Impact of mediterranean diet promotion on environmental sustainability: a longitudinal analysis.

OBJECTIVE: This article aims to estimate the differences in environmental impact (greenhouse gas [GHG] emissions, land use, energy used, acidification and potential eutrophication) after one year of promoting a Mediterranean diet (MD). METHODS: Baseline and 1-year follow-up data from 5800 participants in the PREDIMED-Plus study were used. Each participant's food intake was estimated using validated semi-quantitative food frequency questionnaires, and the adherence to MD using the Dietary Score. The influence of diet on environmental impact was assessed through the EAT-Lancet Commission tables. The influence of diet on environmental impact was assessed through the EAT-Lancet Commission tables. The association between MD adherence and its environmental impact was calculated using adjusted multivariate linear regression models. RESULTS: After one year of intervention, the kcal/day consumed was significantly reduced (-125,1 kcal/day), adherence to a MD pattern was improved (+0,9) and the environmental impact due to the diet was significantly reduced (GHG: -361 g/CO2-eq; Acidification:-11,5 g SO2-eq; Eutrophication:-4,7 g PO4-eq; Energy use:-842,7 kJ; and Land use:-2,2 m2). Higher adherence to MD (high vs. low) was significantly associated with lower environmental impact both at baseline and one year follow-up. Meat products had the greatest environmental impact in all the factors analysed, both at baseline and at one-year follow-up, in spite of the reduction observed in their consumption. CONCLUSIONS: A program promoting a MD, after one year of intervention, significantly reduced the environmental impact in all the factors analysed. Meat products had the greatest environmental impact in all the dimensions analysed.

Egg consumption and risk of cardiovascular disease in the SUN Project.

BACKGROUND/OBJECTIVES: Egg consumption has been associated with the risk of cardiovascular diseases (CVDs), but evidence is scarce and inconsistent. Our aim was to examine the association between egg consumption and incidence of CVD in a prospective dynamic Mediterranean cohort of 14,185 university graduates. SUBJECTS/METHODS: Egg intake was assessed using a 136-item-validated food-frequency questionnaire. Baseline consumption was categorized into no consumption or <1 egg/week, 1 egg/week, 2-4 eggs/week and >4 eggs/week. The presence of cardiovascular risk factors was assessed by questionnaire at baseline, and the incidence of CVD was assessed using biennial assessments. The median follow-up was 6.1 years. Cox regression models were fitted to estimate multivariable-adjusted hazard ratios (HRs) for CVD (myocardial infarction, revascularization procedures or stroke). Outcomes were confirmed by review of medical records. RESULTS: During a median follow-up of 6.1 years, 91 new confirmed cases of CVD were observed. No association was found between egg consumption and the incidence of CVD (HR: 1.10, 95% confidence interval: 0.46-2.63) for the highest versus the lowest category of egg consumption after adjusting for age, sex, total energy intake, adherence to the Mediterranean food pattern and other cardiovascular risk factors. Results were robust to different analytical scenarios. CONCLUSIONS: No association between egg consumption and the incidence of CVD was found in this Mediterranean cohort.

Phenotype changes inherited by crossing pyrethroid susceptible and resistant genotypes from the cattle tick Riphicephalus (Boophilus) microplus.

