BEIJING, Jan. 26 -- Current H7N9 cases are scattered and there is no evidence of constant inter-human transmission, according to a paper on H7N9 diagnosis and treatment issued by the National Health and Family Planning Commission on Sunday.

The paper said that the infection source might be the poultry that carry the H7N9 bird flu virus. The H7N9 bird flu could be infected via respiratory spread, close touch with poultry excretion or contact with contaminated environment.

H7N9 patients who have contact with poultry or been to live poultry markets one week before morbidity, especially the seniors, are high risk groups, the paper said.

According to a survey on H7N9 cases, the incubation period for H7N9 human cases is three to four days, and patients will develop to severe pneumonia three to seven days after morbidity, with body temperature above 39 degrees centigrade.

The paper said that early report, diagnosis and treatment are the best ways to prevent and control the virus.