Investigators are still trying to pinpoint why the three-county region in the south-central part of the state is seeing so many cases of the fatal defect.
The area saw 12 cases in 2012, two in 2011 and seven in 2010. Officials expect only one or two a year.
Anencephaly is always fatal and occurs when the protective neural tube fails to close completely around the spinal cord at the base of the brain. It happens within the first four to six weeks of pregnancy. About three-quarters of affected fetuses are stillborn; the rest die within hours or days of birth.
The explanation might be a combination of social, economic, genetic and environmental factors, said epidemiologist Mandy Stahre, who is assigned to Washington state by the Centers for Disease Control and Prevention.
“You can’t ignore all the risk factors that we see within this population and some of the reasons why we have the higher rates,” she said Tuesday in an interview during a visit to Yakima. “What we’ve been trying to target is if there’s something other than that, but you can’t ignore the social determinants of health: health disparities, high rates of obesity, lack of access to healthy foods, lack of access to prenatal care. ... When you add all that together, you can’t say that that’s not contributing.”
The seven cases last year translate to a rate of 8.7 cases per 10,000 births for the three-county area, while the average rate for the years from 2010-12 was 8.4 cases per 10,000 births — both at least four times the national rate of 2.1.
The Health Department has been pulling records, interviewing families and talking with providers as part of its investigation since the area was first flagged as abnormally high in January 2013. Investigators have mapped the cases, asked the mothers what they ate and where they bought groceries, talked about pesticides, looked at family history of birth defects, but so far nothing has shown up as a common factor.
The cases were spread throughout an area of hundreds of square miles. They did not show up seasonally, as would probably be the case if they were tied to pesticide exposure on farms and orchards, Stahre said. They’re not clustered in any one socioeconomic or ethnic group, nor in any specific geographic area within the three counties. Most cases occurred in families on public water, which is regularly tested for nitrate levels. They’re not focused near the Hanford site, nor did they start showing up only after the Fukushima nuclear disaster in Japan.
If any of those had been the case, Stahre said, the Health Department would have reported it by now.
“About 60 percent of our cases were Hispanic, but the population in this area is about 50 to 60 percent Hispanic. It reflected the population here,” Stahre said.
“A large proportion of the women were on Medicaid, but (the population) reflects that as well. It wasn’t something that made us go, ‘Ah, right here, poverty is the No. 1 thing.’ It’s probably a contributing factor.”
Documenting diet and other behaviors during pregnancy is difficult retroactively, as it means asking women what they ate and where they shopped up to four years ago, depending on when the individual cases occurred.
The one factor experts agree on is folic acid: All women of childbearing age should be taking a multivitamin with 0.4 milligrams of folic acid a day to reduce risks of neural tube defects. Since anencephaly occurs so early in a pregnancy, if women just start taking the supplement when they find out they’re pregnant, it’s usually too late.
Studies have shown that Hispanic women, for example, are at a slightly higher risk genetically, but diet is also a factor. Folic acid is found in leafy green vegetables as well as legumes and citrus fruits. Many products in the grocery store are now enriched with folic acid, like white bread, but masa flour and cornmeal, used more commonly in Mexican cooking, are not.
Yakima County consistently ranks low on access to fresh fruits and vegetables, and high on rates of obesity, diabetes and teen pregnancy, all of which can cause complicated pregnancies. Access to prenatal care and prenatal education — which would tell women to take folic acid — is also an ongoing challenge.
Genetic counselor Susie Ball says that for birth defects like anencephaly to happen, there needs to be overlap of both genetic predisposition and environmental factors.
The perfect storm idea “would make more sense to me than trying to pin it on one single factor,” Ball said Tuesday. “I’m glad they’re looking into it more. I don’t know that we know there is something going on until we’ve finished investigating.”
Comparing the three-county rate to the national rate might be inherently flawed, too, officials say. There is no comprehensive, all-encompassing national surveillance system for these birth defects; the system that is in place does not include data from Washington, Idaho or Oregon, and it only includes parts of California.
Many states, including Washington, are passive reporting states, which means the onus is on providers to inform the state of birth defect cases. What the Health Department has done in Yakima, Benton and Franklin counties is active reporting: Officials personally going to the hospitals to track down every single case.
With passive reporting, sweeps that pick up hospital discharge reports can easily miss cases where a birth defect resulted in a fetal death. The discharge report is for the mother, and doesn’t always say what happened to the fetus. Cases in passive reporting states could be under reported, which would mean the national rate is not an accurate representation of actual numbers.
There is still much science doesn’t know about neural tube defects. Ball said that when she gets lab reports for patients, and it shows the baseline risk for spina bifida, for example, the baselines vary widely from patient to patient.
“There’s other genetic conditions where we feel we know what the occurrence rate is, but we also know the occurrence rate is different in different populations or different parts of the country,” she said. “I think if (Washington) is not included in the national statistics, I would have to have a question about the accuracy of the national statistics.”
The Pacific Northwest might just have a higher prevalence than the rest of the country, Ball said.
“It doesn’t mean anything’s wrong; it could just mean it’s how things work,” she said.
That doesn’t change the fact that health officials and providers want to reduce the number of neural tube defects here. To that end, the Health Department is reaching out into the community for help.
In May, the department is holding two listening sessions — one in Yakima County and one in Benton-Franklin counties — where anyone in the community who wants to talk about birth defects can come and share. Times and locations are not yet finalized.
Then in June, a new committee will meet for the first time to talk about next steps. The committee will include birth defect experts from the CDC, researchers, local health care providers, public health officials and community leaders, and the hope is that they’ll posit something the Health Department hasn’t yet considered.
“From the Department of Health standpoint, we’ve done a comprehensive review of records, reached out to other agencies. ... We’ve exhausted everything we can do at this point,” Stahre said. They even went through handwritten birth logs of every birth in each hospital in the three-county area to make sure no cases slipped through the cracks.
“We want to know what are the next steps we should do,” she said. “Should we go back (to previous years)? Should we expand it to the entire state? These are questions we want the committee to weigh in on, to find the best way to use our resources moving forward.”
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