This Practice Advisory was developed by the American College of Obstetricians and Gynecologists.
Human parvovirus B19 is a seasonal respiratory virus that is highly transmissible by respiratory droplets. Since March 2024, there has been an increased number of cases reported in 14 European countries 1 , and on August 14, 2024, the U.S. Centers for Disease Control and Prevention (CDC) issued a Health Alert Network (HAN) Health Advisory about increased parvovirus B19 activity in the United States2 . Although there is no routine surveillance of parvovirus B19 in the United States, and parvovirus B19 is not a notifiable condition, CDC has received reports of increased parvovirus B19 activity, including a greater than expected number of cases reported in pregnant people (with an increased number of fetal complications) and in people with sickle cell disease2 . An increase in disease activity has been observed across all age groups, with the largest increase among children aged 5–9 years2 .
With acute parvovirus B19 infection during pregnancy, rates of maternal-to-fetal transmission range from 17% to 33%3 . Most cases of fetal infection will resolve spontaneously; however, there is a 5–10% risk of adverse fetal outcomes, including fetal anemia, nonimmune hydrops, and fetal loss2 . The risk of adverse fetal outcomes is greatest if maternal infection occurs between 9 and 20 weeks of gestation2 . Treatment of maternal infection is primarily supportive, with monitoring for fetal anemia.
Considering this noted increase in infection, current recommendations include:
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Maintain increased suspicion for infection with parvovirus B19 in people presenting with common symptoms (eg, fever, myalgia, malaise, reticular rash, arthralgia, characteristic facial rash) or for pregnant people with known exposure to individuals with parvovirus B19.
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Promote CDC recommendations for core prevention strategies to reduce the risk of parvovirus B19 and other respiratory virus infections, including practicing good hand hygiene and taking steps for cleaner air 2 4 5 .
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Although strategies for preventing transmission are limited in situations in which prolonged, close-contact exposure occurs (eg, schools, homes, or childcare centers), pregnant individuals should be counseled to report exposure to people with suspected or known parvovirus B19 infection to their obstetrician–gynecologists or other obstetric care clinicians3 .
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Exposure cannot be eliminated by identifying and excluding individuals with acute parvovirus B19 infection because individuals are infectious before they develop symptoms and as many as 20% of cases are asymptomatic3 .
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Exclusion of pregnant individuals from the workplace during endemic periods is not recommended3 .
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Follow recommended testing and support as listed in clinical guidelines, including ACOG Practice Bulletin No. 151, Cytomegalovirus, Parvovirus B19, Varicella Zoster, and Toxoplasmosis in Pregnancy3 .
The American College of Obstetricians and Gynecologists will continue to actively monitor the situation and update this Practice Advisory with additional information as needed. For further information on parvovirus B19, please refer to the CDC Health Advisory2, ACOG Practice Bulletin No. 151, Cytomegalovirus, Parvovirus B19, Varicella Zoster, and Toxoplasmosis in Pregnancy3, and the Society for Maternal-Fetal Medicine’s Update on Parvovirus B196.
Please contact [email protected] with any questions.