1 / 44

Dan Colley Medical Parasitology; CBIO 4500/6500 19 January, 2012

Basic Concepts in Public Health and Tropical Medicine [Public Health & Infectious Diseases 101] (mainly in relationship to parasitic diseases). Dan Colley Medical Parasitology; CBIO 4500/6500 19 January, 2012.

donatella
Download Presentation

Dan Colley Medical Parasitology; CBIO 4500/6500 19 January, 2012

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Basic Concepts in Public Health and Tropical Medicine[Public Health & Infectious Diseases 101](mainly in relationship to parasitic diseases) Dan Colley Medical Parasitology; CBIO 4500/6500 19 January, 2012

  2. Disease (due to an infectious agent) is what may happen while your immune response tries to control an infection; Disease may be the final outcome if your immune system either fails, or over reacts. Infection does not necessarily equal disease Important words to define and remember: Asymptomatic/Morbidity/Mortality

  3. What are theScariest InfectiousThreats? Bioterrorism (anthrax; sm’pox; etc. Pandemics (influenza; plague;..) Mass casualty events Antimicrobial resistance New infectious agents Ebola; WNV; SARS; Lyme; Hanta; Cryptosp; Cyclospora; E. coli 0157/H7 Nosocomial Infections; Community Acquired MRSA

  4. Mass Casualty Events • Intentional • Bioterrorism(Anthrax, Smallpox…..) • It does not really need to kill to cause terror… • Unintentional • Pandemics (The Plague, Influenza….) H1N1 INFLUENZA as it occurred in 1918 • Camp Devens, Massachusetts Cases September 12, 1 September 18 6,674 September 23 12,604 (727 deaths) • U.S. 25% of Civilian Population Infected 4/100 Died • Global: In 6 months 20 million deaths (maybe as many as 40 million) In 4 years of WWI, 15m deaths; 95% military, 5% civilian In 8 years of WWII, 50m deaths; 33% military, 67% civilian

  5. 1000 800 600 Mortality Rate per 100,000 400 200 0 1900 1920 1940 1960 1980 Year Mortality due to Infectious Diseases in the United States, 1900-1996 • 20th Century Flu Pandemics • 1918 > 500,000 U.S. deaths • > 20,000,000 deaths worldwide (H1N1) • ~ 70,000 U.S. deaths • ~ 1,000,000 – 4,000,000 • worldwide (H2N2) • ~ 33,000 U.S. deaths • ~ 750,000 deaths worldwide • (H3N2) • --------------------------------------------------- • 201? (H5N1??; H1N1?? )

  6. Antimicrobial Resistance • PROBLEM = Selection Pressure • SOLUTIONS….. • Reduce infections (handwashing, vaccines, etc.) • Judicious use of antibiotics (not every ear ache) • Limit human antibiotic use in animals • Combination therapy • Target virulence factors • Competitive exclusion Hospitals are wonderful places when you need them – but be aware they can kill you At least 20,000 people die of nosocomial infections/year – in the USA ….and this number is rising………… Can you say “MRSA”? Can you say “CA-MRSA”?

  7. Chloroquine 16 years Fansidar 6 years Mefloquine 4 years Atovaquone 6 months Parasites, too: Time to Development of Resistance to Antimalarial Drugs 1940 1950 1960 1970 1980 1990

  8. Some Emerging (Emerged)and Re-emerging Infections • Lyme Disease (and other tick-borne diseases) • Dengue Fever (and DHF), WNV, SARS • Hantavirus, Ebola virus and a slew of other HFs • HIV/AIDS • E. coli 0157:H7 • Cryptosporidiosis • Cyclosporiasis • African Trypanosomiasis • Drug-resistant Malaria Focally there are many others (even schistosomiasis…)

  9. Major Factors Contributing to the Emergence of Infectious Diseases 1. Human demographics and behavior 2. Technology and industry 3. Economic development and land use 4. International travel and commerce 5. Microbial adaptation and change 6. Breakdown of public health measures Institute of Medicine Report 1992

  10. The concepts of Public Health sometimes differ from the concepts of individual medical care, … and the skills are often different, tooThey are not mutually exclusive, but they are also not the same-- Public Health deals with populations, prevention and policy --- and includes research on all of these -- Public Health often involves the treatment of individual patients, but that is NOT its focus-- At its core, public health is concerned with populations at risk, not individual medical care [Artemisinin vs. Artemisinin-based combination therapy (ACTs) (when WHO issued a call for companies to stop marketing single treatments of artemisinin)

  11. Epidemiologic terms we need to know • Incidenceof infection • Rate of infection (# new cases/year) • Prevalenceof infection • Proportion of population infected (%) • Intensityof infection • Level of infection (# worms/patient) • Severity of infection (morbidity/mortality) • Infectious diseaseSurveillance • Systematic collection, analysis and use of data on a given infectious disease

  12. Major Types of Public Health Activities • Surveillance • Outbreak investigation • Reference diagnosis and consultation • Research (bench-to-field-to-prevention) • Technical assistance & training (lab & epi) • Initiate & support implementation projects • Health policy and Health communication [Philosophically founded on Epidemiology] Done at the Global (WHO), Bilateral, Federal (CDC), State, and Local Levels – which takes enormous effort to coordinate (due to money; politics; information control; egos)

