Research confirms human to human spread of bird flu in Indonesia

The systematic analysis, claimed to be the first of its kind, was done using a software application called TranStat developed by the Seattlebased Fred Hutchinson Cancer Research Center to run quick tests in the case of infectiousdisease outbreaks, the researchers said in a press release late Tuesday in Seattle.

The case that was studied by the center's researchers occurred among an Indonesian family cluster in the village of Kubu Simbelang in North Sumatra Province in May last year.

In the cluster case, seven people from one family contracted the H5N1 strain of bird flu, one of the biggest human bird flu clusters in the world.

The seven family members  six of them died  were confirmed having contracted the virus in April and May.

The cluster contained a chain of infection that involved a 10 year-old boy who probably caught the virus from his aunt who had been exposed to dead poultry and chicken feces, the presumed source of the infection. The aunt later died, but she is only suspected of having been infected.

In June, the World Health Organization confirmed that ''limited humantohuman transmission'' of bird flu had occurred among the group, saying the boy in the family most probably passed the virus to his father.

The possibility was supported by genetic sequencing data.

''Using a computerized diseasetransmission model that took into account the number of infected cases, the number of people potentially exposed, the viralincubation period and other parameters, the researchers produced the first statistical confirmation of humans contracting the disease from each other rather than from infected birds,'' the research center said in the press statement.

Biostatistician Ira Longini Jr. said that in the Indonesian case, ''it went two generations and then just stopped, but it could have gotten out of control.''

''The world really may have dodged a bullet with that one, and the next time we might not be so lucky,'' Longini, who conducted the analysis with three colleagues in the center, added.

According to him, efforts to contain the spread of the virus in the Sumatra case, during which local health authorities eventually placed more than 50 surviving relatives and close contacts under voluntary quarantine and provided them with antiviral medication, was too late.

''It could have been just luck that the virus burned out,'' he said.

The researchers estimated the secondaryattack rate of the virus in Indonesia, the risk of one infected person passing it to another, to be 29 percent, a level of infectiousness similar to statistical estimates for seasonal influenza A in the United States.

The researchers also tried to make a statistical analysis to confirm humantohuman transmission of a bird flu virus in another cluster in eastern Turkey last year, when eight people were infected and four of them died.But they failed due to a lack of data.

The TranStat software, according to the center, will be soon be available online free of charge on the website of the National Institute of General Medical Sciences' Models of Infectious Disease Agent Study  MIDAS.

''We know the key to preventing a pandemic is early detection, containment and mitigation with antiviral therapy and this tool will enable those on the front lines, such as physicians, epidemiologists and other public health officials, to carry that out efficiently,'' Longini's colleague Elizabeth Halloran said.

As of last Thursday, bird flu had killed at least 195 people in 12 countries since December 2003, according to WHO statistics.

Indonesia's 84 fatalities are the most, followed by Vietnam at 42.

The other 10 countries where fatalities occurred are Azerbaijan, Cambodia, China, Djibouti, Egypt, Iraq, Laos, Nigeria, Thailand and Turkey.

//Kyodo news