More H5N1 avian flu detections have been confirmed in poultry flocks in nine states over the past 2 days, including a massive layer farm in Pennsylvania that has nearly 2 million birds, according to the latest notifications from the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS).

Layer farms have been hard hit in multiple states, and the latest event in Pennsylvania’s Dauphin County will likely add to ongoing egg supply shortages. The virus also struck another commercial farm in Pennsylvania, a broiler facility in Cumberland County that has 30,000 birds.

In Ohio, one of the nations recent hot spots, the virus was confirmed at nine more commercial farms, including six turkey farms, two layer farms, and a layer pullet farm.

Other states reporting events at commercial farms include California (turkeys) and Maryland (broilers). APHIS also confirmed the virus at two live bird markets in New York, one in Queens County and the other in Bronx County.

Five states have new detections in backyard flocks, including Michigan, Arizona, Colorado, Pennsylvania, and Kansas.

Since the outbreaks began in early 2022, the outbreaks have led to the loss of a record 156 million birds across all 50 states and Puerto Rico.

Earlier Nevada dairy herd had original cattle genotype

Following the APHIS’ announcement yesterday of a second H5N1 genotype, D1.1, detected in dairy cattle, a spokesperson from the Nevada Department of Agriculture told CBS News that an earlier detection in December in Nye County involved the earlier genotype, B3.13. However, the four latest detections in Churchill County involved the D1.1 genotype, which is circulating in wild birds and has been linked to two severe human infections. 

The spokesperson said two more Churchill herds are in quarantine, pending USDA lab results, and the symptoms in cows infected with D1.1 are similar to those that were sick with the B3.13 genotype.

In other developments, the APHIS today confirmed two more detections in dairy herds, both from California, raising the national total to 959 and the state’s total to 738.

Data from more than 800 US hospitals show that, despite improvements over the course of the COVID-19 pandemic, antibiotic prescribing for COVID-19 and other viral acute respiratory tract infections (ARTIs) remained higher than it should be, researchers reported this week in Open Forum Infectious Diseases.

The study, led by researchers from the University of Wisconsin-Madison School of Medicine and Public Health, analyzed antibiotic prescribing at 803 US hospitals, focusing specifically on antibiotic prescribed to patients admitted for COVID-19 from March 2020 through December 2023 and patients admitted for non-COVID viral ARTIs from January 2019 through December 2023. While the initial spike in antibiotic prescribing at US hospitals linked to the onset of the COVID-19 pandemic has been well-documented, the researchers wanted to assess the impact of the pandemic on antibiotic usage over time.

Continued need for antimicrobial, diagnostic stewardship

The study included 513,698 hospital encounters for COVID-19 and 106,932 for non-COVID viral ARTIs. In March 2020, antibiotics were prescribed for 82.7% of COVID-19 admissions. The rate of antibiotic prescribing for COVID fell to 30.5% in May 2022, with peaks of 50.8% in July 2021 during the Delta surge and 41.7% in July 2022 during the Omicron surge, then levels decreased to 33.8% in December 2023. For other viral ARTIs, the rate of antibiotic prescribing was 55.8% in January 2019, rose to 64.7% in July 2019, peaked at 68.1% in June 2020, declined to 40% in December 2022, then rose to 58.1% in April 2023.

Overall, 45.8% of COVID-19 admissions and 51.2% of viral ARTI admissions received at least one dose of antibiotic from March 2020 through December 2023.

"The perpetuation of high rates of potentially unnecessary antibiotic prescribing demonstrates a continued need for improved diagnostics, diagnostic stewardship, and antimicrobial stewardship programs to reduce antibiotic overprescribing for viral ARTIs," the study authors wrote. 

"Future work should identify drivers of unnecessary antibiotic prescribing for viral ARTI admissions, implement strategies to promote resiliency in antimicrobial stewardship programs for future moments of operational upheaval, and examine the relationship between COVID-19 antibiotic prescribing patterns and antimicrobial resistance development in hospitals across the U.S."

An analysis of data from five countries found that fluoroquinolone (FQ) antibiotics were not associated with an increased risk of aortic aneurysm or dissection (AA/AD) compared with other antibiotics commonly used for urinary tract infections (UTIs), an international team of researchers reported late last week in eClinicalMedicine.

In December 2018, the US Food and Drug Administration warned that the use of FQs could increase the risk of AA/AD and urged patients with increased risk (eg, those with a history of aneurysms or blockages of other blood vessels) to use other antibiotics unless no other treatments are available. But the warning was based on meta-analysis of four studies that used different analytic approaches, only one of which included an active comparator antibiotic. In addition, subsequent studies have found no association between FQs and increased AA/AD risk.

To further assess the risk, the researchers analyzed data on more than 13.5 million patients aged 35 or older in Australia, Japan, South Korea, Taiwan, and the United States who had initiated systemic FQ or comparable antibiotics (cephalosporins [CPH] or trimethoprim [TMP] with or without sulfamethoxazole) for UTI treatment from 2010 through 2019. The primary outcome was AA/AD occurrence within 60 days of exposure. To account for baseline differences between patients treated with different antibiotics, the researchers used 1:1 propensity score matching.

No difference in AA/AD risk

There were 1,954,798 and 1,195,952 propensity-matched pairs for the FQ versus TMP and FQ versus CPH comparisons, respectively. The 60-day AA/AD risk was not significantly different between FQ and TMP (absolute rate difference [ARD], 0.21 per 1,000 person-years; calibrated hazard ratio [HR], 0.91; 95% confidence interval [CI], 0.73 to 1.15). Similarly, the 60-day AA/AD risk was not significantly different between FQs and CPHs, with a calibrated HR of 1.01 (95% CI, 0.82 to 1.25] and an ARD of 0.11 per 1,000 person-years.  

"The findings of this study suggest that fluoroquinolones can be prescribed for urinary tract infections without consideration of risk of aortic aneurysm or aortic dissection despite contradictory evidence from previous studies and prior warnings," the study authors wrote, adding that other factors, such as antibiotic resistance, should still guide use.

Three more captive deer in three Louisiana parishes have tested positive for chronic wasting disease (CWD), the Louisiana Department of Wildlife and Fisheries (LDWF) reported yesterday.

Authorities detected the cases in Concordia, St Landry, and Tangipahoa parishes after tracing them back to a CWD-positive deer farm in Jefferson Davis Parish identified in November. Concordia and Tangipahoa parishes abut Mississippi's southern and western borders, and St Landry Parish is in the south-central part of Louisiana.

At this time, the disease has not been detected in the wild population in any of the parishes with CWD positive deer pens and associated trace outs.

"In addition to the recent detections, deer from the CWD positive pens have been traced to permitted pens in 11 other parishes," LDWF said in a news release. "No other positives have been confirmed at this time." The 11 parishes are located throughout the western half of the state.

The department has performed statewide surveillance of wild deer since 2002, with the only CWD case in a free-ranging deer found in Tensas Parish in 2022.

LDWF acknowledged that the three recently identified cases have raised concerns about the fatal neurologic disease spreading further into wild deer, but said, "At this time, the disease has not been detected in the wild population in any of the parishes with CWD positive deer pens and associated trace outs."

Testing recommended in CWD-positive areas

CWD, a disease of cervids such as deer, moose, and elk, is caused by prions, infectious proteins that trigger abnormal folding in normal proteins. Infected animals shed CWD prions in body fluids, which can spread to other cervids through direct contact or the environment. 

Although CWD is not known to infect people, the US Centers for Disease Control and Prevention and the World Health Organization advise against eating infected animals. People who hunt in CWD-positive areas should have their deer tested for the disease before consuming the meat.