Until 2015, Zika was an obscure and fairly harmless virus that produced flulike symptoms. First identified in 1947 among monkeys in the Zika forest of Uganda, it later found a foothold in humans and then spread across Africa, Southeast Asia and the South Pacific. The virus is believed to have most likely arrived in Brazil with a traveler attending the World Cup there in the summer of 2014. Scientists are still stumped as to why Zika began causing birth defects.
“We thought of Zika as an inconsequential disease, but then it exploded in Brazil with devastating consequences,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. “The larger lesson for us is that we have to always be prepared for the emergence and re-emergence of viruses and microbes.”
Zika has presented health officials with a number of challenges. Tracking its spread has been difficult because many countries, especially those with weak public health systems, lack the ability to identify new cases. Compounding the problem is that the vast majority of people infected experience symptoms so mild they rarely seek medical care. And because Zika, dengue and chikungunya all produce fever, joint pain and rashes, Zika cases are often misdiagnosed.
One of the biggest obstacles to better surveillance — and to informing pregnant women that they’ve been infected — is the lack of a rapid, inexpensive diagnostic test.
“At this point we can only guess the number of new infections,” said Dr. Scott C. Weaver, a virologist at the University of Texas Medical Branch in Galveston who was among the first to predict Zika’s arrival in the Americas.
As public health experts across the world continue their prevention work, thousands of families here in Brazil are already struggling with Zika’s impact. The first Zika babies are turning 3 and 4, and their families, many of them poor, are increasingly overwhelmed, said Dr. Marques, the researcher from Rio de Janeiro.
“It’s a nightmare for these mothers,” he said. “And as the grow older, it’s not going to get any easier.”