Epidemiology of Zika virus, 1947–2007
The evidence supports the belief that Zika virus circulated in Africa and Asia for decades, and was only recently introduced to the Americas.
Since 1947, Zika virus has been identified sporadically in humans in Africa and Asia, however, clinically consequential Zika virus disease had not been documented in the Americas prior to the current outbreak. This study conducted a systematic literature search to identify evidence of Zika virus infection in humans from 1947 to 2007. Data extracted included seroprevalence, age distributions of positive test results and serologic test modalities used. A total of 76 articles were included in this review. Evidence of Zika virus infection in humans was found in 29 countries in Africa, 8 countries in Asia and 1 country in Europe. Country-level seroprevalence of Zika virus infection ranged from 0.4% to 53.3%. Seroprevalence of Zika virus infection was found to increase across the lifespan, thus 15% to 40% of reproductive-age individuals may have been previously infected. No significant difference was found between estimates of seroprevalence by different serologic test modalities. Risk of bias was not assessed.