# 1095
Almost from the beginning the Karo cluster in April/May of 2006 was strongly suspected to have involved H2H (Human-to-Human) transmission. But suspecting something, and proving it, are two very different matters.
Sixteen months after the event, however, scientists using statistical analysis believe they can `prove' H2H transmission occurred in Indonesia.
World 'dodged bullet' in bird flu spread
From correspondents in Washington | August 29, 2007
A MATHEMATICAL analysis has confirmed that H5N1 avian influenza spread from person to person in Indonesia in April, US researchers reported today.
They said they had developed a tool to run quick tests on disease outbreaks to see if dangerous epidemics or pandemics may be developing.
Health officials around the world agree an influenza pandemic is overdue, and are most worried by the H5N1 strain of avian influenza that has been spreading through flocks from Asia to Africa.
It rarely passes to humans, but since 2003 it has infected 322 people and killed 195 of them.
Most have been infected directly by birds. But a few clusters of cases have been seen and officials worry most about the possibility that the virus has acquired the ability to pass easily and directly from one person to another. That would spark a pandemic.
Ira Longini and colleagues at the Fred Hutchinson Cancer Research Centre in Seattle looked at two clusters - one in which eight family members died in Sumatra in 2006, and another in Turkey in which eight people were infected and four died.
Experts were almost certain the Sumatra case was human-to-human transmission, but were eager to see more proof.
"We find statistical evidence of human-to-human transmission in Sumatra, but not in Turkey," they wrote in a report published in the journal Emerging Infectious Diseases.
"This does not mean that no low-level human-to-human spread occurred in this outbreak, only that we lack statistical evidence of such spread."
In Sumatra, one of Indonesia's islands, a 37-year-old woman appears to have infected her 10-year-old nephew, who infected his father. DNA tests confirmed that the strain the father died of was very similar to the virus found in the boy's body.
"It went two generations and then just stopped, but it could have gotten out of control," Mr Longini said.
"The world really may have dodged a bullet with that one, and the next time, we might not be so lucky."
The researchers estimated the secondary-attack rate, which is the risk that one person will infect another, was 20 per cent. This is similar to what is seen for regular, seasonal influenza A in the United States.
The reaction to this study is interesting. Essentially, nothing has changed, yet the perception of the danger presented by the H5N1 virus has suddenly risen based on this report.
The world `dodged a bullet', according to this, and other news accounts. Something most of us have `known' for over a year.
Perhaps now the useful fiction that `H5N1 has never spread from human-to-human' will be put to rest.
But somehow, I doubt it.
