Epidemiology. Epidemiology involves: –determining etiology of infectious disease –reservoirs of disease –disease transmission –identifying patterns associated.

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Incidence Prevalence Endemic Epidemic Pandemic


Epidemiology Epidemiology involves: determining etiology of infectious disease reservoirs of disease disease transmission identifying patterns associated with outbreaks outlining diagnostic tools and treatment options Incidence Prevalence Endemic Epidemic Pandemic In order for disease to spread: Pathogen must have reservoir Pathogen must be transmitted to susceptible host Reservoirs of infectious disease: Humans Non-human animals Environmental (non-living) Recognizing reservoir can help protect population from disease Human reservoirs Infected humans most significant reservoirs If only reservoir disease is easier to control Symptomatic or Asymptomatic carriers Non-human animal reservoirs Zoonotic transmission (zoonoses) Disease typically more severe in humans Often accidental and may be a dead end for pathogen Environmental reservoirs 2 most important are Water Soil Transmission Successful pathogen must be passed from reservoir to next susceptible host Contact Vehicle Vector Contact Direct contact Occurs when one person physically touches another Hands are the main source Indirect contact Transmission via inanimate objects or fomites Clothing, tissues, doorknobs and drinking classes Droplet transmission Respiratory droplets within three feet of release vehicle transmission Food, water and air Food contamination may originate with animal or occur during food preparation Waterborne disease can involve large numbers of people; prevention involves proper sanitation Respiratory droplets dry; creates droplet nuclei that may remain suspended or become re-suspended Vectors Any living organism that can carry a pathogen Most common are arthropods Mechanical or biological Control of vector-borne disease directed at controlling arthropod population Many disease occur in cycles May be annual or occur over decades Flu plague Herd immunity is an important factor in cycles Low levels could lead to reemergence of disease Small pox Reduction and eradication of disease Some success Efforts directed at: Improving sanitation Reservoir and vector control Vaccination Chemotherapy Why arent all infectious diseases eradicated? Four mechanisms public health agencies use to control disease transmission: 1.Isolation 2.Quarantine 3.Immunization 4.Vector control Infectious Disease Surveillance National disease surveillance network Network of agencies across the country monitor disease development Agencies include Public Health Departments Centers for Disease Control and Prevention (CDC) Notifiable Diseases World Health Organization (WHO) Nosocomial Infections Hospital acquired infections Range from mild to fatal Increased 36% in the last 20 years Leading cause of death in the US 100,000 deaths per year Reservoirs of nosocomial pathogens: Exogenous Other patients Hospital environment Health care workers Endogenous Patients own normal flora


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