disease prevention and control franciosa l.g. gavino, m.d. department of preventive and community...

DISEASE PREVENTION AND CONTROL

FRANCIOSA L.G. GAVINO, M.D.

Department of Preventive and Community Medicine

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


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


> duration between the entry of the infective organism and the first manifestation of disease

B. Clinical Horizon1. Prodrome – mild, non-specific signs and symptoms2. Frank Illness – signs and symptoms are more specific


3. Chronic Stage – disease condition is prolonged

C. Recovery or Death

AGENT

Recovery/Death

Chronic Illness

Frank Illness Prodrome

CLINICAL HORIZONHOST

ENVIRONMENT

INCUBATION PERIOD

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


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


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

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

IMMUNIZATIONB. PASSIVE IMMUNITY > antibody transferred from another

human or animal > usually temporary > transplacental immunity: most important

source of immunity in infancyHERD IMMUNITY> resistance of a group or community to an

infectious agent based on the high proportion of members of the group who are resistant

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 VACCINESA. Live Attenuated Vaccine > weakened form of the virus or bacteria > immune response similar to natural infection > usually effective with one dose

IMMUNIZATION

CLASSIFICATION OF VACCINESA. 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

IMMUNIZATION

CLASSIFICATION OF VACCINESB. 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

IMMUNIZATION

CLASSIFICATION OF VACCINESB. 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

IMMUNIZATIONCLASSIFICATION OF VACCINESB. 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)

IMMUNIZATION

TIMING AND SPACING OF VACCINES1. 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

IMMUNIZATION

TIMING AND SPACING OF VACCINES2. 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

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

IMMUNIZATIONADVERSE REACTIONSA. Local > pain, swelling, redness at site of

injection > common with inactivated vaccines > usually mild or self-limitedB. Systemic > fever, malaise, headache > allergic reaction

IMMUNIZATIONPERMANENT CONTRAINDICATIONS1. Severe allergy to a prior dose or to a vaccine

component2. 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

IMMUNIZATION

INVALID CONTRAINDICATIONS1. Mild illness: low-grade fever, URTI2. Disease exposure or convalescence3. Antibiotic therapy4. Breastfeeding5. Premature birth6. Need for TB skin testing7. Mild diarrhea

IMMUNIZATION

CONDITION LIVE VACCINE INACTIVATED VACCINE

Allergy to vaccine component

C C

Encephalopathy - C

Pregnancy C V

Immunosupression C V

Severe Illness P P

Recent blood product

P V

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).


LABORATORY ANALYSIS FOR WATER1. Physical – turbidity,color,taste, and odor2. Chemical – pH, alkalinity, total solid,

chlorides, hardness and iron3. Bacteriological – the most important

single test; presence of coliform indicates fecal contamination

* Eijkman’s test –differentiate E. coli from non-fecal coliforms


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


PERIODIC EXAMINATION OF WATER1. Bacteriological – every 6 months2. Chemical – every 12 months3. If with suspected radioactive

contamination – every 12 months


CHEMICAL STANDARDS SET BY THE WHO1. Toxic substances: lead, selenium,

arsenic cyanide, and mercury 2. Substances that may affect health

Fluorine (0.5-0.8mg/l)Nitrates - methHgbnemia in infantsPolynuclear aromatic hydrocarbons

(PAH) - carcinogenic


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)


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

ENVIRONMENTAL SAFETYWATER PURIFICATION PROCESS1. 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.


WATER PURIFICATION PROCESS3. SEDIMENTATION – turbidity and bacteria

reduced; coagulated substances removed.

4. FILTRATION – turbidity, iron, manganese and bacterial removed; color, tastes and odors reduced

5. SOFTENING


WATER PURIFICATION PROCESS6. 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


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.



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 .



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


WASTE DISPOSAL3 TYPES:1. Refuse or solid waste- garbage, rubbish, ash2. Excreta or nightsoil – feces3. 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


REFUSE DISPOSAL1. Open dumping2. Sanitary filling or controlled tipping3. Burning4. Composting


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


CONSERVANCY METHODBucket-type latrine (Pail Privy)> manual collection and removal of human

excreta to the disposal point (nightsoil depot)

TRENCHINGCOMPOSTINGINCINERATIONEMPTYING INTO SEWERS


SANITARY LATRINES1. Acceptable to people2. Simple in construction and use3. Cheap4. Not involve manual handling of excreta5. Small amount of water6. Not lead to environmental pollution


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.


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


SANITARY LATRINES1. PIT LATRINEa. 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


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


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; thewater tight tank is usually below the seat.


4. SEPTIC TANK> septic or anaerobic bacterial activity

that occurs2 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)


5. COMPOSTING TOILET> urine and feces are separated> vault constructed above ground so

as to make collection of waste easier


SEWAGE TREATMENT PROCESS:Separation of large solids

Sedimentation and anaerobic

Decomposition

Aerobic decomposition

Disinfection


SEWAGE TERMS:Effluent- liquid flowing out of a tank or

sewage worksScum-light solids float in the septic tankSludge-the sediment settling in the bottom

* Cleaning every 3-5 years should be done to avoid build-up


II. SECONDARY PREVENTION A. Early Diagnosis and Prompt

Treatment 1. To prevent spread of infection

2. To arrest the disease process3. To prevent prolonged disability


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

Thank you and good luck!

disease prevention and control franciosa l.g. gavino, m.d. department of preventive and community...

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