Aedes Albopictus

Aedes albopictus, an Asian mosquito, probably was introduced into Hawaii late in the last century. Until its discovery in Houston, Texas, in August 1985, this species was unknown in the New World. It is believed to be established in 866 counties in 26 states in the continental U.S.

The northernmost established infestation in the U.S. is Chicago, Illinois, although an infestation was found in Minnesota in 1997. In the Northeast, it has been reported from New Cumberland (York County), Pennsylvania and, in 1995, from Cumberland, Salem, and Monmouth counties in New Jersey. It has been found as far south as Cameron County, Texas, and Monroe County, Florida. In the West, it occurs in Del Rio (Val Verde County) and Lubbock (Lubbock County), Texas, and Omaha (Douglas County), Nebraska. Limited focal infestations in at least three northern states, Indiana, Minnesota, and Ohio, apparently have been eliminated through persistent control efforts by state and local agencies, perhaps coupled with severe winter temperatures. Nonetheless, other areas in Indiana and Ohio continue to be infested. During 1994, Georgia became the first state to document Ae. albopictus in all counties of the state and has since been joined by Florida, South Carolina, and Tennessee.

Aedes albopictus is a maintenance (occasionally epidemic) vector of dengue viruses in parts of Asia and is a competent vector of several other viruses under experimental conditions. Since the discovery of Ae. albopictus in the United States, five arboviruses (eastern equine encephalomyelitis, keystone, Tensaw, Cache Valley, and Potosi) have been isolated from this mosquito. Of these five viruses, only eastern equine encephalomyelitis and Cache Valley viruses are known to cause disease in humans.

Ae. albopictus was independently introduced into Brazil in 1986 and is now widespread in seven Brazilian states. In May, 1993, it was found to be established in the Dominican Republic, the first established infestation by this species of a Caribbean Island. In September, 1993, Ae. albopictus was also discovered in two border cities in Coahuila State, Mexico. Subsequent studies indicate that areas of Tamaulipas and Nuevo Leon are also infested. In 1995, the Guatemalan Ministry of Health and Japanese entomologists in Guatemala reported finding Ae. albopictus at three sites in the Department of Izabal on the Atlantic seacoast. Also in 1995, infestations were reported from Cuba and Bolivia, but the current status of those infestations is uncertain. In 1996, infestations were reported from El Salvador and Colombia. In 1997, this species was reported from the Cayman Islands. In 1991, Ae. albopictus was found in Delta and Benue states in Nigeria. During 1994, additional infestations were found in Imo, Anambra, and Enugu states. In Europe, Ae. albopictus has been present in Albania since at least 1979. More recently, infestations have been found in Italy (Genoa in 1990 and Padua in 1991) with a suggestion that the Padua introduction could have resulted from tire imports from the United States. Eighty-five percent of the imported tires came from a single source in Atlanta, Georgia; the remaining 15% came from the Netherlands. Ae. albopictus has rapidly become the most important pest mosquito species in areas of northern Italy and is now present in nine of Italy's 21 political regions, i.e., Veneto, Lombardy, Emilia Romagna, Liguria, Tuscany, Lazio, Piedmont, Campania, and Sardinia. Aedes albopictus is also expanding its distribution in the Pacific. Infestations were discovered in Palau in 1988 and in Yap in 1995. This mosquito was first discovered in Fiji on the island of Viti Levu in 1988, and has since spread to the next two largest islands in the group. Ae. albopictus has been found in port cities of both the north and south islands of New Zealand, and in Queensland and the Northern Territory of Australia, but apparently, has not become established.

Ae. albopictus is a potential vector of epidemic dengue. It is unclear what effect the presence of this species might have on transmission dynamics in the Americas. Ae. albopictus may also affect the disease potential for yellow fever in Brazil by bridging the ecological niche between jungle and urban transmission cycles. DVBID maintains a national database (under construction for web posting) on the distribution of Ae. albopictus, with particular emphasis on detecting its spread in areas in which La Crosse and eastern equine encephalitis viruses are enzootic. DVBID also studies the biology and vectorial capacity of Ae. albopictus and is the primary source of information about its distribution, vector competence, biology, and control in the Americas.

Aedes Japonicus

Origin

Aedes japonicus is an Asian species of mosquito generally found in Japan, Korea, the Ryukyu Archipelago (Okinawa and associated islands), Taiwan, South China, and Hong Kong. In 1998, the subspecies Aedes japonicus japonicus was first detected in the United States in New York and New Jersey. Since that time, Aedes japonicus has been found in six other states: Ohio, Maryland, Connecticut, Massachusetts, Pennsylvania, and Virginia.

Appearance

The adult female of Aedes japonicus is a medium-sized mosquito of dark- to blackish-brown appearance, with white scales on the body and legs.

Breeding Areas

Larvae are found in a wide variety of natural and artificial containers, including rock holes and used tires. Preferred sites usually are shaded and contain water rich in organic matter. The similarity of breeding habitats used by Aedes japonicus to those of other Aedes species suggests that the transport of eggs, larvae, and pupae in used tires may be an important mechanism for introducing the species into previously uninfested areas. Eggs are resistant to desiccation and can survive several weeks or months under dry conditions. Aedes japonicus overwinters as eggs in the more northern parts of its range. However, it is found throughout the winter as larvae as far north as Tokyo (37° N), which is equal in latitude to Norfolk, Virginia.

Disease Associations

Although few studies have been done to assess the public and veterinary health importance of Aedes japonicus, this species is suspected of being a vector of Japanese encephalitis (JE) virus to swine in northern Japan. Under experimental conditions it has been shown to transmit JE virus to mice and also to transmit the virus to its progeny through the eggs. Unpublished studies conducted at the United States Army Medical Research Institute of Infectious Diseases in Fort Detrick, MD, indicate that Aedes japonicus is also a competent experimental vector of West Nile virus, a flavivirus closely related to JE and St. Louis encephalitis viruses.

Behavior

Adult species of Aedes japonicus rest in wooded areas and prefer to bite during the daytime. In the laboratory, they feed readily on chicks and mice, but not on reptiles or amphibians. Further studies on Aedes japonicus are needed to more clearly define their feeding preferences in a variety of situations.

Protection

As with other biting insects, the use of protective clothing (i.e., long-sleeved shirts and long pants) and insect repellent is recommended to prevent bites.

Tags: Disorders and Diseases

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