Hantavirus infections by Puumala or Dobrava-Belgrade virus in pregnant women

Background: Hantavirus infection in humans usually occurs via inhalation of infectious aerosolized excreta of rodents. Horizontal human-to-human transmission was reported only for the highly virulent Andes virus. The likelihood of vertical transmission and the clinical outcome of hantavirus infections in pregnancy is still unpredictable. Objectives: Very few data were published about the impact of hantaviruses in pregnancy. Here we present four cases of pregnant women infected by European hantaviruses. The risk of vertical virus transmission was investigated. Study design: Four pregnant women with clinical signs of acute hantavirus disease were investigated for hantavirus IgM and IgG after onset of clinical symptoms. Furthermore, the newborns were tested for presence of viral RNA and antibodies in cord blood and, if any parameter was found positive, 8-12 months after delivery. Results: Four women suffered from a hantavirus infection, two of them due to infection by Puumala virus and two by Dobrava-Belgrade virus. Three women delivered healthy babies by vaginal route and one woman by Caesarean section (week 28). In no case hantavirus RNA was detected in cord blood after delivery or in the 8-12 month old babies. Hantavirus IgG was detectable in the cord blood of 3 babies (but not in the preterm child); these antibodies disappeared after 8-12 months indicating a passive transfer of immunoglobulins. No child had any clinical sign of hantavirus infection. Conclusions: In this study, the absence of vertical hantavirus transmission was demonstrated for pregnant women with onset of hantavirus disease between gestation weeks 14 and 28.