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DISEASE PREVENTION AND CONTROL FRANCIOSA L.G. GAVINO, M.D. Department of Preventive and Community Medicine.

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Presentation on theme: "DISEASE PREVENTION AND CONTROL FRANCIOSA L.G. GAVINO, M.D. Department of Preventive and Community Medicine."— Presentation transcript:

1 DISEASE PREVENTION AND CONTROL FRANCIOSA L.G. GAVINO, M.D. Department of Preventive and Community Medicine

2 NATURAL HISTORY OF DISEASE PRE-PATHOGENESIS > preliminary interaction of potential infectious agent and the host in the environment > may produce a disease-provoking stimulus in the host

3 NATURAL HISTORY OF DISEASE PATHOGENESIS   begins with the disease-provoking stimulus, which causes defect and disability or even death A. Incubation period > cellular changes are present but host does not present with any signs or symptoms

4 NATURAL HISTORY OF DISEASE > duration between the entry of the infective organism and the first manifestation of disease B. Clinical Horizon 1. Prodrome – mild, non-specific signs and symptoms 2. Frank Illness – signs and symptoms are more specific

5 NATURAL HISTORY OF DISEASE 3. Chronic Stage – disease condition is prolonged C. Recovery or Death


7 LEVELS OF PREVENTION I. PRIMARY PREVENTION > applied during the pre-pathogenesis stage > preventive measures: 1. increasing host resistance 2. destruction of the agent in the environment 3. destruction of the agent in the reservoir of infection 4. avoidance of exposure

8 LEVELS OF PREVENTION I. PRIMARY PREVENTION A. Health Promotion 1. Exercise, Rest, Relaxation 2. Nutrition 3. Personal Hygiene 4. Healthy Social and Sexual Life

9 LEVELS OF PREVENTION I. PRIMARY PREVENTION B. Specific Disease Protection 1. Prophylaxis a. Immunization b. Chemoprophylaxis c. Mechanical Prophylaxis 2. Environmental Sanitation a. Water sanitation b. Proper waste disposal c. Insect, vector and rodent control 3. Occupational Health

10 IMMUNIZATION > provision of an individual with antibodies capable of destroying or inactivating a disease-producing agent OR neutralizing its toxins A. ACTIVE IMMUNITY > protection produced by the host’s own immune system or through vaccination > usually permanent

11 IMMUNIZATION B. PASSIVE IMMUNITY > antibody transferred from another human or animal > usually temporary > transplacental immunity: most important source of immunity in infancy HERD IMMUNITY > resistance of a group or community to an infectious agent based on the high proportion of members of the group who are resistant

12 IMMUNIZATION ANTIGEN: a live or inactivated substance capable of producing an immune response ANTIBODY: protein molecules produced by B- lymphocytes to help eliminate an antigen CLASSIFICATION OF VACCINES A. Live Attenuated Vaccine > weakened form of the virus or bacteria > immune response similar to natural infection > usually effective with one dose

13 IMMUNIZATION CLASSIFICATION OF VACCINES A. Live Attenuated Vaccine > unstable; may interfere with circulating antibodies > Ex. measles, mumps, rubella (MMR), varicella, Yellow fever, oral polio, influenza nasal spray, BCG, oral typhoid

14 IMMUNIZATION CLASSIFICATION OF VACCINES B. Inactivated Vaccine > not live and cannot replicate > not as effective as live vaccines > requires 3 – 5 doses > minimal interference from circulating antibodies > antibody titers fall over time

15 IMMUNIZATION CLASSIFICATION OF VACCINES B. Inactivated Vaccine 1. Whole cell: Viral: influenza, polio, rabies, hepatitis A Bacterial: pertussis, typhoid, cholera 2. Fractional: Subunit: hepatitis B, influenza, acellular pertussis, typhoid Vi Toxoid: diphtheria, tetanus

16 IMMUNIZATION CLASSIFICATION OF VACCINES B. Inactivated Vaccine 3. Polysaccharide: Conjugate: H. influenza type B, pneumococcal Pure: pneumococcal, H. influenza type B, meningococcal 4. Recombinant: Genetically engineered: hepatitis B, typhoid (TY 21 a)

17 IMMUNIZATION TIMING AND SPACING OF VACCINES 1. Interval between a live vaccine and antibody- containing blood products a. if given together, the antibody may interfere with replication of the vaccine b. if the live vaccine is given FIRST, wait for AT LEAST 2 WEEKS before giving the antibody c. if the interval between the vaccine and the antibody is less than 2 weeks, the recipient must be tested for vaccine titer levels or the vaccine dose should be repeated

18 IMMUNIZATION TIMING AND SPACING OF VACCINES 2. There is no contraindication to simultaneous vaccine administration EXCEPT for cholera and Yellow fever. 3. Individual vaccines should not be mixed in the same syringe unless indicated 4. Spacing of vaccine combinations not given simultaneously: if 2 live injected, 4 weeks, all others, none

