Pasteurized Milk Safe from Bird Flu Virus, FDA Says

Preliminary tests on pasteurized milk purchased from grocery stores near areas where cows infected with bird flu virus (H5N1) were found indicate that it is not infectious and cannot make people sick, according to the US Food and Drug Administration (FDA). The FDA has been testing samples of pasteurised milk in which traces of H5N1 have been detected by inoculating fertilized eggs with them. Results from some tests are reassuring as they confirm that live virus is not present, a process known as “gold-standard” for determining whether the virus exists or not. The FDA also reported that infant and toddler formula made using powdered milk did not detect any traces of H5N1 viruses.
The agency emphasized last Thursday, saying 20 percent (or approximately one in every five) samples tested positive for gene fragments from the virus, but this does not necessarily mean it would make someone sick since most milk sold in the US is pasteurised or heated briefly to kill pathogens like viruses. The FDA stated that they are doing additional tests and have seen nothing indicating any threat yet as their results show no significant danger for commercial supplies of dairy products so far.
However, some scientists disagree with this assessment since finding traces of the virus in milk on grocery store shelves means the outbreak is probably more widespread than previously known. Dr Eric Topol from Scripps Research Translational Institute claimed that it was not based extensively on extensive assessments yet and would not engender trust or confidence due to USDA’s mishandling of information about virus detection in cattle farms.
The outbreak has affected more than 30 dairy farms across nine states since the US Department of Agriculture (USDA) confirmed its discovery late last March, marking it as a first for viruses that have been decimating bird populations worldwide to show up in livestock in these locations; sickened cattle displayed discoloured milk and less desire for food. Cats living on farms with infected cows died due to exposure through their ingested contaminated breastmilk, suggesting an initial spread between dairy animals could have been direct infection of mammary glands instead of airborne transmission from respiratory tracts as previously assumed by scientists.
The FDA said that milk produced in farms following the pasteurised milk ordinance is being diverted or destroyed; milk sold through interstate commerce was pastorisable (brief heat-treatment) and it would kill any microbes present, making such dairy products safe for consumption as they do not contain live viruses.
The FDA has long recommended that consumers avoid drinking raw unpasteurised milk due to the potential health risks associated with germs found in them; however, efforts to track virus spread have relied on voluntary reporting so far since avian influenza (bird flu) is required only for poultry and wild birds. The USDA requires producers who detect any signs of illness among their flocks at an early stage to report it as part of a reward system that compensates them financially in return; this approach has encouraged farmers to be forthcoming with information about outbreaks, but there are no such policies for other livestock types.
The major worry is the potential spread of H5N1 virus to pigs since farms often keep multiple animal species together. Flu viruses enter cells through sialic acids and the current strain has not learned how efficiently it can attach itself to human-type receptors; however, if a large outbreak occurs in pig populations that have both bird and human types of these molecules on their respiratory tracts then such a virus could acquire new attachment preferences which may enable future spread among humans too. Drs Peter Hotez and Richard Webby share concerns regarding the potential for this to happen as feral hogs are abundant in Texas, where many cattle farms also exist; these animals have similar sialic acid receptors like pigs or birds and if there’s cross-transmission among all three species then it could lead to a more efficient mixing bowl that allows the virus to learn how efficiently attach itself to human types of molecules.