topic 3 - disease control strategies
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DISEASE CONTROLSTRATEGIES
DISEASE CONTROL (DEMT 2433)
DIPLOMA IN ENVIRONMENTAL HEALTHVICTORIA INTERNATIONAL COLLEGE
BY: MR KHAIRUL NIZAM MOHD ISADEPARTMENT OF ENVIRONMENTAL HEALTH
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Principles of Disease ExposureControl
Disease Exposure Control (DEC) is the process by which
the spread of disease is minimized by limiting contact
between uninfected individuals and other individuals who
are potential spreaders of a contagious disease.
DEC programs are needed when confronting possible
large-scale outbreaks of contagious diseases, and, inparticular, when effective medical or public health
prevention or treatment interventions - vaccines or
antivirals, for example - do not exist, are unavailable, or
are insufficient to halt a fast-spreading disease.
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Principles of Disease ExposureControl
There are five principles that underpin DEC programs.
1. Broaden the scope of crisis response
Government officials should broaden the scope of
response to health crises beyond attention to the sick orexposed, and include plans for those who were not
exposed, and plans for the provision of services beyond
health care.
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Principles of Disease ExposureControl
2. Limit social interactions
Healthy individuals can limit their own exposure to disease, andpotential spreaders can reduce exposing others to disease, by
limiting their interactions with others.
3. Use a toolkit of exposure control measures
Disease exposure control programs should employ a range of
tools:
infection control
isolation
quarantine
community restrictions sheltering
-to reduce person-to-person exposure to infectious agents.
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Infection Control
Infection Control refers to physical measures taken to
protect individuals against coming in direct contact with
infectious material or agents (whether through the air or
by touching people, biological material, or physical
surfaces) and includes such things as proper hand
hygiene and use of personal protective equipment(masks or respirators, gloves, gowns, and eye
protection).
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Isolation
Isolation refers to the identification, separation and restriction
of movement or activities of ill/ infected or suspected (basedupon signs, symptoms or laboratory findings) persons who
have a contagious disease, for the purpose of preventing
transmission to others and for enhancing delivery of
specialized health care to them. Three types of isolation could be employed in DEC regimes:
Airborne Infection Isolation Rooms (AIIR isolation)
Home isolation
Facility isolation
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Isolation
Airborne Infection Isolation Rooms (AIIR isolation) within
a hospital, if there are a limited number of sick or
suspected cases; or in the face of a large-scale
potentially catastrophic outbreak, if there are insufficient
AIIR isolation units available.
Home isolation, useful when limited health care isrequired or available for treating patients.
Facility isolation - establishing isolation wards in sections
of or in entire hospitals, or in other facilities (e.g., clinics,
nursing homes, schools, convention centers, cruiseships, etc.) - when specialized health care may be
required.
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Quarantine
Quarantine refers to the identification, separation and restriction
of movement or activities of persons who are not ill but mayhave been exposed to a contagious disease and at risk of
becoming infected, for the purpose of monitoring their health
and preventing transmission of disease to others.
The use of quarantines in disease exposure control regimes
should not be viewed as a means to immediately stop the
spread of disease, but rather as one of many tools to reduce the
likelihood that new cases will arise from individuals who are
unaware that they are infected.
Over time, as the incidence of new cases declines, the numberof infected individuals will eventually drop to zero.
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Quarantine
The four principal types of quarantine are:
Home quarantine (exposed or potentially exposed persons remain
at home during the incubation period of the infectious agent).
facility quarantine (officials designate a facility to better control the
implementation of a quarantine, or to provide a location for those
unwilling or unable to quarantine at home).
work quarantine (individuals remain at work, or limit travel and
contact with others between work and home, for the duration of
the incubation period).
community quarantine (officials designate neighbourhoods or
geographic regions where a combination of home, work, and/or
facility quarantines may be implemented).
Each type of quarantine may be implemented on either a voluntary or
mandatory basis.
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Community Restrictions
Community Restrictions refers to the reduction of community-
wide interactions through restriction or limitation of publicevents, large public gatherings, interactions or other activities.
Community restrictions are a very different approach to disease
exposure control.
Community restrictions are not directed at individuals orspecific groups, nor do they necessarily apply only to people
who are ill, exposed, or potentially exposed.
Community restrictions limit social interactions across an entire
community, as a means of lessening the likelihood that
unwitting carriers of disease will come in contact with healthyindividuals and infect them.
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Community Restrictions
There are five categories of community restrictions that
policy-makers can draw from and implement:
1. Encourage community-wide infection controls
2. Restrict public travel
3. Cancel public gatherings4. Close public facilities
5. Enhance screening efforts
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Sheltering
Sheltering refers to measures individuals may take to limit their
own social interactions such as by staying at home, to avoidbeing exposed to infected, potentially contagious individuals.
Sheltering is different from isolation and quarantine in that those
who are sheltering may never have been exposed to a pathogen.
In contrast to many community restrictions, furthermore,sheltering is characterized by the fact that there will be no
attempt made at enforcement.
However, the community would voluntarily restrict movement to
avoid potential exposure.
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Principles of Disease ExposureControl
4. Employ least restrictive measures necessary
Disease exposure control programs should be designed
using the least restrictive means necessary to control the
spread of disease, based on the characteristics of the
disease, the extent of its spread, and the physical and
social characteristics of the community at risk.
