COMMUNICABLE DISEASE EPIDEMIOLOGY, CONTROL & PREVENTION Mohamed M.B. Alnoor CHP300

COMMUNICABLE DISEASE Content Sources & Channels of infection Host-parasite relationship Cycle of infection Outcome of infection Disease mechanism Spectrum of disease Levels of disease occurrence Control and prevention of disease Levels of Prevention Natural History of disease

COMMUNICABLE DISEASE DEFINITIONS COMMUNICABLE DISEASE : EPIDEMIOLOGY : CONTROL : PREVENTION :

COMMUNICABLE DISEASE DEFINITIONS Control: Elimination : Eradication: Extinction:

COMMUNICABLE DISEASE SOURCES OF INFECTION CASE OF DISEASE : a patient CARRIER :. Incubatory carrier. Convalescent carrier. Chronic carrier. In-apparent carrier ANIMAL RESERVOIR (ZOONOSIS) INANIMATE RESERVOIR (THE SOIL) DEFINITIONS

COMMUNICABLE DISEASE SOURCES OF INFECTION DEFINITIONS Zoonosis Reservoir animal human

COMMUNICABLE DISEASE SOURCES OF INFECTION DEFINITIONS Hepatitis C -Source = transfusion, blood products -Reservoir = humans Examples: Neisseria gonorrhea -Source = humans -Reservoir = humans Salmonella typhi -Source = food/water -Reservoir = humans Rabies virus -Source = saliva of the dog -Reservoir = the dog

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION: 1- AIR-BORNE 2- FOOD AND DRINK-BORNE 3- ARTHROPOD-BORNE 4- CONTACT TRANSMISSION

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION: 1. Water-washed dis. (Dis. of skin, eye) 2. Faecal-oral disease. (Viral, bact., parasitic) 3. Soil -mediated infections. (Tetanus, intestinal parasites) 4. Diseases of water contact. (Bilharzia, Guinea worm) 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. (Brucellosis, rabies)

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION: 1. Water-washed dis. (Dis. of skin, eye) 2. Faecal-oral disease. (Viral, bact., parasitic) 3. Soil -mediated infections. (Tetanus, intestinal parasites) 4. Diseases of water contact. (Bilharzia, Guinea worm) 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. (Brucellosis, rabies) 1- AIR-BORNE 2- FOOD AND DRINK-BORNE 3- ARTHROPOD-BORNE 4- CONTACT TRANSMISSION

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION:

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION: 1- AIR-BORNE 2- FOOD AND DRINK-BORNE 3- ARTHROPOD-BORNE 4- CONTACT TRANSMISSION

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 1- AIR-BORNE  Droplet infection (direct spread): CSM, Whooping cough  Droplet nuclei (direct air-borne): Measles, Chickenpox  Infected dust (indirect air-borne): TB, Diphtheria

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 1- AIR-BORNE Inhalation Infections:  Respiratory Tract: Pulmonary Tuberculosis. Influenza Sore-throat Pneumonia Common cold

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 1- AIR-BORNE Inhalation Infections:  Other Specific Fevers : Measles. Whooping cough Diphtheria Scarlet fever Chicken pox Mumps Rubella Cerebrospinal fever (Small Pox)

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 2- FOOD AND DRINK-BORNE Categories:  The enteric group (salmonellae)  The dysentery group (shigellae)  The rotaviruses (G.E.)  Hep A  Cholera  Food poisoning (staph).  Amoebic dysentery.  Helminths.

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 2- FOOD AND DRINK-BORNE Methods of transmission:  The human hand Musca domestica House fly  Flies

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 2- FOOD AND DRINK-BORNE Methods of transmission:  Milk: Excellent medium T.B. F.P. Diphtheria Dirty hands of milking man Dirty bottle  Water: Very serious Dirty udder

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 2- FOOD AND DRINK-BORNE Methods of transmission:  Meat: Contaminated meat.  Fresh Vegetables and Fruits : Poor medium. Can be contaminated by: Flies Washing water Dirty hands Manure Diseased animal

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 3- ARTHROPOD-BORNE Methods of transmission:  Biological transmission  Harborage transmission  Transovarial transmission  Mechanical transmission Can be:

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 3- ARTHROPOD-BORNE Methods of transmission: Vector:  Inoculation  Contamination skin or mucous membranes By infectious feces. Body fluids (when crushed)  Inoculation

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 3- ARTHROPOD-BORNE Methods of transmission: Flies: Poliomyelitis. Enteric fevers. Ascariasis. Mucopurulent conjunctivitis. Amoebic dysentery. Food poisoning.

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 3- ARTHROPOD-BORNE Methods of transmission: The louse (Pediculum humanus): Epidemic typhus. L.B. relapsing fever. human body louse Human Head louse

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 3- ARTHROPOD-BORNE Methods of transmission: The Flea (Xenopsylla cheopis; rat flea) : Bubonic plague Endemic typhus

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 3- ARTHROPOD-BORNE Methods of transmission: The Mosquito (female of): - Culex sp. (filariasis) - Anopheles sp. (malaria) - Aedes sp. (yellow fever)

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 3- ARTHROPOD-BORNE Methods of transmission: The Sand Fly: - Cutaneous Leishmaniasis.

