HIV Prevention Method Preferences Within Sexual Partnerships Reported by HIV-Negative MSM and TW in Tijuana, Mexico.

To assess the potential for decreased condom use as pre-exposure prophylaxis (PrEP) is scaled-up in Latin America, we examined HIV prevention method preferences (neither PrEP nor condoms, condoms only, PrEP only, or PrEP with condoms) within 1302 sexual partnerships reported by 397 HIV-negative men who have sex with men (MSM) and transgender women (TW) in Tijuana, Mexico. Using PrEP with condoms (56%) was preferred to using condoms only (24%), using PrEP only (17%), and using neither PrEP nor condoms (3%). Compared to using condoms only, using PrEP only was preferred within primary (adjusted odds ratio [AOR] = 4.13, 95% confidence interval [CI] 1.92, 8.90) and condomless sex practicing (AOR = 6.97, 95% CI 3.92, 12.40) partnerships, suggesting PrEP use may not displace condom use among MSM and TW in Tijuana and other similar settings.

Oral and vaginal HIV pre-exposure prophylaxis product attribute preferences among female sex workers in the Mexico-US border region.

To assess the potential uptake of HIV pre-exposure prophylaxis (PrEP) products among female sex workers (FSWs) vulnerable to HIV infection, we examined the influence of product attributes on willingness to use products among 271 HIV-negative FSWs in Tijuana and Ciudad Juarez, Mexico (2016-2017). Via five-point Likert scale ratings, participants indicated their willingness to use hypothetical products with six attributes: formulation (pill, gel, liquid, or ring), frequency of use (daily, on-demand, or monthly), cost per use (10 or 200 pesos), effectiveness (40% or 80%), side effects (none or mild), and access point (healthcare clinic or non-governmental organization). Conjoint analysis was used to determine the impact of attributes on product ratings and identify preferred product attributes. Multinomial logistic regression was used to identify factors associated with formulation preferences. In both cities, formulation and frequency of use had the greatest impact on ratings. Participants in Ciudad Juarez indicated a strong preference for oral pills, whereas participants in Tijuana indicated roughly equal preferences for oral pills and vaginal gels. Monthly product use was preferred in both cities. Compared to preferring oral pills (38%), preferring vaginal gels (28%) was associated with practicing vaginal lubrication (adjusted odds ratio = 2.08; 95% confidence interval: 1.07-4.04). Oral PrEP may be acceptable to many FSWs in Tijuana and Ciudad Juarez; however, continued development of behaviorally-congruent vaginal PrEP products may also facilitate uptake and ensure sufficient coverage.

Condom use among female sex workers and their non-commercial partners: effects of a sexual risk intervention in two Mexican cities.

The purpose of this study was to examine whether a brief behavioural intervention promoting condom use among female sex workers (FSWs) and their clients had the added benefit of increasing condom use among FSWs and their steady, non-commercial partners (e.g. husbands, boyfriends). Participants were 362 FSWs, aged ≥18 years, living in Tijuana or Ciudad Juarez, Mexico, who received a behavioural intervention to promote condom use with clients. Repeated-measures negative binomial regression was used to assess FSWs' condom use with steady partners versus clients across time. Results showed that FSWs engaged in unprotected sex with steady partners more than with their clients, and that the intervention changed FSWs' condom use with clients but not their steady partners. HIV-prevention interventions for FSWs should promote consistent condom use across partner type. Targeting couples rather than individuals may also be necessary.

Risk factors associated with chlamydia and gonorrhoea infection among female sex workers in two Mexico-USA border cities.

Female sex workers (FSWs) aged ≥18 years without known HIV infection living in Tijuana and Ciudad Juarez, Mexico who had recent unprotected sex with clients underwent interviews and testing for chlamydia and gonorrhoea using nucleic acid amplification. Correlates of each infection were identified with logistic regression. Among 798 FSWs, prevalence of chlamydia and gonorrhoea was 13.0% and 6.4%, respectively. Factors independently associated with chlamydia were younger age, working in Tijuana versus Ciudad Juarez and recent methamphetamine injection. Factors independently associated with gonorrhoea were working in Tijuana versus Ciudad Juarez, using illegal drugs before or during sex, and having a recent male partner who injects drugs. Chlamydia and gonorrhoea infection were more closely associated with FSWs' drug use behaviours and that of their sexual partners than with sexual behaviours. Prevention should focus on subgroups of FSWs and their partners who use methamphetamine and who inject drugs.

Associations between migrant status and sexually transmitted infections among female sex workers in Tijuana, Mexico.

