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Emerging and Re-emerging Infectious Diseases Ashry Gad Mohamed, DrPH Prof. of Epidemiology College of Medicine, KSU. • Emerging infectious diseases: Infectious diseases that have newly appeared in a population. • Global : • Regional: • Re-emerging Diseases: Diseases’ incidence in human has increased during the last 20 years or threatens to increase in the near future. • Global: • Regional: Emerging Infections in the World since 1973 1973 1976 1977 1977 1977 1977 1980 1981 1982 1982 1982 Rotavirus Cryptosporidium Ebola virus Legionella Hantaan virus Campylobacter HTLV-1 Toxin prod. S.aureus E.coli 0157:H7 HTLV-II Borrelia burgdorferi Enteritis/Diarrhea Enteritis/Diarrhea VHF Legionnaire’s dz VHF w/ renal flr Enteritis/Diarrhea Lymphoma Toxic Shock Synd. HUS Leukemia Lyme disease 1983 1983 1988 1989 1990 1991 1992 1992 HIV Helicobacter pylori Hepatitis E Hepatitis C Guanarito virus Encephalitozoon Vibrio cholerae O139 Bartonella henselae AIDS Peptic ulcer dz Hepatitis Hepatitis VHF Disseminated dz Cholera Cat scratch dz 1993 1994 1994 1995 1995 1996 1997 1999 1999 2001 2003 2003 2004 2005 Sin Nombre virus Hanta Pulm. Synd. Sabia virus VHF Hendra virus Respiratory dz Hepatitis G Hepatitis H Herpesvirus-8 Kaposi sarcoma vCJD prion Variant CJD Avian influenza (H5N1) Influenza Nipah virus Encephalitis West Nile virus Encephalitis BT Bacillus anthracis Anthrax Monkeypox Pox SARS-CoV SARS H5N1 Avian Influenza GLOBAL EXAMPLES OF EMERGING AND RE-EMERGING INFECTIOUS DISEASES AS Fauci Economic Impact of Selected Infectious Diseases $50bn SARS China, Hong Kong, Singapore, Canada $30-50bn Estimated Cost $40bn $30bn Foot & Mouth UK $25–30bn $20bn BSE UK, $10-13bn $10bn Foot & Mouth Taiwan, $5-8bn Classical Swine Fever, Netherlands $2.3bn BSE Japan $1.5bn HPAI, Italy $400m Nipah, Malaysia $350-400m 1994 1995 1996 1997 Figures are estimates and are presented as relative size. 1998 1999 Avian Flu Asia, $5–10bn 2000 BSE Canada $1.5bn Avian Flu, NL $500m 2001 2002 BSE U.S., $3.5bn 2003 2004 2005 2006 Factors responsible for emerging of infections. I-Ecological changes and Agricultural development. Placing the people in contact with a natural reserviour or host of a hitherto unfamiliar, but usually already present, Example 1 : Reforestation in USA Increased the number of deer & deer ticks Increased Human contact with deers Deer ticks are natural reserviour of Lyme diseases Human affection by Lyme disease Example 2 : Conversion of grassland to maise cultivation Rodents come to people People go to rodents Rodents are natural reserviour of the virus Argentine Haemorrhagic fever in humans • Example 3: Pig Farm C h i n a Duck farm Mixing vessels Influenza Influenza Influenza Influenza Influenza Increased Rice cultivation in South East Asia. Example 4: Increased human contact with Field mouse Field mouse is natural reservoiur of Hantaan virus Introduction of Korean haemorrhagic fever in Humans Dams: • High dam in Egypt Slowed water flaw allowed snails to go south introduced S. mansoni in Upper Egypt Increased its occurrence in Nile Delta. • Senegal Dam Lakes in Mauritania Rift Valley Fever outbreak 1987. Climate and Weather Global warming-climatologists project temps to increase up to 5.8°C by 2100. Elevated rainfall -creates new breeding habitats for mosquitoes. -decreases salinity which can increase toxic bacteria. -increases vegetation which increases rodents. -increases runoff into drinking reservoirs • Higher ocean temps increase Vibrio parahaemolyticus (shellfish) • Some soil pathogens carried by dry dusty winds (Coccidiodes) II- Changes in Human demographics and behaviours Inflation of population size Insufficient infrastructures Use open containers for water Breading mosquitos Dengue fever in Asia •Urbanization-more people concentrated in cities-often without adequate infrastructure •Increases in the elderly populations •Increases in children in daycare: working woman with kids under 5 was 30% in 1970, is 75% in 2000. •Fast paced Lifestyles- increase in convenience items and more stress •High-risk behavior- Drug use and unprotected sex War and Famine War refugees are a full 