Thursday, September 28, 2017

Delaware DPH Reports An H3N2v Case Likely Linked To Maryland Fair


In what appears to be a spillover from Maryland's fair-related clusters of swine H3N2v infections (see Maryland DOH: 20 Presumptive Positive & Confirmed H3N2v Cases), Delaware is reporting their first case involving a female Sussex County resident (< 18 yrs old) who had recent contact with pigs at a Maryland country fair.

This from
DPH Announces Delaware Flu Case Likely Related to Contact With Pigs At County Fair in Maryland

Date Posted: Wednesday, September 27th, 2017

DOVER – The Delaware Division of Public Health (DPH) announced today the state’s first laboratory-confirmed case of a variant influenza virus (in this instance H3N2v) in a female Sussex County resident under age 18, who had close contact with pigs at a county fair in Maryland. The case is mild and the individual is recovering. No additional information will be released on the individual to protect her privacy.

Any individual who visited a Maryland County fair within the last seven to ten days, had contact with pigs, and has subsequently developed flu symptoms after their last exposure, should call their medical provider to discuss the potential need for a flu test.

When an influenza virus that normally infects pigs is found in people, it is called a “variant” influenza virus. While it is not possible to determine exactly where the individual contracted the variant flu, also commonly known as the “swine flu”, the Maryland Department of Agriculture has been investigating the appearance of this virus in pigs at the fairs in Charles and Frederick Counties. The Delaware resident reportedly had close contact with pigs at the Anne Arundel County Fair, the first suspected case of variant influenza from that event. Today the Maryland Department of Health announced “presumptive” positive cases of variant flu in Maryland residents who had close contact with pigs at the Anne Arundel County Fair as well.
         (Continue . . . .)

Earlier this summer we saw a similar case reported from Pennsylvania where the patient was exposed and infected at a fair in North Dakota (see CDC FluView Week 32: 3 Swine Variant Infections (OH, PA, ND)). A reminder how easily flu can cross borders.
While limited human-to-human transmission of H3N2v has been reported in the past, outbreaks have yet to develop `legs', and have quickly died out after infected pig exposures were eliminated.
The concern, of course, is that these swine viruses are not only varied, they continue to evolve - and as we saw with swine H1N1 in 2009 - have the potential to better adapt to human physiology. 

While generally less severe than  avian flu in humans, swine influenza viruses are nevertheless viewed as having some pandemic potential. The CDC's IRAT (Influenza Risk Assessment Tool) Rankings monitors and characterizes 14 different novel flu viruses, and has this assessment on H3N2v

H3N2 Variant:[A/Indiana/08/11]

Swine-origin flu viruses do not normally infect humans. However, sporadic human infections with swine-origin influenza viruses have occurred. When this happens, these viruses are called “variant viruses.” Influenza A H3N2 variant viruses (also known as “H3N2v” viruses) with the matrix (M) gene from the 2009 H1N1 pandemic virus were first detected in people in July 2011. The viruses were first identified in U.S. pigs in 2010. In 2011, 12 cases of H3N2v infection were detected in the United States. In 2012, 309 cases of H3N2v infection across 12 states were detected. The latest risk assessment for this virus was conducted in December 2012 and incorporated data regarding population immunity that was lacking a year earlier.
Summary: The summary average risk score for the virus to achieve sustained human-to-human transmission was in the moderate risk category (less than 6). The summary average risk score for the virus to significantly impact public health if it were to achieve sustained human-to-human transmission was in the low-moderate risk category (less than 5).

For some recent blogs on Swine variant influenza, and why the CDC closely monitors these infrequent human infections, you may wish to revisit:

EID Journal: Transmission Of Swine H3N2 To Humans At Agricultural Exhibits - Michigan & Ohio 2016
A Reminder About The `Other' Novel Flu Threat
J. Virol: Novel Reassortant Human-like H3N2 & H3N1 Influenza A Viruses In Pigs

MMWR: Investigation Into H3N2v Outbreak In Ohio & Michigan - Summer 2016

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