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Reservoirs
Long term hosts of pathogens
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Inanimate Reservoirs
Primary vs secondary
- 1- microbes are viable and multiply
- 2- viable but dont multiply
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living reservoirs
Humans or animals
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zoonosis
disease that can spread from animal to human
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endemic
infection in population without external inputs, always present in pop
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epidemic
new cases exceding expectation
higher incidence
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Herd immunity
- portin of populat. immune to the disease.
- (vaccination or immunity)
- inable to spread disease
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BOD
biological oxygen demand
- quantity of o2 needed by the bacteria in the water
- increases with age of h2o
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coliform testing
2 tests for lactose microbes
Maconkey = + dark purple, - clear
- Emb agar = + colonies with dark center, - colorless
- ECOLI = metallic green
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Primary water treatment
Physical process, remove solids
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secondary
- biological proces
- trickling filter & activated sludge
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tertiary
- biological
- add lime or alum to remove nitrates and phophates
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septic sys
anaerobic digestion, small only
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pastuerization
72c for 15 sec
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phosphatase test
used to check if pasteurizat worked. should have destroyed enzyme in process
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harm studies
assess causual relationship, treatment and disease
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confounder
anything that independently affects the exposure and the outcome
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hill's criteria for causality
minimal conditions to establish causality
- - temporal relationship
- exp evidence
- dose response relation
- consistency
- plausibility
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cohort study
- prosepctive (or retrospect)
- more ethically permisible
- RR relative risk (strength of causality)
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RR- relative risk
strength of causality, risk of disease in exposed vs not exposed
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case control study
useful if the outcome you want is rare or takes a long time to develop
- retrospective
- true risk of happening cant be calculated
- must check odds ration(OR)
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RR
- if =1 no association
- RR>1, increase risk with exposure
- <1 decreased risk w/ exp
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OR
- =1 no association
- OR>1 exposure increases risk
- <1 reduces risk
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case study
- no comparison with another group
- so cant derive causality
- only good for developing hypothesis
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Ambroise Pare
1500s, found alternative to boiling water for cauterizing wounds
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james lind
tested lime juice prevented scurvy
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Morbidity
incidence or how fast the disease develops
#of new cases/pop. at risk
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mortality
- death rate from disease
- #deaths/pop. that yr
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prevalence
- # of people infected at a specific time
- #of cases/pop.
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hippocrates
epidemic vs endemic
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john graunt
bills of mortality, kept vital statistics
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WHO
un agency - health is human right
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Pan american health organization
- improve health in the americas
- now a part of the WHO
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UNICEF
united nations childrens fund, un partner - protect childrens rights
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