Dengue virus in Aedes aegypti larvae and infestation dynamics in Roraima, Brazil.
OBJECTIVE
To detect the presence of dengue virus in larval forms of Aedes aegypti and to associate vector presence with rainfall and incidence of disease.


METHODS
Eighteen households were randomly selected for egg collection in a neighborhood of the city of Boa Vista, Roraima, in Northern Brazil. Two oviposition traps were installed per home, and removed after one week. This was repeated on a monthly basis between November 2006 and May 2007. Trap positivity rate and egg density were calculated. Following the eclosion of 1,422 eggs, 44 pools of at least 30 larvae each were formed, which were evaluated for presence of dengue virus using RT-PCR and hemi-nested PCR. Dengue incidence rates in the period were correlated with rainfall rates. The association between these two variables and the number of eggs collected was determined using Pearson correlation.


RESULTS
None of the pools tested positive for presence of dengue virus, despite the high incidence of dengue in the neighborhood during the studied period. The density of Ae. aegypti increased with rainfall, but was not correlated with incidence of dengue.


CONCLUSIONS
The results suggest that transovarial transmission of dengue virus in mosquitoes occurs at a very low frequency, and therefore virus persistence in urban settings may not depend on such transmission. The mosquito population increased during the rainy season due to increased formation of breeding sites; the lack of correlation with incidence of dengue may be due to underestimation of incidence data during epidemics.
Zeidler
Julianna Dias
JD
Departamento de Biologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Roraima, Boa Vista, RR, Brasil. interlhama@yahoo.com.br
Acosta
Pablo Oscar Amézaga
PO
Barrêto
Priscila Pereira
PP
Cordeiro
Joel da Silva
Jda S
D000330:Aedes / Q000821:virology*; D000818:Animals; D001938:Brazil / Q000453:epidemiology; D003715:Dengue / Q000453:epidemiology* / Q000635:transmission; D003716:Dengue Virus / Q000302:isolation & purification*; D015994:Incidence; D007303:Insect Vectors / Q000821:virology*; D007814:Larva / Q000821:virology; D011156:Population Density; D011157:Population Dynamics; D011891:Rain; D012621:Seasons