In 20 to 30 percent of adults, infection is asymptomatic. Fever, headache, and flulike symptoms may begin in the last few days of the viremic phase. Several days later, a bright red rash with erythroderma afects the face and gives a slapped-cheek appearance. The rash becomes lacelike and spreads to the trunk and extremities. Adults often have milder rashes and develop symmetrical polyarthralgia that may persist several weeks. Mayama and associates (2014) described a pregnant woman in whom B 19 infection was associated with hemophagocytic lymphohistiocytosis. No evidence suggests that parvovirus infection is altered by pregnancy. With recovery, IgM antibody is generated 7 to 10 days postinfection, and production persists for 3 to 4 months. Several days after IgM is produced, IgG antibody is detectable and persists for life with natural immunity (American College of Obstetricians and Gynecologists, 2017).
here is vertical transmission to the fetus in up to a third of maternal parvovirus infections (de long, 2011; Lamont, 20 11 b). Fetal infection has been associated with abortion, nonimmune hydrops, and stillbirth (Lassen, 2012; Mace, 2014; McClure, 2009). According to the American College of Obstetricians and Gynecologists (2017), the rate of fetal loss with serologically proven parvovirus infection is 8 to 17 percent before 20 weeks' gestation, and 2 to 6 percent after midpregnancy. Currently, no data support evaluating asymptomatic mothers and stillborn fetuses for parvovirus infection.
Hydrops develops in only approximately 1 percent of fetuses of women infected with parvovirus (American College of Obstetricians and Gynecologists, 2017; Pasquini, 2016; Puccetti, 2012). Still, it is the most frequent infectious agent of nonimmune hydrops in autopsied fetuses (Rogers, 1999). Hydrops usually stems from infection in the irst half of gestation. In one report, more than 80 percent of hydrops cases were found in the second trimester, with a mean gestational age of 22 to 23 weeks (Yaegashi, 2000). At least 85 percent of cases of fetal infection developed within 10 weeks of maternal infection, and the mean interval was 6 to 7 weeks. he critical period for maternal infection leading to fetal hydrops was estimated to be between 13 and 16 weeks' gestation, which coincided with the period in which fetal hepatic hemopoiesis is greatest.
An algorithm for diagnosis of maternal parvoviral infection is illustrated in Figure 64 4. Diagnosis is generally made by maternal serological testing for speciic IgG and IgM antibodies (Bonvicini, 2011; Brown, 2015). Viral DNA may be detectable by PCR in maternal serum during the prodrome and persist for months to years after infection. Fetal infection is diagnosed by detection of B 19 viral DNA in amnionic luid or IgM antibodies in fetal serum obtained by cordocentesis (de long, 2011; Weifenbach, 2012). Fetal and maternal viral loads do not predict fetal morbidity and mortality (de Haan, 2007).
Most cases of parvovirus-associated hydrops develop in the first 10 weeks after infection. Thus, serial sonography every 2 weeks should be performed in women with recent infection (see Fig. 64-4). As discussed in Chapter 10 (p. 214), middle cerebral artery (MCA) Doppler interrogation can also be used to predict fetal anemia (Chauvet, 2011). Fetal blood sampling is warranted with hydrops to assess the degree of fetal anemia.