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PubMed2005

Participatory study on feeding strategies for working donkeys used by Campesino farmers in the highlands of central Mexico.

The aim of this work was to describe the feeding strategies for donkeys used by peasant farmers in central Mexico. Feeding strategies for the dry and wet seasons are described, as well as the nutritional characteristics of the main forages and supplements used by the farmers. The extent to which the feeding practices used by farmers matched the digestible energy and crude protein requirements of donkeys for maintenance and work was determined. It was concluded that grazing on native grassland could provide enough energy and protein for donkeys at maintenance level and for those performing only a moderate amount of work. More research in required in order to have better estimates of intake and plant species preferred by donkeys under prevailing grazing conditions.

Agriculture↗
PubMed2006

Respondent-driven sampling of injection drug users in two U.S.-Mexico border cities: recruitment dynamics and impact on estimates of HIV and syphilis prevalence.

Respondent-driven sampling (RDS), a chain referral sampling approach, is increasingly used to recruit participants from hard-to-reach populations, such as injection drug users (IDUs). Using RDS, we recruited IDUs in Tijuana and Ciudad (Cd.) Juárez, two Mexican cities bordering San Diego, CA and El Paso, TX, respectively, and compared recruitment dynamics, reported network size, and estimates of HIV and syphilis prevalence. Between February and April 2005, we used RDS to recruit IDUs in Tijuana (15 seeds, 207 recruits) and Cd. Juárez (9 seeds, 197 recruits), Mexico for a cross-sectional study of behavioral and contextual factors associated with HIV, HCV and syphilis infections. All subjects provided informed consent, an anonymous interview, and a venous blood sample for serologic testing of HIV, HCV, HBV (Cd. Juárez only) and syphilis antibody. Log-linear models were used to analyze the association between the state of the recruiter and that of the recruitee in the referral chains, and population estimates of the presence of syphilis antibody were obtained, correcting for biased sampling using RDS-based estimators. Sampling of the targeted 200 recruits per city was achieved rapidly (2 months in Tijuana, 2 weeks in Cd. Juárez). After excluding seeds and missing data, the sample prevalence of HCV, HIV and syphilis were 96.6, 1.9 and 13.5% respectively in Tijuana, and 95.3, 4.1, and 2.7% respectively in Cd. Juárez (where HBV prevalence was 84.7%). Syphilis cases were clustered in recruitment trees. RDS-corrected estimates of syphilis antibody prevalence ranged from 12.8 to 26.8% in Tijuana and from 2.9 to 15.6% in Ciudad Juárez, depending on how recruitment patterns were modeled, and assumptions about how network size affected an individual's probability of being included in the sample. RDS was an effective method to rapidly recruit IDUs in these cities. Although the frequency of HIV was low, syphilis prevalence was high, particularly in Tijuana. RDS-corrected estimates of syphilis prevalence were sensitive to model assumptions, suggesting that further validation of RDS is necessary.

Adolescent↗
PubMed1991

Early neonatal mortality and cesarean delivery in Mexico City.

The relationship between cesarean delivery and neonatal mortality is presented with information from 292 early neonatal deaths (cases) and 3098 survivors (controls) born in 25 hospitals in Mexico City during the summer of 1984. The overall rate of cesarean delivery was 27%. Variations between health agencies and different social groups were not related to obstetric risk, suggesting that a sizable proportion of the operations were probably unjustified. Babies of normal birth weight (greater than or equal to 2500 gm) delivered by cesarean section were 2.5 times more likely to die in the early neonatal period compared with vaginally delivered babies of the same weight. The excess of mortality could not be explained by the effect of maternal characteristics or complications or by differences in birth weight or gestational age. It is suggested that the conditions under which the operation was performed probably explain the increased risk of early neonatal death. It is likely that poor quality of resuscitation and respiratory care are implicated in the link between "unnecessary" cesarean section and early neonatal mortality.

