First Record of Culicoides Occidentalis in Sinaloa, Mexico.

Culicoides species adults were collected in light traps located on the coast of Elota, Sinaloa, Mexico, in February 2022. All specimens were females, and it was determined based on their morphology that they belonged to the Culicoides variipennis complex. The identification of the species was carried out by means of a comparative analysis of genetic sequences of the cytochrome c oxidase subunit I gene, which resulted in C. occidentalis, this being its first report in Sinaloa and its third nationwide.

First Record of Toxorhynchites moctezuma in Sinaloa, Mexico: Notes about its Morphology.

Mosquito larvae were collected in the urban area of the city of Culiacan, Sinaloa, in September of 2020. The immature stages were placed in emergence containers and fed with Aedes aegypti larvae. The adults that emerged from the immature stages were mounted on insect pins and characterized based on their morphology. The species corresponded morphologically to Toxorhynchites moctezuma, making this the first report of the species for the state of Sinaloa, Mexico. Similarities and morphological variations are discussed with previous analysis for this species.

Natural Vertical Transmission of Dengue Virus Serotype 4 in Aedes aegypti Larvae from Urban Areas in Sinaloa, Mexico.

Dengue virus (DENV) is transmitted to humans by the bite of the vector Aedes aegypti. Several researchers have suggested that the mechanism of vertical transmission of DENV in the vector is a key aspect for the prevalence of the virus in the environment and the potentiation of epidemic outbreaks of the disease. In this context and as part of an integrated study of DENV serotypes in mosquitoes of urban areas in Sinaloa, Mexico, the presence of DENV-4 in larval stages of Ae. aegypti was evaluated to demonstrate the vertical transmission of this serotype. In total, 672 larvae of Ae. aegypti were collected in 16 sectors and were grouped into 36 pools, of which 41.66% (15/36 pools) tested positive for DENV-4, with a minimum infection rate = 22.32. The analysis of the obtained sequences showed a 98% similarity to the DENV-4 with sequences previously reported in GenBank. These results show that Ae. aegypti acts as a natural reservoir for DENV-4 in this region.

Protective effect of CCR5 Delta-32 allele against HIV-1 in Mexican women.

C-C chemokine receptor type 5 (CCR5) is known for its role as a co-receptor for HIV-1 infection. Some individuals possess a 32 bp deletion, known as Delta-32 allele which has been reported to confer resistance to HIV-1 infection. In order to estimate the distribution of Delta-32 allele of CCR5 gene, 1034 mestizo individuals from the Northwest of Mexico, including 385 HIV-1-infected individuals, 472 healthy controls and 177 uninfected female sex workers; were examined by allele-specific PCR. There was no statistically significant difference in the frequency of Delta-32 allele between HIV-1 positive and healthy individuals (OR= 1.1, p= 0.6). However, we found a significantly reduced prevalence of CCR5 Delta-32 heterozygous genotype in female patients (OR= 0.084, 95% CI= 0.011 - 0.630, p= 0.002), as well as in allele frequency, compared to male patients. Furthermore, we observed an inverse relationship between allele frequency and the risk of HIV-1 transmission and AIDS progression among female healthy controls, sex workers and HIV-1 infected groups. Our findings support previous data showing Delta-32 as a genetic protective factor against HIV-1 infection in Mexican women, as well as in women from other populations.