The CDC published an MMWR report, and held a press conference this morning, to explain a change in how they will report the number of pregnant women in the United States and its territories with Zika Virus infection.
Up until now, the numbers reported have only included symptomatic cases with a positive Zika test, or women who have seen an adverse pregnancy outcome and have a positive Zika test.
As studies have emerged suggesting asymptomatic carriage of the virus may also result in microcephaly, or other adverse outcomes, the CDC has been tracking those cases as well.
Starting today, those cases - as long as they have a test suggestive of a Zika virus infection - will also be included.
As a result of this broader definition, the number of pregnant women being reported (delayed by 1 week) has jumped markedly with today's update, adding 122 asymptomatic infections (+167 total).
I've included the summary, but you'll want to follow the link to read the full report.
Possible Zika Virus Infection Among Pregnant Women — United States and Territories, May 2016
Early Release / May 20, 2016 / 65
Regina M. Simeone, MPH1; Carrie K. Shapiro-Mendoza, PhD2; Dana Meaney-Delman, MD3; Emily E. Petersen, MD2; Romeo R. Galang, MD4,5; Titilope Oduyebo, MD2,4; Brenda Rivera-Garcia, DVM6; Miguel Valencia-Prado, MD7; Kimberly B. Newsome, MPH1; Janice Pérez-Padilla, MPH8; Tonya R. Williams, PhD9; Matthew Biggerstaff, MPH10; Denise J. Jamieson, MD2; Margaret A. Honein, PhD1; Zika and Pregnancy Working Group (View author affiliations)
SummaryWhat is already known about this topic?Zika virus infection during pregnancy causes microcephaly and other serious brain abnormalities. However, the full range of outcomes of asymptomatic and symptomatic Zika virus infection during pregnancy are not yet well understood.
What is added by this report?In February 2016, CDC, in collaboration with state, local, tribal, and territorial health departments, launched comprehensive surveillance systems to report and actively monitor pregnancies and congenital outcomes among symptomatic and asymptomatic women with laboratory evidence of possible Zika virus infection. As of May 12, 2016, there were 157 and 122 pregnant women with laboratory evidence of possible Zika virus infection residing in U.S. states and U.S. territories, respectively.
What are the implications for public health practice?This report launches the weekly reporting of pregnant women with laboratory evidence of possible Zika virus infection in U.S. states and territories. Monitoring all pregnant women with possible Zika virus infection during pregnancy, whether asymptomatic or symptomatic, will enhance understanding of possible adverse outcomes and allow better estimates of the number of pregnancies at risk for adverse outcomes. This information will assist health care providers who counsel pregnant women and will facilitate planning services for affected families.