Rodents may hold key to many stillbirths
Infections by a recently discovered virus may be responsible for a significant fraction of stillbirths, Swedish and American researchers reported Thursday in the journal Birth Defects Research.
The Ljungan virus is named after the Swedish river valley where virologist Bo Niklasson of Uppsala University discovered it in voles in 1999. The virus is apparently also common in American rodents, said his coauthor, geneticist William Klitz of the Public Health Institute in Oakland.
Niklasson and Klitz initially observed that the incidence of stillbirths in Sweden was related to the population density of rodents in that country, which varies in a cyclical manner.
In previous studies reported in Birth Defects Research, they showed that 86% of pregnant laboratory mice infected with the virus delivered dead pups, compared with 14% of virus-free mice.
In the new study, they examined stillbirths and placental tissue from humans. They found the virus in 4 of 10 stillbirths that they autopsied and in 5 of 10 placental tissues. They did not find the virus in any of 20 placental tissues from normal pregnancies.
Klitz said that the small size of the sample was because of the difficulty of obtaining the stillbirths, and that the team hoped to expand on the findings.
Klitz suspects the virus may also play a role in preeclampsia, in which a pregnant woman develops high blood pressure and other conditions that threaten her life and that of the fetus.
Ljungan virus is a member of a family of viruses called picornaviruses. Other members of the family cause polio, foot-and-mouth disease, intestinal infections and the common cold, Klitz said.
“We are in a very early stage” of research, “but we have some initial, very powerful clues,” Klitz said. “We need to get more investigators looking at this virus.”
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