Protect Yourself From H5N1 When
Working With Farm Animals [2 MB, 1 page]
#18,400
Yesterday, the CDC held a relatively short telebriefing (see Transcript) on two reports on H5N1 published this week in the MMWR. The first, which we covered in MMWR: Serologic Evidence of Recent Infection with HPAI A(H5) Virus Among Dairy Workers, announced serological evidence of mild and/or asymptomatic infection in farm workers.
The CDC will supposedly release new guidelines on the testing and use of antivirals in exposed, but asymptomatic farmworkers, as soon as today.
A second report in yesterday's MMWR dealt with the use of PPE by farmworkers in Colorado - which has been strongly recommended for more than 6 months - but which has been met with considerable resistance (see STAT news Farmers resist push for workers to wear protective gear against bird flu virus).
However, the recommended PPE can be hot and is often cumbersome to wear, don and doff. Since not all infected livestock are obviously symptomatic and testing remains mostly voluntary, many workers may not realize when they are at risk.
Add in language barriers, and a downplaying of the risks by some farm owners, and PPE compliance has been spotty and the risks of human infection are increased.
Due to its length, I've only posted some excerpts from the report. Follow the link to read it in its entirety. I'll have a postscript after the break.
Personal Protective Equipment Use by Dairy Farmworkers Exposed to Cows Infected with Highly Pathogenic Avian Influenza A(H5N1) Viruses — Colorado, 2024
Weekly / November 7, 2024 / 73(44);999–1003
Kristen E. Marshall, PhD1,2; Cara C. Drehoff, DVM1,3; Nisha Alden, MPH1; Sophia Montoya, PSM1; Ginger Stringer, PhD1; Allison Kohnen, DVM1; Alexandra Mellis, PhD4; Sascha Ellington, PhD4; Jordan Singleton, MD3; Carrie Reed, DSc4; Rachel Herlihy, MD1; Colorado Field Team (VIEW AUTHOR AFFILIATIONS)View suggested citation
Summary
What is already known about this topic?
Use of personal protective equipment (PPE) by farmworkers can protect them when they are working with highly pathogenic avian influenza A(H5N1)–infected cows.
What is added by this report?
Dairy farmworkers in Colorado who were interviewed about PPE use during work activities with ill cows reported 28% higher use of PPE after detection of A(H5N1) virus on the farm than before detection, including a 40% increase in reported use of eye protection during milking. Reported use of respirators and other masks was low.
What are the implications for public health practice?
Establishing strong relationships between public health agencies and agricultural organizations to communicate public health risk and protective practices on U.S. farms after detection of A(H5N1) in cows, and early distribution of PPE before A(H5N1) virus detection, might increase PPE use once an A(H5N1) outbreak is identified.
(SNIP)Reported PPE UseWhen asked about their access to individual elements of PPE before outbreak detection, 88% of workers reported access to gloves, 76% reported access to eye protection such as safety glasses or goggles, 71% reported access to rubber boots or boot covers, and 69% reported access to head covers. Reported use of many individual PPE items was higher among dairy workers who reported exposure to ill cows in the week before or week after the detection of A(H5N1) on the farm, compared with those who did not report exposure to ill cows (Table 2). Dairy workers exposed to ill cows during the week after A(H5N1) virus detection reported higher use of gloves (93%), boots or boot covers (83%), head or hair covers (79%), and eye protection (76%) compared with those who reported exposure to ill cows in the week before detection of HPAI A(H5N1).