  13. Major Killers Malaria; ~400M Chagas’ disease; 15M African Trypanosomes; ~0.3M Visceral Leishmaniasis; ~4M Impair Development/Quality of Life Lymphatic filariasis - 120M Geohelminths – 1.5B(with a B) Schistosomiasis – 240M Onchocerciasis – 18M Cysticercosis ? 50M tapeworm Waterborne/Foodborne protozoans – 1.5B (with a B) Cutaneous Leishmaniasis; 8M Guinea worm – 4M  < 1K Major Parasitic Disease Threats

  14. What does it take for 1 million people to die a year ??? A full 747 crashes (~ 430 dead) (fictional disaster) 7 747 crashes every day all year (~ 1,100,000 dead) Tsunami in Southeast Asia (12/04) (~ 225,000 dead) 5 such tsunami per year (~ 1,125,000 dead) Earthquake (7.0R) in Haiti (01/10) (~200,000 dead) 5 such earthquakes per year (1,000,000 dead) Tornadoes in Alabama & Joplin, MO (05-06/2011) (~ 500 dead) 5.5 such tornadoes per day all year (1,000,000 dead) Each year 1 million children die of malaria

  15. HEALTH & ECONOMIC BURDEN OF MALARIA • ~2.5 Billion (40% World’s Population) At Risk • 400-800 million febrile infections/year • 1 – 2 million deaths/year, >75% African children • ~4 die per minute • ~5000 die per day • ~35,000 die per week • <20% come to attention of the health system • Pregnant women at high risk of dying, low birth weight children • Children suffer cognitive damage and anemia • Families spend up to 25% of income on treatment – (regressive tax) • Major Impediment to Economic Growth and Development, as well as health

  16. International Malaria Schistosomiasis Filariasis (Oncho & Lymphatic) Geohelminths Enteric protozoal diseases Trypanosomiasis (Afr &Amer) Leishmaniasis Neurocysticercosis Echinococcosis [Dracunculiasis] Domestic (USA) + Cryptosporidiosis Giardiasis Neurocysticercosis Toxoplasmosis Trichomoniasis Cyclosporiasis “Pneumocystis pneumonia” Head lice Delusional parasitoses Human Parasitic Diseases with Major PublicHealth Impact Naeglaria is not on the list (small numbers), but perceptions can control what gets considered “public health”……Beware of the neti pots !

  17. Worms are not ProtozoansProtozoans are not Worms • Worms are bigger than protozoans BUT -- The biggest difference, in terms of “host/parasite” relationships is: MOST WORMS DO NOT MULTIPLY IN THE BODY • The “infection/disease” dynamic is very different in a helminthic infection vs. a protozoal infection • Both medical and public health approaches to controlling these diseases may have to differ accordingly

  18. Levels of Limiting Parasitic Diseases or their Consequences • Control(Infection/Transmission vs. Morbidity) • Elimination of disease(as a public health problem) • Elimination of infections(in a defined geographic area) • Eradication (no longer “out there”) • Extinction(no longer anywhere) Conceptual (and practical) differences: • Existence vs. Transmission vs. Morbidity These are meant to be hard and fast definitions but (unfortunately) even their professionals ignore or mix up when it suits them……

  19. Decision Making: Eradication/Elimination/Control • Ability of available tools (vaccines, drugs, Dxs, etc.) • Epidemiologic vulnerability: ability to implement available tools in a cost- effective manner. • Availability of sustained funding ($$$, ¥¥¥, etc.). • Political will: • Burden of disease • Perception and promotion of outcome • Impact on over all health services sector • Impact on over all development • Luck

  20. Essential Partnerships • Multinationals:WHO/HQ; WHO/ROs;WHO/WRs; UNICEF; UNDP; World Bank • Bilaterals:JICA; USAID; DFID; GTZ; SIDA, NHDI …. • Government Agencies:MOHs; CDC; Peace Corps,... • NGOs:Rotary; Lions; Carter Center; Kiwanis, MSF; …. • Foundations:WT; EMCF; BWF; B&M Gates; …. • Industries:Merck; SmithKline Beecham; DuPont, American Cyanamid; Precision Fabrics; Norsk Hydro, …. In many ways these essential partnerships require the most attention, or the real stuff doesn’t get done

  21. Ongoing Dracunculiasis (Guinea Worm) – Eradication Onchocerciasis – Control Lymphatic Filariasis – Elimination Chagas disease – “Erad”/”Elim”/Control Malaria – Control (RBM) [B&MGFdn – Erad] Now being “integrated” Schistosomiasis – Control (Elimination in some settings) Soil-transmitted helminths – Control Trachoma – Elimination Possibles Taeniasis & Cysticercosis – Eradication Echinococcosis; Elimination African Trypanosomiasis; Control Current Status of Global Parasitic Disease Erad/Elim/Cont Efforts Other infections: • Eradication • Polio (virus) • Measles (virus) • Elimination (as “a public health problem”) • Leprosy (bacterium)

