West Nile Virus

West Nile (WN) virus has emerged in recent years in temperate regions of Europe and North America, presenting a threat to public, equine, and animal health. The most serious manifestation of WN virus infection is fatal encephalitis (inflammation of the brain) in humans and horses, as well as mortality in certain domestic and wild birds.

History:
West Nile virus was first isolated from a febrile adult woman in the West Nile District of Uganda in 1937. The ecology was characterized in Egypt in the 1950s. The virus became recognized as a cause of severe human meningoencephalitis (inflammation of the spinal cord and brain) in elderly patients during an outbreak in Israel in 1957. Equine disease was first noted in Egypt and France in the early 1960s. The appearance of WN virus in North America in 1999, with encephalitis reported in humans and horses, may be an important milestone in the evolving history of this virus.

Geographic Distribution:
West Nile virus has been described in Africa, Europe, the Middle East, west and central Asia, Oceania (subtype Kunjin), and most recently, North America. Recent outbreaks of WN virus encephalitis in humans have occurred in Algeria in 1994, Romania in 1996-1997, the Czech Republic in 1997, the Democratic Republic of the Congo in 1998, Russia in 1999, the United States in 1999-2000, and Israel in 2000. Epizootics of disease in horses occurred in Morocco in 1996, Italy in 1998, the United States in 1999-2000, and France in 2000. In the U.S. through September 2000, WN virus has been documented in Connecticut, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and the District of Columbia. Classification: Family: Flaviviridae Genus: Flavivirus Japanese Encephalitis Antigenic Complex Complex includes: Alfuy, Cacipacore, Japanese encephalitis, Koutango, Kunjin, Murray Valley encephalitis, St. Louis encephalitis, Rocio, Stratford, Usutu, West Nile, and Yaounde viruses. Flaviviruses: share a common size (40-60nm), symmetry (enveloped, icosahedral nucleocapsid), nucleic acid (positive-sense, single stranded RNA approximately 10,000-11,000 bases), and appearance in the electron microscope.

Mosquito Control
Your Best Line of Defense…
Knowing and understanding mosquitoes' behavior and where they live (which is usually where you do) will make a big difference when it comes to avoiding getting bitten. To learn where you can spot prime mosquito hangouts in your own yard, be sure to check out how to...
MOSQUITO PROOF YOUR BACK YARD

When a mosquito bites, saliva is injected into the victim to help extract the blood. This is what causes the itching sensation - and potential disease transmission.
The annoying mosquito whine is made by their wings, which beat up to 500 cycles a second, and allow them to fly up to 150 miles during their lifetime.
In one field study, the flight and biting activity of mosquitoes increased by more than 500 percent on nights with a full moon.
Protection from mosquitoes should not be left to chance.
Mosquitoes can carry the West Nile Virus.

Mosquitoes are true survivalists. They've been spotted as high as 14,000 feet, and as low as 3,750 feet below sea level.

Importance
The infestation and subsequent establishment of Aedes albopictus, the Asian tiger mosquito, into the Americas is one of the most significant public health events that has occurred since Ae. aegypti and Anopheles gambiae invaded this region. Aedes albopictus was brought into the United States and other countries through the worldwide transport of used tires. Aedes albopictus is associated with the transmission of dengue, eastern equine encephalitis and dog heartworm, and potentially with St. Louis and LaCrosse encephalitis viruses.

Geographic Distribution
Aedes albopictus occurs throughout the Oriental Region from the tropics of Southeast Asia, the Pacific and Indian Ocean Islands, north through China and Japan and west to Madagascar. During this century it has expanded into the Hawaiian Islands and islands of the southern Pacific. Introductions and subsequent establishment of this species have occurred in North and South America. Recent collections have been made in Europe, Africa, and Australia. In the United States, it is established in most states east of the Mississippi River as far north as Minnesota and Delaware.

Adult Description
Adult males and females are covered with shiny black scales with distinct silver white bands on the palpus and tarsi. Its most striking characteristic is the band of silver scales forming a distinct stripe on the dorsal surface of the thorax and head.

Larval Habitat
The Asian tiger mosquito is a container-inhabiting species which lays its eggs in any water-containing receptacle in urban, suburban, rural and forested areas. The primary immature habitats of this species are artificial containers such as tires, flower pots, cemetery urns/vases, buckets, tin cans, rain gutters, ornamental ponds, drums, even the finger holes of an abandoned bowling ball have been reported. Larvae are also found in natural containers such as treeholes, bamboo pots, and leaf axils.

Associated Species
Because of its widespread distribution Aedes albopictus is found in association with numerous container-inhabiting mosquitoes, including Aedes, Culex, Toxorhynchites, Trichoprosopon, Uranotoenia and Armigeres. In North America it is commonly found with Aedes aegypti, Ae. triseriatus and Culex species. In general, Ae. albopictus is the most abundant species present in shared habitats, but often occurs alone.

Oviposition
This mosquito prefers to lay its eggs above the water surface on dark rounded vertical surfaces. Field studies show a preference for black, red or woody substrates. Eggs can be collected effectively with black oviposition cans fitted with balsa wood strips or seed germination paper. An important biological feature of this species is its photoperiodism. In temperate climates Ae. albopictus overwinters in the egg stage. When adult females experience long days, they produce non-over wintering eggs, during short days they produce eggs that overwintering.

Larval Behavior
Depending on temperature and the availability of food, Ae. albopictus can complete larval development between 5 and 10 days; the pupal stage in 2. Increased larval density or a decrease in food can cause increased mortality and a decrease in adult size. Though limited food is the primary cause of death, parasites (ciliates and neogregarines), and predators (Toxorhynchites larvae) may exert substantial
influence on population size.

Flight and Migration
The flight range of adults is limited, and they have not been observed to fly in strong winds. Its major means of dispersal is through the transport of used and waste tires. The movement of other water-holding containers could also play a role in expanding its range.

Bloodfeeding
Aedes albopictus is a very aggressive daytime biter with peaks generally occurring during the early morning and late afternoon. It feeds on a number of hosts including man (indoors and outdoors), domestic and wild animals and birds. Its generalized feeding behavior contributes to its vector potential.

West Nile Virus Mosquito
The Asian Tiger Mosquito

Click on the following link Center for Disease Control (Destinations) for the latest information to protect yourself.

REMOVE CHILDREN, PETS, BIRDS AND COVER FISH BOWLS. DO NOT SPRAY ON CATS. Doktor Doom Residual Insecticide Spray is Odorless and dries clear. Allow 4 hours for sprayed area to dry. Do not spray on edible food crops.

Read instructions on label.
Shake can before spraying.
Spray in the evening when there is little or no wind.

Areas to spray:
All window and door screens and all outdoor light fixtures.
Mosquitos prefer shaded areas.
A light mist on interior and exterior windows will kill house flies when they contact the window.