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25/12/201025/12/2010 Dr. Salwa TayelDr. Salwa Tayel 22
Associate Professor Associate Professor Family and Community Medicine DepartmentFamily and Community Medicine Department
King Saud UniversityKing Saud University
ByBy
General Principles of Prevention ofGeneral Principles of Prevention of Infectious DiseaseInfectious Disease
Learning Objectives:Learning Objectives:
Identify the levels of prevention of infectious Identify the levels of prevention of infectious
diseases and tools for intervention at each level.diseases and tools for intervention at each level.
Describe the specific control measures for Describe the specific control measures for
infectious diseasesinfectious diseases
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Levels of prevention:
1. Primary prevention.
2. Secondary prevention.
3. Tertiary prevention.
Levels of PreventionLevels of Prevention
• • Primary prevention => pre-event Primary prevention => pre-event phasephase
• • Secondary prevention => event phaseSecondary prevention => event phase
• • Tertiary prevention => post-event Tertiary prevention => post-event phasephase
Promotion (1ry prevention)Promotion (1ry prevention)
Early detection & care (2ry prevention)Early detection & care (2ry prevention)
Rehabilitation (3ry prevention)Rehabilitation (3ry prevention)25/12/201025/12/2010 Dr. Salwa TayelDr. Salwa Tayel 55
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Tertiary Tertiary PreventionPrevention
Primary Primary PreventionPrevention
Secondary Secondary PreventionPrevention
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I- Primary Prevention:
Actions taken prior to the onset of the disease
which aim to remove the possibility that a disease
will ever occur”
It limits the incidence of diseases by preventing
healthy people from developing disease.
Tools for intervention include:
A. Health promotion
B. Specific protection
A. Health promotion
It is intended to improve the general health It is intended to improve the general health
of the individual and community, through:of the individual and community, through:
1.1. Adequate nutritionAdequate nutrition
2.2. Environmental sanitationEnvironmental sanitation
3.3. Personal hygienePersonal hygiene
4.4. Health educationHealth education
5.5. Socio-economic developmentSocio-economic development
6.6. Genetic counseling … etc.Genetic counseling … etc.
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B. Specific Protection is achieved
through:
1. Specific immunizations.
2. Chemoprophylaxis.
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II- Secondary Prevention:II- Secondary Prevention:
Actions that Actions that detect and treat disease at an early detect and treat disease at an early
stagestage thus hinder the progress of a disease and thus hinder the progress of a disease and
prevent complicationsprevent complications. . i.e. intervention in i.e. intervention in early early
pathogenesis pathogenesis phase.phase.
The methods (tools) employed for early The methods (tools) employed for early
diagnosis are:diagnosis are:
1. Screening for sub-clinical disease, either in 1. Screening for sub-clinical disease, either in
screening surveys or in periodic medical screening surveys or in periodic medical
examinations.examinations.
2. Case finding (individual and community).2. Case finding (individual and community).25/12/201025/12/2010 Dr. Salwa TayelDr. Salwa Tayel 1010
25/12/201025/12/2010 Dr. Salwa TayelDr. Salwa Tayel 1111
III- Tertiary prevention:
Actions taken when the disease process has advanced
beyond its early stages
i.e. intervention in late pathogenesis phase.
The aim of tertiary prevention is to limit disability and
prevent further complications or death.
Tools for tertiary prevention include rehabilitation
Rehabilitation:
It is a measure to train disable individuals
to reach the highest level of functional
ability by using combined coordinated
medical, social, vocational, psychological
and educational measures.
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Rehabilitation comprises:1. Medical rehabilitation – restoration of
function or physical loss.2. Educational rehabilitation change of
educational methods.3. Vocational (occupational) rehabilitation
– restoration of the capacity to earn a livelihood.
