Chikungunya virus: A general overview

Chikungunya virus (CHIKV) is a re-emerging mosquito borne alphavirus responsible for the recent outbreak in the Americas. Immunologically naïve population in the Americas favors the spread of epidemics. Chikungunya fever is characterized by an abrupt febrile illness, polyarthralgia and maculopapular rash. In chikungunya fever, shock or severe hemorrhage is very rarely observed; the onset is more acute and the duration of fever is shorter than dengue disease. The pain is much more pronounced and localized to the joints and tendons in chikungunya fever, in comparison to dengue fever. There is no specific and effective antiviral therapy and vaccines are still in trails. The only effective preventive measures consist of individual protection against mosquito bites and vector control. Disease prevention is important due to the economic burden it entails. Clinicians need to distinguish chikungunya fever between dengue fever and other diseases to give a successful treatment and prevent disease spreading

Presencia del virus del oeste del Nilo en el noreste de México

Objetivo. Detectar la presencia del virus del oeste del Nilo (VON) en aves, equinos y seres humanos en el noreste de México. Material y métodos. Se buscó en diferentes localidades del noreste de México la presencia de anticuerpos antivirus del oeste del Nilo (anti-VON) en suero de 33 aves, 24 caballos y 237 personas mediante pruebas de ELISA durante el periodo de julio de 2003 a julio de 2006. En los sueros humanos se buscó también el RNA-VON mediante RT-PCR. Resultados. Se encontraron tres aves seropositivas y 15 equinos. En el hombre, 40% de los sueros fue positivo para anticuerpos IgG y ninguno para anticuerpos IgM. Conclusiones. El VON se encuentra activo en México y se suma a otras enfermedades emergentes transmitidas por vectores que representan un reto a la investigación y a los programas de prevención

Respuesta conductual de Aedes aegypti (Linneaus, 1762) frente adulticidas piretroides de uso frecuente en Salud Pública

Objetivos. Evaluar la respuesta conductual de la generación F1 de Aedes aegyti (L) colectados en el área metropolitana de Monterrey (Nuevo León, México) frente a tres adulticidas piretroides de uso frecuente en salud pública. Materiales y métodos. Se utilizó un sistema modular novedoso denominado HITSS (High-Throughput Screening System), para evaluar dos respuestas de comportamiento (irritación de contacto y repelencia espacial), así como la toxicidad de tres insecticidas DDT, permetrina y bifentrina a diferentes concentraciones (0,025, 0,25, 25 y 250 nmol/cm2). Resultados. En la concentración 2,5 nmol/cm2, el DDT (4,3 ± 2,4) y la permetrina (8,0 ± 1,4) son los insecticidas que tienen mayor efecto irritante (p<0,05); la bifentrina requiere dosis 20 veces más alta para lograr efectos similares. En repelencia espacial, los tres insecticidas evaluados producen respuestas similares en todas las concentraciones; para DDT de 7 a 14%; permetrina de 9 a 15% y bifentrina de 19 a 27%. La permetrina y bifentrina a concentraciones 0,025 nmol/cm2, producen efectos knockdown superiores a 34%, con una mortalidad 19%, el DDT requiere concentraciones diez veces más alta para lograr efectos similares. Conclusiones. El sistema HITTS puede ser usado para evaluar la respuesta conductual frente a insecticidas

Los mosquitos del estado de Quintana Roo, México (Diptera: Culicidae).

A study on the distribution of the mosquitoes of Quintana Roo State of México was carried out by collecting immature and adult stages during September and October 2006. The collections were made from different locations in the three physiogeographical provinces of the state: Carso Yucateco, Carso, Lomeríos de Campeche, and Costa Baja de Quintana Roo. A total of 420 larvae, 294 pupae, and 726 adults representing 13 genera and 41 species were collected. Two genera, three subgenera, and 11 species are new to the mosquito fauna of Quintana Roo State. Collection and bionomical data are included for species collected during the study, and a checklist of species newly and previously recorded from the state is provided.Un estudio de la distribución de los mosquitos del estado de Quintana Roo, México fue realizado por medio de colectas de estados inmaduros y adultos durante Septiembre y Octubre del 2006. Las colectas fueron realizadas en diferentes localidades de las tres provincias fisiográficas del estado: Carso Yucateco, Carso, Lomeríos de Campeche y Costa Baja de Quintana Roo. Un total de 420 larvas, 294 pupas y 726 adultos fueron colectados representando 13 géneros y 41 especies. Dos géneros, tres subgéneros y 11 especies son nuevos registros estatales para Quintana Roo

Transmission dynamics of an iridescent virus in an experimental mosquito population: the role of host density.

1. The transmission of insect pathogens cannot be adequately described by direct linear functions of host and pathogen density due to heterogeneity generated from behavioural or physiological traits, or from the spatial distribution of pathogen particles. Invertebrate iridescent viruses (IIVs) can cause patent and lethal infection or a covert sub-lethal infection in insects. Aedes aegypti larvae were exposed to suspensions of IIV type 6 at two densities. High larval density increased the prevalence of aggression resulting in potentially fatal wounding. 2. The overall prevalence of infection (patent + covert) was positively influenced by host density and increased with exposure time in both densities. The survival time of patently infected insects was extended by ≈ 5 days compared with non-infected insects. 3. Maximum likelihood models based on the binomial distribution were fitted to empirical results. A model incorporating heterogeneity in host susceptibility by inclusion of a pathogen-free refuge was a significantly better fit to data than an all-susceptible model, indicating that transmission is non-linear. The transmission coefficient (υ) did not differ with host density whereas the faction of the population that occupied the pathogen-free refuge (ΠR) was significantly reduced at high host density compared with the low density treatment. 4. The transmission of free-living infective stages of an IIV in Ae. aegypti larvae is non-linear, probably because of density-related changes in the frequency of aggressive encounters between hosts. This alters host susceptibility to infection and effectively reduces the proportion of hosts that occupy the pathogen-free refuge

The neovolcanic axis is a barrier to gene flow among Aedes aegypti populations in Mexico that differ in vector competence for Dengue 2 virus.