Dialelic crosses and backcrosses of pyrethroid resistant (RR) and susceptible (SS) Rhipicephalus (Boophilus) microplus tick strains were carried out and the substitution (Phe-Ile) within the sodium channel gene was monitored in order to analyze the effects of the genotype on the pyrethroid resistance phenotype as measured by the larval packet test (LPT). Parental strains: susceptible (SS) and resistant (RR); dialelic crosses: RS (♂RR × â™€SS), and SR (♂SS × â™€RR); and backcrosses: RS × SS, RS × RR, SR × SS and SR × RR were infested on 280 kg calves. Resistance type (monogenic or polygenic) and effective dominance were determined based on the discriminant concentration (DC) for cipermethrine (0.5%), deltamethrine (0.09%) and flumethrine (0.01%). Allele specific PCR (AS-PCR) was used for genotyping, looking at a sodium channel mutation (Phe-Ile substitution). The mortality rates and allele frequency of susceptible and pyrethroid resistant reference strains were 0% mortality and 90% RR alleles for resistant strain, and 100% mortality and 0% RR alleles as measured by the larval packet test (LPT) and allele specific PCR (AS-PCR) respectively. Backcrossed strain SR × RR showed an effective dominance (D(ML)) of 0.605 for cypermethrin, 0.639 for deltamethrin and 0.498 for flumethrin, while survival of backcrosses RS × SS, RS × RR and SR × SS showed a significant tendency to recesivity. Backcrossed strain SR × RR (69.4%) also showed a higher RR genotype frequency with regards to RS × SS (25.5%), RS × RR (36.7%) and SR × SS (32.0%), however, susceptible allele was inherited in general as an incomplete dominant trait. Monogenic inheritance hypothesis was tested and the results showed monogenic inheritance for cypermethrin and flumethrin (P < 0.05) but not for deltamethrin (P > 0.05). However, significant correlation was found between RR genotype and the survival rate for all three pyrethroids used (P < 0.05), suggesting that a single substitution on the sodium channel gene can be responsible for resistance to pyrethroids as a class, due to the high frequency for RR genotypes. Combination with different mutations or metabolic resistance mechanisms cannot be excluded.

Mediterranean diet and the incidence of cardiovascular disease: a Spanish cohort.

BACKGROUND AND AIM: The Mediterranean diet is considered a model for healthy eating. However, prospective evidence in Mediterranean countries evaluating the relationship between this dietary pattern and non-fatal cardiovascular events is scarce. The aim of the present study was to evaluate the association between the adherence to the Mediterranean diet and the incidence of fatal and non-fatal cardiovascular events among initially healthy middle-aged adults from the Mediterranean area. METHODS AND RESULTS: We followed-up 13,609 participants (60 percent women, mean age: 38 years) initially free of cardiovascular disease (CVD) during 4.9 years. Participants were part of a prospective cohort study of university graduates from all regions of Spain. Baseline diet was assessed using a validated 136-item food-frequency questionnaire. A 9-point score was used to appraise adherence to the Mediterranean diet. Incident clinical events were confirmed by a review of medical records. We observed 100 incident cases of CVD. In multivariate analyses, participants with the highest adherence to the Mediterranean diet (score>6) exhibited a lower cardiovascular risk (hazard ratio=0.41, 95% confidence interval [CI]: 0.18-0.95) compared to those with the lowest score (<3). For each 2-point increment in the score, the adjusted hazard ratios were 0.80 (95% CI: 0.62-1.02) for total CVD and 0.74 (0.55-0.99) for coronary heart disease. CONCLUSIONS: There is an inverse association between adherence to the Mediterranean diet and the incidence of fatal and non-fatal CVD in initially healthy middle-aged adults.

Acaricidal activity of extracts from Petiveria alliacea (Phytolaccaceae) against the cattle tick, Rhipicephalus (Boophilus) microplus (Acari: ixodidae).

The acaricidal activity of crude extracts and fractions from stems and leaves of Petiveria alliacea (Phytolaccaceae) was carried out on larvae and adults of the cattle tick Rhipicephalus (Boophilus) microplus using the larval immersion test (LIT) and adult immersion test (AIT), respectively. Methanolic extracts of stems and leaves of P. alliacea showed 100% mortality on the LIT bioassay. On the other hand, methanolic extracts of leaves and stem on the AIT test showed 26% and 86% of mortality, respectively, egg laying inhibition of 40% and 91%, respectively and hatchability inhibition of 26% and 17%, respectively. Purification of the active stem methanolic extract showed that the activity was present in the n-hexane non-polar fraction. Bioassay-guided purification of the n-hexane fraction produced 10 semi-purified fractions; fraction B had the highest activity against tick larvae (100% mortality). Gas chromatography-mass spectrometry demonstrated that the chemical composition of the active fraction B samples were mainly composed of benzyltrisulfide (BTS) and benzyldisulfide (BDS). These metabolites might be responsible for the acaricidal activity of stem extract of P. alliacea. However, further experiments to evaluate the acaricidal activity of BTS and BDS on larvae and adults of R. (B.) microplus are needed. Our results showed that P. alliacea is a promising biocontrol candidate as acaricide against R. (B.) microplus resistant strains.

