NR503 - Epidemiology Midterm 2023 with verified questions and answers

prevalence number of existing cases / number of population incidence number of new cases / number of persons at risk of developing disease relationship between incidence and prevalence prevalence = incidenceXduration relationship between incidence rate and mortality rate mortality rate easier to obtain than incidence - use when case-fatality rate is high - use when duration of disease is short importance of surveillance - monitor changes in disease frequency - monitor changes in levels of risk factors - conducted for infectious disease passive surveillance - disease reporting is mandated or requested with responsibility for reporting often falling on health care provider or health officer - depends on individual and staff - relatively inexpensive - easy to develop initally active surveillance - project staff recruited to carry out surveillance program - more accurate b/c it is conducted by individuals who have been specifically employed to carry out responsibilities numerator number of health events denominator population at risk absolute risk - incidence of disease in population - indicates magnitudes of risk in group of people with certain exposure - does not indicate whether exposure is associated with an increased risk of disease relative risk - risk of exposed / risk of unexposed mortality rate total no. of deaths from all causes / no. of persons in population X 1000 case-fatality no. of people during specific period of time / no. of people who have the disease X1000 validity ability to distinguish between who has disease and who does not sensitivity ability of test to identify correctly those who have the disease specificity ability of test to identify correctly those who do not have the disease attack rate no. of people who became ill / no. of people who partcipated direct transmission person-to-person contact indirect transmission common vehicle, vector epidemic curve distribution of times of onset of disease immunity ability of an organisms to resist a particular infection/toxin by action of specific antibodies/sensitized WBCs epidemic widespread occurrence of an infectious disease in community/particular time endemic disease/condition regularly found among particular people/in certain area herd immunity resistance to spread of contagious disease within population that results if a sufficient high proportion of individuals are immune to disease, especially through vaccination common-vehicle exposure an outbreak occurs in group people who have shared common inanimate vehicle single exposure (1) explosive; sudden, rapid increase in number of cases (2) cases limited to people who share common exposure; self-evident - first wave of cases would not expect disease to develop in people not exposed (3) food-borne outbreak - cases rarely occur in persons who acquire disease from primary case incubation period interval from receipt of infection to time of onset of clinical illness clinical disease characterized by s/s latent disease infection with no active multiplication of agent subclinical disease not clinically apparent, not destined to become clinically apparent; disease is often diagnosed by serologic response or culture of organism