SUMMARY LECTURES CONTAINMENT STRATEGIES OF INFECTIOUS
DISEASES IN GLOBAL CONTEXT
Health intervention (assignment theory)
To design a health intervention, you have certain frameworks. One of these
frameworks is the precede/proceed framework by Green and Kreuter,
intervention mapping by Bartholomew, or behavior change and communication
models. In this lecture and assignment will we use the 5 intervention steps by
Jenkins:
1. What is the problem (is it a priority health problem)?
a. Burden of disease + potential burden: mortality/morbidity,
incidence/prevalence, DALY, global burden of disease.
b. Socioeconomic impact
c. For whom?
The following research methods can be used to assess this:
- Routine information: National census data, death certification and
registers, hospital and clinic records, disease notification systems, lab
tests
- Epidemiological data: cross-sectional study
- Community appraisals: questionnaires, interviews, focus groups,
visualization and diagramming
2. What factors cause the problem? Where in the causal chain do we need to
intervene to address this problem. For this you can use tools such as the
epidemiological triangle: agent makes you sick, host can get sick,
environment where it happens; sometimes also a vector involved. Problem
tree is another tool.
3. How can these factors be changed. Make a long list of how these can be
changed.
a. Remove the agent
b. Raise host resistance
c. Modify environment
d. Separate agent from host
e. Interrupt transmission (infected to non-infected individual)
Preventive programs deal with complex web of etiology (causation).
Hence, web of interventions needed in many conditions. Risk factor
strategy: reducing risks and increasing protective factors. This requires
intersectoral cooperation, and personal and collective behavioral change.
4. What overall intervention strategies are most appropriate and cost
effective (including what do people want and what are their needs)?
Criteria:
a. Medical effectiveness: extent to which it controls disease
b. Organization feasibility: implementation of intervention (level of
facilities, skills of health workers) – does it fit in with existing
services.
c. Social, cultural, and ‘political’ feasibility: acceptability of
intervention to community and (political) leader.
d. Financial feasibility: costs for personnel and materials, economic
appraisal and sustainability.
Comparing different options is highly complex and laborious, see the WHO
choice program.
5. What needs to be done to reach the goals? With what (sub)populations
shall work be done, and in what sequence, to solve the problem?
Anticipate barriers to implementation and negative side effects.
,
,Control of infectious diseases: basic principles
One health: should see human, animal and environmental health together, there
is a connection between these.
Planetary health: the stake of the earth determines our health, such as climate.
Infection: when a microorganism is present in a host in places where it is not
normally found (replicating).
Infectious disease: when this causes symptoms.
Transmission of infectious diseases can happen:
- Direct: skin-skin, blood/mucous-mucous, across placenta, through
breast milk, sneeze-cough.
- Indirect: food-borne, water-borne, vector-borne, air-borne.
- Exposure: a relevant contact – depends on the agent. Skin, sexual
intercourse, water contact, etc.
Reservoir: where can the agent live. For many diseases, humans are the
reservoir. Can also be animal reservoirs. Important for control, if there are
reservoirs outside humans, we have to get rid of the disease there as well.
Four relevant branches of epidemiology: disease etiology, outbreak investigation
(what was the source), disease screening/surveillance, comparisons of treatment
and effect.
Different outcomes to exposure to an infectious disease:
Dynamics of infectious diseases:
Latent period: not infectious yourself, cannot transmit disease. Some diseases do
not have a non-infectious period, you basically always remain infectious.
Latent period is not the same as incubation period, depends per disease. For
some diseases you can spread it before you show symptoms. But for most cases
symptoms imply that you are infectious. Want to know as soon as possible if
people are infectious, but most people only report to a doctor when they become
sick.
, Different types of cases:
- Index: the first case identified (in the population)
- Primary the case that brings the infection into a population
- Secondary: infected by a primary case
- Tertiary: infected by a secondary case
Sub-clinical patients will not report to GP so they will not show up in the data.
Follow up on contact-tracing is important.
Reproductive rate: how many people one person infects. What does it depend
on:
- Relevant contacts/route of transmission
- Attributes of the agent
- Susceptibility of the host
RR is never stable. If RR is below one the infection will die out.
Odds ratio:
Adequate chain of transmission:
Endemic disease: disease constantly present in a population
Epidemic disease: disease acquired by many hosts in a given area in a short time
(outbreak).
Pandemic disease: worldwide epidemic.
