What happened to Zika

In the current state of the COVID-19 pandemic, other viruses of the past may seem like distant memories. But what ended up happening with the Zika Virus crisis of 2015-2016? Travel restrictions for pregnant women were prevalent and reports of infant brain anomalies were reported for months. First, a look at the Zika virus and its history, before we dive into the rise and dramatic fall of this mosquito-transmitted virus.

The Zika virus was first discovered in 1947 and was named for the Zika Forest in Uganda. The first cases (that we know of) in humans occurred in 1952. The original culprit identified for spreading this disease was the mosquito referred to as Aedes Aegypti. There are theories as to the mosquito’s spreading of the virus and subsequent outbreak originating at the 2014 FIFA World Cup held in Brazil. Additionally, other sporting events and tourism in Brazil have also been identified as causes in spreading the virus. Abnormally warmer temperatures and increased precipitation in South America are also believed to have contributed to the outbreak.

Transmission of the virus is typically spread by infected mosquitos, although transmissions between humans through sexual contact or blood transfusions may also occur. The most concerning transmission of this virus is vertical transmission from pregnant mother to the fetus. The threat to healthy men and women is not too different than having the flu. However, the threat to pregnant women or those trying to get pregnant can be catastrophic. The risk is the child may be born with microcephaly, which would result in the child being born with an abnormally small head which negatively impacts brain development.

In 2016, 5,168 symptomatic cases of Zika were reported in the United States and 36,512 cases in United States territories. Yet, in 2020, only three cases of Zika virus were reported in the United States and only 48 cases when you include United States territories. Although one may wonder if travel restrictions from COVID-19 caused the decrease in numbers, compare those with 2019. In 2019, only 28 cases were reported in the United States and 47 cases were reported in United States territories.

So what caused this sudden and welcome drop-off? Experts believe herd immunity in South America may be one contributing factor. There is also the theory that many of the cases categorized as Zika in 2016 may have actually been chikungunya or a variant of the dengue virus, causing the statistics to be skewed higher. Experts have seen small outbreaks across the world since 2016, but not in the United States.

Although Zika is not on the top of everyone’s minds these days, the CDC still recommends taking steps to prevent mosquito bites when traveling outside the United States. They recommend using an EPA-approved insect repellent, wearing long sleeves and pants, and purchasing clothing treated with permethrin.

Sources: CDC, AAAS