Which best describes what is happening with infectious diseases in the United States?

Correct Answer: D

Rationale: Probably one of the most profound failures in infectious disease control in the United States and elsewhere is that the successes are not equally distributed in the general population. Infectious diseases continue to be differentially distributed by income and ethnic groups, and the poor and minorities continue to experience the greater burden. There continues to be an increase in vector-borne infections, but there has been a decrease in food-borne and waterborne infections. There is concern that deadly pathogens will be weaponized by terrorists.

Correct Answer: C

Rationale: The researchers concluded that ecosocial or contextual conditions strongly enhance sexually transmitted infection risk by increasing sexual risk behaviors and likelihood of exposure to infection. Thus, the environment has been determined to be a more important variable in sexually transmitted infections than the pathogenesis, susceptibility, and the amount of sex education provided.

Correct Answer: B

Rationale: The positive predictive value is affected by what proportion of the tested population has the problem. To increase the positive predictive value, screen populations most at risk for the problem. Testing a large population at once, using a very sensitive or very specific screening test would not increase the positive predictive value of a screening test.

Correct Answer: C

Rationale: The problem with very sensitive tests is that the test picks up almost all people with the disease but also many others who do not have the disease. These 'false positives' result in persons needing follow-up diagnostic tests. Additional time, effort, and expense, as well as worry, result until the negative test results are obtained.

Correct Answer: B

Rationale: Incidence (B) measures new cases over a period, reflecting disease onset. Prevalence (A) is total cases, morbidity (C) is disease burden broadly, and mortality (D) is deaths, not new cases.