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 4- CONTACT Methods of transmission: Can be: Direct Indirect

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 4- CONTACT Types: STD ? Syphilis Herpes simplex Lymphogranuloma (AIDS)

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 4- CONTACT Types: Fungal Infection of the skin - Tinea capitis (ring worm). Tinea pedis (athlete’s foot). - Tinea cruris. (crotch itch)

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 4- CONTACT Types: Mycosis - Moniliasis (Oral Thrush) - Mycetoma Madura foot

COMMUNICABLE DISEASE CHANNELS OF TRANSMISSION OF INFECTION : 4- CONTACT Types: Scabies: mite (Sarcoptes scabiei) Trachoma and other eye infections.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Epidemiologic Triangle Agent (Seed) Environment (Climate) Host (Soil)

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Infectious Disease Model Host Pathogen Environment disease

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Biological Physical Chemical Mechanical Nutrient Disease Agents

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Biological Disease Agents Bacteria Viruses Parasites Protozoa Metazoa Rickettsiae Fungi

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Microbes-humans Relationship Very few microbes are always pathogenic Many microbes are potentially pathogenic Most microbes are never never pathogenic

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Microbes-humans Relationship (Symbiosis)  Mutualism - Association in which both partners benefit  Commensalism - Association in which one partner benefits and other is unharmed  Parasitism - Association in which the microbe befits at expense of host (Flora living on skin) (pathogenic infection) (Bacteria and synthesis of vitamins K and B)

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Agent Factors - 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. Intrinsic Properties of “Agent”

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Agent Factors Properties subject to interaction  Infectivity  Pathogenicity  Virulence  Immunogenicity

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Agent Factors Properties subject to interaction  Infectivity  Pathogenicity  Virulence  Immunogenicity  Dose  Source  Route  Duration before reaching the host  Host characteristics Age Race Nutritional Status

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Host Factors Exposure Susceptibility Response to the agent ( a HOST is a PERSON who can be infected under normal conditions.)

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Host Factors Exposure Age Sex Race S.E.S ( occupation) Behavior Drug abuse Sexual practice

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Host Factors Age Pregnancy Malnutrition Immunity Other diseases Medications Susceptibility and Response to the Agent

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Environmental Factors Climate Geography Water Housing 1- Physical Environment

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Environmental Factors 2- Biological Environment Agents Reservoirs Intermediate hosts Vectors Man Microbes Insects Rodents Animals

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Environmental Factors 3- Psychosocial Environment Education Occupation Beliefs Attitude Behavior

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Reservoir of Infection Types : Most viral and bact. RTIs Most staph and strept. Childhood exanthemata STD 1. Human to Human Human

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Reservoir of Infection Zoonosis Types : 2. Animal to Human animal human

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Reservoir of Infection Types : 3. Complex cycles - Malaria - Bilharzia - Tape worm

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Initial infection ( exposure ) Sign = observable or measurable change in body function eg : rash, fever Onset of clinical disease ( symptoms or signs) Symptom = subjective complaint e.g.: pain, loss of appetite, lethargy The Incubation Period : Phases of Infectious Disease :

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : Initial infection Start of infectiousness The Period of Communicability : 2. before onset after recovery - convalescence - chronic 1. before onset early in disease course The Latent Period :

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : Phases of Disease Cycle : Incubation period: -Variable length -Prior to signs and symptoms Prodromal stage: - The period of early symptoms - Indicates the start of disease before specific symptoms and signs occur. - Often infectious/contagious - Innate immune response starts

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : Phases of Disease Cycle : Decline stage: - Alleviation of signs and symptoms - Recovery/convalescence Illness stage : - Most severe phase - Clear evidence of signs and symptoms - Acquired immune responses begin

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : Cycle of Infection INFECTIOUS AGENT BACTERIA VIRUSES FUNGI PROTOZOA HELMINTH RESERVOIR PEOPLE EQUIPMENT WATER PORTAL OF EXIT EXCRETIONS SECRETIONS DROPLETS SKIN MODE OF TRANSMISSION AIRBOURNE INGESTION INNOCULATION CONTACT PORTAL OF ENTRY BROKEN SKIN MUCOUS MEMBRANES GIT/RESPIRATORY URINARY TRACT SUSCEPTIBLE HOST NEONATES DIABETICS IMMUNOSUPPRESSED CARDIOPULMONARY DISEASE

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : Cycle of Infection

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : PATHOGEN RESERVOIR/ SOURCE PORTAL of EXIT MODEPORTAL of ENTRY SUSCEPTIBLE HOST Cycle of Infection

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : Outcome of Infection H O S T PRASITEPRASITE COLONIZATION C O V E R T O V E R T disease

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : Disease Mechanism – Tissue invasion – Toxin production – Hypersensitivity Outcome of Infection

