Outbreak of tick-borne relapsing fever at the north rim of the Grand Canyon: evidence for effectiveness of preventive measures.

An outbreak of tick-borne relapsing fever (TBRF) originating at the North Rim of Grand Canyon National Park was investigated in 1990. To determine risk factors for the disease, almost 7,000 parties of visitors were surveyed; over half responded, representing > 10,000 people. Fifteen cases of confirmed or probable TBRF were identified in visitors and 2 in employees. All patients except one experienced symptoms after overnight stays in a group of cabins that had not been rodent-proofed after a TBRF outbreak in 1973 (relative risk for visitors [RR] 8.2, 95% confidence interval [CI] 1.1-62). Seven cases of TBRF were associated with a single cabin (RR 98, 95% CI 30-219). Structural flaws and rodent nests were common in the implicated cabins and rare in unaffected cabins. This investigation suggests that measures to rodent-proof cabins at sites where TBRF is endemic prevent reinfestation of cabins by infected rodents and tick vectors, thereby preventing the spread of disease in humans.

Predictors of cesarean section delivery among college-educated black and white women, Davidson County, Tennessee, 1990-1994.

Cesarean section delivery increases the cost, morbidity, and mortality of childbirth. Cesarean section rates vary nationwide with the highest rates occurring in the southern United States. The Department of Health and Human Services has published year 2000 objectives that include a 15% reduction in the cesarean section rate. This study identified factors contributing to cesarean section delivery among a cohort of college-educated black and white women in Davidson County, TN. Logistic regression models were applied to Linked Infant Birth and Death certificate data from 1990-1994. Data on singleton first births for 606 black women and 3661 white women completing 16 years of education were analyzed. College-educated African Americans were at a significantly higher risk of cesarean section delivery than whites. This difference could not be accounted for by controlling for all other variables. The geographic differences in cesarean section rates in this country may be the result of varying in provider practice styles, perceptions, or attitudes. Improving the health of women and children will require establishing a system of maternity care that is comprehensive, case-managed, culturally appropriate, and available to all women.

Predictors of infant mortality among college-educated black and white women, Davidson County, Tennessee, 1990-1994.

Strategies to reduce US infant mortality rates often focus on the black-white disparity in rates. Linked Infant Birth and Death Files for Davidson County, Tennessee, from 1990 through 1994 were used to determine infant outcomes for infants born to college-educated white and black women. Risks for adverse outcomes were identified by comparing infant deaths to live births using logistic regression analyses. The following variables entered the logistic model process: maternal and paternal age; race and education; nativity status; maternal risk factors; interpregnancy interval; parity; infant gender; tobacco or alcohol use; number of prenatal visits; trimester in which prenatal care began; marital status; gestational age; and birthweight. After adjustment for the effects of the other variables, a gestational age < 28 completed weeks of gestation was the most significant independent predictor of infant death. Black race was not identified as a significant predictor of infant mortality. Regardless of race, a decrease in infant mortality rates among college-educated women in this country depends on the prevention of preterm births. Strategies to diagnose early preterm labor must proceed from a comprehensive maternal care program for all women. Open channels of communication between patient and provider will form the cornerstone for preterm prevention-intervention programs. Analysis of state and local infant mortality data may identify regional differences in infant mortality rates and differences in risk factors associated with adverse infant outcomes.