The New York Times
Houston — IF I were a pregnant woman living on the Gulf Coast or in Florida, in an impoverished neighborhood in a city like Houston, New Orleans, Miami, Biloxi, Miss., or Mobile, Ala., I would be nervous right now. If mosquitoes carrying the Zika virus reach the United States later this spring or summer, these are the major urban areas where the sickness will spread. If we don’t intervene now, we could begin seeing newborns with microcephaly and stunted brain development on the obstetrics wards in one or more of these places.
 
There are many theories for Zika’s rapid rise, but the most plausible is that the virus mutated from an African to a pandemic strain a decade or more ago and then spread east across the Pacific from Micronesia and French Polynesia, until it struck Brazil. There, it infected more than a million people over the last one to two years. Today, the extremely poor cities of Brazil’s northeastern states make up the epicenter of the epidemic.
 
There are three reasons that Zika has slammed this particular part of Brazil: the presence of the main mosquito species that carries the virus and transmits it to humans, Aedes aegypti; overcrowding; and extreme poverty.