OBJECTIVE: To examine associations between migration and sexually transmitted infection (STI) prevalence among Mexican female sex workers (FSW). METHODS: FSW aged 18 years and older in Tijuana, Baja California (BC) underwent interviews and testing for HIV, syphilis, gonorrhoea and chlamydia. Multivariate logistic regressions identified correlates of STI. RESULTS: Of 471 FSW, 79% were migrants to BC. Among migrant FSW, prevalence of HIV, syphilis, gonorrhoea, chlamydia and any STI was 6.6%, 13.2%, 7.8%, 16.3% and 31.1% compared with 10.9%, 18.2%, 13.0%, 19.0% and 42.4% among FSW born in BC. A greater proportion of migrant FSW were registered with local health services and were ever tested for HIV. Migrant status was protective for any STI in unadjusted models (unadjusted odds ratio 0.61, 95% CI 0.39 to 0.97). In multivariate models controlling for confounders, migrant status was not associated with an elevated odds of STI acquisition and trended towards a protective association. CONCLUSIONS: Unexpectedly, migrant status (vs native-born status) appeared protective for any STI acquisition. It is unclear which social or economic conditions may protect against STI and whether these erode over time in migrants. Additional research is needed to inform our understanding of whether or how geography, variations in health capital, or social network composition and information-sharing attributes can contribute to health protective behaviours in migrant FSW. By capitalising on such mechanisms, efforts to preserve protective health behaviours in migrant FSW will help control STI in the population and may lead to the identification of strategies that are generalisable to other FSW.

First molecular surveillance report of HIV type 1 in injecting drug users and female sex workers along the U.S.-Mexico border.

HIV prevalence is increasing among high-risk populations in the Mexican-U.S. border cities of Tijuana and Ciudad Juarez. In 2005, the molecular epidemiology of HIV-1 was studied among injecting drug users (IDU) and female sex workers (FSW) in these cities, which are corridors for over two-thirds of the migrant flow between Mexico and the United States. Eleven samples (eight IDU and three FSW) were successfully amplified, sequenced, and analyzed. The results revealed that all 11 samples were subtype B. There was no phylogenetic clustering or separation of the strains between IDU and FSW or between Tijuana and Ciudad Juarez nor was the Mexican strain phylogenetically distinct from other subtype B strains. Two of three drug naive FSWs had low-level HIV-1 resistance mutations. This community-based study demonstrated that HIV-positive IDUs and FSWs in Ciudad Juarez and Tijuana were predominantly infected with subtype B. Further prevalence studies on HIV-1 resistance mutations among FSWs in these border cities are warranted.

Attendance at health promotion programs: baseline predictors and program outcomes.

As part of a family cardiovascular health promotion project, 111 Mexican-American and 95 Anglo-American families with fifth- or sixth-grade children were assigned to either a primary prevention program involving 18 sessions or to a control condition. This article evaluates predictors of attendance at the year long sequence of sessions in the intervention group. In addition it considers the relationship between attendance and program outcomes. Low baseline scores on physical activity and cardiovascular fitness measures were associated with higher attendance for both children and adults. High initial health knowledge and self-motivation were also associated with attendance. Multiple regression analysis showed that adult attendance was significantly predicted by a model including completion of a three-day food record, low exercise, higher socioeconomic status, family adaptability, and self-motivation. Attendance was correlated with greater knowledge gains and larger reductions in blood pressure. The results indicate that motivated families who are in greater need of conditioning attended more sessions in a health promotion program.

A family approach to cardiovascular risk reduction: results from the San Diego Family Health Project.

The effectiveness of a family-based cardiovascular disease risk reduction intervention was evaluated in two ethnic groups. Participants were 206 healthy, volunteer low-to-middle-income Mexican-American and non-Hispanic white (Anglo-American) families (623 individuals), each with a fifth or a sixth-grade child. Families were recruited through elementary schools. Half of the families were randomized to a year-long educational intervention designed to decrease the whole family's intake of high salt, high fat foods, and to increase their regular physical activity. Eighty-nine percent of the enrolled families were measured at the 24-month follow-up. Both Mexican- and Anglo-American families in the experimental groups gained significantly more knowledge of the skills required to change dietary and exercise habits than did those in the control groups. Experimental families in both ethnic groups reported improved eating habits on a food frequency index. Anglo families reported lower total fat and sodium intake. There were no significant group differences in reported physical activity or in tested cardiovascular fitness levels. Significant differences for Anglo-American experimental vs. control adult subjects were found for LDL cholesterol. Significant intervention-control differences ranging from 2.2 to 3.4 mmHg systolic and/or diastolic blood pressure were found in all subgroups. Direct observation of diet and physical activity behaviors in a structured environment suggested generalization of behavior changes. There was evidence that behavior change persisted one year beyond the completion of the intervention program. It is concluded that involvement of families utilizing school based resources is feasible and effective. Future studies should focus on the most cost-effective methods of family involvement, and the potential for additive effects when family strategies are combined with other school health education programs.

Exercise suppresses heritability estimates for obesity in Mexican-American families.

