Association of zoonotic Ljungan virus with intrauterine fetal deaths

BACKGROUND: It has recently been shown that Ljungan virus (LV) is associated with disease in its wild rodent reservoir. In addition, it has been demonstrated that LV causes malformations and perinatal death in a mouse model. The question was therefore raised whether LV is a zoonotic agent in humans. METHODS: Population fluctuations of native rodents in Sweden were compared to the incidence of intrauterine fetal deaths (IUFDs) using the Swedish national hospitalization database. Formalin-fixed tissues from cases of IUFD were investigated using LV-specific immunohistochemistry. RESULTS: Variation in the incidence of IUFDs closely tracked the fluctuations in native rodent populations. LV was detected in the brain tissue in 4 of 10 cases of IUFDs investigated by immunochemistry. LV was also detected in the placenta in 5 of the 10 IUFD cases, but in none of 20 placentas from normal pregnancies. CONCLUSIONS: LV may play an important role in IUFDs. Birth Defects Research (Part A) 2007. © 2007 Wiley-Liss, Inc.