Birth Weight↗
PubMed1994

The introduction of Cyclofem into national family planning programmes: experience from studies in Indonesia, Jamaica, Mexico, Thailand and Tunisia. Task Force on Research on Introduction and Transfer of Technologies for Fertility Regulation, Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, Geneva, Switzerland.

Studies on the introduction of Cyclofem into family planning programmes have been undertaken in Indonesia, Jamaica, Mexico, Thailand and Tunisia. Cyclofem is a once-a-month injectable contraceptive containing 25mg medroxyprogesterone acetate and 5mg estradiol cypionate. A total of 7927 subjects were followed in close to routine service delivery conditions in primary and secondary family planning outlets. The studies confirmed the high efficacy of the method with 12-month pregnancy rates ranging from 0 to 0.7%. Major differences were seen in reasons and rates of discontinuation between countries, the overall 12-month life table discontinuation rates ranging from 33.5% in Indonesia to 71.8% in Tunisia. The reasons for discontinuation in each of the five countries are described, differences between countries contrasted, and service delivery issues which should be addressed further, raised.

Adolescent↗
PubMed1983

A survey of pathogenic and free-living amoebae inhabiting swimming pool water in Mexico City.

A survey of pathogenic and free-living amoebae in swimming pool waters of Mexico City was performed. Among the organisms isolated those which have public health importance were Naegleria fowleri Carter and Acanthamoeba castellanii Douglas. Amoebae of the genera Acanthamoeba, Naegleria, and Vahlkampfia were recovered in their cystic stage while those specimens of the genera Amoeba, Entamoeba, Thecamoeba, and Vanella were recovered only in their trophic stage during this study. Amoebae were concentrated through filtration procedures and subsequently cultured in different culture media. Nonpathogenic amoebae also isolated by culture included: Amoeba proteus (Pallas) Leidy, Amoeba striata Penard, Paratetramitus jugosus Page, Acanthamoeba astronyxis Ray and Hayes, Vahlkampfia avara Page, Vahlkampfia inornata Page, Thecamoeba verrucosa Ehrenberg, and Vanella mira Schaeffer. Trophozoites of Entamoeba gingivalis Gros, were also recovered, both directly and by culture. Most commonly found were amoebae of the species Naegleria gruberi Schardinger (59.02%), N. fowleri (16.77%), and A. castellanii (7.64%). Least-frequently found amoebae belonged to the species Thecamoeba verrucosa (0.12%). All isolated strains of N. fowleri and A. castellanii were thermophilic at 45 and 40 degrees C, respectively, and also pathogenic when inoculated into white mice. More populated by amoebae were those swimming pools of the indoor type with an inner side garden. It was also shown that the free residual chloride values of 0.50 to 1.5 mg/liter, ordinarily used in pool waters, are not adequate for elimination of amoebae.

Amoeba↗
PubMed1990

Aneuploidies, chromosome aberrations and dominant gene mutations detected in 113,913 consecutive newborn children in Mexico.

Data on 113,913 liveborn children from a hospital in Guadalajara, Jalisco (Mexico), were analysed for birth defects (BD); mutation rates were calculated for sporadic aneuploidy, chromosome aberrations and dominant gene mutations. The results showed a general incidence of 13.92 BD cases per 1000 liveborns, of which 1.64% were chromosomal abnormalities, 1.50% were aneuploid, 0.14% were structural chromosome aberrations and 3.23% were dominant gene mutations. The mutation rates were 8.20 x 10(-4) chromosomal abnormalities, 7.5 x 10(-4) aneuploidies, 7.0 x 10(-5) chromosome aberrations and 1.61 x 10(-3) dominant gene mutations/gamete/generation, respectively. The lethality rate was 15.32% of the liveborns with BD. The described findings estimate the incidence of new human mutants detected at birth in a sample of the Mexican population. They show that the rate for some aneuploidies are similar to those found in other populations previously reported in the literature but the rates of chromosome and dominant gene mutations were different.

