H5N1 avian flu strikes another Arizona layer farm

News brief

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed a third H5N1 avian flu outbreak at a large layer farm in Arizona, affecting nearly 1.4 million birds.

Since the middle of May, the virus has hit three of the state’s large layer farms, all in Maricopa County, leading to a loss of more than 5 million birds. The outbreak wiped out about 95% of the birds at Hickman Family Farms’ facilities, and has shuttered all of the company’s West Valley farms, according to a local media report.

Canadian ostriches had novel reassortant

Ostriches at a farm in British Columbia embroiled in a controversy over culling were infected with a novel H5N1 reassortant that included the D1.3 genotype, according to a recent statement from the Canadian Food Inspection Agency (CFIA). The reassortant hadn’t been detected before in Canada, but was identified in March in a serious infection in an Ohio poultry worker.

The outbreak at the ostrich farm was initially reported earlier this spring, and the company has not adhered to Canada’s rules about culling and quarantine, amid a public uproar over the federal laws that require that the birds be destroyed.

Long-COVID diagnoses fairly common in Medicare claims

News brief

Stephanie Soucheray, MA

A recent study in The Journal of Gerontology analyses Medicare data from 3,588,671 Medicare beneficiaries diagnosed as having COVID-19 from October 2021 to March 2023 and finds that 3.9% of beneficiaries—or about 140,000 people—were diagnosed with long COVID after experiencing symptoms for at least 1 year.

The authors also estimated the risk of developing long COVID based on the number of COVID-19 vaccine doses administered prior to the index date, using Medicare Part B claims and pharmacy records.

A greater number of COVID-19 vaccine doses was associated with a reduced relative rate of Long COVID compared to no COVID-19 vaccine dose

"In both unadjusted and fully adjusted models, a greater number of COVID-19 vaccine doses was associated with a reduced relative rate of Long COVID compared to no COVID-19 vaccine dose," the authors wrote.

Multiple vaccine doses lowered risk of long COVID

Overall, beneficiaries with four or more COVID-19 vaccine doses had a 39% lower adjusted rate of long COVID relative to beneficiaries without a prior dose (adjusted hazard ratio, 0.61; 95% confidence interval [CI], 0.60 to 0.62).

"Long COVID diagnoses were relatively common, occurring in nearly 1 in 25 Medicare beneficiaries, but especially in those with certain chronic conditions and without prior COVID-19 vaccine doses," the authors concluded. "COVID-19 vaccine doses may mitigate long COVID risk through reducing viral load and the severity of natural infection, but additional causal inference studies are needed to confirm these hypotheses."

Report highlights evidence, remaining data gaps on vaccines and antibiotic resistance

News brief

Chris Dall, MA

Young girl receives meningitis vaccine — WHO / Flickr cc

The Wellcome Trust last week released a new report on the role that vaccines can play in tackling antimicrobial resistance (AMR).

The report summarizes the findings from 11 Wellcome-funded research projects that aimed to fill critical evidence gaps on vaccines and AMR, particularly in low- and middle-income countries. A World Health Organization (WHO) modeling study published in 2024 estimated that vaccines could avert more than half a million deaths from drug-resistant infections annually, cut AMR-related healthcare costs and productivity losses by billions of dollars, and reduce the number of antibiotics needed to treat infections by 2.5 billion doses annually. The 11 projects looked at real-world data on how vaccines can combat AMR across different pathogens, settings, and research methods.

The report reveals that the relationship between vaccination and its impact on AMR is "rarely straightforward." For example, evidence from flu, typhoid, pneumococcal, malaria, and diarrheal disease studies indicate that vaccines can reduce antibiotic use, but inconsistently, with the effects varying by pathogen, settings, and healthcare system. In addition, vaccination affects microbial population dynamics, and the frequency of horizontal gene transfer, in different and unpredictable ways.

"As a result, it remains difficult to quantify how vaccination does affect antibiotic use or AMR gene prevalence," the report states. "Due to this uncertainty, it is challenging for policymakers to incorporate impact on AMR into decisions on how to use vaccines to best effect."

More data needed

The report also includes conclusions from a 2024 workshop where researchers and policy makers discussed the 11 projects. Their conclusions were that more real-world data is needed, along with agreed-upon protocols and standards for AMR data collection and analysis in vaccine studies. They also identified a need to prioritize policy-relevant evidence.

