Sanitation and Running Water Make Mass Zika Outbreak in US Unlikely

The United States harbors a wide range of environments of various climatic conditions, many of which are favorable to mosquitoes and the transmission of disease. Even more temperate climates, like New England, have shown themselves to be suitable for the transmission of mosquito borne illnesses during the summer, yet the US hasn't suffered greatly from mosquito borne diseases like some other countries in the modern era. Even so, many are worried that climate change and increased globalization could put the country at an increasingly greater risk of a mass outbreak—from Zika virus, yellow fever, dengue fever, or the like. A team of independent medical entomologists, however, has published a paper today in the Journal of Medical Entomology, that argues socioeconomic factors like access to clean water and air conditioning, make the odds of a mass outbreak low.

While the Zika virus has spread explosively throughout Brazil and South America since 2015, carried in the bellies of the Aedes aegypti mosquito, it has not done so in the United States, and likely won't, the authors argue, because of distinct socioeconomic differences between them. The absence of air-conditioning, the absence of screened windows, and the prevalence of household water storage, say the authors—all uncommon in developed countries—perpetuate the spread of mosquitoes carrying disease. These played big parts in the proliferation of the disease in Brazil. While the disease itself is not severe, it's been associated with microcephaly (tiny heads) in newborn infants, and Guillain-Barré syndrome, an autoimmune disease that damages the body's peripheral nervous system, sometimes causing paralysis.

"It seems clear that the main factors keeping outbreaks of these diseases from occurring today are socioeconomic such as lifestyle, housing infrastructure, and good sanitation," write the authors in the paper. "While such conditions are maintained, it seems unlikely that large scale local transmission will occur, especially in Northern states."

This does not mean, however, that localized outbreaks cannot occur in the United States, or that spread of the Aedes aegypti mosquito—which also hosts, yellow and dengue fever, and chikungunya in addition to Zika—doesn't represent a danger to Americans. This should be of particular interest, say the authors, to Southern states—where longer warm seasons, travel to Zika infected countries, and more pockets of low socioeconomic conditions occur.

The authors warn, however, that to make sure a mass outbreak of a mosquito borne illness doesn't occur, the United States needs to properly maintain and invest in the infrastructure and socioeconomic conditions that have protected its citizens up to this point. Strong healthcare, sanitation, and natural disaster relief are key. Natural disasters, for example, create situations where sanitation and clean running water are compromised—a perfect scenario for the spread of mosquito-borne illness—and if the infrastructure is not strong enough to deal with it, that could potentially open the door to a mass outbreak.

If weakened, developmental and socioeconomic protections in the United States will not hold up to the pressures of a changing climate and a globalized society—which will undoubtedly bring more diseases to the country in the future. This also puts it in the United States' best interest to help solve some of these problems that plague developing nations, argue the authors. "The growing interconnection of our global society makes global public health-related issues, such as sanitation and the lack of a continuous supply of running water in developing countries, an important concern to developed countries," they write, "as these developing countries may serve as a source of imported cases of disease."