1. 25/12/2010Dr. Salwa Tayel1

2. 25/12/2010Dr. Salwa Tayel2 Associate Professor Family and Community Medicine Department King Saud University By General Principles of Prevention of Infectious Disease Infectious Disease

3. 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 25/12/2010Dr. Salwa Tayel3

4. 25/12/2010Dr. Salwa Tayel4 Levels of prevention: 1.Primary prevention. 2.Secondary prevention. 3.Tertiary prevention.

5. 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) 25/12/2010Dr. Salwa Tayel5

6. 25/12/2010 Dr. Salwa Tayel 6 Tertiary Prevention Primary Prevention Secondary Prevention

7. 25/12/2010Dr. Salwa Tayel7 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

8. A. 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. 25/12/2010Dr. Salwa Tayel8

9. B. Specific Protection is achieved through: 1. 1. Specific immunizations. 2. 2. Chemoprophylaxis. 25/12/2010Dr. Salwa Tayel9

10. 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). 25/12/2010Dr. Salwa Tayel10

11. 25/12/2010Dr. Salwa Tayel11 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

12. 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. 25/12/2010Dr. Salwa Tayel12

13. Rehabilitation comprises: 1. 1. Medical rehabilitation – restoration of function or physical loss. 2. 2. Educational rehabilitation change of educational methods. 3. 3. Vocational (occupational) rehabilitation – restoration of the capacity to earn a livelihood. 4. 4. Social rehabilitation: restoration of family and social relationships. 5. 5. Psychological rehabilitation: restoration of personal confidence. 25/12/2010Dr. Salwa Tayel13

14. 25/12/2010Dr. Salwa Tayel14 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.

15. 25/12/2010Dr. Salwa Tayel15SummaryE

16. 25/12/2010Dr. Salwa Tayel16 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 Measures

17. 25/12/2010Dr. Salwa Tayel17 Environment The cycle of infection has three major links:

18. 25/12/2010Dr. Salwa Tayel 18 Environment Source - Disinfection -Sterilization Reservoir -Isolation -Treatment - Detection of carriers - Control of animals -Immunization -Chemoprophylaxis -Vector control. -Snail control. -Environmental sanitation

19. 25/12/2010 Dr. Salwa Tayel 19 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

20. Measures Directed to the Reservoir Measures applied to cases Case finding (early diagnosis) Case finding (early diagnosis) Reporting Reporting Isolation Isolation Treatment (Chemotherapy) Treatment (Chemotherapy) Disinfection of contaminated objects with appropriate “enteric precautions,” “respiratory precautions,” “universal precautions” Disinfection of contaminated objects with appropriate “enteric precautions,” “respiratory precautions,” “universal precautions” 25/12/2010Dr. Salwa Tayel20

21. 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 detected 25/12/2010Dr. Salwa Tayel21

22. 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. 25/12/2010Dr. Salwa Tayel22

23. 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). 25/12/2010Dr. Salwa Tayel23

24. Measures to Interrupt the Transmission of Organisms Environmental Measures to prevent transmission of diseases by Ingestion of contaminated vehicles include: Purification of water Purification of water Pasteurization of milk Pasteurization of milk Inspection of food handlers & public food places Inspection of food handlers & public food places Improvements in housing conditions, and Improvements in housing conditions, and Educating people in proper personal hygiene and hand washing. Educating people in proper personal hygiene and hand washing. 25/12/2010Dr. Salwa Tayel24

25. Measures Reduce transmission of respiratory infection: Proper ventilation of public places & classrooms, Minimize close person to person contact (reduce overcrowding) Control of dust. 25/12/2010Dr. Salwa Tayel25

26. Measures to reduce transmission of arthropod borne infections Measures to control (reduce or eradicate) the vector include: biological biological mechanical and mechanical and chemical methods chemical methods 25/12/2010Dr. Salwa Tayel26

27. Measures to reduce host susceptibility Measures to improve the defense mechanism of the host by using proper Chemoprophylaxis, immune-prophylaxis or Vaccination. 25/12/2010Dr. Salwa Tayel27

28. 25/12/2010Dr. Salwa Tayel28 a) 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. e.g. 1.Isoniazid (INH) for contacts of tuberculous patients. 2.Rifampicin for contacts of meningeococcal meningitis. 3.Chloroquine for travelers to malaria areas. b) IPassive immunization): anti-diphtheritic serum. b) Immune-prophylaxis (Passive immunization): anti-diphtheritic serum.

