COMMUNICABLE DISEASE

EPIDEMIOLOGY,

CONTROL &

PREVENTION

Community medicine is the art and science of

studying and assessment of community

health needs, organization and provision

of comprehensive health services and

evaluation and development of health

care programs with the objectives of

promotion of health and prevention of

disease.

SOURCES OF INFECTION* CASE OF DISEASE * CARRIER Incubatory carrier Convalescent carrier Chronic carrier In-apparent carrier* ANIMAL RESERVOIR (ZOONOSIS)* INANIMATE RESERVOIR (THE SOIL)

CHANNELS OF TRANSMISSION OF

INFECTION:

1- AIR-BORNE2- FOOD AND DRINK-BORNE3- ARTHROPOD-BORNE4- CONTACT TRANSMISSION

1. Water-washed dis. (Skin, eye)

2. Faecal-oral dise. (Viral, bact., parasitic)

3. Soil -mediated infections). (Tetanus, intestinal parasites)

4. Diseases of water contact. (Bilharzia, Guinea work)

5. Food-borne dis. (F.P., intestinal flukes)

6. Infectious skin rashes. (Chickenpox, smallpox)

7. Respiratory infections. (Viral, bacterial)

8. Dis. Transmitted via body fluids. (STD)

9. Insect-borne. (Viral parasitic)

10. Zoonoses. (Ectoparasite, domestic)

1-AIR-BORNE- Droplet infection (direct spread): CSM,Whooping cough

- Droplet nuclei (direct air-borne): Measles, Chickenpox

- Infected dust (indirect air-borne): TB, Diphtheria

1-AIR-BORNEInhalation Infections:* Respiratory Tract:Pulmonary Tuberculosis.Common coldInfluenzaSore-throatPneumonia

AIR-BORNE (Cont’d.)Other Specific Fevers:MeaslesWhooping coughDiphtheriaScarlet feverChicken poxMumpsRubellaCerebrospinal fever(Small Pox)

2-FOOD AND DRINK-BORNE:* The enteric group (salmonellae)* The dysentery group (shigellae)•The rotaviruses (G.E.)•Hep A* Cholera * Food poisoning (staph).* Amoebic dysentery.* Helminths.

METHOD OF TRANSMISSION:

* The human hand* Flies. •Milk: Excellent medium T.B F.P Diphtheria - Dirty udder - Dirty hands of milking man - Dirty bottle

* Water : Very serious

METHOD OF TRANSMISSION:•Meat: Diseased animal Contaminated meat* Fresh Vegetables and Fruits: - Poor medium - Can be contaminated by: - Flies - Washing Water - Dirty hands - Manure

3-ARTHROPOD-BORNE * Can be: Biological Transovarian Mechanical * Means of transmission. - Inoculation by a vector. - Contamination (skin or mucous membranes). - By infectious foeces. - Body fluids (when crushed).

ARTHROPOD-BORNE (Cont’d.)FLIES:-Enteric fevers.-Mucopurulent conjunctivitis.-Ascariasis.-Amoebic dysentery.-Food poisoning.-Poliomyelitis.THE LOUSE (Pediculum humanus). - Epidemic typhus. - L.B. relapsing fever.

ARTHROPOD-BORNE

THE FLEA (Xenopsylla Cheopis: rat flea).

- Bubonic plague.

- Endemic typhus

THE MOSQUITO (female of):

- Culex sp (filariasis)

- Anopheles sp (malaria)

- Aedes sp (yellow fever)

THE SAND FLY:

- Cutaneous Lishmaniasis.

4- CONTACT

Can be: - Direct - Indirect- Fungal Infection of the skin - Tinea capitis (ring worm). - Tinea pedis (athlete’s foot). - Tinea cruris.

4- CONTACT

- STD - Syphilis - Herpes simplex - Lymphogranuloma - (AIDS)- Mycosis - Actinomycosis - Moniliasis - Mycetoma- Scabies- Trachoma and other eye infections.

HOST-PARASITE RELATIONSHIP

Agent

(Seed)

(Climate) (Soil)

Environment Host

Intrinsic Properties of “Agent”- Antigenic make-up.- Growth requirements.- Ability to survive outside the host (milk, water, soil).- Viability under varying conditions (temp, humidity).- Spectrum of hosts.- Resistance to treatment.- New genetic information.

