Update on West Nile Virus Investigation

CDC is now reporting additional cases where blood transfusion is being investigated as a suspected cause of West Nile virus. In one case, two individuals who received blood products from the same donor both contracted West Nile virus infections. Both patients received transfusions, but only those from the common donor were found to carry West Nile virus. This case provides additional proof that the virus can be spread through blood products.

The latest investigation of apparent West Nile virus transmission from the blood of a single donor to two recipients, who developed West Nile virus infection provides additional proof that the virus can be transmitted through blood and blood products.

Additionally, CDC investigations of West Nile virus cases continue to yield new information about the virus. For the first time laboratory analysis shows that genetic material from the virus can be found in human breast milk. The case involves a nursing mother from Michigan, one of the two cases previously cited, who contracted West Nile virus infection. The woman has since recovered and the child remains healthy. It should be stressed that CDC has received no reports of West Nile virus transmission by breast milk. CDC continues its investigations of these cases.

The CDC, working in conjunction with the Michigan State Department of Health, will conduct follow-up testing on the infant and conduct additional testing on blood donors.

These findings do not suggest a change in breastfeeding recommendations. The only two conditions where women should not breastfeed are when the mother has HIV infection or human T-cell leukemia virus type 1. Lactating women with DOCUMENTED West Nile virus infection MAY WISH to consult with their physician about breastfeeding. 

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