Go to WHO's cumulative tally of confirmed human H5N1 cases, and you'll see a decade of unanswered questions.
For example, how did H5N1 jump from 4 cases and 4 deaths in China and Vietnam in 2003, to 46 cases and 32 deaths in Thailand and Vietnam in 2004? And how did it then double to 98 cases and 43 deaths in five countries by 2005? Your guess is as good as mine, and probably better.
One question that's bothered me is why Cambodian H5N1 has been so rare and so lethal, compared even to Indonesia and China. The first 7 cases in Cambodia (2004-2007) were all fatal. In 2008 and 2009, Cambodia had just 1 case per year, and both patients lived. Another single case appeared in 2010, and was fatal. Then in 2011 8 persons contracted H5N1 and all died. Three more cases appeared in 2012, and again all were fatal.
So until today's announcement, Cambodia had seen just 21 cases in 8 years, but its case fatality rate was 90 per cent. Today's announcement brings the CFR down to 87.5 per cent, still a shocking rate. (Indonesia's CFR, based on 192 cases and 160 deaths, is 83 per cent.)
Is that the result of people being slow to seek medical aid, or is Cambodia's local H5N1 strain just that much nastier? I have no idea.
It's Friday night in Europe, but WHO in Geneva will probably update its website sometime Saturday morning. I hope the report helps to answer these questions.