Domestic Triatoma spp. Infections with Trypanosoma cruzi, Household Infestations, and Molecular Identification in Oaxaca, México.

In Latin America, Mexico is the country with the second highest annual estimated number of Chagas disease cases, caused by Trypanosoma cruzi, due to vector-borne transmission. The state of Oaxaca is the location of the first documented human cases of Chagas disease in Mexico and contained the highest T. cruzi seropositive rate (3.5%) from blood donors. Here, entomological surveys, from 2017 to 2019, were conducted to collect triatomines in 124 villages of 60 municipalities. Four principal domestic Triatoma spp. (Hemiptera: Triatominae), Triatoma phyllosoma, T. barberi, T. mazzotti, and T. dimidiata, of Oaxaca, Mexico were identified by morphology and molecular analysis of the barcode region of the cytochrome oxidase 1 (cox1 or COI or CO1) gene. A total of 41 out of 83 T. phyllosoma specimens examined by microscopy were positive for T. cruzi (49%), 49 out of 171 for T. barberi (28%), 31 out of 177 for T. mazzotti (17%), and none out of 10 for T. dimidiata (0%). Overall, the infestation index was 3.1% of households containing at least one triatomine; the crowding index was a mean of two Triatoma spp./household; and the colonization index was 0.38 for households based on presence of nymphs. Geographical distribution of triatomines in Oaxaca at the municipality level and endophilic behavior is also reported. Precise identification, endophilic habits, and infection rates of these triatomines are paramount for vector control programs of the Ministry of Health of Oaxaca and beyond.

[Factors associated with tobacco use in patients with asthma during the confinement due to COVID-19 in an urban region with high numbers of SARS-CoV-2 infections]. / Factores asociados al tabaquismo en pacientes con asma durante el confinamiento por COVID-19 en una región urbana con cifras elevadas de infecciones por SARS-CoV-2.

OBJECTIVE: To determine the prevalence and risk factors associated with tobacco use during the period of confinement in light of the COVID-19 pandemic. METHODS: Through an analytical and cross-sectional study, the data of 2, 372 participants were analyzed. The information was collected through a self-administered questionnaire that was built with the Google Forms tool, which was distributed and applied via email and WhatsApp; the private messaging platform. The relationship between the independent variables and the outcome was determined by multivariate logistic regression analysis. RESULTS: Out of the total population, 69.3 % were women, the median age was 20.11±2.01 years, the prevalence of asthma was 12.2 %, and the active tobacco use was 13.3 %. There was a higher number of patients with asthma who smoked (14.2 vs. 13.2 %) than of those who didn't have asthma. The multivariate logistic regression analysis showed that factors like considering that COVID-19 does not exist and not being confined were related to tobacco use in patients with asthma during the implementation of the contingency plan that the COVID-19 pandemic represents. CONCLUSIONS: During confinement to home for COVID-19, the prevalence of tobacco use is higher in patients with asthma than in individuals without this ailment; the factors that favor the aforementioned are present in the family environment.

Objetivo: Determinar la prevalencia y factores de riesgo asociados al tabaquismo durante el periodo de confinamiento ante la pandemia de COVID-19. Métodos: Mediante un estudio analítico y transversal se analizaron los datos de 2372 participantes. La recolección de la información se realizó con un cuestionario autoadministrado construido con la herramienta Google Forms, el cual se distribuyó y aplicó a través de correo electrónico y de la plataforma de mensajería privada WhatsApp. La relación entre las variables independientes y la resultante fue determinada a través de regresión logística multivariada. Resultados: De la población total, 69.3 % fue del sexo femenino, la edad media de 20.11 ± 2.01 años, la prevalencia de asma de 12.2 % y la de tabaquismo activo, de 13.3 %. Una mayor proporción de pacientes con asma fumaba (14.2 versus 13.2 %), en comparación con quienes no padecían asma. La regresión logística multivariante mostró que considerar que COVID-19 no existe y no cumplir con el confinamiento se relacionaron con el tabaquismo en pacientes con asma durante la aplicación del plan de contingencia que representa la pandemia de COVID-19. Conclusiones: Durante el confinamiento en casa por COVID-19, la prevalencia de tabaquismo es mayor en pacientes con asma comparados con los individuos sin esta enfermedad. Los factores que favorecen lo anterior están presentes en el entorno familiar.

Optimization of PCR-based TYLCV molecular markers by response surface methodology.

