Zika virus – Mosquito surveillance update – June 16, 2016

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     This summer the UW-Madison Medical Entomology Lab is partnering with local public health offices from over a dozen locations (additional partners may yet be added) in southern Wisconsin counties to look for potential vectors of the Zika virus. If the Asian tiger mosquito (Aedes albopictus) — one of the types of mosquito known to be capable of carrying and transmitting Zika virus — is living in Wisconsin, it would likely be found near the southern border of the state (this map shows the estimated Aedes albopictus range according to the CDC).

ovitrap in woods     The Asian tiger mosquito is a mosquito that evolved in forested areas to oviposit (lay it’s eggs) in small, water-filled areas such as holes in trees. This is a trait that is well adapted for oviposition in small man-made containers, and in fact some of the most important habitats for this mosquito in urban and suburban environments are areas with accumulations of used tires. We will use a trapping method known as “ovitrapping” that takes advantage of this egg-laying behavior. Each of our public health partners will set out cups partially-filled with water and including an “egg stick” — a setup that is ideal for these container breeders to lay eggs. Egg sticks will be checked each week for mosquito eggs (pictured below), and sent to our lab in Madison if any eggs have in fact been left. Because the Asian tiger mosquito is not the only container breeder that may visit one of our traps, eggs will be hatched, and the larval mosquitoes will be identified (larval Aedes aegypti pictured below). Any potential vectors of Zika virus found this summer will be reported to local public health offices, and if needed, further prevention methods will be pursued.

egg sticks

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Zika Virus

You may have heard about Zika virus disease in the news lately, especially if you have been considering travel to Central or South America. This disease is caused by the Zika virus, which can be transmitted to humans by the bite of a mosquito species in the genus Aedes.

Common symptoms to watch are fever, rash, joint pain, and conjunctivitis, and the infection is usually short-lived. A newly recognized symptom, the ability to cause the birth defect microcephaly when a pregnant woman is infected, has raised considerable recent concerns, and on February 1, 2016, the World Health Organization (WHO) declared Zika a Public Health Emergency of International Concern (PHEIC). (Source: CDC)

Although this an important disease to watch, if you are in Wisconsin, the mosquitoes most likely to carry Zika virus, Aedes aegypti and Aedes albopictus, are not likely to make it this far north. We will be undertaking active surveillance for these mosquitoes this summer nonetheless, so please refer to the mosquito surveillance tab above to get the latest on what we’ve found.zika_map_names_aedes_aegyptiAbove: Centers for Disease Control and Prevention (CDC) updated estimated A. aegypti range.

Below: CDC updated estimated A. albopictus range.zika_map_names_aedes_albopictus