Novel Kdr mutations (K964R and A943V) in pyrethroid-resistant populations of Triatoma mazzottii and Triatoma longipennis from Mexico and detoxifying enzymes.

Although having five different ways of transmission the vector-borne is the principal way of transmission of Chagas disease, which involves insects of the subfamily Triatominae (Hemiptera: Reduviidae). Nineteen of the 31 species that occur in Mexico are associated with humans, and all are capable of transmitting the disease. Pyrethroids are the insecticides recommended for the control of these vectors in Mexico. We determined the susceptibility to the pyrethroids deltamethrin and permethrin of peridomestic populations of Triatoma mazzottii Usinger and two populations of Triatoma longipennis Usinger in comparison with a reference strain for each species. Bioassays were performed for the determination of the LD50 for both field populations and reference strains. A maximum of 27 fold resistance to deltamethrin was observed in T. mazzottii, meanwhile, for permethrin, T. longipennis from Jalisco show the highest value of 3.19 fold. There was significantly increased activity of esterases in field populations in comparison with their corresponding reference strain. The results of the search of kdr mutations related to the resistance to deltamethrin and permethrin in the evaluated species show the presence of mutations in the field populations, as is the case with individuals of T. mazzottii, for which the mutation was found A943V, and for the two populations of T. longipennis included in this study, we report the presence of the kdr mutation K964R. Evaluation of the various mechanisms involved in resistance to pyrethroids in triatomines from Mexico could guide us to the real justification for insecticide resistance monitoring.

[Pediculus capitis in schoolchildren of the urban area of Nuevo León, México: Analyses of associated factors].

INTRODUCTION: Pediculosis capitis is a recurring problem affecting 6 to 12 millions of children annually; there are no epidemiological data on this subject in the state of Nuevo León, and there are few in México. Therefore, new contributions are needed to design control strategies based on factors that may predispose to head lice infestation. OBJECTIVE: To determine the prevalence of Pediculus capitis in primary school children and to evaluate risk factors and individual or socioeconomic characteristics statistically associated with infestation. MATERIALS AND METHODS: We included 840 schoolchildren from six municipalities after parents and children signed an informed consent. Ectoparasites were collected from infested children using a finetoothed comb. Participants were interviewed using a questionnaire on individual and socioeconomic variables including age, gender, education, hair characteristics, overcrowding, and siblings with pediculosis, among others. RESULTS: The overall prevalence of head lice in schoolchildren was 28% (235/840), the highest prevalence was among girls (33.7%, 140/417), and children from the fifth grade (10-11 years old) were the most affected (6.2%; 52/840). Female gender, long hair and the father's education level were significantly associated with P. capitis. CONCLUSION: Our results showed that the P. capitis prevalence in Nuevo León is one of the highest in Mexico, that it constitutes a real public health problem, and that there is need to establish prevention programs at home and school to decrease or to control P. capitis with the support of public health authorities.

Pediculus capitis en niños de escuelas de la zona urbana de Nuevo León, México: análisis de factores asociados / Pediculus capitis in schoolchildren of the urban area of Nuevo León, México: Analyses of associated factors

Resumen Introducción. La pediculosis capitis es un problema recurrente que afecta anualmente de 6 a 12 millones de niños; no existen datos epidemiológicos en el estado de Nuevo León, y en México son escasos, por lo cual se necesitan estudios fundamentados para diseñar estrategias de control basadas en los factores que predisponen a la infestación por piojos. Objetivo. Determinar la prevalencia de Pediculus capitis en niños de educación primaria para detectar factores de riesgo y conocer las características individuales y las condiciones socioeconómicas asociadas estadísticamente con la infestación. Materiales y métodos. Se incluyeron 840 escolares de seis municipios, previa firma del consentimiento informado por parte de los padres y de los niños. Los ectoparásitos se recolectaron en cada niño infestado utilizando un peine fino. Los participantes contestaron una encuesta que incluía variables individuales y socioeconómicas, como la edad, el sexo, el grado escolar, las características del cabello, el hacinamiento y la pediculosis en hermanos, entre otras. Resultados. La prevalencia de pediculosis capitis en los niños fue de 28 % (235/840), con una mayor prevalencia en las niñas (33,7 %; 140/417); los niños del quinto grado (10 a 11 años) fueron los más afectados (6,2 %; 52/840). El sexo femenino, el cabello largo y el nivel escolar de los padres se asociaron significativamente con la pediculosis capitis. Conclusiones. Los resultados demostraron que la prevalencia de pediculosis capitis en Nuevo León es una de las más altas de México y que es un problema real de salud pública,por lo cual es importante establecer programas de prevención en la escuela y en el hogar para disminuirla o controlarla con la ayuda de las autoridades de salud pública.