Levels of limiting infectious diseases:
- Control: reduction of disease incidence, prevalence, mortality and
morbidity
- Elimination: reduction to zero of the incidence of infections caused by a
specific agent
DISEASES IN GLOBAL CONTEXT
Health intervention (assignment theory)
To design a health intervention, you have certain frameworks. One of these
frameworks is the precede/proceed framework by Green and Kreuter,
intervention mapping by Bartholomew, or behavior change and communication
models. In this lecture and assignment will we use the 5 intervention steps by
Jenkins:
1. What is the problem (is it a priority health problem)?
a. Burden of disease + potential burden: mortality/morbidity,
incidence/prevalence, DALY, global burden of disease.
b. Socioeconomic impact
c. For whom?
The following research methods can be used to assess this:
- Routine information: National census data, death certification and
registers, hospital and clinic records, disease notification systems, lab
tests
- Epidemiological data: cross-sectional study
- Community appraisals: questionnaires, interviews, focus groups,
visualization and diagramming
2. What factors cause the problem? Where in the causal chain do we need to
intervene to address this problem. For this you can use tools such as the
epidemiological triangle: agent makes you sick, host can get sick,
environment where it happens; sometimes also a vector involved. Problem
tree is another tool.
3. How can these factors be changed. Make a long list of how these can be
changed.
a. Remove the agent
b. Raise host resistance
c. Modify environment
d. Separate agent from host
e. Interrupt transmission (infected to non-infected individual)
Preventive programs deal with complex web of etiology (causation).
Hence, web of interventions needed in many conditions. Risk factor
strategy: reducing risks and increasing protective factors. This requires
intersectoral cooperation, and personal and collective behavioral change.
4. What overall intervention strategies are most appropriate and cost
effective (including what do people want and what are their needs)?
Criteria:
a. Medical effectiveness: extent to which it controls disease
b. Organization feasibility: implementation of intervention (level of
facilities, skills of health workers) – does it fit in with existing
services.
c. Social, cultural, and ‘political’ feasibility: acceptability of
intervention to community and (political) leader.
d. Financial feasibility: costs for personnel and materials, economic
appraisal and sustainability.
Comparing different options is highly complex and laborious, see the WHO
choice program.
5. What needs to be done to reach the goals? With what (sub)populations
shall work be done, and in what sequence, to solve the problem?
Anticipate barriers to implementation and negative side effects.
,
,Control of infectious diseases: basic principles
One health: should see human, animal and environmental health together, there
is a connection between these.
Planetary health: the stake of the earth determines our health, such as climate.
Infection: when a microorganism is present in a host in places where it is not
normally found (replicating).
Infectious disease: when this causes symptoms.
Transmission of infectious diseases can happen:
- Direct: skin-skin, blood/mucous-mucous, across placenta, through
breast milk, sneeze-cough.
- Indirect: food-borne, water-borne, vector-borne, air-borne.
- Exposure: a relevant contact – depends on the agent. Skin, sexual
intercourse, water contact, etc.
Reservoir: where can the agent live. For many diseases, humans are the
reservoir. Can also be animal reservoirs. Important for control, if there are
reservoirs outside humans, we have to get rid of the disease there as well.
Four relevant branches of epidemiology: disease etiology, outbreak investigation
(what was the source), disease screening/surveillance, comparisons of treatment
and effect.
Different outcomes to exposure to an infectious disease:
Dynamics of infectious diseases:
Latent period: not infectious yourself, cannot transmit disease. Some diseases do
not have a non-infectious period, you basically always remain infectious.
Latent period is not the same as incubation period, depends per disease. For
some diseases you can spread it before you show symptoms. But for most cases
symptoms imply that you are infectious. Want to know as soon as possible if
people are infectious, but most people only report to a doctor when they become
sick.
, Different types of cases:
- Index: the first case identified (in the population)
- Primary the case that brings the infection into a population
- Secondary: infected by a primary case
- Tertiary: infected by a secondary case
Sub-clinical patients will not report to GP so they will not show up in the data.
Follow up on contact-tracing is important.
Reproductive rate: how many people one person infects. What does it depend
on:
- Relevant contacts/route of transmission
- Attributes of the agent
- Susceptibility of the host
RR is never stable. If RR is below one the infection will die out.
Odds ratio:
Adequate chain of transmission:
Endemic disease: disease constantly present in a population
Epidemic disease: disease acquired by many hosts in a given area in a short time
(outbreak).
Pandemic disease: worldwide epidemic.
Levels of limiting infectious diseases:
- Control: reduction of disease incidence, prevalence, mortality and
morbidity
- Elimination: reduction to zero of the incidence of infections caused by a
specific agent