Aneuploidy↗
PubMed1980

The epidemiology of Entamoeba histolytica in Mexico City. A pilot survey I.

Stocks of intestinal amoebae isolated from hospital patients in Mexico City and grown in monoxenic culture were compared among themselves and with those already described (SARGEAUNT & WILLIAMS, 1979), using the electrophoretic patterns of four enzymes: glucose phosphate isomerase (GPI), phosphoglucomutase (PGM), L-malate:NADP+ oxido-reductase (oxalacetate-decarboxylating) (ME) and hexokinase (HK). New isoenzyme groups (SARGEAUNT & WILLIAMS, 1979) of all the amoebae, including Entamoeba histolytica have been demonstrated. Amongst these have been found seven more groups of E. histolytica, two new groups of E. hartmanni, one new group of Dientamoeba fragilis and one new group of E. coli. Of the seven new groups of E. histolytica three are known to originate from patients with clinical amoebiasis whilst the remainder are from asymptomatic subjects. Only 11.2% of the 125 isolations were associated with clinical amoebiasis, and these are clearly distinguished from the isolations from asymptomatic patients by their electrophoretic isoenzyme pattern.

Amoeba↗
PubMedDate not supplied

Giardia lamblia: isoenzyme analysis of 19 axenic strains isolated from symptomatic and asymptomatic patients in Mexico.

Infection of the small intestine of humans with the parasitic protozoon Giardia lamblia may have an asymptomatic course, or it may produce acute or chronic diarrhoea. In order to establish if the different clinical outcome of giardiasis in children could be due, at least partially, to strain differences, 19 isolates from asymptomatic and symptomatic cases studied in Mexico City were cultured under axenic conditions and the isoenzyme electrophoretic patterns of 10 different enzymes were compared. Strains from carriers and from symptomatic cases of giardiasis were equally amenable to isolation and axenization. Isoenzyme electrophoresis demonstrated remarkable homogeneity in 7 enzyme patterns for all 19 isolates, except for phosphoglucomutase, for which 3 different zymodemes were found. Therefore, these isolates of G. lamblia, obtained from a single geographical location, tended to be genetically homogeneous. In addition, there were no consistent zymodeme differences between isolates from symptomatic and asymptomatic human infections.

Animals↗
PubMedDate not supplied

Incidence of localized cutaneous leishmaniasis (chiclero's ulcer) in Mexico.

Cutaneous leishmaniasis in Mexico was first described in 1912. Since then, its existence has been repeatedly confirmed in the forest regions of the peninsula of Yucatan. In order to obtain reliable knowledge about the magnitude of this problem, we questioned and skin-tested a sample of 449 persons randomly selected from men aged 15-45 years. We found a positivity rate of 24 to 90% (mean 43%) in the seven rural health posts studied. Furthermore, 72 patients were examined between January and December 1987 by parasitological investigation (smear, isolation, culture and/or biopsy) and the Montenegro skin test; 56 had acquired the disease in 1987. Based on these data, we found an annual incidence rate of 508 per 100,000 inhabitants. Further long-term studies are indicated to determine the incidence and prevalence rates for this disease in other parts of the country.

Adolescent↗
PubMedDate not supplied

Predisposition of individuals and families in Mexico to heavy infection with Ascaris lumbricoides and Trichuris trichiura.

Stool specimens from 90% of the population of 2 marginal communities in Coatzacoalcos, Mexico, were examined by the Kato-Katz technique for the estimation of eggs per gram of faeces (epg). Average epg values for Ascaris lumbricoides and Trichuris trichiura were calculated for each family in the community, based on the arithmetic mean epg of family members for each parasite. 39 families were classified as either lightly or heavily infected with A. lumbricoides and infected members were treated with mebendazole. A. lumbricoides expelled following treatment were collected from the children 2-10 years of age, and reinfection was monitored monthly for 6 months. At the end of the reinfection interval, a final stool specimen was collected from all family members and those infected were treated. Again, A. lumbricoides expelled by the children 2-10 years of age were collected. There was a significant correlation between the number of A. lumbricoides expelled by the children at the first and second treatments as well as in epg values before the first and second treatments for both A. lumbricoides and T. trichiura in children (2-10 years) and adults (greater than 19 years). At the family level, there were significant correlations between the values of family mean epg before each treatment for both A. lumbricoides and T. trichiura.

