New rodent virus implicated in human sudden infant death syndrome
8 May 2009
Ljungan virus which was only discovered in the 1990s in rodents, has
been found in 11 of 12 cases of Sudden Infant Death Syndrome or SIDS.
Investigators from Sweden and the USA have presented these findings in
the journal Forensic Science in Medicine and Pathology.
Animals infected with the virus suffer from a similar disease, and it
has also been found to cause diseases such as diabetes and malformations
in several animal species. Population cycles of wild rodents carrying
Ljungan virus correlate with the frequency of SIDS cases.
Ljungan virus has recently been associated with malformations and
intrauterine death in pregnant women. Investigators from Sweden and the
USA have now also found this virus in the heart, lung and brain of
children dying during their first year of life from so called Sudden
Infant Death syndrome (SIDS).
“We found the Ljungan virus in four out of five cases where no
natural cause of deaths had been found. The virus was also found in
seven infant deaths that showed signs of myocarditis,” says author Bo
Niklasson adjunct professor at Uppsala University and Research Director
at Apodemus AB Stockholm, Sweden.
Laboratory mice infected with the virus during pregnancy suffer from
a similar disease. Pups die before or after birth sometimes without any
Coauthor Petra Råsten Almqvist, MD, PhD, Department of Forensic
Medicine, Stockholm, Sweden, a department investigating some 10 cases
annually, notes: “Animals carrying Ljungan virus also die without any
visible signs of disease to explain the cause of death just like in
cases of SIDS.”
Ljungan virus is a zoonosis, which means it can be transmitted from
animals to humans. The virus has wild rodents as its main natural
reservoir. Recent studies have found that Ljungan virus is also
associated with severe diseases during pregnancy such as malformation
and foetal death during late pregnancy, so called intrauterine foetal
death (IUFD). The scientists have shown a correlation between the number
of small rodents in nature and the incidence of both IUFD and SIDS.
Ljungan virus has been found in many countries in Europe and in the
USA. “It will be important to investigate whether Ljungan virus
similarly causes prenatal and postnatal death in other parts of the
world,” says Dr William Klitz, geneticist and co-author of the report at
the Public Health Institute in Oakland and the University of California,
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