Week 8 - population health, epidemiology & communicable diseases Flashcards
what are vital statistics?
Birth rates (births per year per 1000 people in the totally population) Death rates (Deaths per year per 1000 people in the total population) Age adjusted rates make different population with different age structures comparable
what is demography
The study of size and composition of human populations
measuring the burden of diseases is…
Foundation for evidence-based policy and practice
Global disease burden
- Causes of death (mortality)
- Causes of disease morbidity
- Disability
- Risk factor rates
Incidence
# of total new cases in a specific time period / total # at risk (describes outbreaks, acute disease) - often decrease if a new vaccine or other preventative measure is available
Prevalnce
# of total existing cases (new & old) / total # of people in population (describes chronic disease in population) Can decrease if there is a new therapy cures a lot of the disease
Challenges of measuring mortality
In many lower-income parts of the world vital statistics are not collected (no death registry)
It can be difficult to assign a single cause of death (either b/c the cause is unknown or because there were many contributing causes)
Life expectancy at birth
Median expected age at death of all babies born alive (which usually includes some child & young adult deaths and many deaths of older adults)
Healthy life expectancy
the number of years the average person born into a population can expect olive without disability
1850-1900
Age of hygiene
1950-1970
Golden age of abs
What are the 3 aspects of an epidemiological triangle
1) Agent
2) Host
3) Environment
what does the epidemiological triangle tell us
how disease moves in a population & how to prevent it
posits that the possibility of the disease occurrence is determined by the interactions ebtweent the host, the agent and the environment
What is the host vs. the AGENT in epidemiological triangle
HOST: susceptible person
AGENT: etiological factors
Agents have been classified as:
1) Nutritive elements
2) chemical agents
3) Physical agents
4) Infectious agents
Factors affecting host susceptibility
1) genetics
2) age
3) gender
4) Ethnic group
5) Physiologic state
6) prior immunologic state
7) pre-existing disease
8) human behaviours
what are environmental factors
Extrinsic to both the host & the agent, however, can either a moderating or mediating relationship with the agent & the host
CAN BE USED TO INFECTIOUS & NON-INFECTIOUS diseases like CAD
Epidemiological triangle for covid
Host: human or animal
agent: infectious agent
environmental: social distances/ masking / or not
CAD epidemiological triangle
Agent: genetic susceptibility (intrinsic) / composition
host: person
Environment: external factors such as diet, exercise, environment can influence someones individual genetic susceptibility to develop or express a trait
Health transitions
~100 years ago, populations around the world had similar health profiles (high birth rates, high death rates, short life expectancies, many diseases and death d/t infectious & undernutrition)
As economies improved & health profile shifted to lower birth rate, lower death rate, higher burden of chronic diseases (d/t over nutrition)
what is a demographic transition
Shift toward lower birth and death rates a populations move from being low-income economies to high-income economies.
population pyramid is a tool used to visualize demographic transition
population will eventually stop growing when the country transitions to high birth & high death rates to
LOW BIRTH & LOW DEATH RATES –> stabilizing the population –> occurs in industrialized countries sb/c less developed follow the advanced countries.
Right now most countries have ____ growth rates
POSITIVE - keeps getting bigger
what is growth rate
Measuring how much the population grows or shrinks over some time period
Calculated - Add both & immigration, subtract death & emigration.
Growth rate = current - individual divided by initial & multiplied by 1000
why do most countries currently have positive growth rate
economic benefits - children work, gov’t may have incentives
religion - promotes large families, more in the faith
cultural - children, pass down own family values
5 stages of demographic transition model
Stage 1 - High stationary (High birth rates, high death rates)
Stage 2 - Early expanding (pop rise as death rates drops, health ,sanitation & food)
Stage 3 - late expanding (death rates continue to drop but birth rates also begin to fall b/c contraceptionn & changing social trend smaller families)
Stage 4 - Low staining (population stabilizes, population is large, USA, AUS)
Stage 5 - speculation Contracting?
Epidemiologic transition
Occurring b.c infectious disease has fallen, esp. in childhood.
- Vaccination
- Insecticide-treated nets
- Water supply, hygiene, sanitation
- Prevention & treatment for diarrhea, pneumonia, malaria, TB, HIV, etc.
shift from infectious disease to chronic, non-communicable disease
initially 3 stages but 2 more were proposed
What are the 5 stages of epidemiological transition
1) Age of pestilence & Famine - no country currently at this level.