4. Social rehabilitation: restoration of family and social relationships.
5. Psychological rehabilitation: restoration of personal confidence.25/12/201025/12/2010 Dr. Salwa TayelDr. Salwa Tayel 1313
25/12/201025/12/2010 Dr. Salwa TayelDr. Salwa Tayel 1414
Examples of rehabilitation:
1. Special schools for blind pupils.
2. Provision of aids for crippled.
3. Reconstructive surgery for leprotics.
4. Modification of life for tuberculous or cardiac
patients.
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Factors affecting choice of appropriate prevention and
control measures:
It depends upon the knowledge of:
• causation and dynamics of disease transmission,
• identification of risk factors and high risk groups
• availability of tools of intervention (vaccine
chemoprophylaxis or treatment,..)
In general, control measures should be directed towards
the link in the infection chain is most susceptible to
interference.
Specific Control MeasuresSpecific Control Measures
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Agent
M.O.
T
HOST
Environment
The cycle of infection has three major links:The cycle of infection has three major links:
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Agent
M.O.T
HOST
Environment
Source- Disinfection -Sterilization
Reservoir-Isolation -Treatment- Detection of carriers - Control of animals
-Immunization-Chemoprophylaxis
-Vector control.-Snail control.
-Environmental sanitation
Measures Directed to the Measures Directed to the ReservoirReservoirMeasures applied to cases Measures applied to cases Case finding (early diagnosis)Case finding (early diagnosis) ReportingReporting IsolationIsolation Treatment (Chemotherapy)Treatment (Chemotherapy) Disinfection of contaminated objects with Disinfection of contaminated objects with
appropriate “enteric precautions,” appropriate “enteric precautions,” “respiratory precautions,” “universal “respiratory precautions,” “universal precautions” precautions”
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Isolation is separation of infected persons from those not infected for the period of communicability.
Isolation is of decreasing value because: in-apparent infection may be large proportion, maximal infectivity may occur during the
early stages, carriers of infective agents may go
undetected, or many mild cases of infection spread disease
without being detected25/12/201025/12/2010 Dr. Salwa TayelDr. Salwa Tayel 2121
Measures applied to carriersMeasures applied to carriers1.1. Detection of carriers: It is important Detection of carriers: It is important
in certain diseases e.g. Enteric in certain diseases e.g. Enteric fever. fever.
2.2. Exclusion from work: in certain Exclusion from work: in certain occupations for example; occupations for example; – food handler (e.g. Typhoid carrier) or afood handler (e.g. Typhoid carrier) or a
– teacher (e.g. Diphtheria carrier).teacher (e.g. Diphtheria carrier).
3.3. Treatment for the carrier state.Treatment for the carrier state.
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Measures applied to animal reservoir
Destruction of infected animals (in rabies,
plague) Inspection or slaughtering (in bovine
tuberculosis) Testing and Immunization (in brucellosis)
Careful husbandry and sterilization of animal
products (in anthrax).
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Measures to Interrupt the Transmission of Organisms
Environmental Measures to prevent transmission of Environmental Measures to prevent transmission of
diseases by Ingestion of contaminated diseases by Ingestion of contaminated vehiclesvehicles
include:include:
Purification of waterPurification of water
Pasteurization of milkPasteurization of milk
Inspection of food handlers & public food placesInspection of food handlers & public food places
Improvements in housing conditions, andImprovements in housing conditions, and
Educating people in proper personal hygiene and hand Educating people in proper personal hygiene and hand
washingwashing..
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Measures Reduce transmission of respiratory infection:
Proper ventilation of public places & classrooms,
Minimize close person to person contact (reduce overcrowding)
Control of dust.
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Measures to reduce transmission of arthropod borne infections
Measures to control (reduce or Measures to control (reduce or eradicate) the vector include:eradicate) the vector include:
biological biological mechanical and mechanical and chemical methodschemical methods
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Measures to reduce host Measures to reduce host susceptibility susceptibility
Measures to improve the defense mechanism of the host by using proper Chemoprophylaxis, immune-prophylaxis or Vaccination.
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a) Chemoprophylaxisa) Chemoprophylaxis: Is the administration of chemicals : Is the administration of chemicals
including antibiotics, to prevent the development of an including antibiotics, to prevent the development of an
infection or the progression of an infection to active manifest infection or the progression of an infection to active manifest
disease.disease. e.g. e.g.
