Exam 12: Epidemiology of Infectious Diseases

Home-canned foods would be a likely source for an outbreak of salmonellosis.

What factors comprise the epidemiologic triangle?

The social environment refers to the totality of behavioral, personality, attitudinal, and cultural characteristics of a group of people.

The case fatality rate of a disease is defined as the number of deaths due to the disease divided by the number of cases of the disease during a specified time period times 100.

Community A receives its water from several sources. The water source responsible for causing an outbreak of disease X is unknown. The best evidence to determine which suspected water supply is responsible would be:

Vectors can be considered as one way in which infectious diseases can be transmitted.

A major resurgence of measles occurred during the period 1989 to 1990.

In two communities of similar size and age structure (A and B), there were outbreaks of viral illnesses (virus A in community A, and virus B in community B), both of which were traced back to a single source. Exposure to these viruses in each community confers permanent immunity. In community A, 200 susceptible people were exposed to an index case, 150 people were infected (not including the index case), 75 people became ill, and 40 people died. In community B, pathogenicity was 40%, infectivity was 90%, and virulence was 60%. Which virus had the greatest infectivity?

An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea; five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. The ratio of severe cases to other clinically apparent cases was:

In two communities of similar size and age structure (A and B), there were outbreaks of viral illnesses (virus A in community A, and virus B in community B), both of which were traced back to a single source. Exposure to these viruses in each community confers permanent immunity. In community A, 200 susceptible people were exposed to an index case, 150 people were infected (not including the index case), 75 people became ill, and 40 people died. In community B, pathogenicity was 40%, infectivity was 90%, and virulence was 60%. Which virus was most virulent?

When an individual comes into contact with a piece of clothing that subsequently infects him or her, that piece of clothing is a fomite, and the infection is direct.

Antigenicity of an infectious agent is measured by the secondary attack rate.

The case fatality rate is the same thing as the cause-specific mortality rate for a disease.

If a disease is fatal, virulence can be measured by the case fatality rate.

An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea; five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. Foods served at the luncheon included home-canned olives, chicken salad, homemade flavored drink mix, freshly baked rolls, and raw vegetables. Based on your understanding of foods that potentially are capable of transmitting salmonella, the most likely source of the outbreak was:

Incubation period refers to the time between exposure to an infectious agent and the first signs and symptoms of disease.

Eradication of smallpox was successful because of a program to immunize its primary reservoir, the green monkey in central Africa.

Which of the following examples involves indirect transmission of disease?

Disease X is one that often results in severe illness but is never fatal. On March 21, 2002, 30 students enrolled in an introductory epidemiology course at a university developed disease X. (Assume all epidemiology students were exposed to the index case, the instructor). Through antibody titers, you were able to determine the following (antibody titers measure the concentration of antibodies in individuals and can be used to provide evidence of infection): Number of exposed students not infected: 40 Number of exposed students with subclinical infection: 10 Number of exposed students with mild symptoms: 10 Number of exposed students with moderate symptoms: 10 Number of exposed students with severe symptoms: 10 Using your knowledge of infectious disease epidemiology, quantify the pattern of disease X in this group (i.e., what are the infectivity and virulence of disease X?). Assume all students were susceptible.

Colonization refers to the spread of plague to the Americas by settlers from Europe.