Natural vertical transmission of dengue viruses byAedes aegyptiin Bolivia

Abstract

The natural transmission of dengue virus from an infected female mosquito to its progeny, namely the vertical transmission, was researched in wild caught Aedes aegypti during an important outbreak in the town of Santa Cruz de la Sierra, Bolivia. Mosquitoes were collected at the preimaginal stages (eggs, larvae and pupae) then reared up to adult stage for viral detection using molecular methods. Dengue virus serotypes 1 and 3 were found to be co-circulating with significant higher prevalence in male than in female mosquitoes. Of the 97 pools of Ae. aegypti (n = 635 male and 748 female specimens) screened, 14 pools, collected in February-May in 2007, were found positive for dengue virus infection: five DEN-1 and nine DEN-3. The average true infection rate (TIR) and minimum infection rate (MIR) were respectively 1.08% and 1.01%. These observations suggest that vertical transmission of dengue virus may be detected in vectors at the peak of an outbreak as well as several months before an epidemic occurs in human population.

Vertical Transmission of Dengue Virus in Aedes aegypti Collected in Surabaya, Indonesia, during 2008^|^ndash;2011

“…The MIRs in wild-caught and laboratory-reared adults ranged from 5.7 to 31.9 in the pools that were positive for viral RNA. These values were consistent with the MIRs reported from other countries (i.e., MIR of 10-40) (12)(13)(14)16). In 2008, when only wild adults were collected in the dry season, DENV genes were only detected in female mosquitoes (MIR of 15.7).…”

“…This mechanism is particularly important for maintenance of the virus, because mosquito eggs are capable of surviving in the environment even under adverse conditions for long periods, sometimes for more than a year (6). Vertical transmission in Aedes aegypti L., the principal vector for DENV1-4, has been proven experimentally (5,(7)(8)(9) and in the field (10)(11)(12)(13)(14). However, the extent to which vertical transmission affects the percentage of infected Ae.…”

Natural transovarial transmission of dengue virus 4 in Aedes aegypti from Cuiabá, State of Mato Grosso, Brazil

“…Albopictus in the same location that examined adults obtained from immature stages was not able to fi nd any positivity for DENV (42) . Studies conducted in Bolivia, Taiwan, Southeast Asia, Singapore and French Guiana have reported relatively low rates of natural transovarial infection, with MIR indexes ranging from 0.13% to 0.97% for various DENV serotypes (26) (43) (44) (45) (46) .…”

“…To explore this phenomenon, several studies have been conducted recently in several regions (26) (27) (28) . Because the country spans much of the continent, dengue epidemiology may vary considerably between regions.…”

Dengue virus type 4 in Niterói, Rio de Janeiro: the role of molecular techniques in laboratory diagnosis and entomological surveillance

“…However, none of the other techniques that were available could confirm infection or verify the infecting serotype. The transovarial transmission of DENV, which occurs when the virus is transmitted to the progeny of an infected female, has been reported previously (Khin & Khin 1983, Joshi et al 2002, Le Goff et al 2011). …”