Properties Subject to Interaction- Infectivity - Pathogenicity - Virulence - Immunogenicity

Properties Subject to Interaction- Infectivity - Pathogenicity - Virulence -Immunogenicity

- Dose

- Source

- Route

- Duration before reaching the host - Host factors - Age

- Race - Nutritional Status

THE RESERVOIR: Human

Human

• Most viral and bact. RTIs

• Most staph and strept.

• Childhood exanthemata

• STD

THE RESERVOIR:

Animal Animal Human

Zoonoses

- Bovine T.B

- Brucellosis

- Anthrax

- Rabies

THE RESERVOIR:

Complex Cycles: - Malaria - Bilharzia - Tape worm

Disease Mechanism:

– Tissue invasion

– Toxin production

– Hypersensitivity

CONTROL OF COMMUNICABLE DISEASE

Can be classified into:

I-Controlling the source of infectionII-Blocking the channels of transmissionIII-Protecting the susceptible population

I. CONTROLLING THE SOURCE OF INFECTION: (CASES, CARRIERS AND ANIMAL RESERVOIR)

- Early diagnosis - Notification - Isolation - Treatment - Quarantine - Surveillance - Disinfection

I. CONTROLLING THE SOURCE OF INFECTION: (CASES, CARRIERS AND ANIMAL RESERVOIR)

- Early diagnosis - Notification - Isolation - Treatment - Quarantine - Surveillance - Disinfection

II. BLOCKING CHANNELS OF

TRANSMISSION.

* Air-borne: - Bed-spacing

- Dust-control

- Suitable ventilation

- Good health habits

- Air disinfection

- Use of masks

- Minimize over-corwding

Food and Drink-borne:– Provision of safe and clean water.– Pasteurization or boiling of milk.– Proper personal hygiene.– Sanitary sewage disposal.– Control of flies.– Washing fresh vegetables.– Meat and slaughter house control.– Refrigeration of unused food.– Control of food handlers and vendors.– Labs for food examination.

* Arthropod-borne:- Lice:

• Personal cleanliness.• Avoiding overcrowding.• Dusting by insecticides.

* Fleas:- Cleanliness of dwellings. - Avoid dust collection.- Spraying & dusting by insecticides.- Rodent control.* Mosquitos:Vector control. Personal protection.

Contact Diseases:- Case finding and treatment.- Tracing of contacts.- Serological examination.- Control of sexual behaviour.- Personal cleanliness.

Contact Diseases:

- Avoid use of common articles: - Comb. - Hair brush. - Towels. - Handkerchief. - Underwear. - Footwear ……. etc.

III.PROTECTING THE SUSCEPTIBLE POPULATION

- Primary Prevention: - Health promotion. - Specific protection.- Secondary Prevention: - Early diagnosis and - Prompt treatment.- Tertiary Prevention: - Limitation of disability. - Rehabilitation.

Primary Prevention:Health Promotion:- Adequate nutrition. - Health education. - Socio-economic development.- Environmental sanitation.- Personal hygiene.- Genetic counseling.

Primary Prevention:

Specific Protection:- Specific immunization.- Protection against occupational hazards.- Protection against accidents. - Protection from carcinogens.- Avoidance of allergens.

Primary Prevention:

Specific Protection:- Specific immunization.- Protection against occupational hazards.- Protection against accidents. - Protection from carcinogens.- Avoidance of allergens.

Secondary Prevention:- Screening for sub-clinical disease.- Case finding- Health education.

Tertiary Prevention:Limitation of disability. - Adequate treatment.

Tertiary Prevention:

Rehabilitation.Vocational: - (Occupational) restoration of capacity to earn.Social: - Restoration of family and community relationship.

Tertiary Prevention:

Rehabilitation.Psychological: - Restoration of personal confidence and independence.Medical: - Physical restoration of function.

ENDEMIC EPIDEMICHost Factors:

- Immunity- Change in behaviour- Population movement

ENDEMIC EPIDEMIC

Environmental Factors:

- Vector: Mosquitos Flies- Adverse conditions: - War - Famine

ENDEMIC EPIDEMIC

Environmental Factors:

- New or Exposure - Change in climate - Irrigation scheme - Energy plants

- Control measures