5. Engage the public as a partner
The public should be engaged as a partner in responding
to a large-scale infectious disease outbreak through anappropriate balance of inducements, enforcements and an
effective public communication strategy.
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Public Health Services also helps control and prevent
communicable disease by:
providing education to individuals and groups;
keeping statistics on common diseases and reporting
the information to the Department of Health;
working with key partners to investigate any disease
outbreaks; and
offering immunization programs in the community
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Surveillance
Surveillance is the ongoing systematic collection,
analysis and interpretation of data in order to plan,
implement and evaluate public health intervention.
This is the process of watching over populations for new
diseases , or for increased frequency of existing
diseases. Surveillance information is used to help control disease.
Surveillance system should be simple, flexible,
acceptable and situation specific.
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Objectives of a surveillance system inan emergency
1. Identify public health priorities2. Monitor the severity of an emergency by collecting and
analyzing mortality and morbidity data
3. Detect outbreaks and monitor response
4. Monitor trends in incidence and case fatality frommajor diseases
5. Provide information to ministry of health, donors to
assist in health program planning, implementation and
resource mobilization.
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Outbreak Control
An outbreak is occurrence of a number of cases of a
disease that is unusually large or unexpected for a given
place and time.
Outbreaks and epidemics refer to the one and same
thing.
Outbreaks in emergency situations can spread rapidly
giving rise to high morbidity and mortality rates.
Aim should be to detect and control the outbreak as
early as possible.
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Major diseases with epidemic potentialin emergency situation
Cholera
Meningococcal disease
Measles
Shigellosis
In certain areas the following diseases have to be
included: malaria, louse borne typhus, yellow fever,
trypanosomiasis, leishmaniasis,viral hemorrhagic
fever,relapsing fever, typhoid and hepatitis A and E.
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Prevention and Control of specificcommunicable diseases
Acute RespiratoryInfections
Cholera
Other diarrhoealdiseases
Conjunctivitis
Dengue
Diphtheria
Hepatitis
HIV/AIDS
Japanese Encephalitis
Leishmaniasis
Malaria
Measles
MeningococcalMeningitis
RelapsingFever(louse borne)
Scabies Sexually Transmitted
Infections
Trypanosomiasis
Tuberculosis
Typhoid
Typhus (Epidemiclouse borne)
Viral Hemorrhagic
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Immunity
Immunity refers to a hosts ability to resist a particular
infectiousdiseasecausing agent.
This occurs when the body forms antibodies and
lymphocytes that react with the foreign antigenic
molecules and render them harmless.
Four types of immunity are important in community health:
Passive immunity
Active immunity
Cross immunity
Herd immunity
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Passive Immunity
Passive immunity refers to short-term resistance that is acquired
either naturally or artificially.
Newborns, through maternal antibody transfer, have natural passive
immunity that lasts about 6 months.
Artificial passive immunity is attained through inoculation with a
vaccine that gives temporary resistance.
Immune globulin (IGIM or IGIV) is used to boost a susceptiblepersons immunity and must be repeated periodically to maintain
immunity levels. It is used to provide passive immunity against certain
infectious diseases or to modify their severity;
Examples include rubeola, rubella, varicella-zoster, and type A
hepatitis. Immune globulin is also used as an alternative to hepatitis B
specific immune globulin (HBIG) to provide passive immunity in
hepatitis B infection.
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Active Immunity
Active immunity is long-term and sometimes lifelong resistance that is
acquired either naturally or artificially.
Naturally acquired active immunity comes through host infection. That is,
a person who contracts a disease often develops long lasting antibodies
that provide immunity against future exposures.
Artificially acquired active immunity is attained through vaccine
inoculation. Such vaccines are prepared from killed, living-attenuated, or
living-virulent organisms administered to artificially produce or increaseimmunity to a particular disease.
The concept of active immunity underlies public health immunization
programs that have successfully kept polio, diphtheria, smallpox, and
other major diseases under control worldwide.
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Cross Immunity
Cross-immunity refers to a situation in which a persons immunity to one
agent provides immunity to another related agent as well. The immunity can be either passive or active.
Sometimes, infection with one disease, such as cowpox, gives immunity to
a related disease, such as smallpox.
The concept of cross-immunity has also been useful in the development
and administration of vaccines. Inoculation with a vaccine made from one disease-causing organism can
provide immunity to a related disease-causing organism.
The vaccine against Mycobacterium tuberculosis appeared to provide
these individuals with a degree of cross-immunity to the related infectious
agent, Mycobacterium leprae, and prevented their contracting the disease.
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Herd Immunity
Herd immunity describes the immunity level that is present in a population
group. A population with low herd immunity is one with few immune members;
consequently, it is more susceptible to the disease.
Nonimmune people are more likely to contract the disease and spread it
throughout the group, placing the entire population at greater risk.
Conversely, a population with high herd immunity is one in which theimmune people in the group outnumber the susceptible people;
consequently, the incidence of the disease is reduced.
High herd immunity (80% or more) provides a population with greater
overall protection because nonimmune people are at less risk of disease
exposure.
Mandatory preschool immunizations and required travel vaccinations are
applications of the herd immunity concept.
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THANK YOU
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