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Geographic Variability in Zika-Related Birth Defects Baffles Scientists
Theories about disease patterns abound, but evidence and explanations are scarce
By Dina Fine Maron on November 16, 2016
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In Colombia, where the number of known Zika infections is second only to Brazil, there have been relatively few cases of related birth defects: 57 compared with more than 2,000 in Brazil, according to the World Health Organization. The U.S. has the third-highest number of Zika-related birth defects, with 31 combined cases and lost pregnancies due to miscarriage...
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That inexplicable geographic variability fueled speculation among scientists attending the American Society of Tropical Medicine and Hygiene Annual Meeting in Atlanta this week about what is causing the disparate patterns of Zika-related birth defects. Some answers may come from comparing the northeastern part of Brazil, where birth defects are the most common, to the rest of Brazil and Colombia, says Pedro Fernando da Costa Vasconcelos, director of Brazil?s National Reference Laboratory for Arboviruses.
One notable variance is that in northeastern Brazil few people receive vaccinations against the yellow fever virus whereas that is the norm in the other two locations, da Costa Vasconcelos says. Researchers need to study that disparity, he adds, because the yellow fever and Zika viruses are closely related, so yellow fever vaccination might provide some cross-reactive protection. Such an analysis should be starting soon, he says.
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Theories about disease patterns abound, but evidence and explanations are scarce
By Dina Fine Maron on November 16, 2016
...
In Colombia, where the number of known Zika infections is second only to Brazil, there have been relatively few cases of related birth defects: 57 compared with more than 2,000 in Brazil, according to the World Health Organization. The U.S. has the third-highest number of Zika-related birth defects, with 31 combined cases and lost pregnancies due to miscarriage...
...
That inexplicable geographic variability fueled speculation among scientists attending the American Society of Tropical Medicine and Hygiene Annual Meeting in Atlanta this week about what is causing the disparate patterns of Zika-related birth defects. Some answers may come from comparing the northeastern part of Brazil, where birth defects are the most common, to the rest of Brazil and Colombia, says Pedro Fernando da Costa Vasconcelos, director of Brazil?s National Reference Laboratory for Arboviruses.
One notable variance is that in northeastern Brazil few people receive vaccinations against the yellow fever virus whereas that is the norm in the other two locations, da Costa Vasconcelos says. Researchers need to study that disparity, he adds, because the yellow fever and Zika viruses are closely related, so yellow fever vaccination might provide some cross-reactive protection. Such an analysis should be starting soon, he says.
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