Original Article

Forensic Science, Medicine, and Pathology

, 5:274

First online:

Sudden infant death syndrome and Ljungan virus

  • Bo NiklassonAffiliated withApodemus ABDepartment of Medical Cell Biology, Uppsala University Email author 
  • , Petra Råsten AlmqvistAffiliated withNational Board of Forensic Medicine
  • , Birger HörnfeldtAffiliated withDepartment of Ecology and Environmental Science, Umeå University
  • , William KlitzAffiliated withSchool of Public Health, University of CaliforniaPublic Health Institute

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Ljungan virus (LV) has recently been associated with perinatal death in its natural rodent reservoir and also with developmental disorders of reproduction in laboratory mice. A strong epidemiological association has been found between small rodent abundance in Sweden and the incidence of intrauterine fetal death (IUFD) in humans. LV antigen has been detected in half of the IUFD cases tested. The question was therefore raised whether sudden infant death syndrome (SIDS) might be associated with rodent abundance, and whether the virus is present in cases of SIDS. Variation in the incidence of SIDS using the Swedish cause-of-death database tracked the changes in the population fluctuations of native rodents. Formalin-fixed tissues from the brain, heart, and lung were investigated from cases of SIDS, SIDS with lymphocytic infiltration of the myocardium (myocarditis) and myocarditis cases using LV specific immunohistochemistry (IHC). Ljungan virus was detected in the brain, heart, and lung tissue from all three of the patient categories investigated using IHC. These studies suggest that LV may play a prominent role in infant death, and that IUFD and SIDS may have common etiological underpinnings.


Forensic science Sudden infant death Sudden unexplained death in infants Myocarditis Ljungan virus Zoonosis Rodent virus Immunohistochemistry