Sep 7, 2016

Zika Just the Latest Pathogen to Emerge

Wynwood, Miami, FL
Robert C. Jones, Jr.
University of Miami News and Events

“Throughout human history pathogens have always co-evolved with us, and despite our best efforts to suppress either the pathogens themselves or the vectors that transmit them, most bugs have been very successful at evading control,” explains Justin Stoler, an assistant professor of geography and regional studies in UM’s College of Arts and Sciences, whose research explores the geographic patterns of urban health disparities, particularly in the developing world.

Could climate change, or more specifically warming temperatures, fuel the spread of disease-carrying vectors? The conditions must be right.

“Mosquitoes don’t like extreme weather either. If it just gets warmer and precipitation declines, things will dry out, and that’s not good for mosquitoes,” said Larry Kalkstein, a bioclimatololgist in the Miller School of Medicine’s Department of Public Health Sciences, who studies the impact of weather on all things living. “Basically what we’re talking about is a potential shifting of the range [of vectors], rather than just an expansion.”

Globalization of travel and trade coupled with unplanned urbanization quite probably plays a much larger role in the proliferation of vector-borne diseases.

“Anything that’s anywhere can easily get everywhere,” said Chris Cosner, a professor of mathematics who has investigated outbreaks of Rift Valley fever in Egypt. “When there was much less global travel, Zika was an isolated, obscure disease in an African forest. But once everybody can get anywhere, it [the disease] is out there trying to be pandemic. And it’s not the only disease out there waiting to do that.”

Cosner states a sobering fact, one with which other experts agree.

“There are many arboviruses (any of a group of viruses that are transmitted by mosquitoes, ticks, or other arthropods) and other pathogens that are obscure in the tropics, but with increased global connectivity and travel, it is likely that these neglected pathogens will potentially move from isolated areas to more populated places outside their restricted ranges,” said Doug Fuller, a professor of geography and regional studies who examines the distribution patterns of mosquitoes around the world.

“Zika is not currently in Wynwood and Miami Beach because of climate change. Zika is here because of globalization and increased air travel and because lower-resource countries are now rapidly developing,” said Stoler. “There are all these other pathogens lurking in tropical forests waiting to emerge, and there are additional superbugs emerging out of livestock populations. But climate change will, to varying degrees, shape how long some of these pathogens disperse and persist.”

It is likely that in the not-too-distant future, physicians and health officials, much like they are doing now with Zika, will be forced to react to a new outbreak of an unheard of virus, searching to find ways to wipe it out. Their efforts could be hampered by a system that merely reacts to crises rather than investigate their root causes and form action plans that can be implemented whenever there’s an outbreak.

“Zika, Ebola, Chikungunya—these are not new pathogens. The clinical community has known about these viruses for decades, but our knowledge of each is still limited. This is because there has not been a great effort to really understand what is making people sick in the Global South (those regions of the world made up of Africa, Latin America, and developing Asia including the Middle East) beyond the major diseases of malaria, HIV/AIDS, and tuberculosis—all of which have been on the decline,” explains Stoler