Be careful who you kiss

The remarkable ability of influenza viruses to reassort their genetic make-up has been illustrated again over the past 12months. A swine influenza subtype A (H3N2) virus acquired the M gene from the 2009 H1N1 pandemic strain, presumably through contact with humans and is termed influenza A variant (H3N2v) virus [1–3]. Such human–pig contact has been a feature of themaintenance of this latest variant virus in the human communitywith a focus on young children attending agricultural fairs in theUSA. These represent an important social event for rural communities where young children vie with each other to present their chosen farm animals in the best light and bring home a prize for doing so. Such animals thus play a role more akin to pets (or companion animals in politically correct terminology) than farm animals reared for food production. It is not surprising that young children (median age 7years for those with this variant of influenza) exhibit strong affection for these companion animals, including putting their arms around them and kissing them on the snout [4]. These behaviours are well documented in photographs on the Internet and shown by US doctors keen to enlighten their lectures about this novel virus. The young children are not only less likely than adults to have cross protective antibodies from prior infections with human influenza viruses, but may well be refractory to parental advice about hygiene, being unwilling to believe that their beloved pet would do anything to harm them. The public health message will therefore have to be innovative, perhaps using cartoon animals, to overcome such deep affection. If a healthy distrust of saliva could be instilled in the younger generation as a default behaviour, one could imagine substantial clinical benefits. Children are a major source of seasonal influenza, because their lack of prior immunity allows them to excrete