Nagpur, August 2: At least 21 cases of swine flu were reported in Nagpur district of Maharashtra in the last three days, a civic health official said on Tuesday. The number of such cases stood at just six from January 1 to June 30, he said.

"The patients with H1N1 flu symptoms started reporting from the second week of July. 28 persons were detected with swine flu from the second week of July till the month end," said the Nagpur Municipal Corporation (NMC) official. Swine Flu in Maharashtra: Elderly Man Succumbs to H1N1 Virus in Thane.

Of them, 21 cases were reported in the last three days- July 29,30, and 31. Explaining various measures, the official said NMC health department personnel visit homes or hospitals to know the health status of such patients. The teams then trace the close contacts of these patients, he added.

"If the samples of the close contacts are found to be symptomatic then they are tested and medicines prescribed on the presumptive diagnosis," he added.

H1N1 flu, commonly known as swine flu, is primarily caused by the H1N1 strain of the flu (influenza) virus. Symptoms of the H1N1 flu are the same as those of the seasonal flu.