disease prevention and control franciosa l.g. gavino, m.d. department of preventive and community...
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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
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
NATURAL HISTORY OF DISEASE
> 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
NATURAL HISTORY OF DISEASE
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
LEVELS OF PREVENTION
I. PRIMARY PREVENTION A. Health Promotion 1. Exercise, Rest, Relaxation 2. Nutrition 3. Personal Hygiene 4. Healthy Social and Sexual Life
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
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).
ENVIRONMENTAL SAFETY
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
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
ENVIRONMENTAL SAFETY
PERIODIC EXAMINATION OF WATER1. Bacteriological – every 6 months2. Chemical – every 12 months3. If with suspected radioactive
contamination – every 12 months
ENVIRONMENTAL SAFETY
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
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)
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
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.
ENVIRONMENTAL SAFETY
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
ENVIRONMENTAL SAFETY
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
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.
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 .
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
ENVIRONMENTAL SAFETY
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
ENVIRONMENTAL SAFETY
REFUSE DISPOSAL1. Open dumping2. Sanitary filling or controlled tipping3. Burning4. Composting
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
ENVIRONMENTAL SAFETY
CONSERVANCY METHODBucket-type latrine (Pail Privy)> manual collection and removal of human
excreta to the disposal point (nightsoil depot)
TRENCHINGCOMPOSTINGINCINERATIONEMPTYING INTO SEWERS
ENVIRONMENTAL SAFETY
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
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.
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
ENVIRONMENTAL SAFETY
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
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
ENVIRONMENTAL SAFETY
ENVIRONMENTAL SAFETY
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.
ENVIRONMENTAL SAFETY
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)
ENVIRONMENTAL SAFETY
5. COMPOSTING TOILET> urine and feces are separated> vault constructed above ground so
as to make collection of waste easier
ENVIRONMENTAL SAFETY
SEWAGE TREATMENT PROCESS:Separation of large solids
Sedimentation and anaerobic
Decomposition
Aerobic decomposition
Disinfection
ENVIRONMENTAL SAFETY
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
LEVELS OF PREVENTION
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
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
Thank you and good luck!