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Mohamed M. B. Alnoor
CHP400COMMUNITY HEALTH PROGRAM-II
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Emerging and Re-emergingInfectious Diseases
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• Definitions
• Emerging Infections since 1973
• Major factors contributing to the emergence of infectious diseases
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Emerging and Re-emergingInfectious Diseases
Emerging Infectious Diseases
Definitions
“New, reemerging
or drug-resistant infections whose incidence in humans
has increased in the past two decades
or threatens to increase in the near future.”
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Emerging and Re-emergingInfectious Diseases
Emerging/New
Re-emerging/Resurging
Definitions
Newly appeared in a population.
Incidence increased over20 years or threatens to increase soon.
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Deliberately emerging:Deliberately emerging:Developed for nefarious useDeveloped for nefarious use
Emerging Infectious Diseases
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Emerging and Re-emergingInfectious Diseases
After great advances in medical research,
antimicrobial drug discovery, technology development,
improvement in sanitation..WHY are microbes still
posing such a problem!!??
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Emerging and Re-emergingInfectious Diseases
قال رسول الله صلى الله عليه وسلم: »لم تظهر
الفاحشة في قوم قط حتى يعلنوا بها إال فشا فيهم
الطاعون واألوجاع التي لم تكن مضت في أسالفهم الذين
مضوا .« رواه ابن ماجه والحاكم
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Major Factors Contributing to the Emergence of Infectious Diseases
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Emerging and Re-emergingInfectious Diseases
Major Factors Contributing to the Emergence of Infectious Diseases1. Ecological changes & agricultural development2. Human demographics and behavior3. Technology and industry4. Economic development and land use5. International travel and commerce6. Microbial adaptation and change7. Breakdown of public health measures
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Emerging and Re-emergingInfectious Diseases
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More Factors Contributing to the Emergence of Infectious Diseases
8. Human vulnerability
9. Climate and weather
10. Poverty and social inequality
11. War and famine
12. Lack of political will
13. Intent to harm
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Emerging and Re-emergingInfectious Diseases
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Major Factors Contributing to the Emergence of Infectious Diseases
1. Ecology & agriculture
Placing people in contact with a reservoir of an infection (zoonotic or arthropod-borne) either by:
- Increasing proximity - Changing conditions
microbe
natural host
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Emerging and Re-emergingInfectious Diseases
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Major Factors Contributing to the Emergence of Infectious Diseases
1. Ecology & agriculture
Reforestation in USA
Increased the number of deer & deer ticks
Human affection by Lyme disease
Increased Human contact with deers
Deer tick
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Emerging and Re-emergingInfectious Diseases
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Major Factors Contributing to the Emergence of Infectious Diseases
Conversion of grassland to maise cultivation
Rodents & people come together
Rodent
Argentine Haemorrhagic fever in humans
1. Ecology & agriculture
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Emerging and Re-emergingInfectious Diseases
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Major Factors Contributing to the Emergence of Infectious Diseases
Mixing vessels
Influenza Influenza Influenza
1. Ecology & agriculture
Pig Farm Duck farmC h i n a
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Major Factors Contributing to the Emergence of Infectious Diseases
Introduction of Korean haemorrhagic fever in Humans
Increased human contact with Field mouse
1. Ecology & agriculture
Increased Rice cultivation in South East Asia.Field mouse
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Emerging and Re-emergingInfectious Diseases
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Major Factors Contributing to the Emergence of Infectious Diseases
Dengue fever in Asia
Inflation of population size
Insufficient infrastructures
Use open containers for water
Breading mosquitos
2. Human demographics and behavior
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Emerging and Re-emergingInfectious Diseases
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Major Factors Contributing to the Emergence of Infectious Diseases
2. Human demographics and behavior
Urbanization•More people concentrated in cities-often without adequate infrastructure•Increases in the elderly populations
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Major Factors Contributing to the Emergence of Infectious Diseases
2. Human demographics and behavior
Urbanization•Increases in children in daycare: working woman with kids under 5 was 30% in 1970, became 75% in 2000.• Fast paced Lifestyles- increase in
convenience items and more stress.• High-risk behavior- Drug use and
unprotected sex
Urbanization
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Major Factors Contributing to the Emergence of Infectious Diseases
3. Technology and industry
• Modern mass production increases 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.
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Major Factors Contributing to the Emergence of Infectious Diseases
• New diagnostics lead to identification of previously unknown microbes for known diseases e.g. Helicobacter pylori and
peptic ulcer.• Medical technology - People living longer, but have weaker immune systems. - Blood & organ transplantation transmit
infections.
3. Technology and industry
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Major Factors Contributing to the Emergence of Infectious Diseases
4. Economic development and land use
• Changing ecology influencing waterborne, vectorborne disease transmission (e.g. dams, deforestation)
• More exposure to wild animals and vectors (Lyme disease, ehrlichiosis, babesiosis, HPS,…)
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Major Factors Contributing to the Emergence of Infectious Diseases
• Circumnavigation: 365 days, now 36 hours• International travelers: 400 millions • Increased incidence of both Tuberculosis and Influenza transmission on long
flights
5. International travel and commerce
• Transportation of products - Rapid transport of disease harboring
fresh products. - Transport of livestock facilitates transport
of viruses and arthropods (esp. ticks)
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Major Factors Contributing to the Emergence of Infectious Diseases
5. International travel and commerce
• Travel and HIV/AIDS.
• Historically:- Silk route and plague.- Slaves trade and yellow fever.- Migration to new world and smallpox.
• Cholera and Hajj.
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Major Factors Contributing to the Emergence of Infectious Diseases
6. Microbial adaptation and change• Lateral transfer is common: shown by
genome sequencing.• Rapid adaptation: due to high mutation
rates in RNA viruses.• Rapid build up of rare mutations: because
of quick reproduction
• Resistance: Antimicrobials used in livestock growth enhancement and over-prescription of antimicrobials by doctors.
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Major Factors Contributing to the Emergence of Infectious Diseases
7. Breakdown of public health measures
• Decrease in chlorine 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
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Emerging and Re-emergingInfectious Diseases
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Major Factors Contributing to the Emergence of Infectious Diseases
7. Breakdown of public health measures
• Inadequate vaccinations and Diphtheria in former USSR independent countries.
• Discontinued mosquito control efforts and dengue and re-emergence of malaria.
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Emerging and Re-emergingInfectious Diseases
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• Infectious diseases will always bethere
• Man and his behavior are the main reasons
• New infectious diseases will always occur
