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Basic Concepts in Public Health and Tropical Medicine [Public Health & Infectious Diseases 101] (mainly in relationship to parasitic diseases)

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Title: Basic Concepts in Public Health and Tropical Medicine [Public Health & Infectious Diseases 101] (mainly in relationship to parasitic diseases)


1
Basic Concepts in Public Health and Tropical
MedicinePublic 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 smpox 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
Mortality due to Infectious Diseases in the
United States, 1900-1996
  • 20th Century Flu Pandemics
  • 1918 gt 500,000 U.S. deaths
  • gt 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
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 0157H7
  • 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
  • Incidence of infection
  • Rate of infection ( new cases/year)
  • Prevalence of infection
  • Proportion of population infected ()
  • Intensity of infection
  • Level of infection ( worms/patient)
  • Severity of infection (morbidity/mortality)
  • Infectious disease Surveillance
  • 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 Parasitic Disease Threats
  • 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 ? lt 1K

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 Worlds Population) At Risk
  • 400-800 million febrile infections/year
  • 1 2 million deaths/year, gt75 African children
  • 4 die per minute
  • 5000 die per day
  • 35,000 die per week
  • lt20 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
Human Parasitic Diseases with Major Public Health
Impact
  • 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

Naeglaria is not on the list (small numbers), but
perceptions can control what gets considered
public healthBeware 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/ROsWHO/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 BM 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
    doesnt get done

21
Current Status of Global Parasitic Disease
Erad/Elim/Cont Efforts
  • Ongoing
  • Dracunculiasis (Guinea Worm) Eradication
  • Onchocerciasis Control
  • Lymphatic Filariasis Elimination
  • Chagas disease Erad/Elim/Control
  • Malaria Control (RBM) BMGFdn 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

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 NGOsNHDI
  • Global 2000/Carter Center BM 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 -- gt 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 (gt97, Sudan 1
    Mali)

26
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27
A few images from a guinea worm trip to
Zabzugu-Tatale, Ghana with Sue Maclain
Where the real work gets done
28
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
29
  • Integrated Disease Control Programs
  • Integrated is the new buzz word and sounds
    greatbut 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

30
Do you know these public health workers?
31
  • 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 ??

32
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

33
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35
Cyclospora Timeline
Spring 1995
1993
mid-late 1980s
June 1994
July 1990
1977-78
1996-98
1st known cases dxd 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
Ortegas paper in NEJM
2 small US outbreaks
Cyclospora cayetanensis ..
36
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40
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
41
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42
The FIRST ever Cyclospora oocyst seen on a food
item implicated in an outbreak of cyclosporiasis
9/99
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
43
Food items at a wedding reception that were
significantly associated with cyclosproriasis in
univariate analyses, Pennsylvania, June 2000
Food Item Cases/Exposed Cases/Unexposed Relative Risk (95 CI)
Wedding Cake 50/53 (94.3) 4/26 (15.4) 6.1 (2.5-15.1)
Fresh Fruit 36/43 (83.7) 18/36 (50.0) 1.7 (1.2-2.4)
Arugula salad 34/41 (82.9) 20/38 (52.6) 1.6 (1.1-2.2)
Focaccia bread 15/16 (93.8) 39/63 (61.9) 1.5 (1.2-1.9)
Hearthbaked bread 23/27 (85.2) 31/52 (59.6) 1.4 (1.1-1.9)
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
44
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