Your Hamster - A Source of Infection ?

By Grant Forrest

Some time ago I was alerted by a friend in the medical profession that hamsters were a source of a virus that could cause meningitis in humans. He'd read about it in a medical journal, and gave me the reference.
When I finally got around to looking it up, I discovered that he was right - but the story didn't really cause me any alarm, and shouldn't cause you any either. It still makes for interesting reading though, so here's a quick summary.

Between 1960 and 1975 there were 3 epidemics of infection with the Lymphocytic Choriomeningitis Virus (LCMV), all in the USA. LCMV infection in humans can cause no symptoms at all, or a flu'-like illness or in more severe cases meningitis or encephalitis (inflammation of the brain). There have even been very rare reports of death following severe infection. It's been known since 1942 that LCMV was carried by mice, but these newer outbreaks were all associated with Syrian hamsters. In the first outbreak, a hamster colony of 200 animals in the basement of the radiotherapy department of a hospital in New York State became infected, probably from infected tissue distributed for research purposes. The basement housed a photocopier and was visited regularly by hospital staff, some of whom developed an illness later shown conclusively to be caused by LCMV. In a later outbreak, several members of a family were infected by a pet hamster. The report states that “all 3 forms of the human illness were observed within one family that had recently purchased a house pet with a propensity for biting its new owners”. In this outbreak, the father suffered meningitis, his mother-in-law became ill with encephalitis and his wife and daughter both suffered flu-like illnesses. His son (who was bitten several times) and several other family members had evidence of infection with the virus, but no symptoms. In total, between 1960 and 1975 at least 181 cases were reported in 12 states, all associated with pet hamsters from a single breeder in Birmingham, Alabama.

Following these outbreaks, further investigation showed that the hamsters could carry the virus without becoming ill themselves. The virus could be found in both urine and faeces, and spread was presumed to occur by airborne particles. I believe that a vaccine is available now for laboratory hamsters and has eliminated the problem. A further outbreak did occur in in 1989, this time the source was a colony of nude mice - mice were known to be hosts for the virus long before hamsters were implicated.

To date I've been unable to locate any references to infection of hamsters with LCMV, nor case reports of LCMV infection in humans related to hamsters either as pets or in laboratory colonies in the UK. However, there is always the potential for spread of disease when we keep and breed animals. I don't think we should suddenly get paranoid and start wearing protective clothing and masks when we clean the cages of our animals, but it's common sense to do the basic things like keep hamster waste away from food and to wash your hands thoroughly after cleaning cages.

These reports should not discourage you from touching and interacting with your animals!

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