9/10/2010Dr. Salwa Tayel1

9/10/2010Dr. Salwa Tayel2 Associate Professor Family and Community Medicine Department King Saud University By General Principles of Prevention of Infectious Disease Infectious Disease

9/10/2010Dr. Salwa Tayel3 Learning Objectives: Identify the levels of prevention of infectious diseases and tools for intervention at each level. Describe the specific control measures for infectious diseases

9/10/2010Dr. Salwa Tayel4 Levels of prevention: 1.Primary prevention. 2.Secondary prevention. 3.Tertiary prevention.

9/10/2010Dr. Salwa Tayel5 Levels of Prevention Primary prevention => pre-event phase Secondary prevention => event phase Tertiary prevention => post-event phase Promotion (1ry prevention) Early detection & care (2ry prevention) Rehabilitation (3ry prevention)

9/10/2010 Dr. Salwa Tayel 6 Tertiary Prevention Primary Prevention Secondary Prevention

9/10/2010 Dr. Salwa Tayel 7 1Nil, except observation 2Review 3Opportunistic or population screening 4Screening or health education 5Protection of current status (Health Promotion) 1Diseased, diagnosed & controlled 2Diagnosed, uncontrolled 3Undiagnosed disease 4Risk factors for disease 5Free of risk factors The pyramid and iceberg of disease Intervention

9/10/2010Dr. Salwa Tayel8 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

9/10/2010Dr. Salwa Tayel9 A. Health promotion It is intended to improve the general health of the individual and community, through: 1. Adequate nutrition 2. Environmental sanitation 3. Personal hygiene 4. Health education 5. Socio-economic development 6. Genetic counseling … etc.

9/10/2010Dr. Salwa Tayel10 B. Specific Protection is achieved through: B. Specific Protection is achieved through: 1. Specific immunizations. 2.Chemoprophylaxis.

9/10/2010Dr. Salwa Tayel11 II- Secondary Prevention: II- Secondary Prevention: Actions that detect and treat disease at an early stage thus hinder the progress of a disease and prevent complications. i.e. intervention in early pathogenesis phase. The methods (tools) employed for early diagnosis are: 1. Screening for sub-clinical disease, either in screening surveys or in periodic medical examinations. 2. Case finding (individual and community).

9/10/2010Dr. Salwa Tayel12 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

9/10/2010Dr. Salwa Tayel13 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.

9/10/2010Dr. Salwa Tayel14 Rehabilitation comprises: 1.M edical rehabilitation – restoration of function or physical loss. 2.E ducational rehabilitation change of educational methods. 3.V ocational (occupational) rehabilitation – restoration of the capacity to earn a livelihood. 4.S ocial rehabilitation: restoration of family and social relationships. 5.P sychological rehabilitation: restoration of personal confidence.

9/10/2010Dr. Salwa Tayel15 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.

9/10/2010Dr. Salwa Tayel16SummaryE

9/10/2010Dr. Salwa Tayel17 Factors affecting choice of appropriate prevention and control measures: It depends upon the knowledge of: causation and dynamics of disease transmission, causation and dynamics of disease transmission, identification of risk factors and high risk groups identification of risk factors and high risk groups availability of tools of intervention (vaccine chemoprophylaxis or treatment,..) 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 Measures

9/10/2010Dr. Salwa Tayel18 Environment The cycle of infection has three major links:

9/10/2010Dr. Salwa Tayel 19 Environment Source - Disinfection -Sterilization Reservoir -Isolation -Treatment - Detection of carriers - Control of animals -Immunization -Chemoprophylaxis -Vector control. -Snail control. -Environmental sanitation

9/10/2010 Dr. Salwa Tayel 20 The best control measures to the first link, the agent are: To control the reservoir or source of infection to reduce the quantity of the agent.To control the reservoir or source of infection to reduce the quantity of the agent. The best control measures to the second link, MOT are: to interrupt the transmission of the source of infection to the susceptible host.to interrupt the transmission of the source of infection to the susceptible host. Examples are: Vector control, Snail control and improvement of Environmental sanitation.Examples are: Vector control, Snail control and improvement of Environmental sanitation. The best means of control to the third link (the host) are: to improve the defense mechanism of the host by using proper Chemoprophylaxis, immune-prophylaxis or Vaccination.to improve the defense mechanism of the host by using proper Chemoprophylaxis, immune-prophylaxis or Vaccination. Interventions to break the cycle of infection

9/10/2010Dr. Salwa Tayel21 Measures applied to cases Case finding (early diagnosis) Reporting Isolation Treatment (Chemotherapy) Disinfection of contaminated objects with appropriate “enteric precautions,” “respiratory precautions,” “universal precautions” Measures Directed to the Reservoir

9/10/2010Dr. Salwa Tayel22 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,in-apparent infection may be large proportion, maximal infectivity may occur during the early stages,maximal infectivity may occur during the early stages, carriers of infective agents may go undetected, orcarriers of infective agents may go undetected, or many mild cases of infection spread disease without being detectedmany mild cases of infection spread disease without being detected

9/10/2010Dr. Salwa Tayel23 Quarantine means separation in a specific place (quarantine) of apparently well persons or animals who have been exposed (contact) to a case of infectious disease. Quarantine is for the duration of the maximal incubation period of the disease counted from date of last exposure. This measure is applied for contacts of pneumonic plague and pneumonic anthrax.

9/10/2010Dr. Salwa Tayel24 Measures applied to carriers 1.Detection of carriers: It is important in certain diseases e.g. Enteric fever. 2.Exclusion from work: in certain occupations for example; –food handler (e.g. Typhoid carrier) or a –teacher (e.g. Diphtheria carrier). 3.Treatment for the carrier state.

9/10/2010Dr. Salwa Tayel25 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).

9/10/2010Dr. Salwa Tayel26 Measures that Interrupt the Transmission of Organisms Environmental Measures to prevent transmission of diseases by Ingestion of contaminated vehicles include: Purification of water Pasteurization of milk Inspection of food handlers & public food places Improvements in housing conditions, and Educating people in proper personal hygiene and hand washing.

9/10/2010Dr. Salwa Tayel27 Measures Reduce transmission of respiratory infection: Proper ventilation of public places & classrooms, Minimize close person to person contact (reduce overcrowding) Control of dust.

9/10/2010Dr. Salwa Tayel28 Measures to reduce transmission of arthropod borne infections Measures to control (reduce or eradicate) the vector include: biological mechanical and chemical methods

9/10/2010Dr. Salwa Tayel29 Measures that reduce host susceptibility Non-specific measures: Measures to increase general resistance (Health education, Personal hygiene, Good standard of nutrition,..) Specific measures: Use of specific passive and active immunization and chemoprophylaxis.

9/10/2010Dr. Salwa Tayel30 a) Active immunization as in case of measles. b) Passive immunization as in case of diphtheria. c) Chemoprophylaxis: Is the administration of chemicals including antibiotics, to prevent the development of an infection or the progression of an infection to active manifest disease.

9/10/2010Dr. Salwa Tayel31 Examples of chemoprophylaxis: 1.Isoniazid (INH) for contacts of tuberculous patients. 2.Sulphadiazine or Rifampicin for contacts of meningeococcal meningitis. 3.Erythromycin or penicillin for unimmunized contacts of a diphtheria case. 4.Tetracycline for contacts of cholera and pneumonic plague. 5.Chloroquine for travelers to malaria areas.

9/10/2010Dr. Salwa Tayel32 The End Thank You Website