Animals↗
PubMed1985

Venom properties of the rattlesnakes (Crotalus) inhabiting the Baja California region of Mexico.

Seven species of rattlesnakes (genus Crotalus) from Baja, Mexico, were investigated for venom yield, protein content, lethal toxicity, 'Mojave toxin' content and hemorrhagic, esterase (BAEE), phosphodiesterase and protease activities. Venom yield was lowest in C. catalinensis and C. enyo enyo and highest in C. ruber ruber. All venoms exhibited esterase and phosphodiesterase activities, except that three (of 14) specimens of C. e. enyo lacked esterase activity. Protease activity was extremely low or absent in adult C. e. enyo, adult C. mitchellii mitchellii, adult C. viridis caliginis and juvenile C. r. ruber venoms. The venom of C. m. mitchellii was the only venom lacking hemorrhagic activity. This venom also had the highest lethal toxicity (i.p. LD50 0.13 - 0.24 mg/kg) in mice, and was the only venom that exhibited a toxin antigenically related to 'Mojave toxin'.

Animals↗
PubMed1994

Scorpionism and serotherapy in Mexico.

In Mexico, scorpionism is an endemic public health problem. The exact number of human accidents is unknown, but partial statistics suggests numbers close to 200,000 per year. The documented number of fatality cases is in the order of 310 people per year. We currently use horse antiserum in patients who show a clear picture of intoxication. Our personal experience in treating 38,068 people, from which over 20,000 received serotherapy, shows that the antiserum is very effective, in that none of the patients died.

Animals↗
PubMed1992

Molecular cloning and sequencing of the Mexico isolate of hepatitis E virus (HEV).

Hepatitis E virus (HEV) is the major causative agent of hepatitis E or what was formerly known as enterically transmitted non-A, non-B hepatitis. The disease has a worldwide distribution but occurs principally in developing countries in any of three forms: large epidemics, smaller outbreaks, or sporadic infections. Genetic variation of different HEV strains was previously noted and it will be important to determine the extent to which this variation may pose problems in the diagnosis and treatment of HEV infection. To analyze differences at the genetic level between HEV(Mexico; M) and the previously characterized HEV(Burma; B) and HEV(Pakistan; P) isolates, overlapping cDNAs were cloned from samples obtained from an infected human and an experimentally inoculated cynomolgus macaque. These cDNA clones, representing the nearly complete (7185-bp) genome of HEV(M), confirmed an expression strategy for the virus that involves the use of 3 forward open reading frames (ORFs). The HEV(M) strain has an overall 76 and 77% nucleic acid identity with the HEV(B) strain and HEV(P) strain, respectively; however, the degree of sequence variation was not uniform throughout the viral genome. A hypervariable region was identified in ORF1 that exhibited a 58 and 54% nucleic acid sequence and 13% amino acid similarity with the Burma strain and the Pakistan strain, respectively. A large number of the nucleotide differences occurred at the third codon position, with the deduced amino acid sequences similarity of 83, 93, and 87% between HEV(M) and HEV(B) isolates in ORF1, ORF2, and ORF3, respectively, and with 84, 93, and 87% amino acid identities between HEV(M) and HEV(P) isolates in ORF1, ORF2, and ORF3, respectively. The nucleotide sequences derived from the highly conserved regions of HEV genome will be useful in developing polymerase chain reaction-based tests to confirm the viral infection. Knowledge of the extent of the sequence variation encountered with HEV will not only aid in the future development of diagnostic and vaccine reagents but also further our understanding of how HEV strain variation might impact the pathological outcome of infection.