Abstract Introduction: Pediculosis capitis is a recurring problem affecting 6 to 12 millions of children annually; there are no epidemiological data on this subject in the state of Nuevo León, and there are few in México. Therefore, new contributions are needed to design control strategies based on factors that may predispose to head lice infestation. Objective: To determine the prevalence of Pediculus capitis in primary school children and to evaluate risk factors and individual or socioeconomic characteristics statistically associated with infestation. Materials and methods: We included 840 schoolchildren from six municipalities after parents and children signed an informed consent. Ectoparasites were collected from infested children using a fine-toothed comb. Participants were interviewed using a questionnaire on individual and socioeconomic variables including age, gender, education, hair characteristics, overcrowding, and siblings with pediculosis, among others. Results: The overall prevalence of head lice in schoolchildren was 28% (235/840), the highest prevalence was among girls (33.7%, 140/417), and children from the fifth grade (10-11 years old) were the most affected (6.2%; 52/840). Female gender, long hair and the father's education level were significantly associated with P. capitis. Conclusion: Our results showed that the P. capitis prevalence in Nuevo León is one of the highest in Mexico, that it constitutes a real public health problem,and that there is need to establish prevention programsat home and school to decrease or to controlP. capitis with the support of public health authorities.

Prevalence of Trypanosoma cruzi infection in dogs and small mammals in Nuevo León, Mexico.

Chagas disease, caused by the protozoan Trypanosoma cruzi, is an important public health concern in areas extending from South America northward into the southern United States of America. Although this hemoflagellate has many wild and domestic mammalians reported as reservoir hosts, studies on this subject are scarce in Nuevo León state, a region located in northeastern Mexico. This cross-sectional study showed that the general prevalence of T. cruzi infection in Nuevo León state was 14.5% (35/241), this percentage matching the ones determined by PCR and traditional diagnostics. Localities and infected mammals did not significantly differ (χ2=6.098, p=0.192); however the number of infected animals was highly correlated with mammalian species (p=0.009). Striped skunks (Mephitis mephitis) were found to be the most infected overall (11/34, 32.3%), while dogs (Canis familiaris) had the lowest prevalence. In conclusion, although the prevalence of T. cruzi infection in small mammals was lower in Nuevo León than in other states of Mexico, our results provide new locality records, including striped skunks, opossums (Didelphis marsupialis) and dogs, and extend the recorded area to woodrats (Neotoma micropus).

Trypanosoma cruzi -infected Triatoma gerstaeckeri (Hemiptera: Reduviidae) from Nuevo León, México, and pathogenicity of the regional strain / Triatoma gerstaeckeri (Hemiptera: Reduviidae) infectada con Trypanosoma cruzi en Nuevo León, México, y capacidad patógena de la cepa regional

Introduction: Four species of triatomines have been reported in Nuevo León, northeast (NE) México, but Triatoma gerstaeckeri has only been recorded from a peridomestic dwelling. Objectives: To assess the natural infection index (NII) of Trypanosoma cruzi in triatomines and the infestation index (II) of T. gerstaeckeri collected in a suburban locality, and to collect histopathological data to understand tissue tropism of the regional T. cruzi strain (strain NE) obtained from the vectors collected after an experimental inoculation in Mus musculus . Materials and methods: Triatomines were collected from 85 houses and peridomiciles in Allende, Nuevo León. Stool samples were obtained to determine the T. cruzi NII and were used in an experimental mice infection. Results: A total of 118 T . gerstaeckeri were captured, and 46 (adults and nymphs) were collected inside the same house (II=1.17%). Thirty-seven reduvids were infected with T. cruzi (NII=31.3%). Tissue tropism of the T. cruzi NE strain was progressive in skeletal muscle, myocardial, and adipose tissues and was characterized by the presence of intracellular amastigotes and destruction of cardiac myocells. Conclusions: The presence of naturally infected domiciliary vectors is an important risk factor for public health in the region considering that these vectors are the principal transmission mechanism of the parasite. The T. cruzi NE strain has similar virulence to that of other Mexican and Texan strains and caused chagasic infections in 11 of 12 mice.

Introducción. En Nuevo León, localizado en el noreste de México, existen cuatro especies de triatominos, de las cuales Triatoma gerstaeckeri ha sido la única reportada en peridomicilios. Objetivos. Evaluar el índice de infección natural de Trypanosoma cruzi en los triatominos y el índice de infestación de T. gerstaeckeri en una localidad suburbana, y obtener datos histopatológicos para comprender el tropismo tisular de la cepa regional (cepa NE) de T. cruzi obtenida de los vectores recolectados después de la infección experimental en Mus musculus. Materiales y métodos. La recolección de triatominos se llevó a cabo en 85 casas y peridomicilios de Allende, Nuevo León, México. Se obtuvieron muestras de las deyecciones para conocer el índice de infección natural por T. cruzi y, con estas, se hicieron inoculaciones experimentales en ratones. Resultados. Se capturaron 118 especímenes de T. gerstaeckeri , 46 (adultos y ninfas) en el mismo domicilio (índice de infestación=1,17 %). Treinta y siete redúvidos estaban infectados con T. cruzi (índice de infección natural, 31,3). El tropismo tisular de la cepa NE de T. cruzi fue progresivo en músculo esquelético, miocardio y tejido adiposo, y se caracterizó por la presencia de amastigotes intracelulares con destrucción de células cardiacas. Conclusiones. La presencia de vectores domiciliarios naturalmente infectados con T. cruzi , es un factor de riesgo importante para la salud pública de la región, considerando que este es el principal mecanismo de la transmisión del parásito y que la cepa NE de T. cruzi tiene una virulencia similar a la de otras cepas mexicanas y texanas, y causó infección chagásica en 11 de los 12 ratones inoculados.