Tomato (Solanum lycopersicum L.) is one of the most economically important vegetables worldwide. However, its production is affected by the tomato yellow leaf curl virus (TYLCV), causing the greatest devastation in the crop. One strategy to cope with TYLCV implies the use of resistant varieties, whose development can be accelerated by molecular markers. The aim of this study was to optimize endpoint PCR protocols for the detection of the molecular markers TG178, TG105A and P6-25, linked to Ty-1, Ty-2 and Ty-3 resistance genes, respectively, through a response surface methodology (RSM) using a central composite design (CCD) for four factors (temperature of annealing (Ta), DNA amount, MgCl2 and primer concentrations). Applicability, the limit of detection and dynamic range were also analyzed. The optimized PCR conditions were: for TG178: Ta = 60 °C, 90 ng DNA, 3.36 mM MgCl2 and 0.13 µM primers; for TG105A: Ta = 54.4 °C, 10 ng DNA, 1.5 mM MgCl2 and 0.9 µM primers; for P6-25, Ta = 52.5 °C, 50 ng DNA, 2.5 mM MgCl2 and 0.5 µM primers. Dynamic ranges varied from 0.42 to 103.3 ng of DNA, while the limit of detection was 3.82, 0.42 and 11.47 ng of DNA for the TG178, TG105A and P6-25 molecular makers respectively and was 100% positive in replicates. CCD allowed the optimization of PCR protocols for molecular markers, which may further apply in identifying TYLCV resistant tomato lines.

Rapid molecular evolution of Spiroplasma symbionts of Drosophila.

Spiroplasma is a genus of Mollicutes whose members include plant pathogens, insect pathogens and endosymbionts of animals. Spiroplasma phenotypes have been repeatedly observed to be spontaneously lost in Drosophila cultures, and several studies have documented a high genomic turnover in Spiroplasma symbionts and plant pathogens. These observations suggest that Spiroplasma evolves quickly in comparison to other insect symbionts. Here, we systematically assess evolutionary rates and patterns of Spiroplasma poulsonii, a natural symbiont of Drosophila. We analysed genomic evolution of sHy within flies, and sMel within in vitro culture over several years. We observed that S. poulsonii substitution rates are among the highest reported for any bacteria, and around two orders of magnitude higher compared with other inherited arthropod endosymbionts. The absence of mismatch repair loci mutS and mutL is conserved across Spiroplasma, and likely contributes to elevated substitution rates. Further, the closely related strains sMel and sHy (>99.5 % sequence identity in shared loci) show extensive structural genomic differences, which potentially indicates a higher degree of host adaptation in sHy, a protective symbiont of Drosophila hydei. Finally, comparison across diverse Spiroplasma lineages confirms previous reports of dynamic evolution of toxins, and identifies loci similar to the male-killing toxin Spaid in several Spiroplasma lineages and other endosymbionts. Overall, our results highlight the peculiar nature of Spiroplasma genome evolution, which may explain unusual features of its evolutionary ecology.

Wolbachia pipientis Associated With Tephritid Fruit Fly Pests: From Basic Research to Applications.

Members of the true fruit flies (family Tephritidae) are among the most serious agricultural pests worldwide, whose control and management demands large and costly international efforts. The need for cost-effective and environmentally friendly integrated pest management (IPM) has led to the development and implementation of autocidal control strategies. These approaches include the widely used sterile insect technique and the incompatible insect technique (IIT). IIT relies on maternally transmitted bacteria (namely Wolbachia) to cause a conditional sterility in crosses between released mass-reared Wolbachia-infected males and wild females, which are either uninfected or infected with a different Wolbachia strain (i.e., cytoplasmic incompatibility; CI). Herein, we review the current state of knowledge on Wolbachia-tephritid interactions including infection prevalence in wild populations, phenotypic consequences, and their impact on life history traits. Numerous pest tephritid species are reported to harbor Wolbachia infections, with a subset exhibiting high prevalence. The phenotypic effects of Wolbachia have been assessed in very few tephritid species, due in part to the difficulty of manipulating Wolbachia infection (removal or transinfection). Based on recent methodological advances (high-throughput DNA sequencing) and breakthroughs concerning the mechanistic basis of CI, we suggest research avenues that could accelerate generation of necessary knowledge for the potential use of Wolbachia-based IIT in area-wide integrated pest management (AW-IPM) strategies for the population control of tephritid pests.

Post-elimination surveillance in formerly onchocerciasis endemic focus in Southern Mexico.

BACKGROUND: All formerly endemic communities of the Southern Chiapas focus of onchocerciasis in Mexico were treated with ivermectin until parasite transmission was eliminated by 2015. Transmission of onchocerciasis did not resume during a period of three years (2012-2014) following the final distribution of ivermectin in 2011; it was thus concluded that transmission remained undetectable without intervention. WHO thus declared the elimination of transmission of onchocerciasis from Mexico in 2015. METHODOLOGY/PRINCIPAL FINDINGS: From 2016 to the present, post-elimination surveillance (PES) based on examination for suspected onchocercomas was performed in the former Southern Chiapas focus. Each year, over 60% of the total population (range = 85,347-104,106 individuals) of the formerly endemic communities were examined for onchocercomas. Thirty-four individuals were found harboring suspected onchocercomas in the PES surveys conducted from 2016-2019. Of these, one female of 7 years of age who had immigrated from a formerly endemic focus, harbored an infertile (sterile) female in the suspected onchocercoma; all others were negative. Skin biopsy assessments were performed from March through May 2017 in three communities where the female resided. None of the 83 individuals of the three communities examined by skin biopsy were mf positive. Similarly, none of the biopsies from the individuals were found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA). CONCLUSIONS/SIGNIFICANCE: These provide support to the conclusion that onchocerciasis has been eliminated from Mexico.