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Infection Phases of Infectious Disease : Disease Mechanism Outcome of Infection Spectrum of Disease fffff fffff fffff fffff TB, Polio, Hep A Measles, Chickenpox Rabies, Amebic Encephalitis, Hemorrhagic Fever. Fatal Sever Moderate Mild Inapparent

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Sporadic Disease : Occurs irregularly and only occasionally in a population. e.g. Typhoid fever (Salmonella typhi)

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Endemic Disease : Constant presence of an infectious disease within a given geographical area or population group. the usual or expected frequency of disease

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Hyperendemic Disease : When occurrence frequency rises, but not to epidemic proportions. e.g. - Common cold in the winter months - high prevalence malaria

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Epidemic : The occurrence of cases of disease, (( specific health related behavior, or other health related events )) clearly more than expected In a given area or among a specific group of people over a particular time. ? One example

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Outbreak : epidemic-like increase in frequency, but in a very limited (focal) segment of the population; Usually of shorter duration. Example: Food poisoning, URTI

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Pandemic : An epidemic occurring over a very wide area (several countries or continents) and usually affecting a large proportion of the population ? One example

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Endemic Epidemic : Number of Cases of a Disease Time Endemic Epidemic

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Endemic Epidemic : Host Factors: - Change in behavior ? - Population movement - Immunity

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Endemic Epidemic : Environmental Factors: - Adverse conditions: - War - Famine - Vector: - Mosquitos - Flies

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Some Concepts of Communicable Disease : Levels of Communicable Diseases Occurrence Endemic Epidemic : Environmental Factors: - New or Exposure - Change in climate - Irrigation scheme (- Energy plants) - Control measures

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : I Controlling the source of infection II Blocking the channels of transmission III Protecting the susceptible population Can be classified into:

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : I Controlling the source of infection : (CASES, CARRIERS AND ANIMAL RESERVOIR) - Early diagnosis - Notification - Isolation - Treatment - Quarantine - Surveillance - Disinfection

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : II Blocking the channels of transmission : Air- borne: - Bed-spacing - Dust-control - Effective ventilation - Good health habits - Air disinfection - Use of masks - Minimize over-crowding

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : II Blocking the channels of transmission : Food and Drink - borne: – Provision of safe/sufficient 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.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : II Blocking the channels of transmission : Food and Drink - borne: FOODDRINK BOTH FOOD and DRINK

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : II Blocking the channels of transmission : Arthropod - borne: Lice: Personal cleanliness. Avoiding overcrowding. Dusting by insecticides.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : II Blocking the channels of transmission : Arthropod - borne: Fleas: Cleanliness of dwellings. Avoid dust collection. Spraying & dusting by insecticides. Rodent control.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : II Blocking the channels of transmission : Arthropod - borne: Mosquitos : Vector control. Personal protection.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : II Blocking the channels of transmission : Contact Diseases : - Case finding and treatment. - Tracing of contacts. - Serological examination. - Control of sexual behaviour. - Personal cleanliness.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : II Blocking the channels of transmission : Contact Diseases : - Comb. - Hair brush. - Towels. - Handkerchief. - Underwear. - Footwear ……. etc. - Avoid use of common articles:

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : III Protecting the susceptible population : - Primary Prevention: - Health promotion. - Specific protection. - Secondary Prevention: - Early diagnosis and - Prompt treatment. - Tertiary Prevention: - Limitation of disability. - Rehabilitation.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : III Protecting the susceptible population : - Primary Prevention: - Health promotion. - Adequate nutrition. - Health education. - Socio-economic development. - Environmental sanitation. - Personal hygiene. (- Genetic counseling.)

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : III Protecting the susceptible population : - Specific immunization. - Protection against occupational hazards. - Protection against accidents. - Protection from carcinogens. - Avoidance of allergens. - Primary Prevention: - Specific protection. - Protection against occupational hazards. - Protection against accidents. - Protection from carcinogens. - Avoidance of allergens. - Protection against occupational hazards. - Protection against accidents. - Protection from carcinogens. - Avoidance of allergens.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : III Protecting the susceptible population : - Secondary Prevention: - Early diagnosis and - Prompt treatment. -Screening for sub-clinical disease. - Health education - Case finding

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : III Protecting the susceptible population : - Tertiary Prevention: - Limitation of disability. - Rehabilitation. - Adequate treatment. - Psychological: - Restoration of personal confidence and independence. - Medical: - Physical restoration of function.

COMMUNICABLE DISEASE HOST-PARASITE RELATIONSHIP Control of Communicable Disease : III Protecting the susceptible population : - Tertiary Prevention: - Rehabilitation. - Vocational: - Restoration of capacity to earn. (Occupational) - Social: - Restoration of family and community relationship.

COMMUNICABLE DISEASE Natural History of Disease Recovery

COMMUNICABLE DISEASE Natural History of Disease Recovery

COMMUNICABLE DISEASE Natural History of Disease Recovery

COMMUNICABLE DISEASE Natural History of Disease Recovery

COMMUNICABLE DISEASE Natural History of Disease Recovery