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PHS Study on Zika led by Professor Leonelo Bautista featured in the Wisconsin State Journal

Professor Bautista explained to WSJ writer, David Wahlberg, that there isn’t enough evidence to claim that Zika virus causes abnormally small heads in babies of mothers infected with the Zika virus.

The UW study found that the prevalence of microcephaly in northeast Brazil, where a Zika outbreak drew worldwide attention in 2015, was similar or lower than in previous years. In addition, an increase in reported Zika infections during pregnancy was not followed by an increase in cases of microcephaly.

Underreporting of microcephaly in the Brazilian system for surveillance of birth defects, before 2015 led to the false impression the condition increased in that year. A change in the definition of microcephaly in the same year, from a head circumference of less than 31 centimeters to up to less than 33 centimeters, also fostered the idea an outbreak was occurring. In addition, the apparent microcephaly outbreak occurred after an outbreak of Zika virus infection, leading to the logical fallacy of "after that, because of that", and eventually to the classic mistake of confusing correlation and causation.

Professor Bautista’s study challenges CDC's conclusion of a causal link between Zika and microcephaly, published in the New England Journal of Medicine in 2016, and endorsed shortly after by the World Health Organization. He argues CDC investigators mistakenly concluded a causal link has been proven because they dismissed errors in the design, analysis, and interpretation of existing studies, and that Zika and microcephaly do not appear associated when those errors are avoided.

He noted in his paper and in the PHS Monday Seminar on January 23rd, 2017 that these agencies created a false public health crisis, and that public health policies such as advising against travel to Latin America, may have led to a drop in tourism revenue. Also, the implementation of public health surveillance of Zika and microcephaly could have resulted in an increased in disease burden due to the diversion of limited resources from more pressing health problems, such as cholera and low birth weight. CDC's advice to women that "your baby will have birth defects if you are infected while pregnant" may have triggered an increase in unnecessary abortions in Latin America and the US. Untoward consequences for African countries and for the US could stem from steering funds to fight Ebola, a highly lethal disease, to fight Zika virus infection, which so far should be considered a mild disease.

Although it is possible Zika causes microcephaly, Professor Bautista states that the evidence available does not prove this and additional research is needed to verify a causal link. In the meantime, public health measures other than mosquito control and preventing mosquito bites do not seem justifiable in terms of their health costs and benefits.

Published in the Wisconsin State Journal Online December 28, 2017. Link for full article:

Link for published paper: