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INFECTIOUS DISEASE EPIDEMIOLOGY.pptx
- 1. DEPT. OF TAHAFFUZI WA SAMAJI TIBB
- 2. The ENTRY and DEVELOPMENT or MULTIPLICATION of an infectious agent in the body of man or animals A body responds in some way to defend itself against the invader, either in the form of an immune response or disease. An infection does not always cause illness.
- 4. • Presence of an infectious agent on a body surface, clothes, beddings, toys, food CONTAMINATION • Distinct from contamination • Implies the presence of offensive but not necessarily infectious matter in the environment POLLUTION • Invasion of the gut by parasitic worms • Ascariasis INFESTATION • Disease resulting from an infection INFECTIOUS DISEASE • A disease that is transmitted through contact • Scabies, STD, Leprosy CONTAGIOUS DISEASE • An illness due to a specific infectious agent or its toxic products capable of being directly or indirectly transmitted from man to man, animal to animal or from the environment (through air, dust, soil, water, food, etc.,) to animal or man COMMUNICABLE DISEASE
- 5. HOST • A person or other animal including birds and arthropods that affords lodgement to an infectious agent under normal conditions • OBLIGATE HOST • DEFINITIVE HOST • INTERMEDIATE OR SECONDARY • TRANSPORT
- 6. •The unusual occurrence of a disease or health-related events in a community or region clearly in excess of expected occurrence •US - cholera EPIDEMIC •Constant presence of a disease or infectious agent within a given geographic area or population group, without importation from outside •Common cold – because somebody always has one ENDEMIC •An epidemic usually affecting a large geographical area •Influenza pandemics of 1918 & 1957 PANDEMIC •Sporadic – scattered about •The cases occur irregularly, haphazardly from time to time generally infrequently •May be the starting point of an epidemic when conditions are favourable for its spread SPORADIC •Diseases which are imported into a country in which they do not otherwise occur •Rabies in UK EXOTIC •An infection or infectious disease transmissible from vertebrate animals to man under normal conditions •Rabies, Plague ZOONOSIS
- 7. • Infection originating in a patient while in a hospital or other health care facility • Hepatitis B NOSOCOMIAL INFECTION • This is an infection by an organism that takes the opportunity provided by a defect in host defense to infect the host and cause disease • AIDS OPPORTUNISTIC INFECTION • Any disease, impairment, handicap, disability or death resulting from a physician’s professional activity • Drug therapy, immunization or diagnostic procedures IATROGENIC INFECTION
- 8. • The continuous scrutiny of the factors that determine the occurrence and distribution of disease and other conditions of ill health • Essential for effective control and prevention SURVEILLANCE • Termination of all transmission of infection by extermination of the infectious agent • Small pox ERADICATION • Sometimes used to describe “eradication” of a disease from a large geographical region • Measles, Diphtheria, Polio ELIMINATION
- 11. • The person, animal, object or substance from which an infectious agent passe or is disseminated to the host SOURCE • Any person, animal, arthropod, plant, soil, or substance in which an infectious agent multiples, on which it depends primarily for survival and where it reproduces itself in such manner that it can be transmitted to a susceptible host • Hookworm infection R- man S- soil • Typhoid fever R- case or carrier S- faeces or urine of a patient or contaminated food RESERVOIR
- 12. *HUMAN RESERVOIR *ANIMAL RESERVOIR *RESERVOIR IN NON-LIVING THINGS
- 13. HUMAN RESERVOIR CARRIERS PORTAL OF EXIT URINARY INTESTINAL RESPIRATORY NASAL OTHERS DURATION TEMPORARY CHRONIC TYPE INCUBATORY CONVALESCENT HEALTHY CASE CLINICAL CASE SUBCLINICAL CASE LATENT CASE PRIMARY CASE INDEX CASE SECONDARY CASE
- 14. DIRECT TRANSMISSION • DIRECT CONTACT • DROPLET INFECTION • CONTACT WITH SOIL • INOCULATION INTO SKIN & MUCOSA • TRANSPLACENTAL (VERTICAL) INDIRECT TRANSMISSION • VEHICLE-BORNE • VECTOR-BORNE • AIR-BORNE • FOMITE BORNE • UNCLEAN HANDS & FINGERS
- 18. •Entry, proliferation, exit, survival in the external environment •Does not produce death, but are vulnerable to the same infection again & again. Eg- common cold SUCCESSFUL PARASITISM •Time interval between invasion by an infectious agent and appearance of the first sign or symptom of the disease •The infectious agent undergoes multiplication INCUBATION PERIOD •The gap in between the onset of the case and the secondary case •The primary case is followed by 2 or 3 secondary cases within a short time SERIAL INTERVAL
- 19. • The interval of time between receipt of infection by a host and maximal infectivity of the host GENERATION TIME • The time during which an infectious agent may be transferred directly or indirectly from an infected person to another person……. COMMUNICABLE PERIOD • The number of exposed persons developing the disease within the range of the incubation period, following exposure to the primary case SECONDARY ATTACK RATE
- 20. FLU ATTACK – How does a virus invades our body
- 21. Young infants Children with special health care needs Equipment in their bodies (catheters, g-tubes) Children with impaired immune systems Pregnant women
- 22. Why Are Children More Vulnerable to Infectious Diseases?
- 23. Good News: Annual Illness Incidence by Age Incidence of illness Age of child
- 24. Virus Frequently get better on their own Limited treatment, other than rest and control of symptoms Few medications to treat viruses Bacteria Often need to be treated with antibiotics Fungus Often on surfaces of body and can be treated with creams or oral medication Parasite Typically cause diarrhea Often need to be treated with antiparasitic medications