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ZIKA VIRUS DISEASE

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Zika disease is caused by the Zika virus (Flavivirus spp.) that is spread to humans mainly by the bite of an infected Aedes aegypti or Aedes albopictus mosquito. Zika was first discovered in macaque monkeys in 1947 in the Zika Forest region of Uganda. The symptoms are usually mild lasting for about a week, with many people showing mild or no symptoms. But infection during pregnancy may cause birth defects in children.

The virus originated in central Africa and had spread quickly to the South Pacific and Western Hemisphere. It is related to West Nile, Yellow Fever, St Louis and the equine encephalitides. As of January 2017, there have been more than 432 reported cases of Zika virus due to human travel to endemic areas. However, local transmission within the continental United States has already begun. In US Territories of the Caribbean, a total of 612 cases have been reported, with 601 being locally acquired, primarily in Puerto Rico (one-third of the population is infected) and the US Virgin Islands.

The virus is spread to humans primarily through the bite of an infected Aedes aegypti or Aedes albopictus mosquito; but pregnant women can pass it to the fetus during pregnancy or near the time of birth. Many who have been infected with Zika show only mild symptoms that endure for about a week. There may be some effects on the nervous system of an infected person also. Once infected it is expected that future infections might not occur. As of 2016 there is no evidence that a previous Zika virus infection poses an increased risk of birth defects in future pregnancies.

The mosquito vectors of Zika virus lay their eggs above the waterline in containers, treeholes, creases in tarpaulins and other vessels that hold water. Aedes aegypti, in particular, will lay eggs in a series of containers after feeding. Both Aedes aegypti,and Aedes albopictus feed day or night when a potential host comes within their limited flight ranges. Aedes agypti is found quite often within houses if conditions are proper. This species is wary often leaving its host before taking a full blood meal when the host moves. Both mosquitoes also seem to prefer feeding on the host’s lower extremities

Prevention is to wear long-sleeved shirts and long pants. Sleep with a mosquito net, especially outdoors, or in a screened dwelling. Air conditioning will also serve some protection from the vector mosquitoes. The application of repellents is also useful. Outdoor sprays are not very effective against Aedes aegypti,, because it is hard to contact them with the sprays. Some success with ultra low volume sprays has been obtained against Aedes albopictus in urban areas, while suburban areas remain refractory. The primary means of controlling both species is to eliminate their oviposition habitats by removing containers where they breed or emptying them and removing eggs laid above the waterline. and wearing of

Zika Virus - Life Cycle

Zika Virus - 2016 World Distribution

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Key References: <medvet.ref.htm> <Hexapoda>

Matheson, R. 1950. Medical Entomology. Comstock Publ. Co, Inc. 610 p.

Service, M. 2008. Medical Entomology For Students. Cambridge Univ. Press. 289 p

Legner, E. F. 1995. Biological control of Diptera of medical and veterinary importance. J. Vector Ecology 20(1): 59_120.

Legner, E. F.. 2000. Biological control of aquatic Diptera. p. 847_870. Contributions to a Manual of Palaearctic Diptera,

Vol. 1, Science Herald, Budapest. 978 p.