UK ups risk assessment for H5N1 in US dairy cattle

By Lisa Schnirring

The United Kingdom's Health Security Agency (HSA) yesterday updated its risk assessment for H5N1 avian influenza B3.13 genotype in US dairy cattle, from three to four on a six-tier scale, noting that it is making the notch up based on moderate confidence.

The group made its initial assessment on the US H5N1 developments in May, when it put the level at three, with a caveat that said it may have risen to four, but with low confidence.

In the update, the HSA said, "There is high uncertainty regarding the trajectory of the outbreak and there is no apparent reduction in transmission in response to the biosecurity measures that have been introduced to date."

Mild zoonotic cases in humans are likely going undetected and unreported, so there isn't enough data to say if the rate is unusually high. 

So far, the B3.13 genotype is limited to the United States, and hard to gauge whether other genotypes in Europe could trigger similar outbreaks.  "Levels are indicators that a zoonotic influenza virus outbreak may be an increasing human health threat, either because the opportunities for it to evolve are increasing or because there is evidence that it has already begun to evolve," the group said.

Colorado testing update, more CDC details on latest cases

Yesterday when it announced two more H5 avian influenza infections in poultry outbreak cullers, the Colorado Department of Public Health and Environment (CDPHE) said it would launch a dashboard on confirmed human cases, presumptive positives, and people tested. The dashboard reflects 10 cases, which include nine related to the poultry culling activities and one worker exposed to poultry. So far, about 118 people have been tested for the virus.

In other developments, the Centers for Disease Control and Prevention (CDC) in its latest weekly FluView shared a few more details about Colorado's four most recent cases, all of which were linked to the poultry farms. All of the patients had reported their symptoms to the CDPHE during regular active monitoring. 

The B3.13 genotype infecting dairy cattle is on both of the large poultry farms, and the CDC said genetic sequencing is underway on specimens from the four latest patients.