disease PREVENTION and control

1. disease PREVENTION and control Dr Santosh K Yatnatti Assistant professor Department of Community Medicine

3. Dynamics of disease tansmission SOURCE OR RESERVOIR MODES OF TRANSMISSION SUSCEPTIBLE HOST

4. Disease control • Disease control involves all measures designed to prevent or reduce as much as possible the incidence, prevalence and consequences of disease • Broadly the steps includes – • Acting on reservoir or source of infection • Acting on routes of transmission • Acting on susceptible host

5. Controlling the reservoir • Disease control in humans include: • Early Diagnosis • Notification • Isolation • Treatment • Quarantine • Surveillance • Disinfection

6. Early diagnosis • This is the cornerstone on which the edifice of disease control is built • Early diagnosis is need for: • The treatment of patients • For epidemiological investigations • To study the time, place & person distribution • For the institution of prevention & control measures

7. Notification • Detected infectious disease Notified to local health authority • An important source of epidemiological information which helps in early detection of disease outbreaks • Includes infectious as well as non communicable diseases as – ie:Cancer, Congenital defects, etc

8. Notifiable diseases under the International Health Regulations (IHR) by the National health authority to the WHO • Diseases subjected to international health regulations(1969),3rd annotated edition(1983): Cholera, Plague, Yellow fever • Diseases under surveillance by WHO : Louse-borne typhus fever, Paralytic polio, Malaria, Viral influenza, etc… • Health administrations should notify the above to WHO Geneva

9. Epidemiological investigations • Called for when there is a disease outbreak. • Includes the • Identification of the source of infection • Factors influencing it’s spread in the community (Geographical situation, Climatic condition, Social, Cultural & behavioural patterns; Character of the agent, reservoir, the vectors & vehicles and the susceptible host population)

10. Isolation • Definition • Separation for the period of communicability of infected persons or animals from others in such places under such conditions as to prevent or limit the direct or indirect transmission of the infectious agent from those infected to those who are susceptible, or who may spread the agent to others. • Goal • To protect the community by preventing transfer of infection from the reservoir to the possible susceptible • The duration of isolation is determined by the duration of communicability of the disease & the effect of chemotherapy on infectivity. • Today isolation is recommended only when the risk of transmission of the infection is exceptionally serious.

11. Treatment • Goal • To kill the infectious agent when it is still in the reservoir. • Advantage • Reduces the communicability of the disease • Cuts short the duration of the illness • Prevents development of secondary cases

12. Quarantine • Definition • Limitation of freedom of movement of such well persons or domestic animals exposed to communicable disease for a period of time not longer than the longest usual incubation period of the disease, in such a manner as to prevent effective contact with those not so exposed. • restriction on healthy contacts of infectious disease

13. Interruption of transmission • “ Breaking the chain of transmission ” • Blocking the routes of transmission imply an attack on environmental factors, that is, to bring about an adjusted equilibrium between host & environment through encouraging some ecological influences & inhibiting others. The susceptible host • Active immunization • Passive immunization • Combined active & passive immunization • Chemoprophylaxis • Non specific meassures

14. Active immunization • It is one of the most powerful & cost effective weapons of modern medicine. • It augments herd immunity • It reduces the risk for those individuals who have escaped vaccination \ who have not developed satisfactory protection. • Current trend is to combine immunizing agents into small packages & thus reduce the number of injections an individual must receive. • A good immunization schedule should be • Epidemiologically relevant • Immunologically effective • Operationally feasible • Socially acceptable

15. National immunization schedule

16. Passive immunization • Types of preparations available • Normal human immunoglobulin • Specific (hyperimmune) human immunoglobulin • Antisera or antitoxins • It’s a short term expedient, useful only when exposure to infection has just occurred or is imminent within the next few days • The duration of immunity induced is short & variable (1-6 weeks)

17. Combined Active & passive immunization • Passive immunization in conjugation with inactivated vaccine products, to provide both immediate ( temporary) passive immunity & slowly developing active immunity • Current recommendations • Immunoglobulin should not be given within 3 weeks before, or until 2 weeks after the administration of a live attenuated vaccine • Exceptions – Hepatitis B vaccine & Hepatitis immunoglobulin given simultaneously

