Asian Tiger Mosquito, a Recent US Introduction
A Vector for Several Debilitating Tropical Diseases
Jul 11, 2009
For the past several years, people living in New York City have been attacked in late summer and early fall by hordes of the Asian tiger mosquito, Aedes albopictus, an aggressive, day-flying, black and white mosquito. Although mosquitoes usually bite around the upper torso, the Asian tiger mosquito bites on the legs or all over the body.
Where Does it Come From?
Ae. albopictus was first identified in the United States in 1985 in a shipment of used automobile tires from Japan to Houston. It can also be transported as larvae and pupae living inside containers of water-grown bamboo, water lilies, lotus plants, and others.
Since first being identified in the US, this mosquito has become well established across the entire South, east coast, and the Mississippi River valley. Although many northern populations die over the winter, more than twenty five states now have regularly recurring populations and this mosquito has sporadically been found in Maine, Michigan, and Illinois.
How Asian Tiger Mosquitoes Spread
This mosquito breeds in small ponds and puddles and stays within six hundred feet of the puddle from which it hatches. Local populations should be controlled by removing stagnant water from bottles, old tires, bird baths, buckets, ditches and the like. It takes only one week for the eggs to produce a new generation, so the eradication process must be repeated often. The use of insect repellent and protective clothing will aid in reducing the numbers of bites if the mosquito is already present when tidying the yard.
This mosquito has two primary methods of spread:
- When its breeding pools are transported from one area to another. The transport and sale of aquatic plants or tropical fish with larvae living in the water. After hatching, the adults disperse to local standing water sources such as listed above from which they eventually spread to most local water bodies.
- Adult mosquitoes hitch rides inside vehicles. Mosquitoes inside of trucks, passenger vehicles, and less often trains and airplanes are rapidly transported from one place to another. Upon exiting the vehicle, a gravid female will first search for a meal and then a small pool of water in which to lay its eggs.
If there are no water sources available after the female feeds, these mosquitoes can lay dormant eggs along the sides of depressions and containers. When the rains fill up these containers, the eggs hatch and a week or so later, the adults are biting people and animals, continuing the cycle.
A Species of Concern
The Asian Tiger mosquito is a vector for several diseases including: Eastern Equine Encephalitis (debilitating, often fatal, sporadically local), La Crosse encephalitis (debilitating, sometimes fatal to children, infrequent in the Appalachians and Midwest), Dengue (“break-bone”) fever (incapacitating, 200 fatalities from 630,000 cases in Caribbean and Central and South America this year), chikungunya fever (debilitating, rarely fatal, Asian tropics - Italy in 2007), West Nile Virus (debilitating, sometimes fatal, uncommon locally), yellow fever (incapacitating, often fatal, sporadic in Southeastern states), and dog heartworm (sudden onset, fatal to dogs without treatment - would be fatal if transferred to humans, common locally in dogs), and others. Any or all of these could increase in frequency or become additions to our region's medical challenges because of this mosquito.
A vector transmits specific disease organisms because their physiologies are complementary. There are currently few or no vectors for the above diseases in and around New York City. In 2007, Ae. alpopictus caused a small outbreak of tropical chikungunya fever in two Italian villages. The epidemic began when a villager returned to Italy after contracting the disease in India where over one million people were affected in India in 2007. When a tiger mosquito bit him, it was able to transmit the disease to several people, each of whom became a new source for further transfers. Eventually, about 100 people were affected.
Luckily, the villages (on opposite sides of a small river) are isolated and small, and the mosquitoes do not fly very far from the pool they hatch from. If the villager had lived in a large city, the disease might have affected thousands and been spread to other areas by travelers, each of whom could have triggered a new local outbreak in his or her next destination.
The Asian tiger mosquito is so well established in the US that it is now a permanent resident. If an infective traveler brings home a case of one of the diseases this mosquito is capable of vectoring, there will most likely be a delay before the medical profession recognizes it, and it is possible the local population of Ae. albopictus will become a source of a major outbreak of a disease previously unheard of in the United States. That this has not already happened is fortuitous.
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