topic 3 - disease control strategies

8/14/2019 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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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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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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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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topic 3 - disease control strategies

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