19 IMMUNIZATION 5. If the spacing between 2 live vaccines < 28 days, the vaccine given second should be repeated, except for Yellow fever given < 28 days after measles 6. Increasing the interval between multi- dose vaccines does not diminish the vaccine’s effectiveness; decreasing the interval may interfere with antibody response and protection 7. It is NOT necessary to restart the series of any vaccine due to extended intervals between doses

20 IMMUNIZATION ADVERSE REACTIONS A. Local > pain, swelling, redness at site of injection > common with inactivated vaccines > usually mild or self-limited B. Systemic > fever, malaise, headache > allergic reaction

21 IMMUNIZATION PERMANENT CONTRAINDICATIONS 1. Severe allergy to a prior dose or to a vaccine component 2. Encephalopathy following pertussis vaccine IMMUNOSUPRESSION: > live vaccines can be given after chemotherapy has been discontinued after 3 months > patients receiving large doses of corticosteroids should not receive live vaccines ( > 20 mg of prednisone/day) > NOT CONTRAINDICATED if steroids are given via aerosols, topical, alternate day, or short courses

22 IMMUNIZATION INVALID CONTRAINDICATIONS 1. Mild illness: low-grade fever, URTI 2. Disease exposure or convalescence 3. Antibiotic therapy 4. Breastfeeding 5. Premature birth 6. Need for TB skin testing 7. Mild diarrhea

23 IMMUNIZATION CONDITIONLIVE VACCINEINACTIVATED VACCINE Allergy to vaccine component CC Encephalopathy-C PregnancyCV ImmunosupressionCV Severe IllnessPP Recent blood product PV

24 ENVIRONMENTAL SAFETY WATER SANITATION   single most important preventive measure against diseases.   Filtration of water reduces mortality not only of water-borne diseases but mortality from other diseases (Mills-Reincke Phenomenon).

25 ENVIRONMENTAL SAFETY LABORATORY ANALYSIS FOR WATER 1. Physical – turbidity,color,taste, and odor 2. Chemical – pH, alkalinity, total solid, chlorides, hardness and iron 3. Bacteriological – the most important single test; presence of coliform indicates fecal contamination * Eijkman’s test –differentiate E. coli from non- fecal coliforms

26 ENVIRONMENTAL SAFETY LABORATORY ANALYSIS FOR WATER 4. Biological – microorganisms responsible for bad odor and taste 5. Radiological – done only for water receiving wastes from nuclear installation or radioisotope lab

27 ENVIRONMENTAL SAFETY PERIODIC EXAMINATION OF WATER 1. 1. Bacteriological – every 6 months 2. 2. Chemical – every 12 months 3. 3. If with suspected radioactive contamination – every 12 months

28 ENVIRONMENTAL SAFETY CHEMICAL STANDARDS SET BY THE WHO 1. Toxic substances: lead, selenium, arsenic cyanide, and mercury 2. Substances that may affect health Fluorine (0.5-0.8mg/l) Nitrates - methHgbnemia in infants Polynuclear aromatic hydrocarbons (PAH) - carcinogenic

29 ENVIRONMENTAL SAFETY 3. Substances that may affect water acceptability (due to changes in color, odor, etc.) Iron, calcium, copper, zinc Bicarbonates and other salts cause hardness of water (preferably moderately hard; too soft - insipid in taste)

30 ENVIRONMENTAL SAFETY WHO CRITERIA FOR SAFETY OF LARGE WATER SUPPLIES > No sample…>3 coliforms per 100 ml > No two consecutive samples…coliform organisms in 100 ml > Not more than 5% samples in 1 year

31 ENVIRONMENTAL SAFETY WATER PURIFICATION PROCESS 1. AERATION – tastes and odors diminished; Fe and Mg made insoluble;CO2 removed, O2 added 2. COAGULATION – Turbidity, color, iron, manganese, and organisms brought together into large flocs that settle readily; natural coagulation by agglomeration of soluble and colloidal material; artificial coagulation by addition of chemicals e.g. aluminum sulfate.

32 ENVIRONMENTAL SAFETY WATER PURIFICATION PROCESS 3. SEDIMENTATION – turbidity and bacteria reduced; coagulated substances removed. 4. FILTRATION – turbidity, iron, manganese and bacterial removed; color, tastes and odors reduced 5. SOFTENING

33 ENVIRONMENTAL SAFETY WATER PURIFICATION PROCESS 6. DISINFECTION (CHLORINATION) – destruction of organisms * CHLORINATION   Chlorine is cheap and reliable   Very effective disinfectant: oxidant   Aids in coagulation, controls odor and taste   Spares spores, ova and viruses of polio and viral hepatitis   Residual chlorine: 0.1 ppm

34 ENVIRONMENTAL SAFETY MEASURES TO PREVENT WATER CONTAMINATION 1. Washing clothes or bathing radius of 25 meters from source of drinking water is prohibited. 2. No artesians, deep or shallow wells, shall be constructed within 25 meters from any source of pollution.

