SAN JUAN, Puerto Rico, Thursday May 4, 2017 – As Zika swept across the Americas last year, US health authorities warned that Puerto Rico was facing a perfect storm and braced for a large number of births impacted by the virus. Yet the number of babies born in the US island territory with microcephaly and other birth defects appears to be unexpectedly low: so low that experts are questioning whether the count is being underreported by authorities on the island.
To date, Puerto Rico has reported only 16 cases of Zika-related congenital defects, even though more than 3,300 pregnant women are known to have contracted the virus and several times that number are thought to have been infected.
This comes in sharp contrast to US states, where the Zika threat was thought to be much lower, and where congenital defects have been reported in 63 foetuses or newborns among 1,300 pregnant women who had contracted the virus.
Some observers believe that the Caribbean island, which is heavily dependent on tourism, is downplaying the scale of Zika’s impact.
“Puerto Rico’s not escaping this. They’re just hiding,” one former US official told Stat News.
The source continued that it was clear months ago that “dozens and dozens” of babies in Puerto Rico bore the hallmarks of Zika damage. But territorial health officials declined to label most of them cases of Zika congenital syndrome.
“They’re kind of in denial about what the problem is,” the former official said. “And six months, a year, two years from now there will be all these babies who aren’t learning and all these problems that will come to light.”
Last October, the Centers for Disease Control and Prevention (CDC) stopped reporting the outcomes of pregnancies in US territories in which women had been infected with Zika. The agency said that Puerto Rico wasn’t counting cases the same way.
According to the CDC website: “CDC is using a consistent case inclusion criteria to monitor brain abnormalities and other adverse pregnancy outcomes potentially related to Zika virus infection during pregnancy in the US states and territories. Puerto Rico is not using the same inclusion criteria.”
In August, researchers from the Puerto Rico health department and the CDC published a study predicting that Zika’s first wave would strike a large number of pregnancies there, based on analyses factoring in the percentage of the population thought to be infected and the number of pregnant women.
Published in the journal JAMA Pediatrics, the study projected that between 100 and 270 babies with Zika-induced microcephaly would be born between mid-2016 and mid-2017.
It did not forecast figures for several other birth defects associated with Zika that were not always apparent shortly after birth, including destruction of brain tissue, damage to newborns’ optical nerves, and hearing impairment.
A more recent CDC study looked at the US Zika pregnancy registry to try to get a clearer picture of how often infections in pregnancy lead to birth defects.
It found that five percent of babies born to women with confirmed or suspected Zika infection during pregnancy had Zika-related birth defects. When the researchers only included women with confirmed Zika infection, the rate was 10 percent.
The rate shot to 15 percent when confirmed Zika infection occurred in the first trimester of pregnancy, when the risk the virus poses to a developing foetal brain is highest.
The same calculations for Puerto Rico cannot be performed, since the health department’s weekly report does not indicate how many of the 3,356 pregnancies with confirmed Zika infections have been completed.
Dr Jose Cordero, a professor of public health at the University of Georgia who has been tracking Zika-related birth defects as part of an international study, said part of the problem may relate to the number of challenges Puerto Rico is facing. The island’s finances are in dire straits, making Zika only one of several major issues facing the territorial government.
The economic situation has also led to the migration of Puerto Ricans elsewhere. Some women who know they’re going to give birth to a baby with Zika birth defects, or who have done so in Puerto Rico, may move to the US mainland in the hope of accessing better services for the child, Cordero said. That could also contribute to a lower-the-expected count of affected pregnancies on the island.
Meanwhile, questions about Puerto Rico’s Zika birth defects count have even started to appear in local newspapers. A former health secretary, Dr Johnny Rullán, described the situation as Puerto Rico’s “Zika baby puzzle” in a recent column in the San Juan newspaper, Nuevo Dia.