The effect of low-fat versus whole-fat dairy product intake on blood pressure and weight in young normotensive adults.

BACKGROUND: Epidemiologic and experimental studies suggest that higher intake of dairy products could be associated with lower risk of hypertension and obesity. Differences in nutrient composition of distinct dairy products suggest that their effect on these outcomes might be heterogeneous. However, little experimental research has examined the potentially different effects of low- and whole-fat dairy products on blood pressure (BP) and weight change. The present study aimed to assess whether supplementing diets with low- or whole-fat dairy products would differentially affect BP levels and weight. METHODS: A randomised crossover trial in 45 normotensive volunteers (18-24 years old, 49% female) was conducted. Participants alternatively received 3.5 servings/day of whole-fat or low-fat dairy products (milk and yogurt) in addition to their usual diet during two 8-week periods, with a 4-week washout period between both interventions. Weight and BP were measured at the beginning and end of each intervention. RESULTS: Whole-fat dairy supplementation significantly increased systolic BP [2.1 mmHg, 95% confidence interval (CI) = 0.1-4.0, P = 0.04] and weight (1.0 kg, 95% CI = 0.5-1.5, P = 0.0002), but not diastolic BP (P = 0.34). Weight and BP did not change significantly after the low-fat dairy intervention (P > 0.10). There were no significant differences in the effect of low-fat or whole-fat dairy products on BP (P > 0.60), but whole-fat dairy increased weight significantly compared to low-fat dairy (1.2 kg, 95% CI = 0.5-1.8, P = 0.0007). CONCLUSIONS: In a young nonhypertensive population, dietary supplementation with whole-fat dairy products, compared to low-fat dairy, was associated with weight gain. No differential effects were observed for levels of BP.

Experiencia en la utilización de la pinza electroquirúrgica de coagulación bipolar plasmacinética en la histerectomía vaginal en el Hospital Central Norte de PEMEX / Electrosurgical bipolar vessel sealer for the vaginal hysterectomy: Central Hospital North of PEMEX experience

Objetivo: Describir la morbilidad, pérdida sanguínea y tiempo quirúrgico en la realización de histerectomía vaginal con el uso de la pinza electroquirúrgica de coagulación bipolar plasmacinética. Metodología: Se realizó un estudio retrospectivo en 18 pacientes sometidas a histerectomía vaginal por patología benigna uterina, utilizando energía plasmacinética durante el período de enero de 2007 a febrero de 2009, en el Hospital Central Norte de Petróleos Mexicanos. Resultados: Tiempo quirúrgico de 59,4 +/- 19,3 min (rango: 50-85 min), sangrado posoperatorio de 76,6 +/- 22,3 mi (rango: 30-110 ml), peso del útero 497,3 +/- 88,9 g (rango: 245-635 g) y tiempo de estancia intrahospitalaria de 2,1 +/- 0,6 días (rango: 1-3 días). No se reportaron complicaciones durante el procedimiento ni en su recuperación posterior. Conclusiones: El uso de la pinza electroquirúrgica de coagulación bipolar plasmacinética, es una alternativa efectiva y segura durante la histerectomía vaginal. Es necesaria la realización de un ensayo aleatorizado para compararla con la técnica tradicional para demostrar otros beneficios.

Objective: To describe morbility, blood loss and procedure time of vaginal hysterectomy using an electro-surgical bipolar vessel sealer. Methods: Patients scheduled for vaginal hysterectomy using electrosurgical bipolar vessel sealer as the hemostasis technique during the period January 2007 to February 2009, at the Central Hospital North of Petróleos Mexicanos. Results: A total of 18 patients underwent vaginal hysterectomy for some benign disease of the uterus. Among these patients, mean procedure time in the electrosurgical bipolar vessel sealer was 59.4 +/- 19.3 min (range: 50-85 min). Mean estimated blood loss was 76.6 +/- 22.3 ml (range: 30-110 ml), weight of the uterus was 497.3 +/- 88.9 g (range: 245-635 g), and length of stay 2.1 +/- 0.6 days (range: 1-3 days). There was no perioperative complication. Conclusion: Electrosurgical bipolar vessel sealer is an effective alternative to sutures in vaginal hysterectomy. Larger adequately-powered studies are however still required.

Seroepidemiological study of Neospora caninum infection in dogs found in dairy farms and urban areas of Aguascalientes, Mexico.

The objective of this study was to describe the seroepidemiology of Neospora caninum infection in dogs in close contact with dairy cattle and dogs from urban areas of Aguascalientes, Mexico, as well as to estimate the possible association between age, gender and size of these groups and seroprevalence. Sera were obtained from samples of 152 dogs in dairy farms and 116 in the urban area, and were subjected to ELISA test. General seroprevalence reached 32%, while the seroprevalence in farm dogs (41%) was significantly higher than in dogs from the urban area (20%) (p<0.05). Regarding age groups, general seroprevalence was greater among dogs between 11 and 15 years of age (67%) remaining equal between males and females (32 and 31%, respectively). Nevertheless, females resident in farms had a higher seroprevalence (42%) than female resident in the urban area. Regarding size, large-sized animals had greater seroprevalence in farms (58%), while in the urban area medium-sized animals were those that had the highest seroprevalence (27%). It was found that dairy farm dogs had a higher risk of infection (OR=2.79; p=0.0004), and that in said group, the age range from <1 to 5 years of age was identified as a risk factor (OR=3.11, p=0.001).

Inheritance of pyrethroid resistance and a sodium channel gene mutation in the cattle tick Boophilus microplus.

A substitution (Phe-->Ile) within the sodium channel gene sequence has been associated with pyrethroid resistance in Boophilus microplus. The aim of the present study was to analyze the inheritance of pyrethroid resistance and the mutant allele, on reciprocal crosses of a susceptible (SS) and a resistant (RR) strain. Bioassays and genotypes were determined to evaluate pyrethroid resistance. The resistance allele frequency of both parental strains were 100% and 2.27% for RR and SS, respectively. The reciprocal crosses show a predominance of the heterozygote genotype, in agreement with the significant decrease of the acaricide resistance to cypermethrin, deltamethrin, and flumethrin. However, the RS progeny showed a complete recessive survival (D (ML) = 0) for deltamethrin and flumethrin, suggesting a complete dominance of the susceptible allele and incomplete dominance for cypermethrin (D (ML) = 0.169). On the other hand, SR progeny showed a partially recessive survival for cypermethrin (D (ML) = 0.380), deltamethrin (D (ML) = 0.319), and flumethrin (D (ML) = 0.258), indicative of a partially dominant inheritance of the resistance. A possible maternal strain effect should be considered for practical purposes and prediction of acaricide resistance and further work needs to be done to elucidate the underlying inheritance of pyrethroid resistance and the sodium channel mutation in B. microplus.

Adherence to Mediterranean diet and risk of developing diabetes: prospective cohort study.

OBJECTIVE: To assess the relation between adherence to a Mediterranean diet and the incidence of diabetes among initially healthy participants. DESIGN: Prospective cohort study with estimates of relative risk adjusted for sex, age, years of university education, total energy intake, body mass index, physical activity, sedentary habits, smoking, family history of diabetes, and personal history of hypertension. SETTING: Spanish university department. PARTICIPANTS: 13 380 Spanish university graduates without diabetes at baseline followed up for a median of 4.4 years. MAIN OUTCOME MEASURES: Dietary habits assessed at baseline with a validated 136 item food frequency questionnaire and scored on a nine point index. New cases of diabetes confirmed through medical reports and an additional detailed questionnaire posted to those who self reported a new diagnosis of diabetes by a doctor during follow-up. Confirmed cases of type 2 diabetes. RESULTS: Participants who adhered closely to a Mediterranean diet had a lower risk of diabetes. The incidence rate ratios adjusted for sex and age were 0.41 (95% confidence interval 0.19 to 0.87) for those with moderate adherence (score 3-6) and 0.17 (0.04 to 0.75) for those with the highest adherence (score 7-9) compared with those with low adherence (score <3). In the fully adjusted analyses the results were similar. A two point increase in the score was associated with a 35% relative reduction in the risk of diabetes (incidence rate ratio 0.65, 0.44 to 0.95), with a significant inverse linear trend (P=0.04) in the multivariate analysis. CONCLUSION: Adherence to a Mediterranean diet is associated with a reduced risk of diabetes.

