Spatio-temporal distribution of vertically transmitted dengue viruses by Aedes aegypti (Diptera: Culicidae) from Arroyo Naranjo, Havana, Cuba.

Objective To study the distribution of vertical transmission of dengue viruses in field-collected Aedes aegypti larvae in the municipality of Arroyo Naranjo in Havana, Cuba. Methods Aedes aegypti larvae and pupae were collected monthly between September 2013 and July 2014 in the seven Municipal Health Areas of Arroyo Naranjo. Pools formed of 30-55 larvae were examined through PCR and sequencing to detect the presence of each serotype. Results We analysed 111 pools of larvae and pupae (4102 individuals) of which 37 tested positive for at least one DENV. More than one DENV type was observed in 10 of the 37 positive pools. Infected pools were detected every month, except in January, suggesting a sustained circulation of DENV in the vector populations. DENV-1 and DENV-3 were the most frequent and dispersed, though all four DENV types were detected. Nucleotide sequencing from positive pools confirmed RT-PCR results for DENV-1 (genotype V), DENV-3 (genotype III) and DENV-4 (genotype II). DENV-2 was detected by RT-PCR but could not be confirmed by nucleotide sequencing. Conclusion Our study of the distribution of natural vertical transmission of dengue virus types highlights extrinsic virus activity patterns in the area and could be used as a new surveillance tool.