The human pandemic swine flu virus H1NI is, for most of us, a disease that other people get. But now, a leading epidemiologist and flu blogger, who goes under the pseudonym Revere at the public health blog Effect Measure, reports first-hand that three generations of his family, including himself, have likely come down with the virus.

In a post last night, Swine flu comes home, he describes how his daughter has come down with lab-confirmed flu, while most of the rest of the family has influenza-like symptoms. In May, Anna Moscona, another flu expert at Weill Cornell Medical College, also diagnosed her 8-year old son as having swine flu, without testing.

Both their diagnoses are more likely correct than not, even without specific testing for swine flu.

With seasonal flu no longer circulating, and swine flu now the predominant flu strain in the United States, the US Centres for Disease Control and Prevention has itself switched away from lab testing cases to instead using national surveillance of influenza-like symptoms as a reliable proxy for the progression of the disease.

Although many media are religiously tracking daily numbers of lab confirmed cases worldwide – today WHO reports 25,288 cases, including 139 deaths, in 73 countries — these case numbers are fairly meaningless, and are only useful at the start of an outbreak in a country, to get an idea of initial spread. But once community spread gets underway, as is the case in North America, the figures describe only the tip of the iceberg – the US had 11,468 probable and confirmed cases as of CDC’s last media briefing on 4 June, but as CDC notes the real numbers are in the hundreds of thousands. Data on case fatality rates are if anything even more uncertain – see this NEJM article for an excellent account of the caveats of the case fatality rate.

Which brings us to Europe, where the spread seems not unexpectedly to lag that of the trajectory of numbers in the US — as it started later — but by how long? The UK and Spain have the largest outbreaks here in Europe, reporting 557 and 291 lab confirmed cases respectively to WHO as of today, along with the start of community spread. But Europe may be underreporting its cases, as it’s only been testing sick people who had come back from infected areas, or were in touch with someone who had, rather than testing anyone showing flu like symptoms. Many European countries have belatedly decided to start wider testing – see Reuters – and casting “’wider nets”. Perhaps we can expect a truer picture soon.

The broader reality is that while the WHO vacillates on whether to call this flu pandemic a pandemic – although it is tiptoeing its way there – it has become inevitable that the virus will spread worldwide as a pandemic. The big question is how severe the pandemic might be. So what’s more important now is working out how severe the pandemic will be and preparing for it.

The US White House has asked Congress for US$9 billion in extra funding to tackle this question, and suggested taking US$3 billion funds from the Bioshield bioterrorism programme. But this has been slammed by the leaders of a bipartisan commission on weapons of mass destruction who say it “would weaken the nation’s preparedness for terrorism”. Whether spending is better reserved for the post 9/11 boondoggle of programmes on some future hypothetical bioterrorism threat, and not a more pressing real biological threat, is perhaps one that needs more scrutiny.