Development of amitraz resistance in field populations of Boophilus microplus (Acari: Ixodidae) undergoing typical amitraz exposure in the Mexican tropics.

The purpose of this study was to determine the effect of amitraz selection pressure on the development of resistance in field populations of Boophilus microplus in the Mexican tropics. Three farms (FA(1), FA(2) and FA(3)) in Yucatan, Mexico, were selected in this study. Amitraz was applied as a whole body sprays to all cattle on each farm for tick control once monthly for 15 months. From each farm, 20-30 B. microplus engorged females were collected every 3 months. The modified larval immersion test was used to test susceptibility of B. microplus to amitraz. Larvae were exposed to serial dilutions of amitraz. Probit analysis was used to determine lethal dose at 50% mortality and associated 95% confidence limits. The resistance factors found in the three farms during the 15 months of amitraz selection pressure were FA(1) (1, 2, 4, 4 and 13), FA(2) (1, 6, 23, 21 and 22) and FA(3) (2, 13, 2, 6 and 6). It is concluded that amitraz selection pressure on field populations of B. microplus increased the resistance level in all populations studied in the Mexican tropics.

Relationships between stable fly infestation with some physical facility characteristics and sanitation practices in several dairy farms in the State of Aguascalientes, Mexico.

The possible relationships between stable fly infestation with dairy farm facilities and sanitation practices were studied using path analysis. Twelve dairies located in four counties of Aguascalientes dairy region were selected. The dairies were monitored from May to November 2003. In each occasion, fly infestation, individual physical facility characteristics, and sanitation practices were recorded. In all, 11 independent variables were involved in the study and related variables were grouped together and analyzed in two blocks by path analysis for each one of five population events (begin of fly season, first peak, fluctuation, second peak and decrease). There were significant regression coefficients only in the second peak for two variables, the distance to the silos and the distance to the dung heap (r(2)=0.96 for the full model). Among the 11 variables examined in the study, none had a statistical significant indirect contribution to fly infestation; direct contribution was observed for distance to the silos and for distance to the dung heap variables. However, only the distance to the silos variable was significantly related to stable fly Infestation.

Survey of Neospora caninum infection by nested PCR in aborted fetuses from dairy farms in Aguascalientes, Mexico.

The aim of this study was to determine by nested PCR probe the presence of Neospora caninum in fetal brain tissue from aborted dairy fetuses in Aguascalientes, a state in the central part of Mexico. Forty-four fetal brains from eight dairy farms were analyzed using single tube nested PCR probe with primers NF1, NS2, NR1 and SR1, with histopathology as the reference technique. From the 44 bovine fetuses studied, 35 (80%) were diagnosed as being infected by N. caninum using PCR probe and 20 (45%) were considered positive by histopathology, because they had lesions suggestive of bovine neosporosis. Fair agreement was observed (31%) between both probes. The age of aborting cows ranged from 1.6 to 2.9-year-old in 17 (49%) of the positive cases diagnosed by PCR. Gestational ages of aborted fetuses ranged from <3 to 9 months, with average of 5.6 months, and no statistical significant difference was observed when ages of infected and no infected fetuses were compared (P > 0.05). The frequency of N. caninum positive cases observed could be considered to be higher than other areas of Mexico and other countries.

Neospora caninum seropositivity and association with abortions in dairy cows in Mexico.

