In new H5N1 avian flu confirmations today, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) reported that the virus hit more flocks in four states, including another massive layer farm in Ohio, the nation’s second biggest poultry producer.

Over the past several weeks, Ohio has been one of main outbreak epicenters, with one of the latest events involving a commercial farm in Darke County that has more than 3 million birds, according to APHIS. The virus also struck another layer farm in Ohio’s Mercer County, a facility that has nearly 85,000 birds.

Elsewhere, the virus struck two more commercial farms in Indiana, another hard-hit state. The latest outbreaks occurred at a turkey farm in Washington County and a commercial duck-breeding facility in Elkhart County. The virus was also confirmed in backyard birds in two states, a location in Florida’s Broward County and a location in New York’s Delaware County.

Over the last 30 days alone, ongoing H5N1 outbreaks have led to the loss of nearly 19 million birds.

In dairy herd developments, over the last few days, APHIS confirmed one more detection, which involves another herd from Nevada. The state now has eight affected herds. Since the virus first emerged in dairy cattle about a year ago, detections have been reported in 973 herds across 17 states.

CDC updates status of two recent human cases

In updates on February 21, the US Centers for Disease Control and Prevention (CDC) confirmed H5N1 in samples from an Ohio poultry worker whose illness was first reported on February 12. The CDC had initially listed as a probable case. 

In its latest FluView update, the CDC added a few more details about the two recent human cases, including the one from Ohio and a patient from Wyoming. It said the patient from Ohio worked on an outbreak farm and was involved in culling activities. The patient was hospitalized with respiratory and nonrespiratory symptoms and now recovering at home. Meanwhile, a recently reported patient from Wyoming who got sick after exposure to backyard poultry remains hospitalized after experiencing both respiratory and nonrespiratory symptoms. 

The CDC has confirmed 70 cases, one of them fatal, since early 2024. The agency has also recorded seven probable cases.

A survey of hospitals in Ontario reveals that the incidence of carbapenemase-producing organisms (CPOs) doubled from 2022 to 2023, according to a report published last week by Public Health Ontario.

The survey, which was distributed to all public hospitals and microbiology labs in the province, found that 1,229 patients were either infected or colonized with a CPO in 2023, up from 560 patients in 2022. The overall rate of new patients with CPOs per 10,000 patients doubled, from 5.1 to 10.2. Of these new CPO patients, 98.2% were infected or colonized with Enterobacteriaceae organisms. The most commonly reported carbapenemase was New Delhi Metallo-beta-lactamase (55.2%), followed by Oxacillinase (26.0%) and Klebsiella pneumoniae carbapenemase (13.7%).

Data from labs also showed increasing resistance to third-generation cephalosporins among Escherichia coli (from 9.6% in 2017 to 12.8% in 2023) and Klebsiella pneumoniae (4.7% to 9.2%) isolates, as well as rising resistance to ciprofloxacin among E coli isolates. Resistance to ciprofloxacin among E coli isolates climbed to 22.3% in 2023, the highest resistance levels reported to date.

MRSA incidence declining

Other key findings include a 17.5% decrease in the number of new patients with methicillin-resistant Staphylococcus aureus (MRSA) isolated from any specimen site compared with 2022 and a decline in the Clostridioides difficile positivity rate (from 12.1% in 2022 to 10.1% in 2023). The incidence of vancomycin-resistant enterococci remained stable, and Candida auris incidence remained rare, with only three cases reported in 2023. 

"The epidemiological data obtained from Ontario laboratories and hospital infection prevention and control programs helps in understanding the impact of AROs [antimicrobial-resistant organisms] and informs recommendations to prevent spread within our province," the report stated. "Continued and improved surveillance of AROs are necessary to understand the current landscape of resistance. Identifying regional variation in incidence of organisms can inform provincial and local decisions regarding appropriate application of infection control policies."

A study conducted among hospitalized children in Ohio shows that rates of macrolide-resistant Mycoplasma pneumoniae (MRMp) are low but have been rising in the wake of the COVID-19 pandemic, researchers reported last week in Emerging Infectious Diseases.

For the study, researchers with Nationwide Children's Hospital (NCH) in Columbus, Ohio, and The Ohio State University analyzed patient data and laboratory findings to determine the rate of MRMp infections in children in Ohio from September 2023 through September 2024. M pneumoniae is a major cause of community-acquired respiratory infection in children, but during the pandemic the hospital saw almost no M pneumoniae activity in pediatric patients. That was followed by an uptick in cases in September 2023 and a sharp increase last summer.

"Unlike other areas where M. pneumoniae has reemerged with case numbers similar to or slightly higher than prepandemic times, the ongoing M. pneumoniae surge in our patient population is the largest we have seen in the past 10 years, >2,000 cases in 4 months (June 2024–September 2024), compared with 1,350 total cases during January 2012–January 2019," the study authors wrote.

'Vigilant surveillance' needed

During the study period, tests performed by the NCH microbiology lab on 2,469 patients identified 2,616 (14.5%) of 18,035 M pneumoniae–positive samples. Positivity rates remained stable from September 2023 through May 2024, then rose sharply in June 2024. The positivity rate among children aged 6 to 10 years was 26.6%, compared with 2.1% in children aged 2 years and younger. Among the patients, 304 (12.3%) were hospitalized and 53 (2.1%) required intensive care unit admission.

Sequencing of 995 M pneumoniae–positive samples detected mutations associated with MRMp in 24 samples (2.4%). The percentage of resistance detected was different every month, with the highest rate (4.4%) detected in September 2024.

"Although MRMp remains low, MRMp is trending upward, underscoring the need for vigilant surveillance to provide accurate information for management of children with M. pneumoniae infection and maintain awareness of antimicrobial resistance," the authors wrote. They add that more work is needed to understand MRMp in different populations and geographic locations and its effects on patient care.

Another Indiana county is reporting its first case of chronic wasting disease (CWD), less than a year after the state's first detection.

A 2.5-year-old white-tailed buck in Posey County tested positive after being harvested by a hunter, the Indiana Department of Natural Resources (DNR) said in a news release late last week. 

The county is in the southwestern part of Indiana, on the border with CWD-positive Illinois and CWD-positive Kentucky, the far opposite of LaGrange County, where the state's first case was discovered in April 2024. LaGrange County abuts CWD-positive Michigan. The other state that borders Indiana, Ohio, has also reported cases of the fatal neurodegenerative disease.

During the 2025-2026 deer hunting season, DNR will enhance its surveillance efforts in Posey County and the surrounding counties to determine the extent of disease in this area.

"During the 2025-2026 deer hunting season, DNR will enhance its surveillance efforts in Posey County and the surrounding counties to determine the extent of disease in this area," the DNR said. "This will allow biologists to develop a targeted response based on the prevalence of CWD in this part of Indiana. CWD testing will be voluntary for hunters in this area."

Cooking doesn't neutralize prions

CWD, a disease of cervids such as deer, moose, and elk, is caused by infectious misfolded proteins called prions, which spread through direct contact and the environment.

The disease isn't known to infect people, but some experts fear it could cause illness similar to another prion disease, bovine spongiform encephalopathy ("mad cow" disease). The US Centers for Disease Control and Prevention warns against eating meat from infected animals, as cooking temperatures cannot deactivate prions.