35 ENVIRONMENTAL SAFETY MEASURES TO PREVENT WATER CONTAMINATION 3. No burial ground shall be located within 50 meters from either side of a river or within 50 meters from any source of water supply. 4. No radioactive sources or materials shall be stored within a radius of 25 meters… adequately and safely enclosed by proper shielding.

36 ENVIRONMENTAL SAFETY MEASURES TO PREVENT WATER CONTAMINATION 5. The installation of booster pump to boost water direct from the water distribution line of a water supply system where low-water pressure prevails is prohibited. * WELLS: major water supply in rural areas; must be located at a distance of 100ft and higher than a source of pollution; should be constructed in areas with sandy loam and not clay or limestone

37 ENVIRONMENTAL SAFETY WASTE DISPOSAL 3 TYPES: 1. Refuse or solid waste- garbage, rubbish, ash 2. Excreta or nightsoil – feces 3. Sullage - called waste water or slop water and comprises all liquid wastes including industrial waste; excludes nightsoil - sullage water + nightsoil = SEWAGE *Lecheate – highly toxic substance formed when solid wastes are dumped together unsorted to form diverse chemical reactions; contaminates groundwater

38 ENVIRONMENTAL SAFETY REFUSE DISPOSAL 1. Open dumping 2. Sanitary filling or controlled tipping 3. Burning 4. Composting

39 ENVIRONMENTAL SAFETY EXCRETA DISPOSAL > Sanitation barrier between feces and man > Two types: 1. Non sewage a. Conservancy methods- manual handling b. Sanitary latrines-disposed of on the spot 2. Sewage method

40 ENVIRONMENTAL SAFETY CONSERVANCY METHOD Bucket-type latrine (Pail Privy) > manual collection and removal of human excreta to the disposal point (nightsoil depot) TRENCHING COMPOSTING INCINERATION EMPTYING INTO SEWERS

41 ENVIRONMENTAL SAFETY SANITARY LATRINES 1. Acceptable to people 2. Simple in construction and use 3. Cheap 4. Not involve manual handling of excreta 5. Small amount of water 6. Not lead to environmental pollution

42 ENVIRONMENTAL SAFETY SEPTIC PRIVY- fecal matter is placed in a septic tank containing water and connected to a drain field but which is not served by a water supply under pressure. BOX AND CAN PRIVY - fecal matter is deposited in a can bucket which is removed for emptying and cleaning.

43 ENVIRONMENTAL SAFETY CONCRETE VAULT PRIVY - A pit privy with the pit lined with concrete in such manner as to make it water tight. CHEMICAL PRIVY - A privy where fecal matter is deposited into a tank containing a caustic chemical solution to prevent septic action while the organic matter is decomposed

44 ENVIRONMENTAL SAFETY SANITARY LATRINES 1. PIT LATRINE a. Shallow pit latrine-1 meter deep and 0.5-1 meter wide with a wooden squatting plate b. Bore hole latrine-3—40 cm diameter pit and 6 meters deep (anaerobic digestion) c. Dug well latrine-0.75 m. diameter pit and 3-3.5m deep; at least 10 meters away from a source of drinking water

45 ENVIRONMENTAL SAFETY PIT LATRINES: Should have a minimum capacity of 50 cu ft for the average family. Bottom of pit should be at least 2 ft above the ground water to prevent ground water pollution


47 2. HANDFLUSH WATER SEAL LATRINE (POUR-FLUSH LATRINE OR PF LATRINE) > for villages with no underground drainage; needs 1-2 liters of water per user 3. AQUA PRIVY > sometimes called a septic toilet; the water tight tank is usually below the seat.

48 ENVIRONMENTAL SAFETY 4. SEPTIC TANK > septic or anaerobic bacterial activity that occurs 2 stages of purification: anaerobic digestion within the tank and aerobic oxidation outside Adv: less bulk and smell; destruction of pathogenic bacteria (EXCEPT: amoebic cysts and ova or roundworms)

49 ENVIRONMENTAL SAFETY 5. COMPOSTING TOILET > urine and feces are separated > vault constructed above ground so as to make collection of waste easier

50 ENVIRONMENTAL SAFETY SEWAGE TREATMENT PROCESS: Separation of large solids Sedimentation and anaerobic Decomposition Aerobic decomposition Disinfection

51 ENVIRONMENTAL SAFETY SEWAGE TERMS: Effluent- liquid flowing out of a tank or sewage works Scum-light solids float in the septic tank Sludge-the sediment settling in the bottom * Cleaning every 3-5 years should be done to avoid build-up

52 LEVELS OF PREVENTION II. SECONDARY PREVENTION A. Early Diagnosis and Prompt Treatment 1. To prevent spread of infection 2. To arrest the disease process 3. To prevent prolonged disability

53 LEVELS OF PREVENTION III. TERTIARY PREVENTION A. Disability Limitation 1. Complete therapy 2. Hospitalization, as needed 3. Home nursing services, as needed B. Rehabilitation 1. Hospitalization and work therapy 2. Public education to utilize the rehabilitated 3. Selective placement

54 Thank you and good luck!

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