Signs of recovery are being shown by China's latest human case of bird flu in the country's southern Guangdong Province, sources with the local health authorities said yesterday.

X-rays showed a shadow on the patient's lungs had diminished but he remained critically ill, said the Health Bureau of Shenzhen City.

The 31-year-old patient surnamed Jiang was confirmed by the Ministry of Health to have contracted bird flu on June 15. This brings China's total number of human infections to 19.

Jiang has been receiving treatment for eight days in a local hospital, which has the most advanced intensive care unit in the city, said the Bureau.

Medical observation of 98 people who had close contact with the patient found no suspected symptoms of bird flu, said a statement from the Shenzhen Center for Disease Control and Prevention.

Bird flu has killed 12 Chinese people since last year. The disease has infected 228 people and killed 130 worldwide, according to figures from the World Health Organization (WHO).

Experts fear the H5N1 strain of the virus could mutate and be transmitted among people causing a global pandemic. To date it seems the majority of human cases had direct or indirect contact with infected birds.

Indonesian Health Minister Siti Sufari Fadillah announced yesterday that the investigation conducted by a WHO team into the world's largest cluster of deaths caused by bird flu in the country's North Sumatra Province found the virus had been transmitted from animal to human and not from human to human.

Seven people in the same extended family died from the highly pathogenic H5N1 virus last month followed by the deaths of two siblings in Jakarta. The minister described it as a cluster.

It's the biggest reported cluster of deaths and has raised international concerns on possible human to human transmission in Indonesia.

Senior Chinese health expert Shu Yuelong said yesterday there was no evidence of human to human transmission in China but cautioned that the evolution of the virus was unpredictable.

No trace of human influenza has been found in the gene of the virus extracted from Chinese bird flu patients, said Shu, director of the National Influenza Center under the Chinese Center for Disease Control and Prevention.

Hong Kong's health chief, York Chow, said on June 16 that the latest human case of bird flu on the Chinese mainland might indicate the virus had mutated and become as infectious in the summer as it is in cooler months.

But a WHO official said it remained unclear whether there were truly distinctive seasonal patterns to outbreaks of bird flu in poultry.

"We do know that the bird flu virus can survive for a time in colder weather but it's really not clear at this point whether the virus is changing in such a way that it can survive in warm weather for a longer period than it was previously able to do," Roy Wadia, spokesman for the WHO office in China, told Xinhua News Agency.

(Xinhua News Agency June 22, 2006)