Two domestic, indoor cats in King and Snohomish counties in Washington state have tested positive for H5N1 avian flu after eating potentially contaminated raw pet food, and more cats are being tested for the virus, the Washington State Department of Agriculture (WSDA) announced yesterday.

The owners told authorities that they fed their cats Wild Coast Raw pet food, the same brand implicated in recent feline illnesses in Oregon. One of the Washington cats had to be euthanized, and the other, from a separate household, is receiving treatment. The cats' household members are being monitored for 10 days.

The cases come on the heels of H5N1 highly pathogenic avian influenza (HPAI) detections earlier this month in 10 pet cats in five states: California, Colorado, Oregon, Kansas, and New Mexico.

People can become infected if the virus enters their eyes, nose, or mouth—such as by handling contaminated pet food or touching contaminated surfaces, especially without thoroughly washing their hands afterward.

"To date, there have been no documented human cases of HPAI following exposure to an infected cat or contaminated raw pet food products," the WSDA said. "The currently circulating strain of HPAI is considered low risk to the public, but there is greater risk for those who handle contaminated raw pet food products or who care for infected animals."

"People can become infected if the virus enters their eyes, nose, or mouth—such as by handling contaminated pet food or touching contaminated surfaces, especially without thoroughly washing their hands afterward," the agency added.

Common signs of H5N1 infection in cats are lethargy, loss of appetite, fever, and hypothermia. The infection can progress to pneumonia, neurologic abnormalities, and upper respiratory infection.

"This is a difficult situation, we love our pets, and it's devastating when they fall ill," WSDA field veterinarian Zac Turner, DVM, said in the news release. "If your cat is showing symptoms, consult a veterinarian as soon as possible."

The WSDA advises against feeding raw pet food or raw milk to animals.

Dairy cattle detections in Nevada, California

Also yesterday, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed 3 more H5N1 detections in dairy cattle, with 2 in Nevada and 1 in California, bringing the national total to 976.

A retrospective study of patients with carbapenem non-susceptible infections and limited treatment options at 24 US hospitals found that imipenem/cilastatin/relebactam (IMI/REL) was effective and well-tolerated, researchers reported yesterday in Open Forum Infectious Diseases.

IMI/REL is a beta-lactam/beta-lactamase inhibitor combination that was approved by the Food and Drug Administration (FDA) in 2019 for treating complicated infections caused by multidrug-resistant (MDR) gram-negative pathogens. While FDA approval was based on data from randomized controlled trials that showed IMI/REL was efficacious, well-tolerated, and noninferior to comparator antibiotics, the type of patients who have MDR gram-negative infections typically aren't eligible for such trials. 

The aim of the study, which was led by researchers at Wayne State University, was to assess the performance of IMI/REL in real-world settings. The primary outcome was clinical success, defined as improvement or resolution of infection-related signs/symptoms while receiving IMI/REL.

Clinical success in 70% of patients

A total of 151 patients (median age, 60; 54.3% male) received IMI/REL for 48 hours. The most common source of infection was the lower respiratory tract, which accounted for 52.3% of cases. Most patients (85.4%) had a carbapenem non-susceptible organism, and 72.2% received IMI/REL for targeted treatment of Pseudomonas aeruginosa. There was a high burden of comorbid conditions among the patients, including diabetes (39.1%), heart failure (28.5%), and chronic kidney disease (25.8%).

Clinical success was achieved in 70.2% of patients, and adverse events occurred in 6%, with three instances of IMI/REL discontinuation. Multivariable analysis found that heart failure, receipt of antibiotics within the past 90 days, intensive care unit admission at time of index culture collection, and isolation of difficult-to-treat P aeruginosa were independently associated with reduced odds of clinical success.

The study authors say the findings offer valuable insights into the demographics and clinical characteristics of patients prescribed IMI/REL.

"Our findings highlight the potential of IMI/REL as a valuable therapeutic option in challenging clinical scenarios," they wrote. "Continued investigation into its application among specific situations, including comparative analyses, will be important to more completely understand its place in therapy to combat the escalating threat of MDR Gram-negative infections."