  22. Dracunculus medinensis (Guinea worm)

  23. Guinea worm being removed in Zabzugu-Tatale, Ghana; 2000

  24. Guinea Worm Dracunculiasis Eradication • Coordinating Programs: • WHO; UNICEF; Peace Corps; World Bank; NGOs;NHDI • Global 2000/Carter Center; B&M Gates Fdn ($28.5M) • WHO Collaborating Center (CDC) • Industrial partners • Critical Elements: • Community-level health education • Safe water: Borehole or scoop wells; Rx source water (temephos); Filter water (nylon nets; PVC pipe filters) • Case Containment, plus rewards • Regional/Country/Local (village level) commitment • Monthly reporting and feedback • Coordination and financing NO Vaccine; NO Drug --- just very hard work, with NO letting up

  25. 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 – 10,674 cases (52%, Sudan; 37%, Ghana) 2006 -- 25,217 cases (82%, Sudan; 16% Ghana) 2007 -- 10,053 cases (63%, Sudan; 33% Ghana) 2008 -- 4,615 cases (78%, Sudan; 11% Ghana) 2009 -- 3,147 cases (85%, Sudan; 8% Ghana) 2010 -- 1,797 cases (95%, Sudan; 3% Mali) 2011 -- 1,060 cases (>97%, Sudan; 1% Mali) [Down from 20 to 4 countries]

  26. A few images from a “guinea worm trip” to Zabzugu-Tatale, Ghana with Sue Maclain Where the real work gets done

  27. What are the major challenges to Guinea Worm eradication? • It requires behavior change !!! • People need to stay out of the water when they have lesions – and this is NOT easily done! • People need to filter their water through nylon nets Largely this depends on knowledge & alternatives • Other aspects are organizational, financial, technical, political and all these involve tenacity Photos from a NYT series

  28. “Integrated Disease Control Programs” • Integrated is the new buzz word and sounds great…but… how to do it is the challenge • Packages of multiple current intervention programs that can be safely, effectively and economically delivered together • Paradigm shift away from single disease model to an “integrated model” • Poverty reduction should be moving in a package, not a list of “single interventions” • “Turf Wars” need to be worn down and treaties signed • (1st they need to be acknowledge……) • WHO needs to coordinate “compatible partnerships” • The driving force should be to “Maximize Coverage” • Combinations of available intervention tools: • Drugs-Insecticides-ITNs-Supplements-Vaccines • But a new day has dawned in global disease efforts

  29. Do you know these public health workers?

  30. It really is a “new day” in terms of global public health • It involves: • Huge involvement of major foundations • Public/Private Partnerships – drug development, etc. • Focus on diseases of poverty • More (but not yet enough) coordination by agencies, governments, NGOs, foundations, people.. BUT: There are some real challenges to getting it done Implementation – i.e, Just getting on with it • Donor fatigue – it takes a long, sustained effort • Drug resistance – the threat of any drug- based anti-infectious disease program - especially with a single drug • Monitoring ?? • Research ??

  31. Challenges to Understanding and Controlling Parasitic Diseases • BROAD SCIENTIFIC CHALLENGES • Vaccine development • Vector manipulation • Drug development • Drug resistance • Host genetic contribution • Rapid surveillance/diagnostic tools • Few new scientists entering the field • BROADER SOCIETAL CHALLENGES • Universal Sanitation/Public Health • Adequate Housing • Adequate Food - nutrition • Available Health Care • Sustainability (Public/Private/Political Commitment) • Few new public health officials entering the field

  32. Cyclospora Timeline Spring 1995 1993 mid-late 1980s June 1994 July 1990 1977-78 1996-98 1st known cases dx’d in Papua New Guinea More reports of cases in various countries Multiple foodborne outbreaks in N. America Waterborne outbreak in USA Waterborne outbreak in Nepal Cyanobacterium-like bodies (CLB); Blue-green algae; Large Cryptosporidium; Fungal spores Ortega’s paper in NEJM 2 small US outbreaks Cyclospora cayetanensis ………..

  33. Timeline for Reporting Cyclospora Cases Illness onset To physician Stool tested Result to health dept. Exposure ~1 week Days to weeks Days++ Days++ Usually Several weeks++

  34. Missouri; 1999 • 7/24/99 Birthday Party • 32/45 (71%) infected • Basil-containing, Chicken Pasta Salad implicated • 7/26/99 – Birthday boy took • the salad to work to • share with co-workers; • 3/3 (100%) infected • -- AND -- • Saved some frozen!!! • LUCKY, LUCKY, LUCKY -- ……..and hard work The FIRST ever Cyclospora oocyst seen on a food item implicated in an outbreak of cyclosporiasis 9/99

  35. Food items at a wedding reception that were significantly associated with cyclosproriasis in univariate analyses, Pennsylvania, June 2000 The wedding cake had a cream filling that included raspberries from Guatemala, and leftover wedding cake was positive for Cyclospora cayetanensis by PCR & DNA sequencing

More Related