Computer models assist forecast spread of Zika virus

With about sixty countries and territories worldwide reporting active forecast spread of Zika virus transmission, assuming the international spread of the mosquito-borne sickness has been challenging for public health officials.

Although, researchers are leveraging large-scale computational models that help socio-demographic and travel data as well as simulations of infection transmission—needing the computing power of 30,000 processors simultaneously—to project the path of the infection.

The Global Epidemic and Mobility (GLEaM) model has been utilized in the past to evaluate the spread of Ebola, H1N1 flu, and other outbreaks on a global scale. Although, in forecast spread of Zika, researchers have depended more on the ancient patterns of mosquito-borne diseases like chikungunya and dengue.

While the forecast spread of Zika virus can also be transmitted sexually, their computer model doesn’t take that mode of transmission into consideration.

In fact, mosquitoes bring an added level of complexity to the equation, provided the uncertainty of their travel behaviors, abundance and lifecycle relying on temperature, as well as the relationship between Zika and its host mosquitoes.

In accordance to Alessandro Vespignani, professor of physics and director of the Network Science Institute at Northeastern University, what makes Zika such an issue to detect and predict is that as many as 80% of individuals infected with the virus are asymptomatic, and it is significantly transmitted by mosquitoes and spread globally through travel.

But by merging real-world data on populations, human mobility and weather with elaborate stochastic models of disease transmission, a group of fourteen researchers—half drawn from Northeastern—has devised projections for Zika cases in the Americas through the year of January 2017.

The great news is that modeling algorithms don’t predict very huge Zika outbreaks in the continental USA, in accordance to Vespignani. While the Florida has had the greatest threat for Zika transmission, he notes that researchers “project at most a total of a some hundred cases in Florida in the next 3 months” and “in other regions of the continental USA, there are very minimal probabilities of certain cases.”

This downward pressure on the forecast spread of Zika virus is being assisted by the end of mosquito season which is reliant on climate conditions. Mosquitoes multiply fastest in tropical and sub-tropical habitats, and decreasing or dropping temperatures this fall and into winter are unfavorable for mosquitoes to thrive.

Yet, there is continued worse news for the U.S. territory of Puerto Rico, which has been ravaged by the virus, and, if present trends continue, as many as 25% of the population of nearly 3.5 million will become infected with Zika virus by the end of the year.

Just like chikungunya and dengue, Vespignani claims that forecast spread of Zika virus is not a danger that is going away anytime soon, and he assumes that it will come in waves as a seasonal phenomenon. “The primary query now is what will happen in the continents of Asia and Africa?” he summarizes, where more than 2 billion individuals could be at threat from contracting the virus.

In addition to the institute of Northeastern University, the research team modeling Zika involves Bocconi University in Milan, the University of Florida in Gainesville, Fla., Italy, Bruno Kessler Foundation in Trento, Italy, Institute for Scientific Interchange Foundation in Torino, Italy, Fred Hutchinson Cancer Research Center in Seattle and the University of Washington.