Friday, January 22, 2016

The Zika Virus

The Zika virus, transmitted by mosquitoes, has captured headlines recently and set off something of a panic. This is technically not a "new" virus, as it was first discovered in the course of researching yellow fever in Africa in 1947. A rhesus monkey, caged near the Zika Forest in Uganda, contracted a fever of unknown origin, later (1952) determined to be caused by what we now call the Zika virus.

Aedes aegypti, one vector of Zika virus

The first human case occurred in Nigeria in 1954. It has remained rare and largely innocuous throughout its distribution in Africa and southeast Asia, until 2007 when an epidemic erupted on Yap Island in Micronesia. Subsequent epidemics in the Polynesia, Easter Island, the Cook Islands, and New Caledonia increased concern, but nothing like events in the last two months.

Two concerns have cropped up that have infectious disease specialists alarmed: Zika has jumped the Pacific Ocean and is now found in many countries in South America, Central America, and a few Caribbean nations. It has therefore been classified as a pandemic; there is also evidence the virus may be linked to birth defects, specifically microcephaly. There is also the possibility that the virus can, rarely, trigger Guillain-Barré Syndrome, a type of autoimmune disease.

What we know for certain is that the virus is not contagious. It cannot be spread from one person to another through casual contact. It is transmitted by mosquitoes in the genus Aedes, and possibly by sexual intercourse. Most people who contract the virus exhibit symptoms typical of the flu, and recover quickly.

Cases of the Zika virus in the U.S. are known from Florida, Illinois, Texas, and Hawaii. All victims had returned from travel overseas to countries known to harbor Zika.

This chain of events prompted the Centers for Disease Control to issue a Level 2 Travel Alert for pregnant women on January 15, 2016. Recommendations are that pregnant women avoid traveling to countries where the Zika virus is known to exist. This includes Puerto Rico.

An explosion of 3,500 microcephaly cases in Brazil between October, 2015 and January, 2016 is certainly cause for alarm; and it is at least suspicious that this coincides with the recent infiltration of Zika from the Old World.

Whether mosquito populations in the Gulf Coast states of the U.S. will become carriers of Zika is open to speculation, but considering the other illnesses vectored by mosquitoes, it is always an excellent idea to practice preventive measures such as wearing pants, long sleeves, and hats when outdoors. Repellents with DEET as the active ingredient can be applied per instructions (follow them to the letter). Emptying reservoirs and containers that trap rainwater is also crucial, as these are breeding grounds for mosquitoes.

Sources: Etymologia: Zika virus. Emerg Infect Dis [Internet]. 2014 Jun [date cited]. http://dx.doi.org/10.3201/eid2006.ET2006
"Zika Virus," Wikipedia

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