Biological parameters of the triatomine, Meccus phyllosomus pallidipennis, fed on two bloodmeal sources under laboratory conditions.

Chagas disease is one of the most important vector-borne diseases in Latin America, including Mexico. Meccus phyllosomus pallidipennis (Stål), 1872 (Hemiptera: Reduviidae) is a Mexican triatomine vector that is commonly associated with hens and rabbits. The biological parameters of two cohorts fed on hens (H) and on rabbits (R) were evaluated. The median lifecycles of the two cohorts were 198 days (H) and 180 days (R). Moreover, mortality was around 30% in both cohorts. Time lapse for beginning of feeding was 0.5-1.9 (H) and 1.1-2.4 min (R). Feeding times of each instar in both cohorts were over 10 min. Most specimens fed on hens defecated immediately after feeding, whereas those that fed on rabbits defecated within 1-5 min post-feeding. Similar numbers of males and females (50%) were obtained in both cohorts. An average of 2.1-2.3 eggs per female per day was noted in both cohorts, with eclosion rates of 95.4 (H) and 88.8% (R). Thus, it can be concluded that M. phyllosomus pallidipennis may take advantage of feeding in hens, as in rabbits, which could imply a higher risk of Trypanosoma cruzi transmission to humans and animals in its distribution area.

Biological parameters of interbreeding subspecies of Meccus phyllosomus (Hemiptera: Reduviidae: Triatominae) in western Mexico.

Understanding the biological parameters of some triatomine subspecies of Meccus phyllosomus (Burmeister) is a crucial first step in estimating the epidemiological importance of this group. Biological parameters related to egg eclosion, egg-to-adult development time, number of blood meals to moult, percentage of females at the end of the cycle, number of laid eggs, and the accumulative mortality for each instar of three M. phyllosomus subspecies [Meccus phyllosomus pallidipennis (Stål), Meccus phyllosomus longipennis (Usinger), and Meccus phyllosomus picturatus (Usinger)] as well as their laboratory hybrids were evaluated and compared. No significant differences (P > 0.05) were recorded among the experimental hybrids (M. p. longipennis × M. p. pallidipennis, M. p. longipennis × M. p. picturatus, M. p. pallidipennis × M. p. picturatus) and reciprocal cohorts. In five of the six studied parameters (egg eclosion, egg-to-adult development time, number of blood meals to moult, number of laid eggs and accumulative mortality), with the exception of the non-significant percentage of females obtained among all the studied cohorts, at least one of the parental cohorts in each set of crosses exhibited better fitness results than by those of their hybrid descendants. The lack of hybrid fitness in our study indicates the maintenance of reproductive isolation of parental genotypes. Moreover, the results lead us to propose that an incipient speciation process by distance is currently developing among the three studied subspecies, increasing the differences between them that modify the transmission efficiency of Trypanosoma cruzi to human beings in Mexico.

Biological characteristics of geographically isolated populations of Meccus mazzottii (Hemiptera: Reduviidae) in southern Mexico.

Chagas disease, caused by Trypanosoma cruzi Chagas, is one of the most epidemiologically important vector-borne zoonoses in Mexico. Among the 32 reported triatomine species from Mexico, Meccus mazzottii (Usinger) (Hemiptera: Reduviidae) is one of the most important vectors of T. cruzi in the southern part of the country. Variability among populations of triatomines has been recorded for several species (Meccus longipennis (Usinger) and Meccus pallidipennis (Stal)) that are closely related to M. mazzottii, showing an apparent influence of local environmental conditions on the biology of each population, which could modify the impact of vector control measurements. Therefore, this study sought to compare the biological features of populations of M. mazzottii from two geographically far apart areas that have similar environmental characteristics and to compare populations from close geographical areas that have different environmental characteristics. The mean longevity, percentages of mortality of nymphs, the total mean number of bloodmeals to molt (considered instar by instar), the mean number of eggs laid by females, and the percentage of hatched eggs were similar between the two localities that are geographically far apart but have similar environmental characteristics. On the other hand, important differences were noticed when a comparison was carried out on the two localities with similar environmental conditions with respect to that locality with different conditions, independent of geographic distance. Most of the studied parameters led us to conclude that the three studied populations are very highly influenced by local environmental conditions. The results of this study indicate the importance of studying the biological characteristics of local populations of triatomines to carry out specific control measurements, instead of using standard ones that could fail if they are not adapted to the target population.

