While the continental United States has mounting fears about the potential of Zika spreading locally, Puerto Rico is currently in the thick of it and the CDC predicts that it's only going to get worse from here on out.
Near the start of the month, there were about 5,500 confirmed infections and the island has been reporting more than a thousand new cases of Zika each week. In fact, things are getting so bad that 20 to 25 percent of the roughly 3.5 million people on the island are expected to be infected with the virus by the year's end.
So, why is Zika on the rise in Puerto Rico now? It's all because of the time of the year.
August is what Tyler Sharp, the lead epidemiologist for the Centers for Disease Control and Prevention's Zika operation in Puerto Rico, refers to as the "Goldilocks zone" for Zika virus replication. Simply put, the weather conditions during this time of year lends itself to the spread of mosquitoes and the virus they carry with them.
"The more rains you get, the more mosquitoes you get. The more mosquitoes, the higher the rate of transmission," he says. "And also the mosquitoes like warmer temperatures and are able to replicate the virus more efficiently at at least slightly higher temperatures."
And, unfortunately for Puerto Rico, this isn't mere supposition. Aedes aegypti, the prime carrier of Zika, has been responsible for past outbreaks of dengue fever and chikungunya, so the CDC and locals are keenly aware of just how well Zika can flourish during the hot, wet summer months in Puerto Rico. What's worse, as opposed to the dengue fever and chikungunya outbreaks — which officials were unable to even stop while it was in progress — Zika is more potent as it can be spread by both Zika and sexual activity.
To be certain, 25 percent of a population sounds quite bad — and it is — but it's also important to remember that most of those infected would only have mild symptoms or even none at all. The primary concern, however, is that such a widespread outbreak could leave thousands of pregnant women exposed, opening their babies up to the risk of having Zika-related birth defects.
So, with Zika poised to spread like wildfire this month, what are island officials going to do about it?
Nothing, really.
There had been plans for aerial spraying of an insecticide called Naled, the same chemical being used in Miami, previously, but San Juan's mayor called the plan "environmental terror" and the governor blocked the proposal late last month.
As a result, Puerto Rico has been forced to fall back on more traditional methods, but even those are limited in effectiveness: people can reduce their risk of infection, but there's nothing officials know that's been scientifically evidenced to show that this will work in regards to actually breaking the epidemic, and the mosquitoes themselves are starting to gain a resistance to the insecticides used against them.
"What we've seen in Puerto Rico, as we see in many regions, is that there is a wide variety of resistance not to all insecticides but to many of them," Sharp notes. "And that [resistance] can change over time depending on what's being used in the communities, in the population."
Fortunately, there is some good news: if the previous outbreaks are any indication, then the high levels of Zika transmission there should start to fall in September or October. However, even if that's the case, that's still a lengthy 25 days that Puerto Rico will have to deal with.