When mortality is high and fluctuating, thus precluding sustained population growth. In this stage the average life expectancy is low and variant 20-40 years
2) Age of receding pandemics - when morality declines progressively
the are of decline accelerates as epidemic peaks becomes less frequent or disappear. The average life expectancy at birth increases steadily from about 30-50 years. Population growth is sustained and begins to describe an exponential curve
3) Age of degenerative and man-made diseases
when morality continues to decline & eventually approaches stability at a relatively low levels. The average life expectancy at birth rises gradually until it exceeds 50 years. It is during this stage that fertility becomes a crucial factor in population growth
4) Age of delayed degenerative disease - the length of life expectancy increases (As the major killer disease of later transitions are bettered treated or delayed) but in which health status may deteriorate as the causes of chronic but non-fatal morbidity are yet to be defeated.
Increasing incidence of mental disorders. This stage evident in developed countries in southeast & east asia
5) Age of emergent & re-emergent infections
Associated with the resurgence of infectious and parasitic disease (both old & new) as a serious public health concern in developed countries.
AIDS - young in north america& Europe. TB, unique attributes of this new trend in infectious disease mortality qualify it as a distinct stage in our epidemiological history
Ebola crises
1976 appears to epidemic / outbreak
2014 - pandemic
lessons learned from ebola crisis
- PPE was ineffective
- Training on protocols (secreening, isolation, decontamination prior to removing PPE)
- Dedicated ebola centers / teams
Factors affected Ebola spread
Political context
Access to health services
cultural practice & super stitiuions
stigma
Emerging disease (a new modern era disease)
MArbug Ebola Mad cow H5N1 SARS MERS
Re-emerging diseases
Re-emergence of older diseases TB Monkey pox dengue Ebola
Pandemic
A pandemic is the worldwide spread of a anew disease
A pandemic occurs weh na new virus emerges and spreads around he world and most people do not have immunity. Viruses that have caused panemics usually form animal influenza viruses
12 Steaps to prevent antimicrobial resistance in hospitalized adults
1) Vaccinate (prevent infection)
2) Get catheters out (prevent infection)
3) target the pathogen (Diagnoses and treat effectively)
4) Access the expects (Diagnoses and treat effectively)
5) Practice antimicrobial control *use wisely)
6) use local data (use wisely)
7) Treat infections not contamination (use wisely)
8) Treat infection not colonization (use wisely)
9) Know when to say no to vancomycin (use wisely)
10) Stop antimicrobial treatment (when infection is treated on unlikely)
11) Isolate the pathogen (prevent transmission)
12) Break the chain of contagion (prevent transmission)
Rise of emerging and re-emerging disease because
- Non-Adherence
- Legal Sanctions compelling a patient to complete treatment (TB)
- septicemia or bloodstream infecion
- Multidrug resistant organism `
Emerging disease & Examples
Any disease that has appeared in a population for the first time
- Marburg
- Ebola (1976)
- Mad Cow
- H5N1
- Nipah virus
- SARS
- Middle east respiratory syndrome
Re-emerging disease and examples
re-appears after a significant decline in incidence, spreads to new places or emerges in a new form. May come back in a different form
- Plague
- Human monkeypox
- Dengue
- Ebola 2014
Key contributing factors to emergence & re-emergence of infectious disease
Microbial adaptation & change Human susceptibility to infection climate& water changing ecosystems economic development & land use Human demographics & behaviour technology & industry International travel & commerce breakdown of public health measures poverty & social inequality war & famine lack of political will Intent to harm MOST ARE ZOONOTIC IN ORIGIN
Resistance forms of disease
Can emerge or re-emerge when bacteria, parasites and viruses are altered by natural selection
-Eg. Malaria resistant to chloroquine or sulfadoxine-pyimerthamine
Multidrug resistant TB
MRSA
TB leading infectious cause of death in the world 5% of active TB in the world are drug resistant.
is drug resistant natural?
RESISTANCE IS A NATURAL PHENOMENON, but human action / inaction can spread or make it worse
Key factors to the development of drug resistance
- Failure of patient to take appropriate doses of drugs
- Inappropriate use of drugs by prescribers, dispensers, pt.