The Neovolcanic axis (NVA) traverses Mexico at the 19th parallel and is considered to be a geographic barrier to many species. We have demonstrated that the intersection of the NVA with the coast in Veracruz state is a barrier to gene flow in Ae. aegypti. This was unexpected because the intersection of the NVA with the Pacific Coast is not a barrier to gene flow. Further studies to identify the actual mechanism(s) that is(are) contributing to the lack of gene flow will provide important information on the trafficking potential of Ae. aegypti, which will be of great value to Ae. aegypti control programs. There are significant differences in vector competence for dengue virus between mosquitoes north and south of the NVA, but the epidemiological significance of these finding remains to be determined. Future studies will determine if, for example, the genes that condition midgut infection and vector competence of Ae. aegypti populations provide biomarkers for risk of dengue transmission. Such biomarkers could be of great value to control programs in resource limited environments by allowing targeting of vector control efforts to areas at most risk for epidemic dengue and dengue hemorrhagic fever

Detection of West Nile virus-specific antibodies and nucleic acid in horses and mosquitoes, respectively, in Nuevo Leon State, northern Mexico, 2006–2007

Abstract. In the last 5 years, there has been only one reported human case of West Nile virus (WNV) disease in northern Mexico. To determine if the virus was still circulating in this region, equine and entomological surveillance for WNV was conducted in the state of Nuevo Leon in northern Mexico in 2006 and 2007. A total of 203 horses were serologically assayed for antibodies to WNV using an epitope-blocking enzyme-linked immunosorbent assay (bELISA). Seroprevalences for WNV in horses sampled in 2006 and 2007 were 26% and 45%, respectively. Mosquito collections in 2007 produced 7365 specimens representing 15 species. Culex mosquitoes were screened for WNV RNA and other genera (Mansonia, Anopheles, Aedes, Psorophora and Uranotaenia) were screened for flaviviruses using reversetranscription (RT)-PCR. Two pools consisting of Culex spp. mosquitoes contained WNV RNA. Molecular species identification revealed that neither pool included Culex quinquefasciatus (Say) (Diptera:Culicidae) complex mosquitoes. No evidence of flaviviruses was found in the other mosquito genera examined. These data provide evidence that WNV is currently circulating in northern Mexico and that non-Cx. quinquefasciatus spp. mosquitoes may be participating in the WNV transmission cycle in this region

EVALUACIÓN DE RIESGO A LA SALUD EN LA COMUNIDAD DE LOMA BLANCA (DISTRITO DE RIEGO 009) VALLE DE JUAREZ (MEXICO), POR EXPOSICIÓN A AGUAS RESIDUALES NO TRATADAS

Loma Blanca, localidad rural dentro del distrito de riego 009 en el Valle de Juárez, está situada enlas márgenes del canal de riego que conduce las aguas residuales no tratadas producidas porCiudad Juárez, Chihuahua. Este sitio se encuentra en un medio agrícola que por 50 años ha sidoobjeto de una prolongada irrigación con aguas negras, y que está contaminado con parásitosintestinales y enteropatógenos.Las infecciones gastrointestinales son de importancia fundamentalen la salud de los habitantes del sitio, y probablemente su prevalencia está asociada a los mediosagua y suelo contaminados. Para conocer el perfil de saneamiento básico de Loma Blanca yevaluar el riesgo a la salud por exposición al medio acuático y al suelo contaminados, se aplicó unaencuesta. Para su evaluación se utilizaron la metodología Health Assessment, de la Agency forToxic Substances and Diseases Registry, modificada para evaluaciones que involucren patógenos;la norma oficial mexicana NOM-048-SSA1-1993; y una matriz de análisis del Department ofDefense, de los Estados Unidos. El resultado de la evaluación señala que la categoría de riesgo esalta. La conclusión se basa en el análisis de datos sobre el medio ambiente, características devivienda, hábitos de consumo de agua y vegetales, percepción del riesgo por parte de lacomunidad, y niveles de morbilidad.AbstractLoma Blanca, rural town inside the district of watering 009 in the Valley of Juárez, it is located in theriverbanks of the watering channel that it not drives the residual waters treated taken place byCiudad Juárez, Chihuahua. This place is in a half agricultural one that has been object of a lingeringirrigation with black waters for 50 years, and that it is polluted with intestinal parasites andpatogens. Las gastrointestinal infections they are of fundamental importance in the health of theinhabitants of the place, and its prevalence is probably associated to the means water andcontaminated floor. To know the profile of basic reparation of Loma Blanca and to evaluate the riskto the health for exhibition to the aquatic means and the contaminated floor, a survey was applied.For their evaluation they were used the methodology Health Assessment, of the Agency for ToxicSubstances and Diseases Registry, modified for evaluations that involve patogens; the Mexicanofficial norm NOM-048-SSA1-1993; and a womb of analysis of the Department of Defense, of theUnited States. The result of the evaluation points out that the category of risk is high. Theconclusion is based on the analysis of data on the environment, characteristic of housing, habits ofconsumption of water and vegetables, perception of the risk on the part of the community, andmorbidity levels.Palabras calve: Loma Blanca, Valle de Juarez, valoración del riesgo, aguas residuales, risk value, residual waters