18. Chemoprophylaxis • The protection from, or prevention of, disease • Can be achieved by causal prophylaxis or by clinical prophylaxis • Causal prophylaxis Complete prevention of infection by the early elimination of the invading or migrating causal agent • Clinical prophylaxis Prevention of clinical symptoms ; doesn’t necessarily mean elimination of symptoms

19. Non specific measures • Includes • Improvement in the quality of life • Legislative measures • Community involvement in disease surveillance, disease control & other public health activities • Changes in the behaviour & lifestyles of people

20. Surveillance • Definition • Continuous scrutiny of all aspects of occurrence & spread of disease that are pertinent to effective control • Object - prevention • Includes • Laboratory confirmation of presumptive diagnosis • Finding out the source of infection, routes of transmission, identification of all cases & susceptible contacts • Others at risk

21. Once control measures have been instituted, their effectiveness should be evaluated. If they were not successful, the reasons for faliure should be identified, the existing measures modified & evaluation continued May comprise of Individual surveillance Local population surveillance National population surveillance International surveillance

22. “To prevent” literally means “to keep something from happening”

23. The goal of medicine and Public health are to - • Promote Health • Preserve Health • Restore Health • Minimize suffering & distress

24. NATURAL HISTORY OF DISEASE

25. Levels of Prevention There are four levels of prevention Primordial prevention Primary prevention Secondary prevention Tertiary prevention

26. Primordial Prevention It is the prevention of emergence or development of risk factors in countries or population groups in which they have not yet appeared. It is a new concept and now receiving special attention in chronic diseases. It is mainly used for non communicable diseases It begins in childhood when lifestyles are formed. parents, teachers, peer groups are important in health education to children.

27. Primordial Prevention (Cont..) • Development of healthy life styles. These include regular balanced diet, Regular physical activity, avoidance of alcohol and smoking. Hypertension and obesity have their early origin in the childhood, because this is the time when life styles are formed. So efforts are directed towards discouraging children from adopting harmful lifestyles.

28. Primordial Prevention( Cont….) To promote age at marriage of girls to 18 and above. It prevents early pregnancies and its complications. Exclusive breast feeding up to 6 months of age. it contains all essential nutrients required for baby in adequate quantity and quality. These babies have less chances of diabetes, hypertension, lymphoma later in life compared to non breast fed babies.

29. Primary Prevention It is defined as “ action taken prior to the onset of disease, which removes the possibility that a disease will ever occur”. It is the intervention in the prepathogenesis phase of disease. The approaches are Population strategy High- risk strategy

30. Primary Prevention (cont..) Population Strategy It means it is directed towards the whole population irrespective of individual risk levels. Measures regarding prevention of CHD include a. Dietary changes b. Control of blood pressure c. Regular physical activity Even a small reduction in average blood pressure of a population would produce large reduction in cardiovascular disease.

31. Population Strategy (cont..) 2. In prevention of lung cancer primary prevention is most important, because 80-90 percent of all lung cancer in developing countries is due to smoking. Methods for controlling smoking epidemic are a. Public education about hazards of smoking through TV, paper, radio b. Legislative measures like health warning on cigarette packets like “smoking is injurious to health” banning of smoking in public places, taxation, sales restriction. c. Since smoking is world wide epidemic it requires coordinated approaches at local, national and international levels.

32. Population Strategy (cont..) 3. Primary prevention is very important in Control of oral cancer. This is by control of tobacco by public education and supported by legislative measures like banning or restriction of tobacco. 4. Universal immunization- protects the population against six killer diseases. 5. Protected water supply- protects the population against water borne diseases.

33. High-risk strategy It is directed towards individual at special risk, e.g. In Rheumatic heart disease the aim of primary prevention is to prevent first attack of rheumatic fever by identifying all patient with streptococcal throat infection and treating them. The high risk group are school children(5 to 15 years). They should be kept under surveillance for streptococcal pharyngitis.

34. High-risk strategy ( Cont….) • Pregnant Woman with bad obstetric history like recurrent abortion, intra uterine death. • Pregnant Woman with previous history of gastational diabetes. • Pregnant Woman with previous history of pregnancy induced hypertension.