- Poor prescribing & dispensing practices
- The use of counterfeit or poor-quality drugs that do not contain the appropriate level of therapetuic ingredients
-Inappropriate use of abx in agriculture
weak health systems with poor lab capacity to dx disease & test for drug susceptibility
ADDITIONALLY - Weak infection control –> hospital born infections
-Poor sanitation & hygiene - Weak surveillance of infections - difficult to detect, enable their spread
the health, social & economic impacts of emerging & re-emerging disease
VERY LARGE - only few deaths but the costs & conseuqneces are not related to death, it’s related to how frightening the disease is.
Cost of anti-microbial resistance is high too
Might be sicker than they usually would be, might die at higher rates
Cost 1x more to treat drug resistance TB than susceptible TB
much more expensive 25-60x more expensive
Measures to address emerging & re-emergin infectious disease
1) Improve land use planning within countries (Zoonotic)
2) enhance public education about these disease
3) Establish national surveillance systems dn public health laboratories
4) share information across countries about disease outbreaks in a timely manner
5) Strengthen implementation of the international health regulations
6) Enhance the capacity for a coordinated and timely global response
7) Improve the financing for such a response
Measures to address anti-microbial resistance
1) studies of economic burdens of drug resistance
2) a global surveillance system for resistance
3) Better regulate nand stricter monitoring of prescribing practice for ABX
4) enhanced education of the danger of overprescribing ABX
5) Phase out the use of ABx in animals
6) the development of new models for research and development of ABX
7) ) Involve governance of ABX both nationally and globally
what is the public health approach?
1) Surveillance - wha tis the problem
2) Risk factor identification - what is the cause
3) Intervention evaluation - what works
4) Implementation - how do you do it? (response)
What is epidemiology
the study of distribution & determinants of health-related state among specified population & the application of that study to the control of health problems
Purpose of epidemiology
- Discover the agent, host & environmental factors that affect health
- Determine the relative importance of causes of illness, disability & death
- Identify those segments of the population that have the greatest risk form specific causes of ill health
- Evaluate effectiveness of health programs and services in improving population health
4 steps of solving health problems
Step 1 - Data collection (Surveillance, determine time, place & person)
Step 2 - Assessment (inference)
Step 3 - Hypothesis testing (determine how & why)
Step 4 - Action (intervention)
Epidemic or outbreak
Disease occurrence among a population in excesss of what is expected in a given time & places
Cluster
group of cases in a specific time & place that might be more than expected
endemic
Disease or condition present in a population at all times
Pandemic
a disease of condition that spreads across regions
Rate
number of cases occurring during a specific period always depending on the size of the population during that period
Descriptive epidemiology vs. Analytic epidemiology
DESCRIPTIVE: collect info to characterize / summarize problem
- When was the population affected
- where was the population affected?
- Who was affected?
ANALYZED: comparison between groups to test a hypothesis
- how was the population affected?
- why was the population affected ?
Cross-sectional study:
subjects are selected b/c they are members of a certain population subset at a certain time.
- Random telephone survey at a university, exercise habits, obesity
- Time is important
- eg. A study of women 50-60 years old in a community located close to a nuclear power facility
Cohort:
Subjects are categorized on the basis of their exposure to one or more risk factors
- IF an optional healthy eating choices class - follow up to see patterns. Eg. subjects who have not received nutritional counselling and those who did
Case control:
Subjects identified as having a disease or condition are compared with subjects without the same disease of condition.
Move backwards form those two have disease (Eg. cruise ship)
Four remedies to prepare the world for a global pandemic
1) Faster pipelines - such as the coalition on epidemic preparedness - pre-emptively develop vaccines for diseases predicted to cause outbreaks in near future
2) Point of care diagnostics that can be used by frontline responders or patients themselves to detect infectious nright away where they live
3) Greater global coordination to address the currently fragmented responsibility for controlling pandemics
4) Stronger local health systems that con provide routine case & when needed, coordinate with international responders to contain new outbreaks
Pandemics now occurs with greater frequency d/t
1) Climate change
2) Urbanization
3) International travel
4) Weak health organizations
5) Potentially massive cuts to funding ro US scientific research & foreign Aid including the UN
