The sketchy numbers behind Brazil’s Zika crisis

[Gert van der Hoek]

See also: Brazil's surge in small-headed babies questioned by report

January 29, 2016 ?


There are a lot of big numbers flying around as the world struggles to understand and hopefully control the spread of the Zika virus.

The epicenter of this apparent crisis is northeastern Brazil, where there has been a reported surge in children born with abnormally small heads — a condition know as microcephaly.

Media outlets have been quick to jump on a scary connection thought to be between a fast-spreading virus and disfigured babies. But a closer look at the numbers and the terminology being used by government officials and the media suggests everybody should stop to take a very deep breath.

On Friday, the journal Nature published extracts from an eye-opening report by the medical body responsible for monitoring birth defects in Latin America. The report concluded that the apparent spike in babies with small heads “is probably due to active search and over-diagnosis.” This over-diagnosis is being spurred by intense media interest in the story, the report says, and the data so far collected is inconclusive on any connection between Zika and microcephaly.

That’s pretty huge.

But a possible over-diagnosis is not the only problem with the numbers and reporting coming out of Brazil. Let’s take a look at some of the confusing or incorrect information out there, and why it is important to understanding this issue:

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[Emily]

http://www.nytimes.com/2016/02/01/health/microcephaly-spotlighted-by-zika-virus-has-long-afflicted-and-mystified.html?_r=0

Microcephaly, Spotlighted by Zika Virus, Has Long Afflicted and Mystified

By CATHERINE SAINT LOUISJAN. 31, 2016

The images pouring out of Brazil are haunting: struggling newborns with misshapen heads, cradled by mothers who desperately want to know whether their babies will ever walk or talk.
There are thousands of these children in Brazil, and scientists fear thousands more might come as the Zika virus leaps across Latin America and the Caribbean. But the striking deformity at the center of the epidemic, microcephaly, is not new: It has pained families across the globe and mystified experts for decades.
... An estimated 25,000 babies receive a microcephaly diagnosis each year in the United States. Microcephaly simply means that the baby?s head is abnormally small ? sometimes just because the parents themselves have unusually small heads.

....
In Brazil, researchers say they are seeing a disproportionate number of microcephalic infants with what appear to be severe deformities, many with four striking malformations at once: a large degree of brain tissue loss; unusually smooth, wrinkleless brains; many calcium deposits; and smaller cerebellums, which play a role in motor control.
?We can see many of these findings in other congenital infections,? said Dr. Albert I. Ko, an infectious-diseases specialist at Yale School of Public Health who is helping Brazilian health officials put together a study of Zika infection and birth defects. ?It?s the degree and pattern of findings that presumably make Zika different, and perhaps unique.?...

[Emily]

http://news.vanderbilt.edu/2015/07/gates-grant-bolsters-study-of-tdap-boosters-in-pregnant-women/

See Inside a Rehab Center for Babies with Likely Zika-Related Birth Defects

• Alexandra Sifferlin / Recife, Brazil @acsifferlin

11:51 AM ET
...
Da Silva?s son was born before everyone in Brazil was talking about Zika. She knew her son?s head was small, but it wasn?t until she started seeing Zika on the news that she decided to take a closer look at his records. The diameter of his head was 32 centimeters, which is considered the upper limit for microcephaly classification. Da Silva also remembered that about a month or so into her pregnancy, she came down with a rash and a fever. That?s when she put two and two together...

Rash and fevers are symptoms of dengue, too, but now they all count as Zika.