Exam_4_32-33 - Lectures 32 and 33 Epidemiology- study of...

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Lectures 32 and 33 Epidemiology- study of the prevalence, incidence, and transmission of disease in populations Prevalence- fraction or percent of a given population that has a disease Common source epidemic- disease transmitted from a single source, e.g. batch of contaminated food or water Outbreak- sudden increase in cases above normal low levels Endemic- disease is present in a population at a constant, low level Epidemic- disease occurring within a population at a higher than normal frequency Pandemic- occurrence of disease over several continents Mortality- Deaths due to disease divided by the Total number of infected individuals Morbidity- incidence of an infectious disease within a population, Incidence of a disease (fatal or non-fatal) divided by the Total population Carrier- individuals with asymptomatic or subclinical infections; can expose others to infectious diseases Types of carriers •Acute – carrier state lasts for a short time; e.g. someone with flu before symptoms become apparent •Chronic – constant carrier of an infectious disease but have no symptoms; appear normal and healthy but spread disease Reservoirs- place where infectious disease is maintained between outbreaks; can be inanimate or a living organism. Some examples: Soil – infection occurs from accidental introduction into host. Humans and animals are also reservoirs. Zoonosis- disease occurs primarily in animals but can be transmitted to humans Vectors- indirect transmission facilitated by live agents such as insects, rodents, ticks, fleas, e.g. West Nile virus, malaria Fomites- inanimate, contaminated objects e.g. toys, bedding. Some modes of transmission and dispersal: Coughing/sneezing, open skin (wounds, sores), insect bites, feces and urine, blood Nosocomial infections- acquired in a hosipital setting and about 5-10% of hospital patients acquire this type of infection. Transmitted by contact, airborne, devices
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(medical). Antibiotic resistance of pathogens is increasing. Some major nosocomial infections are respiratory, urinary tract, bacteremias, and surgical wounds. Delayed sequelae- a follow-up disease. Sequelae = A pathological condition resulting from a disease Superantigen- a hyper-immune response leading to tissue destruction; 30% fatality rate. Examples: Exotoxins and M-Proteins.
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Exam_4_32-33 - Lectures 32 and 33 Epidemiology- study of...

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