29. Acquired immunity 25/12/2010 Dr. Salwa Tayel 29 Active immunity Natural (Post-infection) Artificial (Vaccination) Passive immunity Natural (trans-placental) Artificial (Immune-serum)

30. Vaccination Vaccines protect against disease by inducing immunity. They are widely and routinely administered around the world. Vaccines protect against disease by inducing immunity. They are widely and routinely administered around the world. Expanded Programme on Immunization (EPI) was initiated in 1974 Expanded Programme on Immunization (EPI) was initiated in 1974 It is estimated that over 2.5 million deaths are prevented through vaccination every year. It is estimated that over 2.5 million deaths are prevented through vaccination every year. 25/12/2010Dr. Salwa Tayel30

31. Criteria for effective Vaccines Should meet the quality requirements of WHO policy on vaccine quality. Should meet the quality requirements of WHO policy on vaccine quality. Be safe and have a significant impact in all target populations. Be safe and have a significant impact in all target populations. Be easily adapted to the schedules and timing of the national childhood immunization service. Be easily adapted to the schedules and timing of the national childhood immunization service. Not interfere significantly with the immune response to other vaccines given simultaneously. Not interfere significantly with the immune response to other vaccines given simultaneously. Be formulated to meet common technical limitations, e.g. in terms of refrigeration and storage capacity. Be formulated to meet common technical limitations, e.g. in terms of refrigeration and storage capacity. 25/12/2010Dr. Salwa Tayel31

32. Benefits of immunization Immunization is a proven tool for controlling and even eradicating infectious diseases. Through vaccination Smallpox was eradicated Through vaccination Smallpox was eradicated Poliomyelitis has been eliminated from most countries in the world. Poliomyelitis has been eliminated from most countries in the world. Poliomyelitis infections have fallen by 99%, and some five million people have escaped paralysis. Poliomyelitis infections have fallen by 99%, and some five million people have escaped paralysis. 25/12/2010Dr. Salwa Tayel32

33. Between 2000 and 2007, measles deaths dropped worldwide by over 74%, and some regions have set a target of eliminating the disease. Between 2000 and 2007, measles deaths dropped worldwide by over 74%, and some regions have set a target of eliminating the disease. Maternal and neonatal tetanus has been eliminated in 12 of the 58 high- risk countries. Maternal and neonatal tetanus has been eliminated in 12 of the 58 high- risk countries. 25/12/2010Dr. Salwa Tayel33 Benefits of immunization

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35. Vaccine Type Route BCG Live attenuated Bacteria Intradermal DTP D&T = Toxoids P = inactivated bacteria Intramuscular Hepatitis B(HBV)Inactivated viral antigen Intramuscular Haemophilus Influenza b(Hib) Polysaccharide Intramuscular MMRLive attenuated viruses Subcutaneous OPVLive attenuated virus Oral IPVInactivated virus Intramuscular BCG = Bacillus Calmette – Guerin vaccine (tuberculosis). DPT = Diphtheria, pertussis and tetanus vaccine. MMR =Live attenuated measles, mumps and rubella viruses in a combined vaccine. IPV = Inactivated Poliovirus vaccine OPV = Oral attenuated poliovirus vaccine 25/12/201035Dr. Salwa Tayel

36. The End 25/12/2010Dr. Salwa Tayel36 Thank You Website http://faculty.ksu.edu.sa/73234/default.aspx salwatayel@hotmail.com