Hélène Delatte1,2,3, Amélie Desvars4, Anthony Bouétard1,2, Séverine Bord4, Geoffrey Gimonneau1,2, Gwenaël Vourc'h4, Didier Fontenille1,2
Vector-Borne and Zoonotic Diseases. 2010, 10(3): 249-258. doi:10.1089/vbz.2009.0026

Chikungunya virus (CHIKV) has long been considered to be transmitted to humans by the human-biting mosquito Aedes aegypti, especially in Africa. However, the recent outbreak of CHIKV involved another vector, Aedes albopictus, and serological data in the literature suggest that several species of domestic or human-related vertebrates can be contaminated by this virus. However, the role of Ae. albopictus mosquitoes as potential enzootic vectors for CHIKV has not yet been evaluated. Here we investigate Ae. albopictus feeding and resting behaviors in an area where a CHIKV epidemic recently occurred, which means deciphering host-seeking and feeding behaviors on several vertebrate species, measuring endophagous/exophagous (activity), endophilic/exophilic (resting) behaviors and its diel (24h, day/night) biting activity. Ae. albopictus was found to have bimodal daily feeding activities and was found to have exophagic (89%) and exophilic (87%) behaviors. Ae. albopictus showed an opportunistic feeding behavior on a wide range of hosts (from cold-blooded to warm-blooded animals), supporting that it can be implicated in various vertebrate–virus pathosystems. However, with equal availability of one of the four vertebrate hosts (calf, chicken, dog, and goat) proposed against human, Ae. albopictus significantly preferred human, supporting earlier data about its high degree of anthropophily. Multiple blood feeding was also reported in every combination (animal/human) offered to Ae. albopictus, enlightening the higher risks to spread an arbovirus to human population because of interrupted feeding. Such catholic behavior suggests that Ae. albopictus may act as a bridge vector for zoonotic viruses. Further epidemiological implications of this issue are discussed.

Link to the article

VBORNET comment: 2010-06-21
This paper encompasses the interesting results of a very detailed study on feeding and resting pattern of Aedes albopictus in La Réunion. Epidemiological models consider mostly human to human transmission for CHIKV diffusion; therefore Ae. albopictus was always regarded as a secondary vector for CHIKV because of its zoophilic behavior. However, since the major CHIKV outbreak from 2004 to 2007 its potential and importance as CHIKV has been demonstrated; but its precise role in potential enzootic transmission remains unclear. Recently, a number of studies targeting this knowledge gap started. Based on extensive experiments with several host species the authors could conclude that Ae. albopictus is an opportunistic feeder that utilizes a wide variety of hosts, is capable of multiple blood feeding but shows a significant preference for human; making it a primary candidate for the transmission of several arboviruses. They emphasize the exophagic and exophilic nature of the species and underline its vector potential especially in areas where sylvatic cycles are common. It would be very good if these experimental findings could be further confirmed and validated during field studies. The authors conclude that their findings have also implications to vector control which is off course the case; however indoor spraying was never applied on large scale control of Ae. albopictus. A future line of research could be to test the patterns of susceptibility of Ae. albopictus to several insecticide families, frequently applied in vector control; since a study in Thailand (Ponlawat et al., J. Med. Entomol. 2005) demonstrated already resistance to permethrin for some strains.

1. Research Unit #016, Institut de Recherche pour le Développement (IRD), Saint Pierre, France.
2. Laboratoire de Lutte contre les Insectes Nuisibles (LIN), Research Unit #016, Institut de Recherche pour le Développement (IRD), Montpellier, France.
3. UMR C53 PVBMT CIRAD-Université de la Réunion, CIRAD Pôle de Protection des Plantes, Saint Pierre, France.
4. UR346 Unité d'Epidémiologie Animale, Institut National de la Recherche Agronomique (INRA), Saint-Genès-Champanelle, France.