The mosquito Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae), originally
indigenous to South-east Asia, islands of the Western Pacific and Indian Ocean, has
spread during recent decades to Africa, the mid-east, Europe and the Americas (north
and south) after extending its range eastwards across Pacific islands during the early
20th century. The majority of introductions are apparently due to transportation of
dormant eggs in tyres. Among public health authorities in the newly infested countries
and those threatened with the introduction, there has been much concern that Ae. albopictus
would lead to serious outbreaks of arbovirus diseases (Ae. albopictus is a competent
vector for at least 22 arboviruses), notably dengue (all four serotypes) more commonly
transmitted by Aedes (Stegomyia) aegypti (L.). Results of many laboratory studies
have shown that many arboviruses are readily transmitted by Ae. albopictus to laboratory
animals and birds, and have frequently been isolated from wild-caught mosquitoes of
this species, particularly in the Americas. As Ae. albopictus continues to spread,
displacing Ae. aegypti in some areas, and is anthropophilic throughout its range,
it is important to review the literature and attempt to predict whether the medical
risks are as great as have been expressed in scientific journals and the popular press.
Examination of the extensive literature indicates that Ae. albopictus probably serves
as a maintenance vector of dengue in rural areas of dengue-endemic countries of South-east
Asia and Pacific islands. Also Ae. albopictus transmits dog heartworm Dirofilaria
immitis (Leidy) (Spirurida: Onchocercidae) in South-east Asia, south-eastern U.S.A.
and both D. immitis and Dirofilaria repens (Raillet & Henry) in Italy. Despite the
frequent isolation of dengue viruses from wild-caught mosquitoes, there is no evidence
that Ae. albopictus is an important urban vector of dengue, except in a limited number
of countries where Ae. aegypti is absent, i.e. parts of China, the Seychelles, historically
in Japan and most recently in Hawaii. Further research is needed on the dynamics of
the interaction between Ae. albopictus and other Stegomyia species. Surveillance must
also be maintained on the vectorial role of Ae. albopictus in countries endemic for
dengue and other arboviruses (e.g. Chikungunya, EEE, Ross River, WNV, LaCrosse and
other California group viruses), for which it would be competent and ecologically
suited to serve as a bridge vector.