A recent groundbreaking study using sequencing of the DNA from the Zika virus found that the virus reached Miami not just once, but at least four times last year, and potentially up to forty times.
The study also found that there was a direct correlation between the number of mosquitoes and the number of Zika cases—when the mosquito control campaign lowered the number of mosquitoes, it stopped new locally-transmitted cases from occurring.
Although Zika infections could break out in most areas of the country, Miami is especially susceptible to outbreaks of the virus because it is home to Aedes aegypti mosquitoes that are very good transmitters of the virus, plus it has more people who travel there from Zika-infested areas of the world. Even though Zika has spread throughout Central and South America and the Caribbean, most of the Zika lineages in Miami were traced to strains of the virus from the Caribbean. Over half of the international travelers that enter Miami by air or via cruise ships come from the Caribbean.