Hidden Zika Detection

Cuba had a previously unreported outbreak of Zika in 2017.

Sharon Isern, Steampunkphage.com

The mosquito-borne Zika virus quickly gained world attention because of its devastating impact on brain development in the children of mothers infected during pregnancy, resulting in infants born with abnormally small heads, or microcephaly. By the time public health officials identified Zika in Brazil in May 2015, the virus had already spread to more than forty countries. Although swift intergovernmental action helped slow Zika—with the World Health Organization declaring the emergency epidemic over in late 2016—researchers have recently found that a previously unknown Zika epidemic swept Cuba in 2017.

The discovery of Cuba’s Zika epidemic came unexpectedly through analysis of the timing and spread of the Zika outbreak in the Americas. A large team of researchers, led by Sharon Isern and Scott Michael of Florida Gulf Coast University, Andrea Morrison of the Florida Department of Health, and Kristian Andersen of the Scripps Research Institute of La Jolla, California, combed through reports of international travel-associated Zika cases kept by the Florida Department of Health and the European Centre for Disease Prevention and Control. “We noticed a steady number of travel-related Zika cases that continued well beyond the main epidemiological peak in the rest of the Western Hemisphere,” said Michael.

In almost all the Zika cases, the travelers had traveled from Cuba. The research team delved further by obtaining genomic sequences of the Zika virus isolated from blood samples of nine infected travelers and compared the sequence to an available Zika genome from mosquitoes in Cuba. Amidst this genetic trove, the team examined the small mutations that naturally occurred in the virus genomes over time. This allowed the scientists to identify the origins and timing of individual infections and link them back to a clandestine Cuban outbreak.

This approach—called genomic epidemiology—could prove a valuable tool in identifying and monitoring disease scourges, especially in cases where local reporting is spotty in countries with less-developed surveillance networks. Said Isern, “The ability to reconstruct unreported outbreaks using sequencing and traveler data will make it much more difficult for infectious diseases to hide from detection.” (Cell)