Clinical guideline developed for flu testing in emergency departments
US scientists have developed and validated a clinical decision guideline (CDG) for flu testing in emergency departments, according to a study yesterday in Clinical Infectious Diseases.
To develop the CDG, researchers conducted a cohort study involving 1,941 patients with fever or respiratory symptoms seen at four US emergency departments in 2013 and 2014. Of those patients, 118 (9.4%) tested positive for influenza virus.
Based on clinical signs and intake, the researchers derived a CDG that included four criteria: new or increased cough (2 points), headache (1 point), subjective fever (1 point), and triage temperature greater than 100.4°C (1 point). A score of 3 or more points indicated influenza testing was warranted.
When applied to study participants, 66.1% of the symptomatic population met the CDG criteria for influenza testing. The CDG is not meant to be used in pediatric populations, the authors said, and should be used in conjunction with highly sensitive influenza testing.
"The use of this CDG in practice could have important impacts on individual patient's treatment, as well as the population as a whole, through focused infection control measures," the authors said.
May 21 Clin Infect Dis study
Genetic analysis of Midwest poultry H5N2 outbreaks yields new clues
A new analysis of highly pathogenic H5N2 avian flu outbreaks that struck the Midwestern poultry industry in 2015 found that road density was a driver of viral spread, hinting a human role in carrying the virus between farms, and multiple introductions from wild birds doesn't appear likely. Researchers from the University of Georgia, the University of Connecticut, and the US Department of Agriculture published their findings yesterday in the preprint server bioRxiv.
To learn more about what fueled the outbreak, the group analyzed 182 full-genome H5N2 sequences collected from commercial layer and turkey farms hit by the outbreaks and then factored the information into models that included epidemiologic and geographic information.
The investigators found that layer chickens and turkeys seemed to represent two separate host populations that interacted with each other, but did not receive the virus from an ongoing external source. Their models suggested that layer chicken farms were infectious much longer than turkey farms, possibly explaining why the transmission rate from chicken farms to turkey farms was higher than from turkey farms to chicken farms. Though turkeys survived longer than chickens, turkey premises were depopulated more quickly than layer facilities.
The researchers note that their genetic findings support earlier findings that virus spread among Minnesota's poultry farms were distance-dependent. High road-density findings correlate with better logistic connectivity between farms, boosting the chances that an infected farm will export the virus to nearby farms and counties, a factor seen in earlier poultry outbreaks overseas. One factor they looked at that had a relatively small effect size was the proportion of a county covered by surface water, which in countries like China has been associated with greater avian influenza dispersal due to waterfowl migration.
Implications for future surveillance and control may be that though wild birds can initially introduce the virus, outbreaks can be maintained without additional ones, the team wrote. Biosecurity measures may have been enough to prevent continued introductions from outside sources, but may not have been as effective against local farm-to-farm transmission. The authors point out that biosecurity factors might explain why the Midwest's broiler chicken industry was spared from the outbreak.
A better understanding of how affected farms are connected would help with control efforts, they say. "With the knowledge of how these farms share personnel and equipment, future outbreaks could be contained by disruption of the transportation network," they wrote.
May 21 bioRxiv study