The tiger mosquito is an aggressive outdoor day biter that has a very broad host range and attacks humans, livestock, amphibians, reptiles and birds (Eritja et al. 2005). In one survey of biting rates a level of 30 to 48 bites per hour was recorded (Cancrini et al. 2003).
Mosquitoes are vectors of many relevant human diseases from Malaria to filariasis (caused by Dirofilaria immitis (Naya and Knight 1999, in Eritja et al. 2005)). Ae. albopictus may be a matter of particular concern as a bridge vector for the West Nile virus because it inhabits rural areas and has a wide host range including birds, so that it can readily pass enzootic cycles to humans.
There are a total of four Flaviviruses, ten Bunyaviruses and seven Alphaviruses that Ae. albopictus is known to be receptive to in laboratory conditions. These include Yellow Fever, Rift Valley Fever, Chikungunya and Sindbis (all of which are present in the Mediterranean). Of these Ae. albopictus is known to be receptive in field conditions to three Flaviviruses (Dengue, West Nile and Japanese Encephalitis), six Bunyaviruses (Jamestown Canyon, Keystone, LaCrosse, Potosi, Cache Valley and Tensaw) and one Alphavirus (EEE). Other circulating viruses in the Mediterranean that are pathogenic to humans (but which the receptivity of Ae. albopictus has not been observed or tested in the laboratory) include Israel Turkey virus, Tahyna and Batai. However the extent to which Ae. albopictus can transmit diseases in the real world is unclear and depends on many factors including numbers, whether it bites humans, whether it takes blood meals from multiple people and how effectively the virus makes it from the mosquito’s gut to its salivary glands. Currently there is solid evidence for the tiger mosquito’s role in the transmission of only two diseases: Dengue and Chikungunya (Enserink, 2008). However, the recent outbreak Chikungunya virus in the Indian Ocean vectored by Ae. albopictus has been shown to be caused by a single nucleotide mutation in the virus that allowed it to more effectively use the tiger mosquito as a vector. Similar scenarios could happen with Dengue and other viruses that the mosquito was shown to transmit in the lab (Enserink, 2008).
Ae. albopictus has been demonstrated to have a competitive advantage over a number of other mosquito species including Ae. Aegypti (O’Meara et al. 1995; Juliano, 1998; Lounibos, 2002; Braks et al. 2004 in Vezzani and Carbajo, 2008). Ae. aegypti is an even more important vector of diseases than Ae. albopictus. This is largely because Ae. albopictus has such as wide host range compared to Ae. aegypti which feeds almost exclusively on humans (Enserink, 2008). Because diseases like Dengue affect only primates, if Ae. albopictus feeds on a lizard or bird after a human, the disease is not transmitted. Thus the actual consequence of the potential displacement of Ae. aegypti by Ae. albopictus in terms of diseases transmission remains unknown in many regions. Professor Gubler predicts that the spread of Ae. albopictus will actually result in a net gain for public health because in many places, it is displacing Ae. aegypti populations (Enserink, 2008). Indeed there are many studies that report Ae. albopictus outcompeting mosquito larvae of other species such as Ochlerotatus triseriatus, a vector for La Crosse Virus (Bevins, 2008) and Ae. japonicas (Armistead et al. 2008). However Didier Fontenille of the Institute of Research for Development in Montpellier, France disagrees with Gubler citing outbreaks of Chikungunya in the Indian Ocean Islands, La Reunion island and Italy as evidence of the tiger mosquito’s potential devastating impacts (Enserink, 2008).
Location Specific Impacts:
Disease transmission: Although Ae. albopictus is not presently considered of primary importance in dengue transmission, its occurrence could favor a linkage between urban and forest cycles of yellow fever and other arboviruses in Brazil.
Disease transmission: Ae. albopictus was responsible for a Chikungunya outbreak in Gabon in 2007 (Vazeille et al. 2008). Sequence analysis of the virus genome revealed that these recent outbreaks were caused by a new variant characterized by a mutation in the E1 envelop glycoprotein gene (A226V) (Schuffenecker et al. in Vazeille et al 2006). This mutation has favoured better transmissibility of the virus by Ae. albopictus (Vazeille et al. 2007).
Disease transmission: Invasive Ae. albopictus have been recovered infected with chikungunya virus in Italy (Enserink 2007 in Armistead et al. 2008).
Disease transmission: Vector of the Chikungunya virus.
Disease transmission: In January 2006, an outbreak of denguelike syndrome (DLS) was reported in Toamasina, on Madagascar’s east coast. Ae. albopictus was found to be responsible for vectoring the disease.
Reunion (La Réunion)
Disease transmission: Known vector for Dengue on Reunion Island. A major epidemic of chikungunya fever on the island of Reunion in 2005-2006 (population 770 000) has resulted in 265 000 clinical cases (34% of the population) and 237 deaths (Reiter et al, 2006).
Competition: In Spain, interspecific competition between the tiger mosquito and native tree-hole mosquitoes might affect Aedes (Finlaya) geniculatus (Olivier 1791), Ochlerotatus (Ochlerotatus) berlandi (Se´guy 1921), Anopheles (Anopheles) plumbeus (Stephens 1828) and the less frequent Orthopodomyia (Orthopodomyia) pulcripalpis (Rondani 1872), among others.
Competition: Many native Aedes species occur in Switzerland.
United States (USA)
Disease transmission: Invasive Ae. albopictus have also been recovered infected with eastern equine encephalitis (Mitchell et al. 1992 in Armistead et al. 2008) and LaCrosse encephalitis viruses (Gerhardt et al. 2001 in Armistead et al. 2008) in the United States
Hawaii (United States (USA))
Disease transmission: Ae. albopictus was responsible for a dengue outbreak in Hawaii in 2001-2002. The epidemic was unique in that virus was transmitted by Ae. albopictus mosquitoes. This ineffi cient vector produces a slow-movingoutbreak by contrast to the sharp epidemics associated with Ae. aegypti