In a recent issue of the American Journal of Tropical Medicine and Hygiene, Joshi and others1 reported on the persistent transovarial infection of successive generations of Aedes aegypti mosquitoes with dengue-3 virus. This is an important and informative paper, but unfortunately these investigators incorrectly claim this to be the first demonstration of transovarial transmission of dengue viruses over multiple mosquito generations. In fact, this was demonstrated over a decade ago with dengue-1 virus in Ae. albopictus.2
In fairness to Joshi and others, their study is more comprehensive than my earlier study with Ae. albopictus. However, it is important to point out that both of the principal dengue vectors have now been demonstrated to be capable of sustained transovarial maintenance of virus in the absence of any horizontal transmission from vertebrate blood meals. Viewed in light of the mechanism of transovarial maintenance of the bunyavirus San Angelo in Ae. albopictus,3 it is unlikely that this mode of transmission is without biologic significance, and merely a curiosity.
Joshi V, Mourya DT, Sharma RC, 2002. Persistence of dengue-3 virus through transovarial transmission passage in successive generations of Aedes aegypti mosquitoes. Am J Trop Med Hyg 67 :158–161.
Shroyer DA, 1990. Vertical maintenance of dengue-1 virus in sequential generations of Aedes albopictus. J Am Mosq Control Assoc 6 :312–314.
Shroyer DA, 1986. Transovarial maintenance of San Angelo virus in sequential generations of Aedes albopictus. Am J Trop Med Hyg 35 :408–417.