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.
In crowded places, mosquitoes have lots of access to lots of people. Poor people often live in proximity to garbage, including old tires, plastic containers and drainage ditches filled with stagnant water, where this species of mosquito lives and breeds. And they often have homes with torn screens on their windows. The combination creates ideal conditions for the Zika virus to spread.
The same factors are present in the poorest urban areas of coastal Texas, Louisiana, Mississippi and Alabama, in addition to South Florida, and an area around Tucson. In the Fifth Ward of Houston (a historically African-American neighborhood that was populated by freed slaves after the Civil War), just a few miles from the medical center where I work, there is an astonishing level of extreme poverty. A brief tour reveals water-filled drainage ditches in place of gutters, as well as evidence of dumping — a common practice in which people toss old tires and other garbage into residential areas rather than designated landfill sites — right next to shabby and crumbling housing.
These are also the major areas in the continental United States where Aedes aegypti is found. This mosquito has transmitted viruses such as yellow fever and dengue throughout the Gulf Coast for centuries. Most recently, in 2003, it transmitted an outbreak of dengue here in Houston that was associated with at least two deaths.
It’s only April, but temperatures are hitting the 80s in the afternoons, and Aedes mosquitoes are already here. By May or June we will start seeing those mosquitoes in much larger numbers.
I develop vaccines for neglected tropical diseases. Several Zika vaccines are being created, but none will be ready in time for this year’s epidemic. In place of a vaccine we need a robust program of mosquito control and environmental cleanup in the poorest neighborhoods of our Gulf Coast cities and in Florida. This should include removing garbage and debris, and installing gutters to replace drainage ditches. We need to improve access to contraception, and provide pregnant women with proper window screens for their homes and information about the risk of Zika. Finally, we will need to train teams to visit homes in poor neighborhoods and instruct occupants on how to empty water containers and spray for mosquitoes, just as we are doing now in Puerto Rico.
At the federal level this effort would need to bring in the Environmental Protection Agency, the Centers for Disease Control and Prevention and the Department of Housing and Urban Development. But we’ll also need parallel approaches at the state, county and city levels.
This coordination is labor intensive and will not be easy, but if we don’t start working now, by the end of the year, I am afraid we will see microcephaly cases in Houston and elsewhere on the Gulf Coast. This could be a catastrophe to rival Hurricane Katrina or other recent miseries that disproportionately affect the poor. Zika is a potentially devastating health crisis headed for our region, and we might have only a few weeks to stop it before pregnant women become infected.
Peter J. Hotez, a pediatrician and microbiologist at Texas Children’s Hospital, is dean of the National School of Tropical Medicine at Baylor College of Medicine.