Wednesday, April 03, 2024

USDA: Testing Recommendations Of Influenza A In Cattle


The USDA has published an interim guidance document on the testing of cattle for influenza A.  Since cattle were presumed unlikely hosts for HPAI up until a little more than a week ago, this guidance is subject to change as more is learned about the threat. 

The high points from this 5-page document include:

  • Testing remains voluntary
  • The criteria for testing is fairly narrow, with only symptomatic dairy cows currently eligible for testing

Due to its length, I've only reproduced some excerpts.  Follow the link to read the document in its entirety.  I'll have a brief postscript after the break.


Please note: This situation is evolving rapidly. Check back frequently for updated versions. 

Testing Recommendations for Influenza A in Cattle 

BACKGROUND: The Animal and Plant Health Inspection Service, Food and Drug Administration (FDA), Centers for Disease Control and Prevention (CDC), State Animal Health and Public Health Officials, and National Animal Health Laboratory Network (NAHLN) laboratories are continuing to investigate an illness among dairy cows that is causing decreased lactation, low appetite, and other symptoms. APHIS has confirmed highly pathogenic avian influenza (HPAI) H5N1 in bovine-origin samples associated with the illness.

This document provides APHIS’ current recommendations regarding testing of affected or exposed cattle. This is a rapidly evolving situation and new information is being received, reviewed, and analyzed constantly to inform and adjust recommendations accordingly.

APHIS will share new information with our valued partners and stakeholders as soon as it is available. At this time, APHIS is not requiring testing. Testing may be done on a voluntary basis and is a tool producers may use to help manage this disease or reduce the risk of introducing the disease. APHIS may fund some testing as outlined below. 

TESTING AFFECTED CATTLE (Cattle that meet the Case Profile) 

New suspect cases: 

Dairy farms and other cattle herds with an active event: cows must be exhibiting clinical signs; there may be dead/sick birds, cats, or other mammals. All would be eligible for reimbursement by APHIS through NAHLN or Unexplained Morbidity/Mortality Event (UME) funding; please see specifics as outlined below. 

Working Case Profile:

  • Sudden drop in feed intake with concurrent decreased rumination and rumen motility. 
  • Subsequent marked drop in herd level milk production. More severely affected cows may have thickened milk that almost appears like colostrum or may have essentially no milk. 
  • Changes in manure - most reporting indicates tacky to dry manure in affected cattle. 

A FAD/EP number is required prior to testing to qualify for reimbursement. Although the HPAI (H5N1) virus itself is a foreign animal disease (FAD), we are considering this as an emerging disease in cattle. APHIS encourages states and industry to use the established FAD/Emerging Disease investigation process to investigate credible reports of HPAI (H5N1) virus in dairy cattle (and beef cattle or other domestic livestock species).

APHIS will fund the NAHLN laboratory influenza PCR testing for up to 20 mammals (no more than two samples per mammal) and unlimited birds per premises. If lactating, one sample must be milk/mammary tissue. Samples must go to a NALHN laboratory approved to test for avian influenza.


Retrospective cases: 

Herds with no clinical signs, but had a previous event that meets the case profile (see above for definition) since November 1, 2023:

APHIS is working to gather as much information as possible to help improve the understanding of this event. As such retrospective testing can provide insight into the movement of this virus as well as performance of serological assays for potential future use. Banked or retained milk/tissue. APHIS is willing to fund influenza testing on banked samples from cattle and other mammals on the premises that match the case profile.


UNAFFECTED CATTLE - Movement Testng for (Influenza A)

APHIS does not reimburse for movement testing. 

At this time, we strongly recommend minimizing movement of cattle as much as possible, with special attention to evaluating risk and factoring that risk into movement decisions. Do not move sick or exposed animals. 

Based on our current information, it appears the virus has an affinity to replicate in mammary tissue. We have yet to identify animals with confirmed virus replication in tissues other than mammary tissue and milk. 

          (Continue . . .)

This is, as stated, a rapidly evolving situation - and while it might be desirable to cast a wider testing net - it takes time to gear up to deal with a new threat.  As it is, it is taking up to a week to confirm test results. 

Hopefully, this outbreak is limited to producing dairy cows, but we won't know that for sure until wider testing can be arranged. 

Stay tuned.