The seroprevalence of Neospora caninum infection was estimated from a sample of 813 cattle from 20 dairy herds in five regions in Mexico. The true prevalence of infection was estimated to be 42% (95% CI: 39, 46). Seropositivity was associated with abortion (odds ratio (OR)=2.0) and was higher among cows raised on-farm (41%), than among replacement cattle purchased outside the farm (28%). The ORs relating abortion to seropositivity in individual herds ranged from 1.3 to 10. Overall, 26% of the abortions were attributed to N. caninum.

Analysis of BoLA class II microsatellites in cattle infested with Boophilus microplus ticks: class II is probably associated with susceptibility.

The aim of this study was to determine the role of certain bovine lymphocyte antigens (BoLA) regions in the resistance or susceptibility to Boophilus microplus tick infestation in two different breeds of cattle. The breeds were maintained, one in natural conditions and the second one in an experimental setting at the research station in Martinez de la Torre, Veracruz, Mexico. The study took place from June to August 2001 (natural infestation) using 33 crossbreed steers (crossbreed is here defined as 3/4 European = 1/2 Simmenthal x 1/4 Holstein x 1/4 Zebu, a cross resulting from F1 x Simmenthal), ranging from 15 to 20 months old. Fifty-nine F1 cows (1/2 Holstein x 1/2 Zebu) were included in the experimental setting, infested and followed during 25 days in November 2001 and 2002. Experiment A included thirty-one 2-7-year-old F1 cows, and experiment B included twenty-eight 18-24-month-old F1 heifers. Both groups were analysed separately and were not comparable because of the different infestation methods and genetic background. All ticks > or =4mm long were counted on the total body of F1 animals and on one side of the 3/4 European steers. In this case, susceptible animals were defined when having ticks = X + 1S.D. (29 +/- 16). In the experimental setting susceptibility was defined when the number of ticks was over the 75 percentile (> or =79). DNA was extracted from peripheral blood samples of all animals. The BoLA DRB3, DRBP1, RM185 and BM1815 microsatellite loci were amplified using a PCR method. Genescan software was used for analysis in an ABI sequencer. The SPSS statistical program was used and the comparisons were assessed using the Fisher's exact test. In the naturally infested animals, DRB3-184 was found positively associated with tick infestation (P = 0.018; Pc = NS; OR = 5; EF = 28%). DRBP1-128 was also found to be increased (P = 0.03; Pc = NS; OR = 6; EF = 42%). In the experimentally infested animals, two more loci were found to be associated, BM1815-152 (P = 0.01; Pc = NS; OR = 15; EF = 74%) and DRBP1-130 (P = 0.05; Pc = NS; OR = 4; EF = 77%). None of them remained significant after correction, indicating that a larger sample size is needed to confirm the results. This is the first study showing MHC genes associated with tick infestation based on class II microsatellite polymorphisms. Further studies are needed to confirm the susceptibility traits and to determine haplotype segregation in families.

Factors that influence the prevalence of acaricide resistance and tick-borne diseases.