[Seropositivity to Helicobacter pylori among university students and their families. A comparative cross-sectional study]. / Seropositividad a Helicobacter pylori entre estudiantes universitarios y sus familias. Estudio comparativo.

OBJECTIVE: To associate serologic response to Helicobacter pylori (Hp) among seropositive university students and their families in western Mexico. METHODS: We conducted a comparative transversal study, and randomized 30 nuclear families of 14 Hp-seropositive university students and 14 Hp-seronegative university students. We carried out seropositivity measurements (IgG) to Hp using the ELISA method. An analysis was performed utilizing the chi-squared and Mann-Whitney U tests, with the aid of EPI INFO 2000 and SIGMA STAT 3.2 software. RESULTS: Global seropositivity in the families of infected students was 57 vs. 13% of the relatives of non-infected students (p = 0.000002). In families of Hp-positive students we found the following frequencies: parental (father and mother) 70%; mother 71%, and siblings 42%, while for seronegative individuals incidences were: parental 17% (p = 0.00005), mother 12% (p = 0.001), and siblings 10% (p = 0.0076). CONCLUSIONS: There is a greater prevalence of antibodies against Hp in the relatives of seropositive students.

Seropositividad a Helicobacter pylori entre estudiantes universitarios y sus familias. Estudio comparativo / No disponible

Objetivo: asociar la respuesta serológica a Helicobacter pylori(Hp) entre estudiantes universitarios seropositivos y sus familiasen el occidente de México.Métodos: estudio transversal comparativo aleatorizado de30 núcleos familiares de 14 estudiantes universitarios seropositivospara Hp, y 16 negativos. Se realizó determinación de seropositividad(IgG) a Hp por método de ELISA. El análisis se hizo utilizandochi cuadrado y U de Mann Whitney, con la ayuda de losprogramas EPI INFO 2000 y SIGMA STAT 3.1Resultados: la seropositividad global del núcleo familiar delos estudiantes infectados fue del 57 vs. el 13% de los familiaresde los estudiantes no infectados (p = 0,000002). En las familiasde los estudiantes positivos a Hp se encontró una frecuencia de:binomio paterno (padre y madre) 70%, madres 71%, hermanos42%, mientras que en los seronegativos fue: binomio paterno17% (p = 0,00005), madres 12% (p = 0,001), hermanos 10% (p= 0,0076).Conclusiones: existió mayor prevalencia de anticuerpos aHp en los familiares de los alumnos seropositivos

Objective: to associate serologic response to Helicobacterpylori (Hp) among seropositive university students and their familiesin western Mexico.Methods: we conducted a comparative transversal study, andrandomized 30 nuclear families of 14 Hp-seropositive universitystudents and 14 Hp-seronegative university students. We carriedout seropositivity measurements (IgG) to Hp using the ELISA method.An analysis was performed utilizing the chi-squared andMann-Whitney U tests, with the aid of EPI INFO 2000 and SIGMASTAT 3.2 software.Results: global seropositivity in the families of infected studentswas 57 vs. 13% of the relatives of non-infected students(p = 0.000002). In families of Hp-positive students we found thefollowing frequencies: parental (father and mother) 70%; mother71%, and siblings 42%, while for seronegative individuals incidenceswere: parental 17% (p = 0.00005), mother 12% (p = 0.001),and siblings 10% (p = 0.0076).Conclusions: there is a greater prevalence of antibodiesagainst Hp in the relatives of seropositive students

Importance of species of Triatominae (Heteroptera: Reduviidae) in risk of transmission of Trypanosoma cruzi in western Mexico.

