Influence of sampling on estimates of clustering and recent transmission of Mycobacterium tuberculosis derived from DNA fingerprinting techniques.
The availability of DNA fingerprinting techniques for Mycobacterium tuberculosis has led to attempts to estimate the extent of recent transmission in populations, using the assumption that groups of tuberculosis patients with identical isolates ("clusters") are likely to reflect recently acquired infections. It is never possible to include all cases of tuberculosis in a given population in a study, and the proportion of isolates found to be clustered will depend on the completeness of the sampling. Using stochastic simulation models based on real and hypothetical populations, the authors demonstrate the influence of incomplete sampling on the estimates of clustering obtained. The results show that as the sampling fraction increases, the proportion of isolates identified as clustered also increases and the variance of the estimated proportion clustered decreases. Cluster size is also important: the underestimation of clustering for any given sampling fraction is greater, and the variability in the results obtained is larger, for populations with small clusters than for those with the same number of individuals arranged in large clusters. A considerable amount of caution should be used in interpreting the results of studies on clustering of M. tuberculosis isolates, particularly when sampling fractions are small. (+info)
Correlates of sexually transmitted bacterial infections among U.S. women in 1995.
CONTEXT: Sexually transmitted diseases (STDs) of bacterial origin such as gonorrhea and chlamydial infection can lead to pelvic inflammatory disease (PID) and infertility. Identifying behaviors and characteristics associated with infection may assist in preventing these often asymptomatic diseases and their sequelae. METHODS: Data from 9,882 sexually active women who participated in the 1995 National Survey of Family Growth describe the characteristics of women who report a history of infection with a bacterial STD or of treatment for PID. Multivariate analysis is used to determine which demographic characteristics and sexual and health-related behaviors affect the likelihood of infection or the occurrence of complications. RESULTS: Overall, 6% of sexually active women reported a history of a bacterial STD, and 8% reported a history of PID. Women who first had sexual intercourse before age 15 were nearly four times as likely to report a bacterial STD, and more than twice as likely to report PID, as were women who first had sex after age 18. Having more than five lifetime sexual partners also was associated with both having an STD and having PID. PID was more common among women reporting a history of a bacterial STD (23%) than among women who reported no such history (7%). In multivariate analyses, age, race, age at first intercourse and lifetime number of sexual partners had a significant effect on the risk of a bacterial STD. Education, age, a history of IUD use, douching and a history of a bacterial STD had a significant impact on the risk of PID, but early onset of intercourse did not, and lifetime number of partners had only a marginal effect. CONCLUSIONS: The pattern of characteristics and behaviors that place women at risk of infection with bacterial STDs is not uniform among groups of women. Further, the level of self-reported PID would suggest higher rates of gonorrhea and chlamydial infection than reported. (+info)
Where do people go for treatment of sexually transmitted diseases?
CONTEXT: Major public health resources are devoted to the prevention of sexually transmitted diseases (STDs) through public STD clinics. However, little is known about where people actually receive treatment for STDs. METHODS: As part of the National Health and Social Life Survey, household interviews were performed from February to September 1992 with 3,432 persons aged 18-59. Weighted population estimates and multinomial response methods were used to describe the prevalence of self-reported STDs and patterns of treatment utilization by persons who ever had a bacterial or viral STD. RESULTS: An estimated two million STDs were self-reported in the previous year, and 22 million 18-59-year-olds self-reported lifetime STDs. Bacterial STDs (gonorrhea, chlamydia, nongonococcal urethritis, pelvic inflammatory disease and syphilis) were more common than viral STDs (genital herpes, genital warts, hepatitis and HIV). Genital warts were the most commonly reported STD in the past year, while gonorrhea was the most common ever-reported STD. Almost half of all respondents who had ever had an STD had gone to a private practice for treatment (49%); in comparison, only 5% of respondents had sought treatment at an STD clinic. Respondents with a bacterial STD were seven times more likely to report going to an STD clinic than were respondents with a viral STD--except for chlamydia, which was more likely to be treated at family planning clinics. Men were significantly more likely than women to go to an STD clinic. Young, poor or black respondents were all more likely to use a family planning clinic for STD treatment than older, relatively wealthy or white respondents. Age, sexual history and geographic location did not predict particular types of treatment-seeking. CONCLUSIONS: The health care utilization patterns for STD treatment in the United States are complex. Specific disease diagnosis, gender, race and income status all affect where people will seek treatment. These factors need to be taken into account when STD prevention strategies are being developed. (+info)
Women's interest in vaginal microbicides.
CONTEXT: Each year, an estimated 15 million new cases of sexually transmitted diseases (STDs), including HIV, occur in the United States. Women are not only at a disadvantage because of their biological and social susceptibility, but also because of the methods that are available for prevention. METHODS: A nationally representative sample of 1,000 women aged 18-44 in the continental United States who had had sex with a man in the last 12 months were interviewed by telephone. Analyses identified levels and predictors of women's worry about STDs and interest in vaginal microbicides, as well as their preferences regarding method characteristics. Numbers of potential U.S. microbicide users were estimated. RESULTS: An estimated 21.3 million U.S. women have some potential current interest in using a microbicidal product. Depending upon product specifications and cost, as many as 6.0 million women who are worried about getting an STD would be very interested in current use of a microbicide. These women are most likely to be unmarried and not cohabiting, of low income and less education, and black or Hispanic. They also are more likely to have visited a doctor for STD symptoms or to have reduced their sexual activity because of STDs, to have a partner who had had other partners in the past year, to have no steady partner or to have ever used condoms for STD prevention. CONCLUSIONS: A significant minority of women in the United States are worried about STDs and think they would use vaginal microbicides. The development, testing and marketing of such products should be expedited. (+info)
Pregnancies averted among U.S. teenagers by the use of contraceptives.
