER CLIMATE CHANGE Baseline2000 2025 2050 2075 2100 Source: Kris Ebi

  23. Baseline20002025 2050 2075 2100 Source: Kris Ebi

  24. Baseline200020252050 2075 2100 Source: Kris Ebi

  25. Summary Humans, domestic animals and wildlife are inextricably linked by epidemiology of infectious diseases (IDs). IDs will continue to emerge, re-emerge and spread. Human-induced environmental changes, inter-species contacts, altered social conditions, demography and medical technology affect microbes’ opportunities. Also: New research, technology and collaborative networks will also elucidate role of infection in diverse, mostly chronic, diseases of unknown cause . . . .

  26. INFECTIOUS CAUSES OF CHRONIC DISEASE: Examples Disease Cervical cancer Chronic hepatitis, liver cancer Lyme disease (arthritis) Whipple’s disease Bladder cancer Stomach cancer Peptic ulcer disease Atherosclerosis (CHD) Diabetes mellitus, type 1 Multiple sclerosis Inflammatory bowel disease Cause Human papilloma virus Hepatitis B and C viruses Borrelia burgdorferi Tropheryma whippelii Schistosoma haematobium Helicobacter pylori Helicobacter pylori Chlamydiaepneumoniae Enteroviruses (esp. Coxsackie) Epstein-Barr v, herpes vv? Mycobacterium avium sub-spp. Paratuberculosis, Yersinia

  27. Conclusion I: Understanding what promotes human-microbe contacts • Intensified modification/exploitation of natural environments and food production. • Disturbance of natural ecosystems and their various internal biotic controls. • Poverty, crowding, social disorder, mobility and political instability.

  28. Conclusion II: Microbes as Co-Habitants Microbes’ interest is in survival and reproduction. They have no malign intent; morally neutral! Their evolution-based drive to survive is as strong as ours (and draws on much longer experience).

  29. That’s all, folks

  30. Backwards trajectory analysis of JE Cyclone Sid: Precursor to 1998 Japanese Encephalitis incursion? Air trajectories @ 100 m altitude 27 Dec 1997: Tropical Cyclone Sid

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