Enzyme-linked immunosorbent assay (ELISA) with mycobacterial crude antigens for the sero-epidemiological diagnosis of active tuberculosis.

In search for reliable, nonexpensive procedures for tuberculosis diagnosis suitable for seroepidemiological studies in leprosy-endemic areas, enzyme-linked immunosorbent assays (ELISAs) with whole intact bacilli, whole lipid-free bacilli and protein-enriched soluble extracts from the H37Rv Mycobacterium tuberculosis strain were evaluated. Sera tested came from 47 active, pulmonary tuberculosis adult cases, 60 household contacts of active tuberculosis cases, 20 lepromatous leprosy adult patients, and 67 healthy adult controls obtained from low and high leprosy and tuberculosis endemicity areas. There was no influence of such endemicity levels in the number of positive results in control sera. Antibody levels obtained with each of the antigens in ELISAs were significantly different in tuberculosis patients and the control groups. Ten percent of tuberculosis contacts were positive with some of the antigens and three of them showed suggestive chest radiographs. The best combination for a high number of positive results with tuberculosis sera and low positive results with leprosy sera was the BCG soluble extract (91% and 15%, respectively). This preparation also yielded excellent sensitivity and specificity values for tuberculosis (91.5% and 92.5%, respectively). These data suggest that BCG soluble extract ELISAs could provide helpful information to estimate tuberculosis prevalence only in leprosy-free areas, under a situation of unavailability of purified antigens. In pulmonary cases, sputum microscopic examination and culture have higher sensibility than serodiagnosis; therefore, the utilization of BCG soluble extract ELISAs as a diagnostic aid in individual patients with suspected active tuberculosis only can be useful in extrapulmonary cases.

[The epidemiology of AIDS/HIV in Mexico: from 1983 to March 1995]. / Epidemiología del SIDA/VIH en México; de 1983 a marzo de 1995.

The purpose of this study is to analyze the HIV/AIDS magnitude, distribution, frequency, patterns, trends, risk factors, risk groups, estimation and evaluation of interventions in Mexico during the last twelve years. Results of a summary of statistics and results from several sources are presented including the National Registry of AIDS cases, HIV sentinel surveillance in 18 cities of the country, analysis of death certificates, cross-sectional, longitudinal, observational, and intervention studies. As of March 1995, 34,230 AIDS cases, 120,000 HIV infections and 21,000 AIDS deaths are estimated. A damaged exponential growth with duplication of AIDS cases every 18 months can be seen. Epidemiological patterns of transmission are found primarily among men with homosexual and bisexual practices. The male:female ratio is 6 to 1. In 1992 AIDS was the 19th cause of death among the general population. At least two patterns of transmission have been identified: one is the western-urban pattern which contributes with more than 90% of cases and the other, more recent, has been described as Caribbean-rural. Blood transmission of AIDS shows a downward trend, and heterosexual and perinatal transmission is slightly increasing. Seroprevalence among adults is 0.06%: however, among groups with risk practices, rates up to 50% have been found. Risk factors are similar to those described in the literature in other countries, and have been used for designing interventions. Evaluation of interventions has been accomplished by demonstrating positive results in the prevention of blood transmission and sexual transmission among female commercial sex workers; prevention efforts directed to men with homosexual practices have not been successful. Between 77,000 and 88,000 cumulated AIDS cases are estimated in Mexico for the year 2000.

[Sexually transmitted diseases and the HIV/AIDS epidemic]. / Las enfermedades de transmisión sexual y la epidemia de VIH/SIDA.

Studies on sexually transmitted diseases (STD) during the previous years in Mexico are discussed. The information sources were: a) Surveys among commercial sex workers. Since 1990, 1,386 women have been studied in four federal states through structured questionnaires and laboratory tests. Prevalence of different STD's has been significant (syphilis (VDRL, FTA-abs) 23.7%; chlamydiosis (Ag IF) 12.9%; gonorrhea (Ag, ELISA) 11.5%; anti-HBs 11.0%; herpes 1,2 (IgM) 9.3%, HBsAg 5.7%. Frequency of HIV (ELISA, Western blot) has been low; 0.5%. In 1994, 662 women were studied in Mexico City, with different laboratory techniques for chlamydiosis and gonorrhea (culture), hepatitis B (anticore antibodies) and herpes (total antibodies) with the following results: syphilis 1.5-12%; chlamydiosis 10.8-11.7%; gonorrhea 0-5.9%; hepatitis B 0-7.1%; herpes 44.7-78%; and HIV 0-1.4%. b) Surveys among men with homosexual and bisexual practices. 325 subjects have been studied in three federal states using methods similar to those of the 1990 survey. Contrasting with results among women, HIV prevalence was found to be high; (18.8%), and considerable for other STD's: anti-HBsAg 28.6%, syphilis 34.9%, recent herpes 10.9%, HBsAg 5.0%, chlamydiosis (Ag, IF) 4.3%, herpes simplex 1,2 (Ag, IF) 4.7%, gonorrhea (Ag, ELISA) 2.8%. c) Patient clinical studies. The clinical interrelationship between different STD and HIV infection has been studied; clinical differences are described between patients with condylomata or syphilis depending on HIV serostatus. Implications of the interrelationship between different STD's and HIV infection for the prevention and control of these diseases are discussed.