Reported use of N95 FFRs or other respirators and other types of masks was low (9% and 27%, respectively) among workers exposed to ill cows the week before A(H5N1) outbreaks were detected, with higher usage reported among exposed workers in the week after outbreak detection (26% and 36%, respectively). Use of all CDC-recommended PPE was low among workers both in the weeks before (2%) and after (5%) A(H5N1) virus detection. Workers also reported use of items such as sunglasses and bandanas or gaiters; these items are not recommended PPE.Adjacency matrix frequencies identified a group of work duties with the highest reported PPE use in the weeks before and after A(H5N1) virus detection (Figure). Workers transporting cows, cleaning cow manure, and milking cows reported the highest frequency of use of gloves, rubber boots or boot covers, head covers, and eye protection. The mean use frequency of these PPE items while performing the same activities increased 28% during the week following detection of A(H5N1) virus. The largest increase in reported use frequency of eye protection from the week before to the week after detection of A(H5N1) occurred in workers who milk cows (40%). The highest correlations of work duty and PPE use (24 workers) were wearing gloves while transporting cows and wearing gloves while cleaning manure or feces (Figure).DiscussionThe lower mortality rate of cows infected with highly pathogenic avian influenza A(H5N1) viruses compared with that of birds can result in prolonged dairy farm worker exposures to ill cows through poorly understood transmission routes. Reported PPE use among workers at three dairy farms with A(H5N1) influenza outbreaks was high for some items, with the largest increase reported in frequency of use of eye protection once outbreaks were detected. Milking cows, the most frequently reported work duty by interviewed workers, is thought to pose higher risk for cow-to-human A(H5N1) virus transmission because of exposure to raw milk (6). A previous human case of A(H5N1) in a dairy worker identified in Michigan reported milk splashing into the eyes before receiving a positive A(H5N1) test result (9). The reported increase in eye protection among workers milking cows after A(H5N1) detection is important for protecting against A(H5N1) exposure. Dairy farms might isolate ill cows to reduce transmission, but the occurrence of asymptomatic A(H5N1) virus infections in cows means that workers can still be exposed during the milking process, highlighting the need for and importance of PPE during milking for all cows on dairy farms with A(H5N1) virus infections detected (10).Reported use of N95 FFRs and other types of masks was low during most work activities. Dairy farmworkers’ duties often involve exposure to manure or milk that can contaminate respirators and masks, which might result in lower worker compliance with use as well as possible influenza A(H5N1) exposure despite wearing a mask. Hot weather and humid environments found in milking parlors can also make wearing respirators and masks uncomfortable, potentially reducing the likelihood of their use by workers carrying out farm activities, especially during hot summer months.In this analysis, other types of masks were used more frequently than were N95 FFRs. Development of messaging by public health agencies that is consistent with CDC PPE recommendations (7) would help to educate farm owners and workers about the risks associated with caring for ill dairy cows on farms with A(H5N1) detected and could encourage recommended respirator use. Additional data are needed to guide recommendations for PPE use to protect worker health in these environments. Engaging dairy industry representatives and producers to recommend practices limiting worker contact with dairy cattle and their milk, along with PPE use recommendations in high-risk scenarios such as milking, might increase PPE use.(SNIP)Implications for Public Health PracticePublic health agencies should continue to conduct outreach to farms and educate farm owners about the importance of workers using PPE during farm duties and exposure to ill cows, as well as understanding and reporting signs of human illness during A(H5N1) herd outbreaks. Collaboration with state agricultural partners can strengthen relationships and public health practice at dairy farms. As the A(H5N1) outbreak in dairy herds evolves, providing PPE to farms before outbreaks occur might help increase PPE use, especially during high-risk activities such as milking, and prevent human cases of A(H5N1).
The CDC is an advisory agency, with little regulatory power. They can produce reams of guidance, but it is up to other agencies (state, local, and federal) and the private sector to decide which they will adopt and/or enforce.
Unfortunately, HPAI H5's spread in livestock (and wild mammals) has been treated by these entities as more as a political or economic problem, than as a genuine public health concern.
`Don't test, don't tell' remains a popular option for many farmers, which is why we don't have a good handle on how widespread HPAI H5 is in dairy cows, and other livestock (including pigs).
Nor do we know how may human infections have occurred, since testing has been voluntary, sporadic, and largely limited to obviously symptomatic farmworkers.
While there are some recent signs that may be changing, it comes only after months of a slow and fragmented response. One which has granted the virus time to further evolve, and become better established in herds across the country.
