In 2010, an outbreak of febrile illness with arthralgic manifestations was detected at La Estación village, Portuguesa State, Venezuela. The etiologic agent was determined to be Mayaro virus (MAYV), a reemerging South American alphavirus. A total of 77 cases was reported and 19 were confirmed as seropositive. MAYV was isolated from acute-phase serum samples from 6 symptomatic patients. We sequenced 27 complete genomes representing the full spectrum of MAYV genetic diversity, which facilitated detection of a new genotype, designated N. Phylogenetic analysis of genomic sequences indicated that etiologic strains from Venezuela belong to genotype D. Results indicate that MAYV is highly conserved genetically, showing ≈17% nucleotide divergence across all 3 genotypes and 4% among genotype D strains in the most variable genes. Coalescent analyses suggested genotypes D and L diverged ≈150 years ago and genotype diverged N ≈250 years ago. This virus commonly infects persons residing near enzootic transmission foci because of anthropogenic incursions.

Oropouche virus (OROV), genus Orthobunyavirus, family Bunyaviridae, is an important cause of human illness in tropical South America. Herein, we report the isolation, complete genome sequence, genetic characterization, and phylogenetic analysis of an OROV species reassortant, Madre de Dios virus (MDDV), obtained from a sick monkey (Cebus olivaceus Schomburgk) collected in a forest near Atapirire, a small rural village located in Anzoategui State, Venezuela. MDDV is one of a growing number of naturally occurring OROV species reassortants isolated in South America and was known previously only from southern Peru.

We studied the spatial localization of mosquitoes in a sylvatic focus of Venezuelan equine encephalitis virus in western Venezuela to identify mosqui

The ecology of Venezuelan equine encephalitis (VEE) virus transmission was compared at three enzootic foci: two forest sites in the Catatumbo region of western Venezuela that have yielded small numbers of virus isolates since the 1970s, and another focus in the middle Magdalena Valley of Colombia that has consistently yielded many VEE virus isolates. Our results demonstrated dramatic differences in VEE virus isolation rates from sentinel hamsters, as well as differences in mosquito species composition and captured mammals with antibodies to VEE virus, between the Colombian and Venezuelan study sites. The higher isolation rate of enzootic VEE virus in the Colombian site was associated with a more abundant fauna of spiny rats (Proechimys spp.), known reservoir hosts of enzootic VEE virus. Mosquito collections demonstrated that the Colombian forest had a higher mosquito diversity and species evenness than either of the Venezuelan forests. The Colombian focus was especially richer in its Culex (Melanoconion) spp. fauna, a subgenus that includes all proven enzootic vectors for VEE virus. Our results suggest that the greater abundance, diversity, and stability of enzootic vector populations, combined with the greater density of rodent reservoir hosts, explains the higher levels of VEE virus circulation in the Colombian focus compared with the Venezuelan forests.

This study represents the first attempt to understand the current distribution and evolutionary history of Culicidae in Venezuela and adjacent areas using cladistic methods. We studied the association between immature mosquitoes and their aquatic habitats in plants (phytotelmata) in 16 protected natural areas of Venezuela. A total of 68 mosquito species was collected from 47 host-plant species. Parsimony Analysis of Endemicity using localities and mosquito species was used to find the most parsimonious cladograms depicting the biogeographic relationships. Varying degrees of mosquito-plant associations were observed, with the greatest specificity existing at the genus and subgenus levels. Implicit enumeration algorithms obtained one parsimonious tree (L=101 steps) with four well-supported groups named "Amazonas" (southern Venezuela), “Bolivar” (southeastern Venezuela), "Los Andes Cordillera” and "Coastal Cordillera" (northern Caribbean mountain range). These results support the hypothesis that the Guayana Shield was an ancestral center of speciation, followed by the Andean Region, whereas the mosquito fauna from the Central Cordillera was derived from the latter.

Morfometría geométrica alar para la identificación de Chrysomya albiceps y C. megacephala (Diptera: Calliphoridae) de Venezuela