1. Infection & Disease Unit 5

2. Stages of clinical infections 1. incubation period time from initial contact to first signs of symptoms 2. prodrome period 1-2 days - initial symptoms 3. invasion period multiplies at high levels, reached target tissue, greatest toxicity during this stage. 4. convalescent period recovery period

3. Patterns of Infection Localized infection - microbe remains confined to specific tissue (ex: warts) Systemic infection - infection spreads to several sites (usually through circulatory system). (ex:viruses, some fungal and bacterial infections). Focal infection - a local infection but the toxins produced from pathogen travel to other sites to cause damage (toxemia). (ex: TB) Mixed infection - several microbes at work! (ex: dental caries & biofilms) Primary vs secondary infection - example the flu (primary infection) can develop into pneumonia (secondary infection)

4. Portal of Exit Very important to epidemiologists looking to contain infection What are the various portals of exit?

5. Asymptomatic Carriers

6. Transmission of Infectious Disease Reservoirs: Where pathogens persist! reservoir: the natural host or habitat for the pathogen (human, animal, soil, water) infection source: individual or object from which the infection was acquired. vector - an animal that transmits infectious agents from one host to another. Majority of vectors are arthropods such as: mosquitoes, flies, fleas, and ticks. (mechanical vs biological vectors)

7. Vectors Biological vectors vs. Mechanical vectors Biological vector - actively participates in a pathogens life cycle serving as a site it can complete it’s life cycle and/or multiply. usually transmitted through biting a human or around open wound Mechanical vector - not necessary to the life cycle of the pathogen - merely transports. usually transmitted by touch of contaminated animal. Flies can spread more than 20 different infections just due to contaminated feet and mouthparts.

9. Epidemiology CDC & WHO Morbidity - incidence of a specific notifiable disease Mortality - deaths from notifiable disease Morbidity rate: = # of ppl affected in relation to the total population in a given time period Mortality rate: Number of deaths from a disease in relation to the population in a given time

10. Epidemiology Statistics Prevalence - the total cumulative # of cases of a disease in a certain area and time period. Incidence - the number of new cases of disease occurring during a time period.

12. Epidemiological Classification of Disease Emerging –New diseases –Diseases that effected a few people hundreds of years ago, but have recently affected enough of the population that they are noticed (AIDS and Ebola) –Diseases that affected people hundreds of years ago but have recently been recognized due to a pathogen (ulcers by Helicobacter pylori) Re-emerging - diseases that have increased in incidence after a decline Endemic/Peristent - diseases that have remained relatively constant in incidence

13. Emerging Infectious Diseases Modern transportation West Nile virus Ecological disaster, war, and expanding human settlement Coccidioidomycosis Animal control measures Lyme disease

14. Emerging Diseases

15. Re-emerging Diseases

16. Emerging Infectious Diseases Diseases that are new, increasing in incidence, or showing a potential to increase in the near future Contributing factors Genetic recombination E. coli O157, avian influenza (H5N1) Evolution of new strains V. cholerae O139 Inappropriate use of antibiotics and pesticides Antibiotic-resistant strains Changes in weather patterns Hantavirus

17. Disease Prevention: Decision Making