Flu Scan for Oct 24, 2017

High-risk flu and antivirals
Severe influenza C cases
US H7N9 risk

Antiviral drugs infrequently prescribed to high-risk flu patients, study finds

A US Centers for Disease Control and Prevention–led study published yesterday in Clinical Infectious Diseases reveals that antiviral drugs are prescribed to only 15% of outpatients who have acute respiratory infections (ARIs) and a high risk for influenza.

The data underscore a need to increase appropriate prescribing, the authors said.

The team looked at antiviral prescription and clinical data for high-risk outpatients aged 6 months and older who had an ARI and were enrolled in the US Influenza Vaccine Effectiveness Network during the 2011-12 to 2015-16 flu seasons. They found that only 718 of 4,861 high-risk patients (15%) who presented within 2 days of symptom onset—when antivirals are shown to be most effective—were prescribed the drugs. In addition, only 40% of high-risk outpatients who had influenza reported within 2 days of first symptoms.

The researchers did find that earlier presentation to a clinic was associated with fourfold-higher odds of receiving antiviral medication. They also reported that a fourth of high-risk outpatients had no fever.

The team concluded, "Influenza antiviral medications were infrequently prescribed for high-risk outpatients with ARI who would benefit most from treatment. Efforts to increase appropriate antiviral prescribing are needed to reduce influenza-associated complications."
Oct 23 Clin Infect Dis study


Study of influenza C patients identifies some severe cases

Influenza C, which is not very common, is reported to typically cause mild symptoms, but a study of influenza C cases in Minnesota found some severe cases, especially among people who had comorbidities, according to a separate study in the same journal yesterday.

Experts from the University of Minnesota and the Minnesota Department of Health detected influenza C among 59 (0.58%) of 10,202 hospitalized ARI cases and 11 (0.48%) of 2,282 outpatient ARI cases from May 2013 to December 2016, with 73% of cases occurring in the 2014-15 flu season. The highest rate (1.2%) occurred among children 2 years old and younger.

Among the 59 hospitalized cases, 7 (12%) required intensive care, all of whom had comorbidities. Comorbidity prevalence among all hospitalized patients was 58%.

At least one other respiratory pathogen was detected in 40 (66%) of the hospital cases, most commonly rhinovirus or enterovirus (25%) and respiratory syncytial virus (20%). The finding of severe influenza C cases suggests a need for further study of the role of the virus in respiratory disease, the authors write.
Oct 23 Clin Infect Dis study


Study: US poultry H7N9 avian flu isolates pose low human health threat

Low-pathogenic and highly pathogenic H7N9 avian flu viruses isolated in poultry outbreaks in the southeastern United States earlier this year appear to pose a low threat to human health in their current form, according to researchers from the US Centers for Disease Control and Prevention (CDC) who conducted experiments in mice, ferrets, and human airway cells. They reported their findings yesterday in Emerging Infectious Diseases.

The outbreaks in poultry began in March in Tennessee, where highly pathogenic H7N9—not related to the strain in China—was detected. Over the next several weeks a low-pathogenic version of the virus struck poultry in Alabama, Kentucky, Georgia, and Tennessee, which led to the culling of about 270,000 birds. No human cases were reported.

Mice and ferrets experimentally infected with either of the viruses showed only mild illness. Transmissibility tests in ferrets found that only the low-pathogenic virus spread to healthy cage mates of infected animals, with the virus passing to only about a third of the animals that weren't inoculated.

Tests on human bronchial epithelial cells found that both the low-pathogenic and highly pathogenic virus replicated to high titers, with the low-path virus showing significantly higher levels—higher than an earlier North American H7N9 virus but lower than a 2013 H7N9 virus from China.

The researchers concluded that the viruses for now are a low threat to human health, but they bear watching, especially in flyway and high-poultry-density regions, given that North American H7 subtypes have shown the ability to acquire genetic changes after recombination with host RNA and have the potential to adapt to mammals.
Oct 23 Emerg Infect Dis report

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