Basic Concepts in Public Health and Tropical Medicine Infectious Diseases and Public Health 101 main

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Basic Concepts in Public Health and Tropical
MedicineInfectious Diseases and Public Health
101(mainly in relationship to parasitic
diseases)

• Daniel G. Colley
• Medical Parasitology CBIO 4500/6500
• 24 January, 2008

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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
Asymptomatic/Morbidity/Mortality
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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
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Mass Casualty Events

• Intentional
• Bioterrorism (Anthrax, Smallpox..)
• It does not really need to kill to cause terror
• Unintentional
• Pandemics (The Plague, Influenza.)
• DYNAMICS OF A HYPOTHETICAL BIOLOGICAL
  ATTACK
• DATE CASES
• 9/12 1
• 9/18 6,674
• 9/23 12,604 (727 deaths)
• In 6 mos, 25 of the population will be
  infected 4 of the Population will die

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H1N1 INFLUENZA as it occurred in 1918

• Camp Devens, MA , 1918 Cases
• 9/12 1
• 9/18 6,674
• 9/23 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
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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)
• --------------------------------------------------
  -
• 200? ?????? (H5N1??)

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January 21, 2008
Spreading still, but no pandemic..yet.
Vigilance is the price of freedom
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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?

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Parasites, too Time to Development of
Resistance to Antimalarial Drugs
1940
1950
1960
1970
1980
1990
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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)

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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

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Public Health
Moving on to

• The concept of Public Health differs from the
  concept of individual medical care, and the
  skills are very often different
• 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,
  but rather populations at risk

Artemisinin combination therapy to Rx or to
thwart malarial drug resistance? (WHO issued
a call for companies to stop marketing single
treatments of artimisinin)
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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/disease (morbidity/mortality
  )
• Infectious disease Surveillance
• Systematic collection, analysis and use of data
  on a given infectious disease

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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/run implementation programs
• 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 gt
  politics gt egos)

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Major Parasitic Disease Threats

• Major Killers
• Malaria 400M
• Chagas disease
• 18M
• African Trypanosomes
• 0.5M
• Visceral Leishmaniasis
• 4M

• Impair Development/Quality of Life
• Lymphatic filariasis - 120M
• Geohelminths - 2B
• Schistosomiasis 200M
• Onchocerciasis 18M
• Cysticercosis ? 50M tapeworm
• Waterborne/Foodborne protozoans 1.5B
• Cutaneous Leishmaniasis 8M
• Guinea worm 4M ? lt 15K

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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)
Earthquake (7.6R) in Pakistan (10/05) (80,000
dead) 14 such earthquakes per year ( 1,120,000
dead)
Tsunami in Southeast Asia (12/04) ( 225,000
dead) 5 such tsunami per year ( 1,125,000 dead)
Each year 1-2 million children die of malaria
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HEALTH ECONOMIC BURDEN OF MALARIA

• 2.5 Billion (40 Worlds Population) At Risk
• 400-900 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
• Major Impediment to Economic Growth and
  Development, as well as health

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• A few thoughts on the impact of global infectious
  diseases
• In 2000 about 11 million children died before
  their 5th birthday -- more than 99 of these 11
  million died in low- to middle-income countries
  most from infectious diseases
• The household costs due to malaria are often
  5-10 of the annual income, and when seen based
  on income level, it soared to 30 of the income
  of very poor families, i.e., these costs are very
  regressive the poorer you are, the worse they
  hit you
• These and other facts like them have caused
  global economists and international development
  officials to see the relationships between
  POVERTY, HEALTH DEVELOPMENT in a new light
• Development ? Health
• Health ? Development

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Improved health contributes to economic growth
in four ways

• Reduces production losses caused by worker
  illness
• Permits or improves uses of natural resources
  inaccessible due to disease
• Increases enrollment in school and allows
  children to learn Future
• Frees up resources spent on treating illness for
  alternative uses
• The World Bank World Development Report,
  Investing in Health,1993 This publication
  represents a major change in thinking on
  development

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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 health
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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

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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 hard and fast definitions that
  (unfortunately) even their makers ignore when it
  suits themcurrent situation in Chagas and
  Malaria

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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. Based on the LIFE CYCLE
• 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

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Infectious diseases

• Some are global
• Some are geographically focal
• Some are economically important
• Some are socially important
• Need to consider all these aspects -- not just
  assemble the right tools.
• Need to think of the conceptual differences
  between medical care and public health, and how
  the two should interact in a complementary way

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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 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

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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
• Piloted now
• Schistosomiasis Control
• Soil-transmitted helminths Control
• Possibles
• Taeniasis Cysticercosis Eradication
• Echinococcosis Elimination
• African Trypanosomiasis Control

Other infections
Eradication Polio (virus) Measles (virus)
Elimination (complete, or as a public health
problem) Trachoma (bacterium) Leprosy
(bacterium)
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Dracunculus medinensis (Guinea worm)
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Guinea worm being removed in Zabzugu-Tatale,
Ghana 2000
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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

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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)
• Down from 20 to 5 countries
• Niger (11), Nigeria (73), Mali (313), Ghana
  (3,358), Sudan (6,298)

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

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Do you know these public health workers?
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• 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 ??

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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