Zika presence in Americas older than previously thought
New York: The Zika virus was present in Haiti several months before the first Zika cases were identified in Brazil in March last year, new research has found.
"We know that the virus was present in Haiti in December of 2014," said one of the researchers Glenn Morris, professor of medicine at the University of Florida in the US.
"And, based on molecular studies, it may have been present in Haiti even before that date," Morris said.
Although the findings suggest that the Zika virus was circulating in the Americas prior to 2015, what remains unclear is exactly what confluence of factors caused the virus to take off in Brazil that has confirmed 91,387 cases of Zika so far this year, including 7,584 pregnant women at risk of having babies with birth defects.
The findings were published in the journal PLOS Neglected Tropical Diseases.
The Zika virus was virtually unknown outside of public health circles prior to the 2007 outbreak in the Yap Islands, a small group of islands in Micronesia where an estimated 73 percent of residents three years of age and older were infected with the virus.
Researchers hope further inquiry would shed light on the factors that led to the proliferation of Zika virus in Brazil as well as the sharp rise in the number of birth defects in that nation in cases where pregnant women were infected with the then-uncommon flavivirus, the genus of viruses that include Zika.
Scientists from University of Florida isolated the Zika virus from three patients while studying the transmission of dengue and chikungunya in Haiti in 2014.
School children exhibiting febrile illness within the Gressier/Leogane region of Haiti were taken to a free outpatient clinic, where blood samples were drawn and screened for dengue, chikungunya and malaria.
Upon isolation, the viruses were first considered "mystery" viruses, as tests indicated they were neither dengue nor chikungunya viruses, and little attention had been paid to the possibility that Zika virus might be present in the Caribbean.
Using a sophisticated method, the researchers subsequently sequenced and identified them as Zika virus sequences.
The plasma samples that yielded Zika virus were taken three months before March 2015, when Brazilian scientists first confirmed via genetic analysis that Zika virus was present in Brazil and causing a significant disease burden in the South American nation.