Trypanosoma cruzi -infected Triatoma gerstaeckeri (Hemiptera: Reduviidae) from Nuevo León, México, and pathogenicity of the regional strain.

INTRODUCTION: Four species of triatomines have been reported in Nuevo León, northeast (NE) México, but Triatoma gerstaeckeri has only been recorded from a peridomestic dwelling. OBJECTIVES: To assess the natural infection index (NII) of Trypanosoma cruzi in triatomines and the infestation index (II) of T. gerstaeckeri collected in a suburban locality, and to collect histopathological data to understand tissue tropism of the regional T. cruzi strain (strain NE) obtained from the vectors collected after an experimental inoculation in Mus musculus . MATERIALS AND METHODS: Triatomines were collected from 85 houses and peridomiciles in Allende, Nuevo León. Stool samples were obtained to determine the T. cruzi NII and were used in an experimental mice infection. RESULTS: A total of 118 T . gerstaeckeri were captured, and 46 (adults and nymphs) were collected inside the same house (II=1.17%). Thirty-seven reduvids were infected with T. cruzi (NII=31.3%). Tissue tropism of the T. cruzi NE strain was progressive in skeletal muscle, myocardial, and adipose tissues and was characterized by the presence of intracellular amastigotes and destruction of cardiac myocells. CONCLUSIONS: The presence of naturally infected domiciliary vectors is an important risk factor for public health in the region considering that these vectors are the principal transmission mechanism of the parasite. The T. cruzi NE strain has similar virulence to that of other Mexican and Texan strains and caused chagasic infections in 11 of 12 mice.

Distribution of ixodid ticks on dogs in Nuevo León, Mexico, and their association with Borrelia burgdorferi sensu lato.

This study aimed to document the geographic distribution of Ixodes tick species in dogs and the prevalence of Borrelia burgdorferi s.l. in adult ticks and blood samples by amplification of the ospA region of the B. burgdorferi genome. The study area included nine localities in Nuevo León state. DNA amplification was performed on pools of ticks to calculate the maximum likelihood estimation (MLE), and the community composition (prevalence, abundance, and intensity of infestation) was recorded. A total of 2,543 adult ticks, representing four species, Rhipicephalus sanguineus, Dermacentor variabilis, Rhipicephalus (Boophilus) annulatus, and Amblyomma cajennense, were recorded from 338 infested dogs. Statistically significant correlations were observed between female dogs and infestation (P = 0.0003) and between R. sanguineus and locality (P = 0.0001). Dogs sampled in Guadalupe and Estanzuela were positive by PCR (0.9 %) for B. burgdorferi. Rhipicephalus sanguineus had the highest abundance, intensity, and prevalence (10.57, 7.12 and 94.6, respectively). PCR results from 256 pools showed that four pools were positive for D. variabilis (1.6 %), with an MLE of 9.2 %; nevertheless, it is important to consider that in the area under examination probably other reservoir hosts for D. variabilis and B. burgdorferi are present that, very likely, play a much more important role in the ecology of Lyme borreliosis than dogs, which could be considered in future studies.

Update on seroprevalence of anti-Trypanosoma cruzi antibodies among blood donors in northeast Mexico.

Chagas disease has become frequent in non-endemic areas, where it can be transmitted by blood transmission. Therefore, we explored seroprevalence of anti-Trypanosoma cruzi antibodies among blood donors at the Cardiology Hospital, Mexican Institute of Social Security at Monterrey, Nuevo León, by both an enzyme-linked immunosorbent assay and indirect hemagglutination. Blood samples from 1,000 healthy blood donors were selected. A seropositivity of 2.8% was shown among the studied population, of which 2.59% (21/809) were inhabitants of Nuevo León, whereas 3.07% (2/65) and 3.96% (5/126) were from Coahuila and Tamaulipas, respectively. Our result is higher than that of a previous study from 1998, where a prevalence of 0.5% was reported. This once again corroborates the importance of installing a surveillance program to detect and prevent the transfusion of T. cruzi from asymptomatic blood donors in blood banks located in urban cities recognized as non-endemic.