The arrival of the Zika virus to the U.S. and Canada has been covered incessantly by North American media outlets for the past few months. All of this coverage has succeeded in creating an atmosphere of fear for potential travelers to tropical regions of Central and South America, fearful that they too will contract the Zika virus courtesy of a dangerous creature lurking in the shadows, ready to bite them.
That creature, a mosquito, Aedes aegypti in particular, is the only known vector of the Zika virus. A person carrying the virus is bitten by Aedes aegypti which then bites another person thereby spreading the virus to the second victim. Zika was first identified in rhesus monkeys in Uganda in 1947 and in humans in 1952 in Uganda and Tanzania. Symptoms of Zika virus include fever, skin rashes, muscle and joint pain and headache. Recently in Brazil, health authorities have observed an increase of Guillain-Barré syndrome and in northeastern Brazil, an increase of babies born with microcephaly. Both coincided with recent Zika virus infections, although there is no known direct link between Zika and Guillain-Barré or Zika and microcephaly.
The Aedes aegypti mosquito also transmits dengue, chikungunya and yellow fever, with the resulting infections displaying mostly the same symptoms as Zika. However, unlike Zika, yellow fever and dengue infections can and have resulted in death. A vaccine exists for yellow fever but not for dengue or Zika, so the only means of halting the spread of these diseases is a combination of education and mosquito control.
Governments, mainly in South America, are attempting to eradicate Aedes aegypti in urban areas with the use of pesticide fumigation, citizen education and the introduction of genetically modified mosquitoes that, once mated with an Aedes aegypti population outside of the lab, produce offspring unable to continue their lifecycle. The attempt to eradicate Aedes aegypti is not a uniquely modern day concept.
The Pan American Health Organization, in 1947, established a campaign of Aedes aegypti eradication that stretched from the U.S. through to Central and South America. By the early 1960s, this program had succeeded in its goal of eradicating Aedes aegypti in 23 of the 27 countries participating in the program. Unfortunately, the U.S. was one of the four countries unable to be certified as eliminating the mosquito. A lack of funds budgeted by Congress played a major role in the U.S. not being able to accomplish the task. The director of the Center for Disease Control’s efforts, Donald Schliessmann, described the funds allotted as “equivalent to instructions to fly across the Atlantic with a half a tank of gas.” In the late 1960s, as a result of the lack of funding, instead of species eradication, the U.S. adopted a surveillance program and Aedes aegypti eggs were unwittingly exported to Central and South America in used automobile tires. Today, Aedes aegypti is found in more areas of South America, Central America and mainland U.S. than before the eradication program started in 1947.
The opportunity to eliminate Aedes aegypti as a carrier of disease has long passed and with it the chance to prevent the sickness, suffering and death that threatens millions of people in the Americas. Before long, Zika will also be endemic to the U.S. and the cost of prevention, treatment and lost productivity will undoubtedly be many times that which would have been required to top up that “half a tank of gas.”
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