Latest Miami Zika outbreak hits another high-vacancy neighborhood

Two weeks ago, Florida Governor Rick Scott announced that a new zone of mosquito-borne Zika transmission had been identified, in Miami’s Little River neighborhood.

That makes three. The first, in Miami’s Wynwood district, ended in September after 45 days with no confirmed transmission. The second, in Miami Beach, has remained active since August. (With frustration mounting, its city commission has asked permission to release bats to attack Aedes aegypti mosquitos.)

Miami Beach wasn’t a surprising spot for an outbreak: large numbers of tourists, many from Zika-affected countries in Latin America, increases chances that local mosquitos will pick up the virus. And controlling mosquito populations amidst Miami Beach’s high-rise hotels has proven especially difficult.

The outbreak in Wynwood, a lesser-known neighborhood north of Miami, seemed harder to explain. I suggested here, however, that problem could have been vacant homes—the area around Wynwood leads Miami-Dade County in residential vacancy—combined with concentrated poverty. Vacancy has been linked to mosquito-borne disease outbreaks in California and Florida in recent years, and socioeconomic status is a well-recognized determinant of Aedes-borne disease risk.

I went back to the USPS and U.S. Census data to see how Miami’s latest outbreak compares. Like Wynwood, Little River falls in the 90th percentile for both vacancy and poverty, compared to other Miami-Dade census tracts. They’re two out of just 13 tracts (among 517 in Miami-Dade) that share the distinction:

Miami outbreaks and vacancy/poverty percentile

So, if you thought high vacancy and high poverty predicted Zika risk, you wouldn’t be surprised to see the Wynwood and Little River outbreaks.

These findings don’t prove a link; moreover, the districts are close enough neighbors that we might wonder how independent the outbreaks are.

Still, I think these two outbreaks combine for pretty suggestive evidence. As I noted in the last post, the mechanisms make some sense. Mosquitos can thrive at vacant properties—perhaps especially Aedes aegypti, which prefer to breed in discarded tires and other types of human debris often found at vacant properties. A lack of residents can leave mosquitos undetected and hamper government cleanup efforts.

Meanwhile, concentrated poverty could weaken a community’s other defenses—and by U.S. Census 2009-2014 estimates, both Wynwood and Little River surpass the 40% mark delineating “extreme poverty.”

In Miami, this connection would be reason to buckle down on the areas shaded above. Before turning to far-out solutions, city officials could make a big push to clean up vacant properties.

The same is true for other at-risk cities, which have got plenty of reasons to address vacant and abandoned properties, and a growing set of best practices for doing so. In upcoming posts, I’ll look at other Gulf Coast cities and where they might align efforts at Zika prevention and urban improvement.