Aedes albopictus, vecteur des virus du chikungunya et de la dengue à la Réunion : biologie et contrôle

Abstract

Summary : AEDES ALBOPICTUS, VECTOR OF CHIKUNGUNYA AND DENGUE VIRUSES IN REUNION ISLAND: BIOLOGY AND CONTROLChikungunya virus (CHIKV) and dengue virus (DENV) are mosquitoborne viruses transmitted by the Aedes genus. Dengue is considered as the most important arbovirus disease throughout the World. Chikungunya, known from epidemics in continental Africa and Asia, has up to now been poorly studied. It has been recently responsible for the severe 2004-2007 epidemic reported in the Indian Ocean (IO), which has caused several serious health and economic problems. This unprecedented epidemic of the IO has shown severe health troubles with morbidity and death associated, which had never been observed before. The two major vectors of those arboviruses in the IO area are Aedes aegypti and Aedes albopictus. The latest is considered as the main vector in most of the islands of the area, especially in Reunion Island. Ae. albopictus showed strong ecological plasticity. Small disposable containers were the principal urban breeding sites, and preferred natural developmental sites were bamboo stumps and rock holes in periurban and gully areas. The virus has been isolated from field collected Ae. albopictus females, and in two out of 500 pools of larvae, demonstrating vertical transmission. Experimental works showed that both Ae. albopictus and Ae. aegypti from west IO islands are efficient vectors of dengue and chikungunya viruses. Since 2006 and all along the epidemic of CHIKV, measures for the control of larvae (temephos then Bacillus thuringiensis) and adults (fenitrothion, then deltamethrine) of Ae. albopictus where applied along with individual and collective actions (by the use of repellents, and removal of breeding sites around houses) in Reunion Island. In order to prevent such epidemics, a preventive plan for arboviruses upsurge is ongoing processed. This plan would allow a quicker response to the threat and adapt it according to the virus and its specific vector. Résumé : Les virus du chikungunya (CHIKV) et de la dengue (DENV) sont transmis par des moustiques du genre

Failure to demonstrate experimental vertical transmission of the epidemic strain of Chikungunya virus in Aedes albopictus from La Réunion Island, Indian Ocean

“…As for previous authors, we were unable to detect vertical transmission despite the use of a very high dose of infectious particles in the infectious blood-meal and the very high load of infectious particles detected in mothers (i.e., infected females) (Vazeille et al 2007). However, our negative results are not surprising considering the low rate of vertical transmission described in Delatte et al (2008), i.e., two positive pools out of 6,853 individuals. Thus the minimum infection rate for field records was then two out of 6,853, not significantly different from the results of our laboratory study performed on 3,384 mosquitoes (p > 0.05, Fisher's exact test).…”

“…albopictus as the main vector responsible for the massive outbreak in La Réunion, raised concerns about a possible maintenance of the virus during the dry season. Therefore, specimens were collected in the field in La Réunion in 2006 and a low rate of vertical transmission was detected (Delatte et al 2008). In the same year in Madagascar, the presence of CHIKV RNA was also detected in Ae.…”

“…Vertical transmission of CHIKV has not yet been demonstrated in the laboratory (Jupp et al 1981, Mourya 1987), but has been proven to occur in the field in Ae. albopictus, in La Réunion (Delatte et al 2008) and in Madagascar (Ratsitorahina et al 2008). However, the transmission rate was low and only viral RNA was detected, with no virus isolated.…”

Detection of Persistent Chikungunya Virus RNA but not Infectious Virus in Experimental Vertical Transmission in Aedes aegypti from Malaysia

“…For comparison, previous studies of vertical transmission of CHIKV in Aedes mosquitoes were summarized ( Table 2). RT-PCR was the most common method used to detect CHIKV, in seven of nine studies, 8,9,14,18,[20][21][22] and only one of those failed to detect CHIKV RNA. 22 RNA detection rates otherwise ranged between 0.4% and 100%, in both experimentally and naturally infected samples.…”

Impact of environmental factors on mosquito dispersal in the prospect of sterile insect technique control

“…albopictus has long been considered as a secondary vector of human pathogens [28] because of its opportunistic feeding behavior: it bites preferentially mammals but can also feed on reptiles, birds and amphibians. Its status has been revisited after the epidemics of chikungunya in Réunion Island in 2006 [17], and in Central Africa [43]. It can also transmit dengue and yellow fever.…”