Birth defects strongly linked to the Zika virus during pregnancy increased in Puerto Rico, southern Florida and one South Texas county where mosquitoes infected women in 2016, according to a new report.

The Centers for Disease Control and Prevention reported Thursday a 21 percent increase in abnormally small heads, or microcephaly, and other neurological defects during the second half of 2016 in those areas but didn’t provide a breakdown. It included Texas’ Cameron County, though local spread of Zika wasn’t detected there until late 2016.

“That suggests Zika might have been introduced into Texas, as well as Florida and Puerto Rico, earlier than thought,” said Dr. Peter Hotez, founding dean of the National School of Tropical Medicine at Baylor College of Medicine and Texas Children’s Hospital. “It also suggests we’re likely in store for an even more dramatic rise in 2017.”

But Hotez, a renowned Zika expert, acknowledged that the increase in the CDC report might mostly reflect the 2016 epidemic in Puerto Rico, where about 36,000 cases of locally transmitted cases were reported. There were six such cases reported in Cameron County in November 2016, none of them involving pregnant women.

DOUBLING BACK URGED

Hotez said it would be good if Texas public health officials doubled back to test the mothers of such babies for the virus, given Zika antibodies should still be present if the women were infected at the time. But a Texas Department of State Health Services spokesman said there are no such plans.

The spokesman said that in 2016, there were 1,708 birth defects in Texas consistent with Zika infection, only 10 of which were among mothers with evidence of Zika infection while pregnant. Because of privacy concerns, he said, the department doesn’t break the cases down by region or county.

CDC researchers said they do not know if the increase is due to the local spread of Zika or other factors because of a lack of laboratory evidence of infection in mothers who delivered babies with defects associated with the virus — either because they were never tested, weren’t tested at the right time or weren’t exposed to the virus.

Zika is not considered fatal, but it has been linked to thousands of babies born with microcephaly. It also can result in seizures, developmental delays with speech or motor function, intellectual disability, feeding problems, and hearing and vision problems.

‘CRITICALLY IMPORTANT’

“The takeaway here is that it’s critically important for public health officials to continue monitoring for Zika,” said Peggy Honein, a lead author on the report and the acting director of congenital and developmental disorders at the CDC. “It remains a serious threat to pregnant women and their babies.”

Honein said CDC officials anticipate another increase when 2017 data is analyzed because many pregnant women exposed to Zika in late 2016 gave birth in 2017.

Zika emerged as a global threat in 2007, then started spreading extensively in 2015 and 2016, reaching at least 58 countries and territories, most in the southern hemisphere. Local transmission was reported in the U.S. in the second half of 2016, first in Florida, then in Texas.

There were a number of Zika-related birth defects in Harris County in 2016, all involving women who had contracted the disease while traveling. But the CDC report did not find a statistically significant increase in 2016 in areas characterized by a significant number of such travel-related Zika cases.

‘MORE EXTENSIVE’

CDC researchers, who analyzed nearly 1 million births from 2016 in 15 states and territories, found about three of every 1,000 babies in those locations had a birth defect possibly associated with the Zika virus. Of those, about half were born with microcephaly or other brain abnormalities; 20 percent had neural tube defects and other early brain abnormalities; 10 percent had eye abnormalities; and 22 percent had nervous system damage, such as joint problems and deafness.

Hotez said the report vindicated the alarm he sounded in 2016, when he advocated vocally for federal funding. He said then that “transmission might have been more extensive than we know” and that “it could take years before pediatric neurologists fully comprehend the long-term neurological effects of Zika.”

In all, there were 315 reported Zika cases Texas in 2016, all travel-related except for the six in Cameron County. There were 48 cases in 2017, including 11 in Harris County, all but two of which travel related. The two locally transmitted cases occurred in Cameron and Hidalgo counties.

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