1.1. IsoniazidIsoniazid (INH) for contacts of (INH) for contacts of tuberculoustuberculous patients. patients.
2.2. RifampicinRifampicin for contacts of for contacts of meningeococcalmeningeococcal meningitis.meningitis.
3.3. ChloroquineChloroquine for travelers to for travelers to malariamalaria areas. areas.
b) Ib) Immune-prophylaxis (Passive immunization): Passive immunization): anti-diphtheritic anti-diphtheritic
serum.serum.
VaccinationVaccination
Vaccines protect against disease by Vaccines protect against disease by inducing immunity. They are widely and inducing immunity. They are widely and routinely administered around the world. routinely administered around the world.
Expanded Programme on Immunization Expanded Programme on Immunization (EPI) was initiated in 1974(EPI) was initiated in 1974
It is estimated that over 2.5 million deaths It is estimated that over 2.5 million deaths are prevented through vaccination every are prevented through vaccination every year.year.
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Criteria for effective VaccinesCriteria for effective Vaccines
Should meet the quality requirements of WHO policy Should meet the quality requirements of WHO policy on vaccine quality. on vaccine quality.
Be safe and have a significant impact in all target Be safe and have a significant impact in all target populations. populations.
Be easily adapted to the schedules and timing of the Be easily adapted to the schedules and timing of the national childhood immunization service. national childhood immunization service.
Not interfere significantly with the immune response Not interfere significantly with the immune response to other vaccines given simultaneously. to other vaccines given simultaneously.
Be formulated to meet common technical limitations, Be formulated to meet common technical limitations, e.g. in terms of refrigeration and storage capacity.e.g. in terms of refrigeration and storage capacity.
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Benefits of immunizationBenefits of immunization
Immunization is a proven tool for controlling Immunization is a proven tool for controlling and even eradicating infectious diseases. and even eradicating infectious diseases.
Through vaccination Smallpox was Through vaccination Smallpox was eradicated eradicated
Poliomyelitis has been eliminated from Poliomyelitis has been eliminated from most countries in the world. most countries in the world.
Poliomyelitis infections have fallen by Poliomyelitis infections have fallen by 99%, and some five million people have 99%, and some five million people have escaped paralysis. escaped paralysis.
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Between 2000 and 2007, measles Between 2000 and 2007, measles deaths dropped worldwide by deaths dropped worldwide by over 74%, and some regions have over 74%, and some regions have set a target of eliminating the set a target of eliminating the disease.disease.
Maternal and neonatal tetanus Maternal and neonatal tetanus has been eliminated in 12 of the has been eliminated in 12 of the 58 high-risk countries.58 high-risk countries.
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Benefits of immunizationBenefits of immunization
Vaccine Type Route
BCG Live attenuated Bacteria Intradermal
DTPD&T = Toxoids
P = inactivated bacteriaIntramuscular
Hepatitis B(HBV) Inactivated viral antigen Intramuscular
Haemophilus
Influenza b(Hib) Polysaccharide
Intramuscular
MMR Live attenuated viruses Subcutaneous
OPV Live attenuated virusOral
IPV Inactivated virusIntramuscular
BCG = BCG = Bacillus Calmette – Guerin vaccine (tuberculosis).Bacillus Calmette – Guerin vaccine (tuberculosis).DPT = DPT = Diphtheria, pertussis and tetanus vaccine.Diphtheria, pertussis and tetanus vaccine.MMR =MMR =Live attenuated measles, mumps and rubella viruses in a combined vaccine.Live attenuated measles, mumps and rubella viruses in a combined vaccine.IPV =IPV = Inactivated Poliovirus vaccine Inactivated Poliovirus vaccineOPV =OPV = Oral attenuated poliovirus vaccine Oral attenuated poliovirus vaccine
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The EndThe End
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Thank YouWebsite http://faculty.ksu.edu.sa/73234/default.aspx