Blog | Thursday, May 16, 2013

Influenza at the human-animal interface

The first three novel avian influenza A (H7N9) viruses have been sequenced, and the sequences uploaded to the Global Initiative on Sharing All Influenza Data (GISAID). Not surprisingly, there were genetic changes found that have been associated with increased transmissibility of other avian flu strains to mammals.

I have no deep thoughts on this--it is what influenza does, after all, with avian and other non-human strains occasionally making the leap to humans. The few things we know about this particular strain, as of late yesterday, can be found at the CDC and WHO websites, and include the following:
--A total of 21 cases have been laboratory confirmed in China, including six deaths, 12 severe cases and three mild cases.
--More than 530 close contacts of the confirmed cases are being closely monitored.
--The viruses isolated to this point appear to be susceptible to neuraminidase inhibitors (e.g. oseltamivir) but resistant to adamantanes (e.g. amantidine, rimantadine).
--There is no current evidence of "ongoing human-to-human transmission."
--The virus should be detectable with existing PCR methods as an "unsubtypeable" influenza A virus (the CDC is working on adding this strain to their testing approach so that it can be more quickly subtyped if it spreads outside of China).

The most recent interim guidance for case investigation, testing, infection control and treatment are here.

Finally, for those interested in a regular update on the threat of non-human flu strains, the WHO publishes monthly updates on influenza at the human-animal interface. (Wait, aren't Homo sapiens also animals? Maybe it should be, "influenza at the human-nonhuman interface" ...)

Daniel J. Diekema, MD, FACP, practices infectious diseases, clinical microbiology, and hospital epidemiology in Iowa City, Iowa, splitting time between seeing patients with infectious diseases, diagnosing infections in the microbiology laboratory, and trying to prevent infections in the hospital. This post originally appeared at the blog Controversies in Hospital Infection Prevention.