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Gene for West Nile Found in Breast Milk

No live virus found, and baby hasn't tested positive yet

FRIDAY, Sept. 27, 2002 (HealthDayNews) -- Genetic material from the West Nile virus has turned up for the first time in breast milk, raising the prospect that the disease could be spread through nursing, health officials said today.

A 40-year old Michigan woman tested positive for West Nile on Thursday, about four weeks after giving birth. The U.S. Centers for Disease Control and Prevention is now testing the newborn's blood for signs of the infection. Researchers are also testing the mother's milk for live virus particles. So far the baby, whose gender was not released, has not fallen ill, health officials said.

"At the present time we do not know if there was live virus in these milk samples," said Dr. Lyle Petersen, a CDC West Nile expert. However, Petersen said, "if there is any risk, that risk would become negligible in a very short period of time."

The agency is advising women who have documented West Nile fever to talk with their doctor about whether to suspend nursing. The woman decided to stop breast-feeding after consulting her physician, said Dr. Matthew Boulton, Michigan's state epidemiologist. Boulton said the tests to determine if the infant was infected should be completed within a week.

Petersen noted that only four infants this year have contracted West Nile, out of more than 2,200 cases. "This would suggest that the risk of West Nile virus infection due to breast milk is going to be low, if there is any risk at all," he said.

Two tick-borne viruses -- a form of encephalitis and Kyasanur forest disease -- related to West Nile have been shown to be transmitted to humans through animal milk, Petersen said. The same has not been seen for West Nile.

The woman was one of two Michigan residents who received blood from a donor infected with the virus. Although she may have been infected by a mosquito, Petersen said those cases clinch the theory that the pathogen can pass from person to person in blood and blood products.

The CDC has "very strong evidence" that four people acquired West Nile virus through organ transplants this year. One died. Three others, including the two Michigan cases, got it through transfusions, Petersen said. "All three of these persons are alive and doing well," he added.

Dr. Jesse Goodman, deputy director for the U.S. Food and Drug Administration's Center for Biologics Evaluation and Research, said the agency is still trying to decide whether to test the nation's blood supply for West Nile. "We think people should be aware of this risk," which he added was small.

Still, people awaiting surgery may want to consider banking their own blood or delaying elective procedures. For those facing necessary operations, the benefits of the procedures likely outweigh the risk of infection, Goodman said.

At last count, 2,206 people in 32 states and Washington, D.C., have contracted West Nile virus this year, health officials said. Of those, 108 have died.

The average patient this year is a few years younger than in years past. But Petersen said the reason is that more people are being diagnosed with West Nile, rather than more serious encephalitis or meningitis.

The epidemic appears to have peaked in the southern and northern states, although new cases are appearing, Petersen said.

Meanwhile today, researchers from Abambis Inc. reported that an experimental West Nile virus vaccine kept the disease at bay in mice. More tests are planned, the researchers said at the 42nd annual Interscience Conference on Antiomicrobial Agents and Chemotherapy in San Diego.

What To Do

For more on West Nile virus, try the Centers for Disease Control and Prevention or the Michigan Department of Agriculture.

SOURCES: News teleconference with Lyle Petersen, M.D., M.P.H., medical epidemiologist, Centers for Disease Control and Prevention; Matthew Boulton, M.D., State Epidemiologist, Michigan Department of Community Health; Jesse Goodman, M.D., deputy director, U.S. Food and Drug Administration Center for Biologics Evaluation and Research
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