Download Disease and Public Health 101

Basic Concepts in Public Health
and Tropical Medicine
[Infectious Diseases and Public Health 101]
(mainly in relationship to parasitic diseases)
Daniel G. Colley
Medical Parasitology; CBIO 4500/6500
19 January, 2010
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
What are the
Scariest InfectiousThreats?
Bioterrorism (anthrax; sm’pox; etc.
Pandemics (influenza; plague;..)
Ebola; WNV;
SARS; Lyme;
Hanta; Cryptosp;
Cyclospora;
E. coli 0157/H7
Nosocomial
Infections;
Community
Acquired MRSA
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
H1N1 INFLUENZA as it occurred in 1918
• Camp Devens, MA , 1918
9/12
9/18
9/23
Cases
1
6,674
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
Mortality Rate per 100,000
Mortality due to Infectious Diseases
in the United States, 1900-1996
1000
20th Century Flu Pandemics
1918
800
1957
600
~ 70,000 U.S. deaths
~ 1,000,000 – 4,000,000
worldwide (H2N2)
1968 ~ 33,000 U.S. deaths
~ 750,000 deaths worldwide
(H3N2)
--------------------------------------------------201? ~ ??? (H5N1??; H1N1?? )
400
200
0
1900
> 500,000 U.S. deaths
> 20,000,000 deaths
worldwide (H1N1)
1920
1940
Year
1960
1980
International Co-circulation of 2009 H1N1 and Seasonal Influenza
(as of January 04, 2010)
H1N1 as of 01/05/10 – in the USA:
37,778 hospitalizations; 1,735 deaths (lab
confirmed) – estimated 20%-infected
Vigilance is the price of freedom……..
Percentage of outpatient visits for Influenza-like Illness (through ILINet)
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”?
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
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…)
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
The concepts of Public Health sometimes differ from
the concepts of individual medical care,
… and the skills are often different, too
They 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 artimisinin)
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
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; egos)
Major Parasitic Disease Threats
• Impair Development/Quality of Life
• Major Killers
– Lymphatic filariasis - 120M
– Malaria; ~400M
– Chagas’ disease; – Geohelminths - 2B
– Schistosomiasis – 200M
18M
– Onchocerciasis – 18M
– African
– Cysticercosis ? 50M tapeworm
Trypanosomes;
– Waterborne/Foodborne
~0.5M
protozoans – 1.5B
– Visceral
– Cutaneous Leishmaniasis; 8M
Leishmaniasis;
– Guinea worm – 4M  < 15K
~4M
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)
Earthquake (7.0R) in Haiti (01/10) (~200,000???dead)
5 such earthquakes per year (1,000,000 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
HEALTH & ECONOMIC BURDEN OF
MALARIA
• ~2.5 Billion (40% World’s Population) At Risk
• 400-900 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
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]
Naeglaria is not on the list (small numbers), but perceptions
can control what gets considered “public health”……
• Domestic (USA) +
–
–
–
–
–
–
–
Cryptosporidiosis
Giardiasis
Neurocysticercosis
Toxoplasmosis
Trichomoniasis
Cyclosporiasis
“Pneumocystis
pneumonia”
– Head lice
– Delusional parasitoses
Worms are not Protozoans
Protozoans 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
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 them……current situation in Chagas’ and Malaria
Decision Making:
Eradication/Elimination/Control
• Ability of available tools (vaccines, drugs, Dxs, etc.)
• Epidemiologic vulnerability: ability to
implement available tools in a costeffective 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
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
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) [B&MGFdn – Erad]
Now being “integrated”
• Schistosomiasis – Control
• Soil-transmitted helminths – Control
• Trachoma – Elmination
Possibles
• Taeniasis & Cysticercosis – Eradication
• Echinococcosis; Elimination
• African Trypanosomiasis; Control
•
Other infections:
Eradication
Polio (virus)
Measles (virus)
Elimination (as “a public
health problem”)
Leprosy (bacterium)
Dracunculus medinensis
(Guinea worm)
Guinea worm being removed in Zabzugu-Tatale,
Ghana; 2000
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
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)
[Down from 20 to 5 countries]
Sudan (2690), Ghana (242), Mali (186), Ethiopia (24) Niger (5)
A few images from a “guinea worm trip” to Zabzugu-Tatale, Ghana with Sue Maclain
Where
the real
work
gets
done
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
“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
Do you know
these public
health
workers?
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 ??
Challenges to Understanding and
Controlling Parasitic Diseases
• BROAD SCIENTIFIC CHALLENGES
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–
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–
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Vaccine development
Vector manipulation
Drug development
Drug resistance
Host genetic contribution
Rapid surveillance/diagnostic tools
Few new scientists entering the field
• BROADER SOCIETAL CHALLENGES
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–
–
–
–
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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