RESUMEN
Prior to 2006, West Nile virus (WNV) had not been definitively detected in Chiapas, the southernmost state of Mexico, although it circulates elsewhere in Mexico and Central America. We collected over 30,000 mosquitoes and blood-sampled 351 domestic animals in Chiapas in search for evidence of current or recent transmission of WNV. Two mosquito pools tested positive for WNV RNA and 17 domestic animals tested positive for specific WNV-neutralizing antibodies, including young animals (<1 year old) in four of five sampled locations. The two WNV-positive mosquito pools were collected on the Pacific coastal plain of Chiapas in June, 2006, and included a pool of Culex nigripalpus, a suspected vector of WNV, and a pool of Cx. interrogator. The sequence of a 537-nucleotide portion of a cDNA amplicon derived from the WNV NS5 gene from the Cx. interrogator pool contained a single silent nucleotide substitution when compared to WNV strain NY99.
Asunto(s)
Enfermedades de los Animales/epidemiología , Animales Domésticos/sangre , Culicidae/virología , Fiebre del Nilo Occidental/veterinaria , Virus del Nilo Occidental/aislamiento & purificación , Enfermedades de los Animales/sangre , Enfermedades de los Animales/virología , Animales , Anticuerpos Antivirales , Bovinos , Femenino , Caballos , México/epidemiología , Aves de Corral , Porcinos , Fiebre del Nilo Occidental/sangre , Fiebre del Nilo Occidental/epidemiologíaRESUMEN
The capability of Phormidium animalis, a cyanobacterium commonly found in larval habitats of Anopheles albimanus in southern Mexico, to support larval development of this mosquito was investigated. First-stage larvae were reared under insectary conditions with P. animalis ad libitum and their development was compared with larvae fed with wheat germ. The time of pupation and adult mosquito size, assessed by wing length, were similar in both groups, but fewer adult mosquitoes were obtained from larvae fed with the cyanobacteria. Nevertheless, these observations indicate that P. animalis is ingested and assimilated by larval An. albimanus, making this cyanobacterium a good candidate for genetic engineering for the introduction of mosquitocidal toxins for malaria control in the region.
Asunto(s)
Anopheles/fisiología , Cianobacterias , Animales , Anopheles/crecimiento & desarrollo , Femenino , Larva/crecimiento & desarrollo , Larva/fisiología , Masculino , México , Pupa/fisiología , Factores de TiempoRESUMEN
Cyanobacteria associated with Anopheles albimanus Wiedemann larval habitats from southern Chiapas, Mexico, were isolated and identified from water samples and larval midguts using selective medium BG-11. Larval breeding sites were classified according to their hydrology and dominant vegetation. Cyanobacteria isolated in water samples were recorded and analyzed according to hydrological and vegetation habitat breeding types, and mosquito larval abundance. In total, 19 cyanobacteria species were isolated from water samples. Overall, the most frequently isolated cyanobacterial taxa were Phormidium sp., Oscillatoria sp., Aphanocapsa cf. littoralis, Lyngbya lutea, P. animalis, and Anabaena cf. spiroides. Cyanobacteria were especially abundant in estuaries, irrigation canals, river margins and mangrove lagoons, and more cyanobacteria were isolated from Brachiaria mutica, Ceratophyllum demersum, and Hymenachne amplexicaulis habitats. Cyanobacteria were found in habitats with low to high An. albimanus larval abundance, but Aphanocapsa cf. littoralis was associated with habitats of low larval abundance. No correlation was found between water chemistry parameters and the presence of cyanobacteria, however, water temperature (29.2-29.4 degrees C) and phosphate concentration (79.8-136.5 ppb) were associated with medium and high mosquito larvae abundance. In An. albimanus larval midguts, only six species of cyanobacteria were isolated, the majority being from the most abundant cyanobacteria in water samples.