1% of the global population War refuges are forced onto new areas where they are exposed to new microbes from vectors and people. War and famine are closely linked. In 2001, tracking 16 countries with “food emergencies”, showed that 9 were because of civil unrest. Famine is also caused by social, economic, and political forces. Weather and HIV/AIDS • III-International travel and Commerce. • 365 days to circumnavigate the globe…now it takes 36 hours • -used to quarantine ships, but 36 h faster than disease incubation • 400 million people per year travel internationally • increased incidence of both Tuberculosis and Influenza transmission on long flights • -Transportation of products is an increased concern. • -rapid transport of disease harboring fresh products. • -transport of livestock facilitates movements of viruses and arthropods (especially ticks) Travel and HIV/AIDS. -Silk route and plague. -Slaves trade and yellow fever. -Migration to new world and smallpox. Cholera and Hajj. IV- Technology and industry • Modern mass production increased the chance of accidental contamination and amplifies the effect of such contamination. -Contamination of hamburger meat by E.coli strains causing haemolytic uraemic syndrome. -Feeding cattle by byproducts of sheep causing bovine spongiform encephalitis. • Concentrating effect of blood and nasocomial infections e.g. Ebola fever by contaminated hypodermic apparatus. • New diagnostic technology lead to identification of previously unknown microbes for known diseases e.g. Helicobacter pylori and peptic ulcer, human herpes virus 6 and roseola. • Medical technology People living longer, but have weaker immune systems. Blood & organ transplantation transmit infections. V-Microbial Adaptation and Change A number of microbes utilizing different genetic mechanisms -genome sequences show that lateral transfer is common -high mutation rates in RNA viruses-rapid adaptation -quick reproduction so rare mutations build up rapidly Antimicrobials for livestock growth enhancement and over -prescription of antimicrobials by Drs. (convenience) -evolve modifying enzymes and “drug pumps” • Increased antibiotic resistance with increased use of antibiotics in humans and food animals (VRE, VRSA, penicillin- and macrolide-resistant Strep pneumonia, multidrug-resistant Salmonella,….) • Increase virulence (Group A Strep?) • Jumping species from animals to humans (avian influenza, HIV?, SARS?) Parasites, too: Time to Development of Resistance to Antimalarial Drugs Chloroquine 16 years Fansidar 6 years Mefloquine 4 years Atovaquone 6 months 1940 1950 1960 1970 1980 1990 Emerging Vancomycin-resistant Enterococcal Infections in NNIS Hospitals 25 20 % 15 ICU Non-ICU resistant 10 5 0 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 Is malaria an “emerging” disease? [At least drug-resistant malaria is an emerging disaster] YES !!! VI- Breakdown of public health measures. • -Decrease in choline in water supplies lead to rapid spread of cholera in South America. • Non functioning water plant in Wisconsin, USA lead to outbreak of waterborne cryptosporidium. • Inadequate vaccinations and Diphtheria in former USSR independent countries. • Discontinued mosquito control efforts and dengue and malaria re-emergence. Major Factors Contributing to the Emergence of Infectious Diseases 1. 2. 3. 4. 5. 6. Human demographics and behavior Technology and industry Economic development and land use International travel and commerce Microbial adaptation and change Breakdown of public health measures Institute of Medicine Report 1992 Progress in the Eradication of Dracunculiasis (Guinea Worm) • • • • • • • • • • • • 1981 -- > 4,000,000 cases 1986 -- 3,500,000 cases 1989 -890,000 cases 1992 -374,000 cases 1995 -129,000 cases 1998 -79,000 cases (61%, Sudan) 1999 – 80,000 cases (70%, Sudan) 2000 -70,000 cases (73%, Sudan) 2001 -60,000 cases (78%, Sudan) 2002 -50,000 cases (74%, Sudan) 2003 -31,000 cases (62%, Sudan; 27%, Ghana) 2004 -16,026 cases (45%, Sudan; 45%, Ghana) • 2005 -- • [Down from 20 to 10 countries; 5 of them had fewer than 100 cases in 2005] 10,715 cases vs. 14,418 in 2004 (Jan-Oct)(61%, Sudan; 29%, Ghana)