This manuscript provides a summary of the results presented at a symposium organized to accumulate information on factors that influence the prevalence of acaricide resistance and tick-borne diseases. This symposium was part of the 19th International Conference of the World Association for the Advancement of Veterinary Parasitology (WAAVP), held in New Orleans, LA, USA, during August 10-14, 2003. Populations of southern cattle ticks, Boophilus microplus, from Mexico have developed resistance to many classes of acaricide including chlorinated hydrocarbons (DDT), pyrethroids, organophosphates, and formamidines (amitraz). Target site mutations are the most common resistance mechanism observed, but there are examples of metabolic mechanisms. In many pyrethroid resistant strains, a single target site mutation on the Na(+) channel confers very high resistance (resistance ratios: >1000x) to both DDT and all pyrethroid acaricides. Acetylcholine esterase affinity for OPs is changed in resistant tick populations. A second mechanism of OP resistance is linked to cytochrome P450 monooxygenase activity. A PCR-based assay to detect a specific sodium channel gene mutation that is associated with resistance to permethrin has been developed. This assay can be performed on individual ticks at any life stage with results available in a few hours. A number of Mexican strains of B. microplus with varying profiles of pesticide resistance have been genotyped using this test. Additionally, a specific metabolic esterase with permethrin-hydrolyzing activity, CzEst9, has been purified and its gene coding region cloned. This esterase has been associated with high resistance to permethrin in one Mexican tick population. Work is continuing to clone specific acetylcholinesterase (AChE) and carboxylesterase genes that appear to be involved in resistance to organophosphates. Our ultimate goal is the design of a battery of DNA- or ELISA-based assays capable of rapidly genotyping individual ticks to obtain a comprehensive profile of their susceptibility to various pesticides. More outbreaks of clinical bovine babesisois and anaplasmosis have been associated with the presence of synthetic pyrethroid (SP) resistance when compared to OP and amidine resistance. This may be the result of differences in the temporal and geographic patterns of resistance development to the different acaricides. If acaricide resistance develops slowly, herd immunity may not be affected. The use of pesticides for the control of pests of cattle other than ticks can affect the incidence of tick resistance and tick-borne diseases. Simple analytical models of tick- and tsetse-borne diseases suggest that reducing the abundance of ticks, by treating cattle with pyrethroids for example, can have a variety of effects on tick-borne diseases. In the worst-case scenario, the models suggest that treating cattle might not only have no impact on trypanosomosis but could increase the incidence of tick-borne disease. In the best-case, treatment could reduce the incidence of both trypanosomosis and tick-borne diseases Surveys of beef and dairy properties in Queensland for which tick resistance to amitraz was known were intended to provide a clear understanding of the economic and management consequences resistance had on their properties. Farmers continued to use amitraz as the major acaricide for tick control after the diagnosis of resistance, although it was supplemented with moxidectin (dairy farms) or fluazuron, macrocyclic lactones or cypermethrin/chlorfenvinphos.

Serological survey of Neospora caninum infection in dairy cattle herds in Aguascalientes, Mexico.

A serological survey for antibody activity to Neospora caninum was carried out in Aguascalientes, a state in the central part of Mexico. One-hundred and eighty-seven serum samples from 13 dairy herds were tested by the ELISA test. The herd prevalence was 100% and the overall prevalence was 59% (n=110). Seventy-six of 97 seropositive cows had previous records of abortion. There was a statistically significant difference between the groups (P<0.05). However, the odds ratio was 1.4, suggesting an association between abortion and seropositivity. Neosporosis in dairy cattle appears to be widespread in Mexico, warranting more epidemiological studies to determine the distribution of the causative protozoan.

Anti-tick effects of Stylosanthes humilis and Stylosanthes hamata on plots experimentally infested with Boophilus microplus larvae in Morelos, Mexico.

The anti-tick effects of the tropical pasture legumes Stylosanthes humilis and Stylosanthes hamata were evaluated and compared with two common grasses, Cenchurus ciliaris and Andropogon gayanus, in the state of Morelos, Mexico, on plots experimentally infested with larvae of the tick Boophilus microplus. The effect was evaluated by recovery of larvae from the experimental plots by flagging during a 4 week period. The anti-tick effect due to Stylosanthes was significantly higher for S. humilis and S. hamata (p < 0.05) and slightly better for S. humilis (3% survival) than for S. hamata (12% survival). Further studies are required to determine the potential role of Stylosanthes plants for tick control in Mexico.

Seasonal distribution of Rhipicephalus sanguineus ticks (Acari: Ixodidae) on dogs in an urban area of Morelos, Mexico.

Between 1993 and 1995, we examined 1742 dogs at two veterinary clinics in Cuernavaca City in Mexico for the presence of Rhipicephalus sanguineus ticks. The overall tick infestation prevalence was 20% and there were no significant differences (p > 0.05) between different years. The prevalence was somewhat higher in spring, summer and autumn (20% or more) than in winter (13.7%). A positive correlation (p < 0.01) was found between prevalence of ticks and rainfall in spring, summer and autumn, whereas in winter there was only a correlation with temperature. Different stages of the tick were found and it was calculated that 2.5 generations could be completed each year. It is concluded that the environmental conditions of Cuernavaca City favour development and maintenance of R. sanguineus ticks throughout the year and that its role as a vector of diseases poses a threat to dogs and may have potential zoonotic risks.