In multivariate analysis, suppressor variables attenuate the true relationship between predictor and outcome variables. Although suppressor variables relationships were described more than 45 years ago, few examples have been reported in the health care literature. We studied the correspondence between body mass in 111 Mexican-American families. Estimates of exercise suppressed the correlation between body mass for some dyads within these families. We concluded that the suppressor variable relationship may cause underestimates of heritability in multivariate studies.

Predictors of dietary change in Mexican American families participating in a health behavior change program.

Previous research indicates that Mexican Americans have dietary patterns related to cardiovascular disease risk factors. Research on health beliefs in this ethnic group suggests that Mexican Americans may be less amenable to interventions based on cognitive-behavioral change models. Our study derives from the experience in a community trial, the San Diego Family Health Project, in which Mexican American families were recruited for a structured heart health intervention program. We examined correlations between one-year dietary change scores (three-day sodium, three-day fat, 24-hour sodium, 24-hour fat) and a set of predictor variables derived from social learning theory. Both adults and children had lower intake scores after the intervention, except for children's 24-hour sodium scores. Our correlational analysis found only weak and somewhat inconsistent relationships between theoretically based predictor and outcome variables for adults. The children's results showed statistically significant correlations between two theoretical variables (self-efficacy and supporting others' dietary change) and three-day fat and 24-hour sodium intake. We discuss the implications for cardiovascular disease risk reduction interventions with Mexican Americans.

Aggregation of dietary calories, fats, and sodium in Mexican-American and Anglo families.

There seems to be a consensus that family influences on dietary habits are important, but few studies have addressed this issue directly. To clarify inconsistent findings, we studied the aggregation of dietary fats, sodium, and calories in 95 Anglo and 111 Mexican-American families. Their diet was determined by 24-hour recall, a three-day food record, and a food frequency questionnaire, along with a measure of the urinary sodium-potassium ratio. There was evidence of moderate aggregation of all dietary variables in both ethnic groups. In Anglo families, spouse-spouse, but not sibling-sibling, correlations tended to be significant. The diets of the younger children, but not the older children, were related to their parents' diets. In Mexican-American families, both spouse-spouse and sibling-sibling correlations tended to be significant. The mothers' diets were more highly correlated with the children's diets than were the fathers'.

Aggregation of physical activity habits in Mexican-American and Anglo families.

It is believed that families are important influences on the development of health habits, and the purpose of the present study was to examine the familial aggregation of physical activity. Physical activity habits were assessed by standardized interview in adults and children in 95 Anglo families and 111 Mexican-American families. The results indicated a moderate degree of aggregation of physical activity in both samples, and adjustment for body mass index was inconsequential. Intrafamily correlations tended to be higher in Mexican-Americans. Mother-child correlations usually were higher than father-child correlations. These findings support the hypothesis that the family is a significant influence on physical activity.

Aggregation of blood pressure in Anglo-American and Mexican-American families.

We investigated the aggregation of blood pressure within 95 Anglo-American and 111 Mexican-American families. Degree of genetic relatedness was evaluated by calculating separate correlations for spouses and for each spouse with both same-sex and opposite-sex offspring. In addition, sibling correlations were evaluated. These analyses were performed separately for Anglo-American and Mexican-American families. Replicating earlier findings, correlations between blood pressures of Anglo spouses were nonsignificant. However, there were significant spousal correlations in the Mexican-American group. For Anglo-American families, there were significant associations between blood pressures of fathers and sons and between blood pressures of mothers and daughters. Correlations between blood pressures for opposite-sex parent-child pairs were nonsignificant. In the Mexican-American group, there were significant correlations between fathers' blood pressures and those of both male and female offspring. For mothers, blood pressures were weakly correlated with all other family members. These relationships remained after adjustment for age, body mass index, and measures of dietary habits and activity levels. In general, blood pressure aggregation was greater in Mexican-American families.

Recruitment issues, health habits, and the decision to participate in a health promotion program.

To understand the external validity of experimental studies, it is important to estimate the extent to which the participants are representative of the general population. This paper describes recruitment methods and considers the representativeness of participants in the San Diego Family Health Project. The study was designed to experimentally evaluate the effectiveness of a family-based behavior change intervention in Anglo and Mexican-American families. Initial contact with the families was made through a household health survey that was sent home with all fifth- and sixth-grade children in 12 participating elementary schools. The survey asked about a variety of demographic characteristics, dietary habits, and physical activity habits. Parents were also asked if they were interested in participating in the project. Respondents were classified by level of participation into one of three groups: not interested, expressed initial interest but did not attend the recruitment meeting, and volunteered to participate. Level of participation was the independent variable in the analyses. In separate analyses for Anglo and Mexican-American responders, our data suggested many similarities and a few differences among participant groups. The differences that were observed suggest that participants may already have healthier diets than nonparticipants, although only one of four dietary variables differed by participation status in each ethnic group. The external validity of these data and general recruitment issues are discussed.