A new study posits that Zika caused early, unreported miscarriage in Brazil in 2016, leading to a 15% drop in the birth rate of that country.
Meanwhile Taiwan reports its first Zika case of the year, and the US Department of Health and Human Services (HHS) has funded a potential new Zika diagnostic test.
Zika and live-birth decline
A recent correspondence in the New England Journal of Medicine noted that there were fewer microcephaly cases in Brazil in 2016 than in 2015, leading researchers to propose why and how the mosquito-borne virus was affecting pregnant women in the country hit hardest by the current outbreak.
The authors of that letter said that another mosquito-borne disease, chikungunya, and not Zika, may have been responsible for Brazil's second wave of illness. And because prenatal infection with chikungunya doesn't cause birth defects, fewer babies were born with microcephaly.
The new study, published on the preprint server bioRxiv, suggests that the drop in microcephaly cases could be because women infected with Zika virus had earlier, unreported miscarriages. Many first-trimester miscarriages are not documented, especially in the early weeks of pregnancy when a woman may not even know she's pregnant.
The authors used data on live births from the city of Rio de Janeiro in 2016, and showed that there were 5,154 fewer births in the second half of 2016 (7,484 for the whole year) compared with previous years (a 14.85% drop in births). The authors said the decline shows a positive correlation with the incidence of Zika 37 to 42 weeks earlier, or the duration of a typical pregnancy. Including the incidence of chikungunya in the analysis did not affect the drop-off in pregnancies.
"Although the analysis presented does not completely rule out other influences on Rio de Janeiro's birth rate, it demonstrates a strong correlation between the drop in the birth rate and the number of Zika cases," the authors concluded.
"The actual range of lags of the influence and the lack of an association with Chikungunya, which happened at approximately the same period, points strongly to Zika being a causal factor in this loss of babies."
First case in Taiwan
Today Taiwan reported its first case of Zika in 2017, in a patient who had recently worked in Africa, where he was thought to have contracted the disease.
According to Focus Taiwan News, the Taiwanese man is in his 20s and tested positive for Zika after returning from Angola in mid to late March. In 2016, Taiwan reported 14 Zika cases, all in people who contracted the disease while traveling overseas.
New diagnostic test
Finally today, the HHS's Office of the Assistant Secretary for Preparedness and Response (ASPR) announced an $8.9 million agreement with Siemens Healthineers to develop a new Zika diagnostic test that could expand testing capacity across the United States at a lower cost to patients.
"This new diagnostic test will greatly enhance our domestic testing capacity and speed the availability of test results to help more people know whether they recently have been infected with the Zika virus, which can have devastating effects for pregnant women and their babies," said Rick Bright, PhD, director of ASPR's Biomedical Advanced Research and Development Authority (BARDA), in an HHS press release.
The automated lab test, called the ADVIA Centaur Zika IgM Assay, would provide results in 58 minutes. The serologic test looks for immunoglobulin M, or IgM, antibody in response to infection by the Zika, which can be detected anywhere from 2 weeks to 3 months post-infection.
See also:
Apr 12 bioRxiv study
Mar 30 CIDRAP News scan on N Engl J Med letter
Apr 13 Focus Taiwan news story
Apr 12 HHS press release
