[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.

[The HIV/AIDS epidemic and women in Mexico]. / La epidemia de VIH/SIDA y la mujer en México.

This study presents an analysis of AIDS cases and seroprevalence of HIV infection among Mexican women, from the onset of the epidemic through June 1994, as well as the analysis of the social and cultural factors that put women in a powerless situation regarding the adoption of preventive measures. Since 1985, when the first AIDS cases among women were reported in Mexico and until June 1, 1994, a total of 2,767 cases have been reported, representing 14.8% of the total number of cases. The first cases of AIDS among women were associated to infected blood transfusions; however, in 1986, heterosexually transmitted cases began to appear. Currently, only 35% of newly reported AIDS cases are associated to blood transfusions while 64% of them are related to heterosexual transmission. In fact, two epidemics are evident: one transmitted through blood, showing a downward trend (duplication time 45 months), and a second one, heterosexually transmitted, increasing twice as fast (duplication time 27 months). The latter is expected to dominate AIDS epidemiology among women in the future. In general, women are more vulnerable to HIV/AIDS biologically, but also socially and culturally. Women's economic, social and cultural subordination to their sexual partners results in a situation that makes it difficult for them to assess their infection risk and even more, to negotiate taking preventive measures. This situation is even more disadvantageous to rural women and, together with the recent trend of the AIDS epidemic to ruralization and with internal and international migration (temporary work force migration to the USA), can result in deep demographic and social effects. We conclude that it is necessary to work on the design and assessment of preventive measures under women's control, that empower them to protect themselves even without their partner's awareness. Also, it is necessary to promote sexual education among young heterosexual couples on how to talk about sexual issues and negotiate the use of preventive measure according to their actual sexual practices.

[AIDS cases in the rural area in Mexico]. / Casos de SIDA en el área rural en México.

The objective of this paper is to describe the AIDS epidemic in rural areas of Mexico. Information from the National AIDS Registry and the 1990 XI National Census was used. Rural AIDS cases and urban cases were compared regarding notification time, sex, risk categories and migration information. Of the 19,090 AIDS cases reported to the first of July 1994, 699 (3.7%) were rural cases. The first five of these cases were reported in 1986, three years after the first cases had been reported in Mexico. The number of AIDS cases has been growing each year but in 1991. Cases have been reported by all Mexican states. The state with the highest prevalence was Nayarit with 102 cases per million inhabitants, followed by Morelos with 99, Jalisco with 90, and Colima and Tlaxcala with 84. A total of 25% of the rural cases are migrants who have been to the US, against 6.1% of cases from urban areas. The distribution by sex shows 21.3% of women affected against 14.4% of urban cases (p < 0.05). The rural female to male ratio is 1:4, while the urban ratio is 1:6. The prevalence rates are almost three times greater in men than in women. The rural AIDS pattern represents a problem not because of the number of people affected but because of the heterosexual way of transmission. We do not think that migration to the US is going to change. The rural AIDS epidemic is more recent and growing faster than that occurring in the urban setting.

[The strategy for preventing HIV/AIDS transmission via the blood and its derivatives in Mexico]. / La estrategia de prevención de la transmisión del VIH/SIDA a través de la sangre y sus derivados en México.

This study presents blood-associated AIDS epidemic trends in Mexico, including cases due to blood transfusions, cases in professional blood donors and hemophiliacs. We present also an overview of preventive measures--both legal and educative--undertaken to prevent this type of transmission and its effects on the epidemic. The first blood-associated AIDS cases in Mexico were reported in 1985, since then and up to July 1, 1994 a total of 1,728 adult cases and 116 pediatric cases have been reported (12.3% and 25% of the total cases, respectively). As in many other parts in the world, in Mexico women were markedly affected by this form of transmission; the women to men morbidity ratio is 1.35. Another group particularly affected by AIDS in Mexico are professional blood donors, who were infected because of improper management and recycling of blood transfusion centers bank materials such as plasmapheresis sets, in some blood transfusion centers in our country. Blood screening is mandatory for all blood donors in Mexico since May, 1986. A year later blood commercialization was banned because of the extremely high HIV infection prevalences found in some professional blood donors (7.2%). Since that time a whole set of preventive measures has been implemented in our country, including blood quality and safety control as well as educative interventions. Results of these measures began to become evident by the end of 1991, when newly reported blood associated AIDS cases started to decrease, as opposed to their continuous growth seen in previous years. Up to July 1, 1994 we estimate that a total of 2,750 AIDS cases have been prevented through these measures, recovering an average of 36 years of potential life for each of them. Although blood transmission preventive measures have rendered significant achievements, we still have to face some very complex challenges such as potential ruralization of the epidemic and its impact on HIV infection prevalences among potential blood donors and therefore the need to ensure blood screening in rural areas.

[The diagnosis of dengue in Mexico: an update and outlook]. / El diagnóstico del dengue en México: actualidad y perspectivas.

Few diseases have unique clinical findings sufficient to identify them. Dengue fever is not one of them, being necessary the clinical and laboratory support to confirm its diagnosis. Since dengue virus was first isolated, there has been a worldwide effort to develop cheaper and more accurate serologic diagnostic tests. Dengue hemorrhagic fever deserves closer attention because of its devastating clinical effects and lethal outcomes. In addition to the wide circulation of serotypes 1, 2 and 4 for over a decade in the Americas, the presence of Den-3 was detected again in 1994 since its last appearance in 1963 and 1977. Given the high rates of vectorial infestation and the presence of a susceptible population, the probability of circulation of this serotype in our continent is high. The present work defines the wide range of diagnostic methods available today, their advantages and disadvantages, and their importance in the epidemiological surveillance of dengue fever in Mexico.

[Mexican phenotype and genotype Vibrio cholerae 01]. / Vibrio cholerae 01 fenotipos y genotipos México.

This paper presents the phenotypical and genotypical characterization of 26922 Vibrio cholerae 01 strains isolated in Mexico from 1991 to 1993. All strains isolated were El Tor biovar. Strains were sensitive to antibiotics excluding furazolidone, streptomycin and sulfisoxasole to which we found resistance in 97% and we are using this characteristic as epidemiological markers. We detected a marked change in frequency of Inaba serotype from 1991, when it was dominant, with 99.5%, until 1992 when Ogawa serotype turned to be dominant with 95% of isolates. All Vibrio cholerae 01 strains, except one Ogawa strain, were to igenic, and V. choleraeno 01 were not toxigenic by ELISA, PCR and cell culture tests. Dominant ribotype was 5, but we found some strains with 6a pattern and two with ribotype 12. We are searching for ribotype 2 among hemolytic strains in order to learn if there is any relation to Gulf Coast strains prevalent in the USA, but until now we have not found any V. cholerae ribotype 2 in our isolates. Even if rapid tests are recommended for immediate diagnosis of cholera, it is necessary to continue bacterial isolation in order to have strains for phenotyping and genotyping studies that may support epidemiological analysis.

[Epidemiology and etiology of infectious diarrheas. The case of Mexico]. / Epidemiología y etiología de las diarreas infecciosas. El caso de México.

Gastrointestinal infections represent a health problem. It is estimated that 1647 million cases of diarrhea and 3.2 million deaths due to this cause occur among children less than five years of age per year. Those belonging to this age group have 15 times more risk of dying because of diarrhea. Cases of liquid acute diarrhea with blood represent 80% of cases, diarrhea with blood represent 10%. Most frequent causes of liquid diarrhea are enterotoxigenic Escherichia coli and rotaviruses and most frequent causes of bloody diarrhea are Shigella, E. coli (EHEC and EPEC). Campylobacter jejuni and Entamoeba histolytica. Annually 15,000 cases of typhoid fever are reported that continue being a public health problem. A negative correlation has been observed between the use of oral rehydration and infant mortality due to diarrhea. After prevention and control measures for cholera, a decrease in morbidity and mortality due to diarrhea has been observed. However, to reduce mortality due to this cause, it is necessary to treat the cases of acute dysentery and persistent diarrhea as well as to increase coverage of health care, to standardize the studies of etiology of diarrhea in Mexico, to establish surveillance centers for the study of diarrhea that give information on the distribution, frequency and trends of microbial agents and to achieve standardized microbiological and parasitological studies of etiology of diarrhea that support public health interventions as vaccination and selective administration of antibiotics.

[Years of potential life lost: their usefulness in the analysis of mortality in Mexico]. / Años de vida potencial perdidos: su utilidad en el análisis de la mortalidad en México.

The evolution of the epidemiology of mortality in developing countries requires the use of indicators additional to cause specific mortality rates. This paper presents the leading causes of potential years of life lost in Mexico in 1983, by sex. Methodologic discussion focused on age limits and relative numbers. The indicator proved useful to assess the impact of infectious diseases, accidents and homicides as causes of premature death. It was also useful to identify years of potential life lost attributable to specific age and sex groups. The use of years of potential life lost provides valuable information to epidemiologic mortality analysis.