LJUNGAN virus infection
ALEX M BARLOW
Animal Health Veterinary Laboratories Agency, Langford, Bristol, UK
Ljungan virus )LV) is a member of the Parechovirus genus in the family Picornaviridae that was first isolated in 1998 from bank voles )Myodes glareolus) in Sweden.
It has now been identified in wild voles, lemmings )Lemmus lemmus) and laboratory rats in the USA. A recent study in Northern Italy using RT-PCR confirmed LV in 50% of bank voles and 10% of yellow-necked mice )Apodemus flavicollis) sampled. The presence of the virus has been demonstrated in these species together with striped field mouse )A. agarius), long tailed field mouse )A. sylvaticus), harvest mouse )Micromys minutus) and house mouse )Mus muscu- lus) in Germany.Experimentally LV has been shown to induce type-2- like diabetes, uterine reabsorptions, malformations and neonatal death in laboratory house mice )Mus musculus). Recent studies have shown that the incidence of intrauterine fetal deaths )IUFD), type-1 diabetes, Guillain-Barre Syndrome and myocarditis in the human population in Sweden varied with the rodent population cycle. This might suggest a possible but unproven association.
The presence of LV has now been confirmed in human fetal brain tissue from elective abortions, due to hydrocephaly and anencephaly, in Sweden. It has been further identified that children with newly diagnosed type-1 diabetes have significantly increased levels of LV antibodies compared to controls. It has also been suspected as the cause of hydrocephalus in red fox )Vulpes vulpes) cubs in Great Britain. The presence of LV was indicated by immunohistochemistry )IHC). Red foxes would prey on small rodents and could act as a sentinel species for infection in them.
These preliminary studies indicate that LV could be geographically widespread in wildlife and it may have a role as a zoonotic agent causing reproductive problems and diabetes in man.
However only limited studies have so far been carried out and the testing protocols are experimental and have not been fully validated consequently these possible health risks for humans remain speculative.REFERENCES
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