Yesterday I was ready to hit SEND on the first of my Pandemic 2009-2024 Eras Tour posts when the FDA shared that H5N1 viral particles have been detected in the commercial milk supply. And while I would love to share stories from and the epidemiological picture of the 2009 H1N1 influenza outbreak, it feels out of place; maybe even confusing. Making sense of and ensuring accurate information about what is happening TODAY with H5N1 is more important.
And so I am interrupting my planned programming to bring you up-to-date on H5N1.
Nearly three weeks ago (on April 4) I shared a post titled Avian Influenza — What You NEED to Know. While you may remember this post because it is the one with the big type-o in it, I also reported that on Monday, April 1, a person who had close contact with dairy cows in Texas tested positive for H5N1.
Since that report, the Animal and Plant Health Inspection Service (APHIS) National Veterinary Services Laboratories sequenced the entire genome of the current H5N1 virus on April 21st. Just yesterday, APHIS issued a Federal Order requiring testing for and reporting of highly pathogenic avian influenza (HPAI)1 in livestock.
Additionally, yesterday afternoon, the FDA reported that particles of the H5N1 influenza virus were detected in pasteurized milk that was commercially purchased.
Let’s start at the beginning…
Dairy cattle with H5N1 (or any avian influenza) is novel/never seen before (at least not at this scale — with 33 herds infected) and the situation is evolving.
About a month ago, when we first learned that dairy cows were sick with H5N1, the FDA and USDA said that milk from sick cattle did not enter the commercial supply. This was followed by reminders that commercial milk sold in the United States must be pasteurized, and the process of pasteurization should kill any influenza virus that makes its way into the milk.
However, since this is an evolving situation, the decision was made to monitor the commercial milk supply. Preliminary results were shared yesterday…
The FDA has stated that its goal is to gather samples from a large representative national sample of the milk supply. Currently, we do not know how many samples have been taken, from where, and from which milk producers.
More information is needed.
What we do know is that milk that was purchased in grocery stores was analyzed via a PCR test (yes, the same technology used to determine if you have COVID). PCR tests amplify specific genetic material. In this case, the PCR test used on the milk was able to amplify or highlight the presence of H5N1 genetic material (DNA or RNA) in the milk.
What is REALLY IMPORTANT to note here is —
PCR tests are accurate. PCR tests can precisely identify the unique genetic material belonging to a specific virus.
However, PCR tests canNOT distinguish between a live virus and viral fragments leftover from a virus that was killed during the pasteurization process.
What we know today is that the genetic material from the H5N1 virus was found in the milk. What do NOT know is whether it is the live virus — with the ability to make us sick — or if it is the leftovers of the pasteurization process.
During pasteurization, the milk is heated to 162*F for 16 seconds. The process is thermal (involving a lot of heat). The process does NOT involve the removal/straining of any viruses or bacteria that are killed by the heat. Dead genetic material can be left behind in the milk. This dead genetic material could be detected by a PCR test.
This is what we think has happened… pasteurization has killed the virus and some of the viral particles were left behind in the milk. They are harmless, we assume.
According to Andrew Pekosz at Johns Hopkins University —
“Pasteurization kills much sturdier viruses than influenza, so we expect it to work [for H5N1]. But it’d be great to have the data.”
And that is what we are waiting for —
More data is needed.
The FDA has said it is trying to see if it can grow the virus from milk found to contain evidence of H5N1, which is the gold standard test to see if there is a viable virus in the milk.
It will take a few more days to see if there is any live virus in the milk.
So we wait…
In the meantime, while we do not know for sure, the preponderance of the scientific evidence supports the conclusion that the pasteurized milk supply is safe.
So I will repeat the messages I shared on April 4 & 5 —
First — this is news, NOT an alarm.
The first thing to know — H5N1 has been around for two decades and it is going to continue to spread. As the virus spreads, public health researchers are going to continue to conduct research — and the results of all of the research will be made available to you.
There will continue to be news about H5N1.
When you hear of a new case of H5N1 or viral particles found in the milk supply, this is NOT an immediate cause for concern.
News of a PCR test finding H5N1 in the milk supply is the report of a discovery.
Second — drink pasteurized milk.
Drinking unpasteurized (also known as raw) milk can make you very sick. And with H5N1 in dairy cows, there are increased risks and a lot of uncertainties associated with drinking unpasteurized milk.
Therefore, we drink PASTEURIZED milk. ONLY.
Finally — this situation is evolving and we will be hearing more from the FDA, USDA, and CDC (as well as the International Dairy Foods Association). I will be providing updates and summaries of the news (as needed). Be sure you are subscribed so you don’t miss a single update.
And be sure to share this information with your friends & family.
“Knowledge is power.”
Epi(demiology) Matters is written by Dr. Becky Dawson, PhD MPH — an epidemiologist, teacher, mom, wife, and dedicated yogi. She is a tenured professor at Allegheny College, Research Director at a community hospital, and an exclusive contributor (all things health & medicine) at Erie News Now (NBC/CBS). Her goal is to create healthy communities for all. She writes Epi Matters — first & foremost because epidemiology does matter (to all of us) and she hopes that each post will help to educate and empower readers to be healthy and create healthy communities.
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NOTE: H5N1 is a highly pathogenic avian influenza. In the news and literature from governmental agencies, those terms are used interchangeably. Other synonyms include “bird flu” or “avian influenza.”