The epidemiological risk of infection by Trypanosoma cruzi Chagas in human populations of western Mexico is still under study. Although most vectors in this region and their vector capability are already known, new studies estimating the risk and the importance of individual Triatominae species (Hemiptera: Reduviidae) for T. cruzi transmission are necessary. For 1 yr, every month, > 400 human dwellings and their surroundings in eight communities of two western Mexico states were searched for triatomines. More than 1,000 specimens representing four species were collected and checked for T. cruzi infection. Based on the usual entomological indices, only the inhabitants of Gavilán El Progreso-La Villita are at serious risk of vectorial infection by T. cruzi. A population of Meccus longipennis (Usinger) was found living in peridomestic rock pile boundary walls after an insecticide spraying. It was confirmed the major role of peridomestic habitats as shelter areas for triatomines, particularly in rock pile boundary walls and chicken roosts. Triatominae presence also was verified in certain sylvatic habitats, including primarily heaps of stones. The important role of M. longipennis in the potential transmission of T. cruzi in the region and the secondary role of M. picturatus (Usinger) and Triatoma barberi Usinger also were confirmed. Null colonization of houses by T. barberi, which was collected primarily in peridomestic habitats, differs from its common intradomiciliary collection in other studies. Meccus pallidipennis (Stål) most probably does not exist in Nayarit. Meccus mazzottii (Usinger) and Meccus phyllosomus (Burmeister) are no longer found in Nayarit and Jalisco. Additional studies are necessary to determine the current epidemiological situation in other areas of western Mexico.

Epidemiological and clinical characteristics of scorpionism in Colima, Mexico (2000-2001).

We analyzed 13,223 clinical records of patients treated for scorpion sting in hospitals of the Mexican Institute of Public Health and the Ministry of Health in the state of Colima, Mexico, during the years 2000-2001. A database containing demographic, epidemiological and clinical information was constructed and analyzed retrospectively. Patients were classified in the categories as mild (49.2%), moderate (33.8%) and severe (17.0%) according to commonly accepted standards. Most common symptoms recorded were local pain (94.7%), local paresthesia (67.2%), pruritus/itching (54.3%), sensation of a lump or hair in the throat (47.3%), and sialorrhoea (27.7%). The median time from sting to admission to the emergency room (patient delay) was 33min (interquartile range: 12-60). We found that older and clinically severe patients were significantly associated with longer times of admission to the emergency room. Age was significantly associated with clinical severity: the age group 0-10 years included a higher proportion of severe cases than the group 11 years and older. In four cases, patients died. An educational campaign to inform the population about the importance of receiving prompt attention following a scorpion sting has potential value in reducing complications in the emergency room.

The effects of surgically removing subcutaneous fat on the metabolic profile and insulin sensitivity in obese women after large-volume liposuction treatment.

The aim of this study was to identify the effects of surgically removing subcutaneous fat on the metabolic profile and insulin sensitivity in obese women after large-volume liposuction treatment. An open clinical trial with a non-intervention parallel group was carried out on 12 young, obese women. After randomization, six volunteers were selected to the surgical intervention consisting of large-volume liposuction; the other six women were considered as the non-intervention group. Metabolic profiles and insulin tolerance tests to assess insulin sensitivity were performed on all volunteers before intervention or non-intervention and 21 - 28 days afterwards. There were a significant decrease in glucose (4.9 +/- 0.4 vs. 4.6 +/- 0.2 mmol/l, p < 0.05) and uric acid (250.8 +/- 56.2 vs. 224.0 +/- 53.4 micromol/l, p < 0.05) levels after liposuction; insulin sensitivity improved after the surgical intervention (4.3 +/- 0.9 vs. 5.3 +/- 0.8 %/min, p = 0.046). In conclusion, surgical removal of subcutaneous fat by large-volume liposuction led to an improvement in insulin sensitivity and a decrease in glucose and uric acid concentrations.