Amino Acid Sequence↗
PubMed1990

Toward a population-based assessment of death due to pulmonary embolism in New Mexico.

During a 5-year period (1981 through 1985), 586 of 46,512 (1.26%) deaths in New Mexico had pulmonary embolism (PE) listed on the death certificate. The frequency of death due to PE was mentioned more frequently in the autopsied than in the non-autopsied component of the study (2.4% v 1.1%). This observation, together with published data on the accuracy of clinical diagnostics among persons dying with autopsy-documented PE, suggests that the frequency of death due to this disease is considerably higher than previously thought. Among autopsied persons who died of PE, risk factors and associated diseases are not appreciably different for those who die in or out of the hospital. Important associations with respect to persons dying of PE include male gender, advanced age, serious medical or surgical disease, immobilization, and trauma.

Adolescent↗
PubMed1982

Correlation between T.S.P., F.S.P. and visibility in a high altitude city (Mexico City).

the metropolitan area of Mexico City is located in a high altitude basin (2 240 m above sea level) at a latitude of 19 degrees 26'13" North. It has a population of 15 million inhabitants, and the motor vehicles cruising in the city amount to 1.5 million and around 21% of the total industrial activity of the country is sited in the metropolitan area. All this activity has created an acute air pollution problem in the area which, as a direct result, has resulted in decreased visibility and possible health effects.

Air Pollution↗
PubMed1993

Radon concentration levels in ground water from Toluca, Mexico.

Concentration levels of 222Rn have been analysed in water samples from deep wells of the aquifers around the City of Toluca, Mexico. The 222Rn source is the decay of 226Ra within the solid matrix of the aquifer. With a half life of 1600 years the 226Ra continuously releases 222Rn to the pores, from which it diffuses into the main body of water. This paper describes the methods used for sampling and measuring solubilized and 226Ra-supported 222Rn in the water samples, in order to evaluate possible health hazards due to the presence of radon in the drinking water supplies. The relationship of 222Rn with the hydrogeologic characteristics of the zone is also described. The analytical method involves laboratory extraction of 222Rn into toluene. Alpha disintegrations of 222Rn and contributions from short-lived daughters are counted by the liquid scintillation technique. The system was calibrated using a 226Ra standard solution. Results up to 11.3 Bq/l of 222Rn were obtained in the water samples.

Fresh Water↗
PubMed1994

Lead exposure in students in Mexico City.

The present study was done between 1989 and 1991 and performed on 263 children 7 to 9 years of age who lived in Mexico City. The goal was to determine the association between risk factors entering the body through the respiratory or digestive path and lead concentration in deciduous teeth. Exposure to risk factors was surveyed through a questionnaire; lead was determined by atomic absorption spectrophotometry with a graphite oven and reported in microgram Pb/g tooth. Statistical significance was found for the habit of sucking toys OR 4.98 (IC 95% 1.23-28.67), the use of glazed earthenware utensils for the preparation and serving of food and drinks OR 2.47 (IC 0.80-8.47), and the ingestion of tinned food, particularly juices OR 3.31 (IC 1.03-12.50). No positive results were found for risk factors involving the respiratory path. A possible explanation for these results is a different risk level for each of the two paths of access.

Child↗
PubMed1991

Volunteer otolaryngology practice in rural Mexico.

Medical missions, particularly with religious or military affiliation, are becoming more commonly performed in the Third World. Modern surgical techniques for correcting congenital anomalies frequently require staged operative procedures with long-term follow-up. However, in remote or isolated Third World villages, operative procedures must often be done at a single setting, without staging, utilizing limited intraoperative equipment. Very short postoperative hospitalizations may be all that are available and follow-ups are severely limited. We report our experience on a two-week mission to Mexico where 46 major otolaryngologic surgeries were performed. Follow-up was limited, in most patients, to visits within only a few days of the surgical procedure. Techniques for Third World otolaryngologic surgical experience are discussed including the correction of cleft deformities.

Humans↗