CONTEXT: The personal and social costs associated with teenage pregnancy in the United States concern many policymakers and researchers, yet the role of contraception in preventing these pregnancies has not been adequately quantified. METHODS: Published estimates of contraceptive effectiveness were applied to 1995 National Survey of Family Growth data on sexual and contraceptive practices in order to estimate the number of pregnancies averted through the use of contraceptives by U.S. teenagers. Four scenarios of contraceptives access--from current levels of access to highly restricted access--and teenagers' sexual and contraceptive practices in response to such restrictions are used to project the potential impact on pregnancies among teenagers. RESULTS: Current levels of contraceptive use averted an estimated 1.65 million pregnancies among 15-19-year-old women in the United States during 1995. If these young women had been denied access to both prescription and over-the-counter contraceptive methods, an estimated one million additional pregnancies (ranging from 750,000 to 1.25 million) would have occurred, assuming some decrease in sexual activity. These pregnancies would have led to 480,000 live births, 390,000 abortions, 120,000 miscarriages, 10,000 ectopic pregnancies and 37 maternal deaths. CONCLUSIONS: Contraceptive use by teenage women prevents pregnancies and negative pregnancy-related health consequences that can disrupt the lives of adolescent women and that have substantial societal costs. Continued and expanded access to contraceptives for adolescents is a critically important public health strategy. (+info)
Ethanol as a hypnotic in insomniacs: self administration and effects on sleep and mood.
The purpose of this study was to assess the effects of low ethanol doses on sleep and mood and to assess its reinforcing effects used as a hypnotic. Twenty healthy adults, aged 21-45 yrs, all moderate social drinkers, were studied: eleven subjects had insomnia and nine were normal sleepers, as documented by clinical polysomnography. On two sampling nights each, ethanol (0.5 g/kg) or placebo was administered before sleep in color-coded cups presented in three doses (0.2, 0.2, and 0.1 g/kg) separated by 15 min. On three subsequent nights subjects chose their preferred presleep beverage (0.2 g/kg ethanol or placebo) based on cup color and were given an opportunity for 3 additional refills (0.2 g/kg each) of the chosen beverage at 15 min intervals, yielding a total possible dose of 0.8 g/kg. Insomniacs chose ethanol 67% of nights and normals 22%. Insomniacs chose significantly more ethanol refills than normals for an average nightly dose of 0.45 g/kg and normals took significantly more placebo refills. On the sampling nights 0.5 g/kg ethanol reduced REM sleep for both groups for the 8-hr sleep period and in insomniacs increased stage 3-4 sleep and reduced stage 1 sleep during the first half of the night to the level seen in the normals. Other sleep variables were not altered in either group or halves of the night. Presleep improvements in the Profile of Mood States tension and concentration factors were also associated with ethanol administration. Thus, acutely, both sleep and mood effects appear to be associated with the reinforcing effects of ethanol as a hypnotic for insomniacs. (+info)
Prevalence and social correlates of cardiovascular disease risk factors in Harlem.
OBJECTIVES: This study examined the prevalence, social correlates, and clustering of cardiovascular disease risk factors in a predominantly Black, poor, urban community. METHODS: Associations of risk factor prevalences with sociodemographic variables were examined in a population-based sample of 695 men and women aged 18 to 65 years living in Central Harlem. RESULTS: One third of the men and women were hypertensive, 48% of the men and 41% of the women were smokers, 25% of the men and 49% of the women were overweight, and 23% of the men and 35% of the women reported no leisure-time physical activity over the past month. More than 80% of the men and women had at least 1 of these risk factors, and 9% of the men and 19% of the women had 3 or more risk factors. Income and education were inversely related to hypertension, smoking, and physical inactivity. Having 3 or more risk factors was associated with low income and low education (extreme odds ratio [OR] = 10.2, 95% confidence interval [CI] = 3.0, 34.5 for education; OR = 3.7, CI = 1.6, 8.9 for income) and with a history of unstable work or of homelessness. CONCLUSIONS: Disadvantaged, urban communities are at high risk for cardiovascular disease. These results highlight the importance of socioenvironmental factors in shaping cardiovascular risk. (+info)
Changing trends in barriers to cataract surgery in India.
Cataract is a major cause of blindness in Asia. Efforts in India to provide cataract surgical services have had limited success in reaching the cataract-blind population. Earlier studies identified the major barriers to cataract surgery as poverty, lack of transportation or felt need, or sex related; and the critical barriers in rural areas as lack of awareness, difficult access, and cost. Compared with these earlier data, the results of the present study in Karnataka State indicate a shift in the character of the barriers. They now appear to be more related to case selection and service provision. These shifts are analysed and alternative strategies to increase the uptake to cataract surgery are recommended. (+info)