35. Modes of Intervention The modes of intervention in the primary prevention are a. Health promotion b. Specific protection

36. Health Promotion “It is the processing of enabling people to increase control over, and to improve health.” It is not directed any particular disease, but it is intended to improve general health and well being of individual and community. The well – known interventions in this area are Health education Environmental modifications Nutritional interventions Lifestyle and behavioural changes

37. Health Promotion (cont..) 1. Health Education • This is one of the most cost effective intervention. • A large number of disease could be prevented with little or no medical intervention if people were adequately informed about them. • The target for health educational efforts may include general public, patients, health providers, community leaders and decision makers. 37

38. Health promotion (cont….) 2.Environmental modifications These includes provision of safe water, installation of sanitary latrines, control of insects and rodents etc.. 3.Nutritional interventions These comprise food distribution and nutrition improvement of vulnerable groups, child feeding programmes, food fortification, nutrition education, etc…

39. Specific Protection It comprises measures applicable to a particular disease or group of disease in order to interrupt the causes of disease before they involve man. To avoid diseases all together is the ideal habit, but this is possible only in a limited number of cases, e.g. Immunization- BCG vaccine for protection of TB, polio vaccine for protection of polio. Vitamin Aprophylaxis

40. Specific Protection ( cont….) • ORS to prevent dehydration in case of gastroenteritis. • Food fortification and enrichment- Enrichment of salt with iodine protects against iodine deficiency disorders. Enrichment of vitamin A to milk, dalda etc.. For success of food fortification we should select a food that is consumed in sufficient quantity by groups at risk. • Avoidance of carcinogens and treatment of precancerous lesions helps to protect against particular cancer.

41. Specific Protection ( cont….) • Use of condoms protects against pregnancy and also against sexually transmitted diseases like AIDS, syphilis and others. • Use of helmets while driving two wheeler. They reduce head injury by 30% and fatalities by 40%. Use of seat belts for front seaters in car reduces fatalities and non fatal injuries by approximately 50% each. • use of spectacles while wielding, use of helmets and gloves for construction workers.

42. Specific Protection ( cont….) Two doses of TT immunization at 16-20 weeks of pregnancy four weeks apart protects mother against puerperal and post abortive tetanus and baby against neonatal tetanus. Iron and folic acid prophylaxis in pregnancy to prevent anaemia Chemoprophylaxis – chloroquine is used for malaria prophylaxis. Tetracycline is used for cholera.

43. Secondary prevention • It is defined “ as action which halts the progress of a disease at its incipient stage and prevents complication.” • It is the action taken in the early pathogenesis phase. • It attempts arrest the disease process before the irreversible pathological changes have taken place.

44. Secondary prevention (cont..) • It may also protect others in the community from acquiring infection and thus provide at once secondary prevention for infected individual and primary prevention for the contacts • The specific intervention are early diagnosis and treatment

45. Early diagnosis and treatment It is defined as “the detection of disturbance of homeostatic and compensatory mechanism while biochemical, morphological and functional changes are still reversible.” For many diseases health promotion and specific protection is not applicable. Early diagnosis and treatment are main intervention of disease control in such cases.

46. Early diagnosis and treatment (cont.) The objectives are • To prevent spread to others if disease is communicable one • To cure or arrest the disease process in order to prevent the complications • To prevent prolonged disability

47. Early diagnosis and treatment (cont.) • Treatment of anaemia in pregnancy. • Urine examination for albumin and sugar in pregnancy to detect diabetes. • Testing for HIV and syphilis in pregnancy. • Screening baby for congenital abnormality like imperforate anus, cleft lip, tracheo-esophagial fistula.

48. Early diagnosis and treatment (cont.) Early detection and control of acute respiratory diseases and diarrheal diseases. Early detection and treatment of anaemia, rickets and nutritional blindness in children. Detection of hypertensive patients by screening and treatment started when B.P is greater than 140/90 mm of Hg. It prevents coronary heart disease.

49. Early diagnosis and treatment (cont.) Some disease like dental fluorosis early diagnosis and treatment is the only mode of intervention. It do not become manifest untill pathogenic process has run its course. However the detection of dental fluorosis may lead to treatment of water supply in the community and eventually prevention of disease in others.

50. Tertiary prevention • It is defined as “all measures available to reduce or limit the impairments and disabilities, minimize suffering caused by existing departure from good health and to promote the patient’s adjustments to irremediable conditions.” • It is action taken in the late pathogenesis phase • the interventions are Disability limitation and Rehabilitation