At least six people have been killed by a mysterious illness linked to hamsters and mice after the patients received organ transplants or a blood transfusion. Officials say there is no evidence yet that the disease can be spread through the blood supply.

Health experts are concerned about the virus and how it spreads especially after discovering that West Nile Virus and rabies can be spread through organ donations.

'We don't know how commonly it occurs,' Doctor Matthew Kuehnert, assistant director of blood safety for the federal Centers for Disease Control and Prevention told the Associated Press. 'We're learning as we go here. This is a new phenomenon.'

Three people recently died after receiving organs donated by a woman whose hamsters recently tested positive for lymphocytic choriomeningitis virus or LCMV.

One previous instance of the disease spreading through organ transplants is on record. In December 2003, four organ transplant recipients died after receiving organs from the same person. Each of the deceased tested positive for LCMV making the donor the likely source.

'We would encourage people who are on the waiting list (for organ donations) not to be concerned with this,' said Rhode Island health director David Gifford. 'This is an extremely rare and unusual event.'

LCMV is present in roughly five percent of hamsters, rats and other rodents.