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Virus Found in Stillborn Babies May Impact Future Pregnancies, Study Finds

February 01, 2009

A virus connected to human stillborn babies may impact an affected woman's subsequent pregnancies and cause defects in the developing nervous system, according to recent studies published in the science journal Birth Defects Research.

Prepared by researchers at the California-based Public Health Institute and the Swedish research organization Apodemus, the series of three peer-reviewed journal articles sheds new light on the causes of stillbirth, which can cause tremendous sorrow and confusion among families affected. It also adds to a growing body of knowledge about the Ljungan (pronounced "yoon-gun") virus, which was first isolated in Swedish field mice following an investigation into the sudden deaths of several young Swedish athletes in the 1990s.

The first in this most recent series of studies found that the Ljungan virus and its effects persist through time. Using a mouse model for the disease, researchers discovered that among otherwise healthy female mice, the virus continued to disrupt reproduction over the course of multiple pregnancies. Because the same group of international researchers previously found the virus in stillborn human cadavers, they now believe that their October 2008 report suggests that women suffering from stillbirths may have an increased risk for stillbirth in subsequent pregnancies.

In a second report, appearing online on January 29, 2009, the researchers found a surprising association between the Ljungan virus and anencephaly and hydrocephaly, the two most common abnormalities of human brain development. The virus was present in 90 percent of hydrocephalus cases and 55 percent of anencephaly cases, but only six percent of control groups with neither hydrocephalus nor anencephaly. For this reason, the study's co-authors now believe that the Ljungan virus may be associated with a substantial percentage of human nervous system malformations.

"The dramatic part of these findings is that we found the virus in the majority of cases with brain abnormalities, but a very small percentage in the control group," said William Klitz, a co-author of the articles and principal investigator at the Public Health Institute. "People have been working on these conditions for years. Here suddenly we are suggesting a specific cause that applies to both of these conditions. That is the real interest and novelty here. No one suspected that. Here we are saying when you find these malformations, the virus will also be present."

In a third study, the researchers found that the virus can be detected by two independent techniques: immunohistochemistry, which uses virus-specific antibodies, and RT-PCR, which detects the genetic sequence of the virus. They tested these techniques using frozen and formalin-fixed specimens. Because of the potentially serious effects of the virus, the scientists now believe that diagnostic investigations should be made routine in cases of stillbirth.

"It is time to cross the line into a real-world application of this knowledge," said Klitz. "That would include diagnostics." Added Klizt, "This is not the first study we have done on this topic. This is some follow-up research that affirms earlier suggestions of a viral role. The science has reached such a level of confidence that it makes sense to begin regular testing of clinical samples."