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Study: Zika could cause more miscarriages than we realize

26 percent of nonhuman primates lost pregnancies despite not showing symptoms
Zika research
More women could be losing their pregnancies to the Zika virus without knowing they’re infected, suggests a collaborative study published in Nature Medicine. (OHSU)

More women could be losing their pregnancies to the Zika virus without knowing they’re infected, suggests a collaborative study published in Nature Medicine.

The study found 26 percent of nonhuman primates infected with Zika during early stages of pregnancy experienced miscarriage or stillbirth even though the animals showed few signs of infection.

Daniel Streblow, Ph.D.
Daniel Streblow, Ph.D.

“This is the first time we’ve been able to categorically demonstrate that Zika-related miscarriage and stillbirth happens in nonhuman primates that experience no symptoms,” said one of the paper’s five lead authors, Daniel Streblow, Ph.D., of OHSU’s Vaccine and Gene Therapy Institute and Oregon National Primate Research Center.

“Examining this important issue will help us better understand how the Zika virus damages the placenta and learn how to prevent the tragic pregnancy loss it can cause,” said Streblow, who is also an associate professor of molecular microbiology and immunology in the OHSU School of Medicine.

Zika research has previously only measured miscarriages and stillbirths in women who displayed symptoms. A recent study of women who were known to be infected found that 5.8 percent experienced miscarriage and 1.6 percent experienced stillbirth during their first trimester. Miscarriage involves losing a pregnancy before a fetus has grown inside a uterus for 20 weeks, while stillbirth occurs after that point.

The Zika virus is widely known for causing children to be born with a brain abnormality called microencephaly and other malformations. The largest number of U.S. Zika cases have been reported in Florida, Texas and New York, but most other states – including Oregon – have also experienced cases. Symptoms in humans include fever, rash, headache, joint and muscle pain, as well as red eyes.

OHSU partnered with five other national primate research centers to examine the issue in a total of 50 nonhuman primates. OHSU scientists specifically studied rhesus macaques for this paper. The other institutions involved in this research are:

  • University of California-Davis, home to the California National Primate Research Center
  • Texas Biomedical Research Institute, home to the Southwest National Primate Research Center
  • Tulane University Health Sciences Center, home to the Tulane National Primate Research Center
  • University of Washington-Seattle, home to the Washington National Primate Research Center
  • University of Wisconsin-Madison, home to the Wisconsin National Primate Research Center
  • Baylor College of Medicine
  • Seattle Children’s Research Institute
  • University of California-San Francisco

For more information, read news announcements from other institutions involved in this study:

This research was supported by the National Institutes of Health Office of Research Infrastructure Programs (grants P51OD011092, R21HD091032, P51OD011104. P51OD010425, P51ODOD011133), National Institutes of Health (grants R01AI099795‐05, R01AI100989, R01AI083019, R01AI104002, R01HL105704, R21AI129455), five anonymous Florida donors, University of Washington Department of Obstetrics & Gynecology, Seattle Children’s Research Institute and Texas Biomedical Research Institute.

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