Washington D.C, Aug 3 : There's a large disparity between the number of reported and projected Zika cases, reveals a new study.
With the report from Florida Governor Rick Scott on Monday that 14 people in the state have been infected with the Zika virus most likely through mosquito transmission, the concern about out-breaks in the U.S.
has intensified. The news comes on the heels of new research by Northeastern University's Alessandro Vespignani that can help countries in the Americas plan a response.
The study, along with interactive maps, provides current numbers as well projections for the number of Zika cases in the Americas through January 2017.
It also provides projections for the number of microcephaly cases associated with the disease through October 2017, a date chosen to allow for the nine months of preg-nancy.
Microcephaly is a serious neurological birth defect characterized by a smaller than normal head. Tackling Zika has been "a call to arms," said Vespignani. "We've been working on the modeling around the clock since January," added coauthor Matteo Chinazzi. The team of 14 researchers used large scale computational epidemic models that integrate socio-demographic and travel data of target populations along with simulations of infection transmission among millions of individuals to reconstruct disease spread in the past and project it into the future.
Underreporting is rife in affected countries because up to 80 percent of people with the disease are asymptomatic, noted Vespignani.
"Even of those with symptoms, probably only one-third will go to the doctor and get diagnosed," he added.
Indeed, the number of travel associated cases of Zika in the U.S. reported by the Centers for Disease Control and Prevention may be just the tip of the iceberg, according to the research.
The team, half of which is at Northeastern, projected that as of June 15 there were close to 30,000 cases of travel-related Zika in the U.S., a number 25 times greater than that reported by the CDC on the same date.
The discrepancy results from the difference between reported cases of the mosquito-borne virus, those actually diagnosed and reported to the CDC's surveillance system, and those that fly under the radar but that the researchers' modeling algorithms can project.
The risk of contracting Zika as a result of the 2016 Olympics in Rio de Janeiro is extremely small, stated Vespignani.
That's because the increase in air travel from Zika affected areas will be minimal, less than 1 per-cent.
The number of cases in Brazil, where the virus surfaced between August 2013 and April 2014, reached its peak in the first half of 2015 and has been declining since, affecting close to 10 to 15 percent of the population.
Given all the uncertainties, the researchers cautioned that their findings are "projections," rather than "forecasts." "We use 'forecast' when we have a level of confidence in past data, such as the origin of the disease and the progression of outbreaks, that allows us, even with some fluctuations, to project into the future," concluded Vespignani.
"With Zika we are saying, 'These are the scenarios based on a number of assumptions and an attempt to get some plausible path for the future'.".