Terrifying Zika Virus: Is There a Climate Link?
January 19, 2016
A hotter, more humid world is already becoming a world of more serious virulent infectious diseases. West Nile, dengue fever, chagas, Lyme disease, yellow fever, chikungunya, Rocky Mountain Spotted Fever, Rift Valley fever, Japanese encephalitis and malaria are just a few of the many infectious diseases spreading far beyond their previous geographic confines.
Many insect-borne diseases never before seen in the United States have arrived at our doorstep. One of these is a truly frightening new kid on the infectious disease block called “Zika.” It is spread by mosquitoes, and erupted this year in Brazil after an unusually hot and rainy “El Niño” summer and the worst flooding in 50 years.
One in five people infected with Zika will develop symptoms, the most common of which are mild fever, rash, joint pain and conjunctivitis typically lasting about a week. All these other infectious diseases are bad enough, so why all the new fuss about Zika? If a pregnant mother contracts Zika, her baby can develop a freakish, devastating deformity called microcephaly — i.e. unusually small skull and brain, the result of incomplete brain development.
The first case of Zika in the Western Hemisphere was reported in Brazil last May. In less than eight months, Zika has infected between 500,000 and 1.5 million Brazilians. Since October, 3,530 microcephalic babies have been born in Brazil, over 24 times more than all of last year. An explosive and terrifying epidemic is under way. Most mothers whose babies were born with the defect reported Zika symptoms during pregnancy. The virus has been isolated from placentas, amniotic fluid, and from brains of two of the babies that died from it. Brazilian health authorities state there’s no question Zika is the cause. The CDC has said, “The evidence is becoming very, very strong of the link between the two.”
Brazil is in full-blown panic mode. The country’s health ministry declared Zika a national emergency even though its connection with microcephaly is not completely understood or conclusively proven. The Brazilian government has deployed thousands of army troops and inspectors making door to door searches for mosquito breeding grounds like stagnant pools of water. Brazilian officials have even gone so far as to advise women to avoid getting pregnant if at all possible. The director of the South American Institute of Government in Health, predicted 15,000 babies will be born with microcephaly in Brazil in 2016.
The proliferation of the Zika virus could be linked to climate change, a top researcher told NBC News on Monday.
“Their lifestyles, their behaviors, the speed with which they grow up is tightly related to climate,” Heidi Brown at the University of Arizona said.
El Niño, which is not caused by climate change, could also raise temperatures in areas where mosquitoes are already common in the U.S. — and turn a problem into a plague.
“The idea is that mosquitoes might start emerging earlier in the year, as it’s warming up earlier in the year,” Brown said.
Jeffrey Shaman, an associate professor for environmental health sciences at Columbia University and an expert on mosquito-borne disease transmission, said it is too soon to say for sure that El Niño is helping spread the Zika virus.
“Certainly, changes in meteorological conditions, including temperature and precipitation, in a given locality, might favor mosquito reproduction and/or increase their contact with humans, which might favor Zika transmission,” Shaman wrote in an email to NBC News. El Niño “can influence local meteorological conditions.”
What’s Zika virus?
It’s a mosquito-borne condition spread by the Aedes mosquito, the same species that carries dengue fever, chikungunya virus and other infections. Infected mosquitos spread the virus person to person; in rare cases, expectant mothers have passed it on to children at the time of birth, possibly causing birth defects.
Zika has been found in parts of Africa since the late 1940s, according to the World Health Organization. Since that time, it has spread to Southeast Asia and India. May 2015 saw the first cases in Central and South America (namely, Brazil), and in December 2015, the U.S. Centers for Disease Control and Prevention announced its arrival to Puerto Rico. Weather and climate patterns might be playing a role in the spread though several other factors are in play.
What are the symptoms?
As with many mosquito-borne illnesses, mild fever, rash, muscle pain, joint pain, headache and conjunctivitis characterize Zika. Travelers to areas where the virus is active who develop these symptoms should seek medical attention. Note that the illness is usually mild, and no deaths from Zika have been reported, according to the World Health Organization.
Should Americans worry?
Yes and no. International travelers to areas where the disease is transmitted should take care to prevent bites with protective clothing and other measures. Because the disease has spread relatively quickly in recent months, it might pose a problem in warmer areas of the U.S. in the future, as the related chikungunya virus has. But infection rates are likely to be very small, and the disease’s symptoms minimal.
How is it diagnosed and treated?
Saliva and urine tests can confirm a Zika infection though some with it might never seek medical attention due to its mild nature. It can be misdiagnosed as dengue as well, WHO states on its website. There’s no specific treatment; health care providers focus on treating individual symptoms, such as fever and aches.
How can it be prevented?
As insect-borne diseases become more common in the face of the warming planet, experts urge common sense pest-thwarting strategies. Clear your home and yard of any standing water; use screens or nets to keep mosquitos at bay; wear long-sleeved shirts and pants when outside if possible, and use insect repellent.