Wednesday, April 13, 2016

Zika Hits US

The Zika virus outbreak that began in Brazil and is threatening the summer Olympic Games in Rio has reached Puerto Rico with 117 confirmed cases.  The disease is alarming the health officials at the Center for Disease Control.  At a White House press conference this week a public health doctor said the disease is "scarier than initially thought" and could have a greater impact on the US. Doctors writing in medical journal said the virus could have "explosive pandemic potential".  There are 346 confirmed cases of the disease in the US;  all are associated with travel.  Researchers now think the mosquito-transmitted virus may be responsible for a range of birth defects besides microcephaly.

credit: BBC
The vector mosquito, Aedes aegypti, thrives in human built environments.  It lays it eggs in small amounts of stagnate water which are plentiful in urban centers. Large centers like Rio and Singapore have big problems with spread of the insect.  Only the female bites humans to obtain a high-protein blood meal, and transmits the disease virus through infected blood. This species also spreads yellow fever, chikungunya, and dengue fever.  They are indolent flyers but great hitch-hikers, sipping only a small amount of blood from each human victim to avoid being swatted.  Despite its limitations the insect has spread around the world.  A cousin of Aedes aeqypti which is primarily a tropical species, is Aedes albopictus which inhabits temperate zones including the southeastern United States.  It transmits chikungunya, but it not known if it is capable of transmitting zika too.

Eradication campaigns in the Americas were successful in eliminating the vector mosquito by 1962 in eighteen countries, but pesticide resistance and more dense human populations have led to its rebounding now.