Prevalence and risk factors for Chlamydia trachomatis infection in low-income rural and suburban populations of Mexico.

BACKGROUND AND OBJECTIVES: In rural and suburban populations in developing countries, there is a lack of knowledge about the occurrence of Chlamydia trachomatis infection and the risk factors involved. Knowledge of the prevalence of infection is necessary to develop screening policies. GOALS: To estimate the prevalence of C. trachomatis infection in a rural and a suburban area of Oaxaca, Mexico, and to identify behavioral and demographic risk factors, as well as clinical findings, that may be related to this disease. STUDY DESIGN: A cross-sectional survey was conducted among 559 women attending the Rural Hospital of Tlacolula, Oaxaca in 1994. Genitourinary signs and symptoms were recorded using a structured questionnaire and a speculum examination of the cervix. Endocervical specimens were obtained for the direct immunofluorescent diagnosis of chlamydial infection. RESULTS: Results for 41 women (7.3%) were positive for chlamydia. The prevalence was the same in rural and suburban women. In a multiple logistic regression analysis, chlamydial infection was correlated highly with young age (OR, 2.3; 95% CI, 1.2 to 4.6), oral contraceptives (OR, 2.2; 95% CI, 0.7 to 6.9), number of sex partners, and genitourinary signs or symptoms. The simultaneous presence of mucopurulent cervical discharge, cervix friability, inflammatory signs of the cervix, and urinary symptoms had the highest specificity (99.6%) and positive predictive value (86.7%) for chlamydial infection detection. CONCLUSION: C. trachomatis infection is a common sexually transmitted disease in rural and suburban women in Mexico. Nearly 1 of 8 women 15 to 25 years of age may be infected. A risk factor-based screening program should be implemented in rural and urban populations in Mexico. In rural settings, women with mucopurulent cervical discharge should be treated for chlamydial infection, even without a laboratory diagnosis.

Induction of humoral immune response to Salmonella typhimurium in mouse Peyer's patches.

The mechanisms of immune response generation and regulation at the intestinal level are not well known, mainly due to the lack of suitable and reproducible methods to measure local immune responses. The Cunningham direct and indirect hemolytic plaque assay for the quantification of antibody producing cells against Salmonella in Peyer's patches of mice orally infected with Salmonella typhimurium was used. After infection IgM and IgG producing cells were determined on days 6, 9, 12 and 19. Specific antibody producing cells appeared after bacterial invasion of Peyer's patches, nine days after infection. At this time, there were more antibody producing cells in the distal part of the intestine, which correlated with a higher infection of these Peyer's patches as detected by bacterial culture. After day nine, the number of plaque forming cells was similar in both parts of the intestine. The peak of response was on day 12 and diminished on day 19. The number of IgM and IgG producing cells was similar in all days analyzed. Histological analysis of Peyer's patches of infected mice showed inflammation with disorganization and tumefaction.

[The need, supply and demand for epidemiological research personnel in the Instituto Mexicano del Seguro Social]. / Necesidades, oferta y demanda de personal en investigación epidemiológica en el Instituto Mexicano del Seguro Social.

In 1991 the Directorate of Public Health was created at the Mexican Institute for Social Security, with its epidemiologic activities oriented towards surveillance and research. This new vision, as well as the epidemiologic transition in Mexico, have raised the need for researchers training. In 1988 the Specialization Course in Public Health was developed as a response to the detected needs. This course was reformed three years later in duration, depth and name (Epidemiology instead of Public Health). The requirement of a thesis has led to the development of epidemiologic and health services research. Two diplomates in epidemiology and immunology and microbiology were also developed as a response to the need of actualization due to the advances in epidemiologic methodology in the past decades. A demand for actualization and continuous education has been expressed by the epidemiologists through a survey. The Directorate has also proposed priority themes for research in order to guide the requirements of research raised by the epidemiologist already trained at the Institute.

[Posttransfusion hepatitis. A prospective study]. / Hepatitis post transfusión. Estudio prospectivo.

This prospective study was carried out on thirty patients transfused with blood or blood products, by ten (33.3%) posttransfusion hepatitis was diagnosed; this is 15.75 cases per 1,000 U transfused. Four patients developed jaundice; six remained asymptomatic. In nine patients (90%) non-A, non-B hepatitis was diagnosed and one (10%) case was classified as hepatitis B. Two patients with non-A, non-B hepatitis developed chronic hepatitis, corroborated through percutaneous liver biopsy.

Polyclonal activation of B lymphocytes in patients with amoebic hepatic abscess.

In the course of tissue invasion by the amoeba, cellular immune responses are generated with the production of lymphokines by T lymphocytes that could induce activation of B cells. Therefore, it is possible that besides the induction of B lymphocytes specific for amoebic antigens, there could be activation of B cells with different specificities, that is, polyclonal in nature. IgM antibodies against some natural and synthetic antigens were quantified in both sera from amoebic hepatic abscess (AHA) patients and healthy controls by means of an ELISA. Titers in each case analyzed were significantly higher in AHA patients than in controls. Results indicate that there is polyclonal activation of B lymphocytes in this disease.