New Delhi, Feb. 23: India has no human case of bird flu, medical scientists said today after detailed studies on four samples of human blood and throat secretions that had sparked suspicions following preliminary tests.

The test result from one remaining sample ? from the 95 samples taken from people in Navapur ? is expected on Saturday morning.

Twelve persons who have been under observation have some mild symptoms of cold and cough. “Their chest X-rays show their lungs are clear, and they are all improving,” an official said.

Tests on 90 out of the 95 samples had shown no sign whatsoever of the H5N1 virus, the officials said. However, in five samples, the first tests did reveal some “non-classical (genetic) signals”, Dr Nirmal Kumar Ganguly, the director general of the Indian Council of Medical Research, said. Scientists then used more sophisticated tests to go through each of these signals to rule out H5N1, he said.

“Such non-classical signals mean nothing,” Dr Ganguly said. Even then, the investigators subjected the samples to a highly sensitive test that can detect as low as 100 copies of viral genetic material in a sample. The results were negative in four of the five samples. Tests on the fifth sample are now under way at the National Institute of Virology in Pune, he said.

Ganguly said the test that prompted detailed analysis was a 30 per cent match with what appeared to be viral genetic signatures. Independent virologists said a 30 per cent match does not signify infection.

“From the public health point of view, this is good news,” said Sunil Lal, a senior scientist at the International Centre for Genetic Engineering and Biotechnology.