The Centers for Disease Control and Prevention today reported the first death from influenza A H3N2 variant (H3N2v), the swine flu strain that has been crossing intermittently from pigs to humans since last year. The victim was an “older adult with multiple underlying health conditions,” according to the CDC, and the Associated Press fills in that the victim was a 61-year-old woman from “central Ohio’s Madison County [who] died this week… after having contact with hogs at the Ross County Fair.” In a statement, the Ohio Department of Health says that she was one of 102 cases so far in the state this year. In total, the CDC says, there have been 289 cases so far this year (with Indiana leading, at 138 cases); in 2011, there were 12. Fifteen people have been hospitalized.
The CDC has been urging people for several weeks now to consider the risk of flu in state fair pig areas, and to stay away if they are in any of several categories that tend to have diminished immune systems and thus be more vulnerable to any strain of flu: younger than 2, older than 65, pregnant, or suffering from a chronic medical condition such as asthma, diabetes, heart disease or a few others. Most of the cases have some link to state fair swine barns (though Minnesota’s two cases arose in successive weeks from visits to a live-animal market).
In state-fair barns, for those of you who haven’t been — I spent some time in the Minnesota barn while reporting Superbug the book — families effectively camp out to keep their animals company and to keep them prettied-up for judging. They may not sleep there, precisely, but the kids in particular — who may have raised the animals for 4-H, school cash or both — eat and nap and hang out all day.
(Update: The Minnesota Department of Health is now announcing that they have found three cases of presumed pig-to-human transmission at their state fair — but it isn’t from H3N2v. Instead, it’s from yet another variant, H1N2v. The three victims are a teen girl who was showing pigs and a school-aged boy and a woman in her 70s who spent a lot of time in that swine barn.)
Most agriculturally focused state fairs in the US end about Labor Day — though not all; my former CIDRAP colleague Lisa Schnirring lists some exceptions in her story today, including North Carolina, Texas and Wisconsin. (Georgia, where I live, holds its fair Oct. 4-14 this year.) For fairs that continue through fall, the CDC has written guidance for anyone exhibiting pigs or visiting them.
In most of the US, then, the immediate risk of exposure from fair animals will end soon. However, the CDC has pointed out that there has been limited person-to-person transmission of this virus in the past two years, and has written some guidance for school systems who may want to be watching for ongoing clusters of infection.
The distant concern with flu is always that it is unpredictable, and may mutate into a more infectious or more virulent form. Adding pigs into the picture always alarms public health people a little, because the immunoanatomy of pigs’ lung epithelium is similar to humans’, allowing pigs to possibly serve as a “mixing vessel” for reassorting strains of flu. While concern over the H3N2v outbreak has seemed muted, it’s clear the CDC and the rest of the public health establishment do not take it lightly; 10 days ago, for instance, the CDC published standards for “enhanced surveillance” for any laboratories examining isolates from this flu.
With luck, and with deference to the victims — especially this sad death in Ohio — the H3N2v will remain a curiosity rather than become a source of alarm. But even so, it is yet another of the periodic reminders we get, that flu should never be taken for granted.
Update: Just as I hit the button on this, supreme flu reporter Helen Branswell of the Canadian Press published a piece emphasizing the concerns over transmission as kids return to school. Separately, I asked on Twitter for any sightings of blog posts on H3N2v, as I hadn’t seen any. The loose consensus is that the indefatigable Mike Coston of Avian Flu Diary is the only blogger to examine it this far. If you saw others, please let me know. Oops: Profound apologies to Crawford “Crof” Kilian, who has been covering it as well.