Studies investigating differences in risk factor behaviors and prevalence of the human papillomavirus (HPV) infection and Chlamydia trachomatis, among women living on both sides of the U.S. Mexico border had never been conducted, until now. Determination of HPV infection and Chlamydia are not routinely conducted among reproductive age women in either country. In addition, differences in cytology reporting methods between countries prohibits the direct comparison of rates of cervical dysplasia along the U.S. Mexico border from readily available clinic data. Only specifically designed research projects, such as this one, which standardize cytology reporting systems and assess the prevalence of sexually transmitted diseases in a healthy reproductive age population of women could begin to address the problem of sexually transmitted diseases (STDs) and cervical cancer along the U.S. Mexico border.

A cross sectional survey was conducted, recruiting women aged 15 years and older living in the following pairs of Arizona, U.S.-Sonora, Mexico communities: Douglas-Agua Prieta; Nogales AZ-Nogales SO; Yuma-San Luis Rio Colorado; Tucson-Hermosillo. A total of 2,437 participants were recruited from those women attending health clinics for routine gynecological care.

Women aged 15 years and older were recruited from Family Planning Clinics at Community Health Centers and Planned Parenthood clinics located in the Arizona border cities, and Public Health Clinics in the clinics in the Sonora Mexico border cities. Approximately 300 women at each clinic were screened for HPV, Chlamydia and abnormal cytology, and were asked to complete a risk factor questionnaire. By the end of the study, 2,437 women had been interviewed - 1,400 in Sonora, Mexico and 1,037 in Arizona, U.S.

1,257 (89.8%) had Pap smears which were reviewed. Of those enrolled in the U.S., 980 (94.5%) had Pap smears which were reviewed. There were 143 (10.2%) Pap smears in Mexico and 57 (5.5%) in the U.S. which were unavailable for review.

Significant findings from the Pap smear data collected on both sides of the border show that Mexican women have higher prevalence of abnormal cytology than women in the United States (11.2% vs. 6.9%) with the overall prevalence 9.3% abnormal. Women enrolled at the Agua Prieta/Cananea clinic site had the highest prevalence of abnormal Pap smears (12.4%) and women enrolled at the Nogales Arizona clinic site had the lowest (5.2%). All Mexican study sites had the higher prevalence rates of abnormal Pap smears than their sister U.S. sites.

Mexican women had a higher prevalence of cervical dysplasia than U.S. women (5.1% vs. 1.6%). In addition, Mexican women had higher rates of inflammatory changes on Pap smears than U.S. women (61.2% vs. 40.9%). The main finding of the Pap smear data collected in this study is that in spite of an apparent lower risk profile of known predisposing factors for cervical dysplasia and neoplasia in Mexican women (i.e. lower age at first intercourse and fewer number of lifetime male partners), they manifest higher rates of abnormal Pap smears overall, and higher rates of cervical dysplasia, specifically.

"Mural de la Serpiente (Mural of the Serpent)" Nogales, Sonora