"Further empirical research which is embedded within vaccine trials and/or observational studies, and guided by policy and use needs, could close knowledge gaps and provide a clearer picture of how vaccination affects AMR in real-life contexts," the authors wrote. "This would provide greater clarity on the additional AMR-related public health value of vaccination."

Testing migrants for key infectious diseases may speed diagnosis, cut risk of spread

News brief

Mary Van Beusekom, MS

Instituting routine testing of migrants for certain infectious diseases leads to earlier diagnoses and treatment, improving health outcomes and lowering the risk of onward community spread, suggests an observational UK study published late last week in eClinicalMedicine.

The researchers gauged the efficacy of testing migrants for tuberculosis (TB) with an interferon gamma release assay, HIV, hepatitis B virus (HBV) with surface antigen testing, and hepatitis C virus (HCV) with antibody testing and polymerase chain reaction (PCR) testing. The team tested patients when they first registered with general practices (GPs) in Leicester and analyzed test positivity rates, numbers of new diagnoses, and other healthcare data from 2016 to 2019.

"While some testing for infectious disease may take place at the discretion of individual GPs currently, this is neither the norm and typically happens in silo," senior author Manish Pareek, of the University of Leicester, said in a university news release.

Vast majority completed treatment

Of 4,004 migrants referred for testing, the test positivity rate was 0.5% for HIV, 3.3% for HBV, 0.2% for HCV, and 19.4% for TB. Among the 437 TB patients, 7% had active disease, and 92% had latent infections.

Importantly, this study has demonstrated that this testing approach is acceptable to migrants when they register with a GP, and the vast majority who test positive are being successfully treated.

Rebecca Baggaley, PhD

In total, 55% of active TB, 99% of latent TB, 61% of HBV, 35% of HIV, and 83% of HCV infections were new diagnoses. Of these patients, 98% of new latent TB patients were offered drugs to prevent active illness; 94% of them began treatment, and 95% of them completed it. All six newly diagnosed HIV patients, 97% of 71 new HBV patients, and all five new HCV patients completed follow-up.

"Importantly, this study has demonstrated that this testing approach is acceptable to migrants when they register with a GP, and the vast majority who test positive are being successfully treated," lead author Rebecca Baggaley, PhD, of University College London, said in the release. "The next step is to evaluate its cost effectiveness as a healthcare package and the feasibility of rolling out such testing, when GP clinics’ time and resources are already overstretched."

Northern Idaho CWD cases in deer now tally 6, after 3 more detections

News brief

Mary Van Beusekom, MS

White-tailed buck — jacosammie / Flickr cc

Idaho reports three new chronic wasting disease (CWD) cases in white-tailed deer in the Panhandle Region.

Idaho Fish and Game (IFG) said the infections were identified during the 2024 deer-hunting season in the Unit 1 CWD-Management Zone, which includes Coeur d'Alene, east of Spokane, Washington. The new detections push the total number of CWD-positive free-ranging deer in northern Idaho to six since the first identification in July 2024.

Low estimated prevalence

In total, 936 white-tailed deer were tested for CWD in Unit 1 during the 2024 hunting season, a large increase from 2023.

Early detection of CWD is critical, as it creates opportunities to take action to slow the rate of spread of the disease.

"Relative to many other states, the current estimated prevalence rate (less than 1%) of the disease in the management zone is low," IFG wrote. "Low prevalence rates suggest that Fish and Game in collaboration with hunters detected the disease early. Early detection of CWD is critical, as it creates opportunities to take action to slow the rate of spread of the disease."

During the 2025-26 Big Game Season Setting process, IFG staff proposed five new controlled hunts for white-tailed deer in Unit 1, which the Fish and Game Commission adopted in March 2025.

"Between the addition of 100 extra antlered white-tailed deer tags, addition of 1,000 extra antlerless white-tailed deer tags and reduction of 750 antlerless white-tailed deer tags in Unit 1, there is a net increase of 350 extra deer tags available in Unit 1, with a targeted focus to increase harvest within the CWD management zone," IFG wrote.

CWD, which affects cervids such as deer, elk, and moose, is caused by infectious misfolded proteins called prions. The fatal neurodegenerative disease spreads through cervid-to-cervid contact and environmental contamination. There is no vaccine or cure.