Avian Flu Threat Still Low and Vaccine Measures Are Ready

Milk Is Likely the Source of Transmission

“We haven’t seen anything that would change our assessment that the commercial milk supply is safe,” says Donald Prater, DVM, acting director of the Center for Food Safety and Applied Nutrition at the US Food and Drug Administration (FDA).

In the federal and state milk safety system, he explained, nearly 99% of the commercial milk supply comes from farms that participate in the Grade A program and follow the Pasteurized Milk Ordinance, which outlines pasteurization requirements.

Because detection of the virus in dairy cattle is new, there are many questions to be answered in research, he reported. Among them:

• What level of virus might be leaving the farms from shedding by apparently healthy cows?
• Does any live virus survive the pasteurization process?
• Do different methods of pasteurization and dairy production have different effects on the viability of H5N1?
• Are effects different in various forms of dairy products, such as cheese and cream?

A critical question regarding the potential risk to humans is how much milk would have to be consumed for the virus to become an established infection. That information is essential to determine “what type of pasteurization criteria” are needed to provide “acceptable public health outcomes,” Dr. Prater said.

The CDC is currently using the flu surveillance system to monitor for H5N1 activity in people. The systems show no current indicators of unusual influenza activity in people.

A version of this article appeared on Medscape.com.