Zika Virus Infections Drastically Underreported During 2015 Epidemic

Over 100 million Zika virus infections within Central and South America and the Caribbean went undetected between 2015 and 2018, reports a new study. The findings of the study are published in the journal PLOS Neglected Tropical Diseases.

The researchers said the results revealed a need for improvement in the current infectious disease surveillance systems. It also gives insight into the potential severity of future outbreaks and the current state of herd immunity of Zika in the West.

‘Once infected, people who recover from the Zika virus are believed to have lifelong immunity.’

"Fewer than one percent of cases were actually reported and it shows our surveillance systems catch only a small percentage of actual infections," stated the study's lead author Sean Moore.

"We need to think about how to enhance surveillance systems to get a better sense of transmission, particularly in cases of diseases that yield a high number of asymptomatic infections," says Moore.

The first confirmed Zika case in America was reported in Brazil in 2015, with the infection spreading swiftly, reaching as far north as Florida and Puerto Rico. In 2016, the World Health Organization (WHO) announced the epidemic of a Public Health, Emergency of International Concern.

The Pan American Health Organization, which assists as an international agency for America and as a regional office of the WHO, calculated symptomatic infections of Zika at over 800,000 between 2015 and 2018, a number far below the results of the Notre Dame study.

Moore's team predicted 132.3 million infections across Latin America and the Caribbean, having collected data from 15 countries and territories in Central America, South America, and the Caribbean with a combined 507.1 million population.

"There are few similarities to the current situation with COVID-19," stated Moore.

"Between 20 percent and 50 percent of infections are asymptomatic. Even when symptoms are present, they are mild and are not severe enough for a person to seek medical attention that can go undiagnosed," Moore added.

According to the researchers, understanding the scope of underreporting is particularly essential to gain an accurate sense of herd immunity in the region. Once infected, people who recover from Zika virus are believed to have lifelong immunity.

While cases have declined substantially since 2018, a remaining concern is a potential for future outbreaks.

"Our research recommends a need for a better understanding of how much transmission is happening within a community," stated Moore.

Source: Medindia