Not any more. The second wave (150 cases in the city so far) is not localised, health authorities say. The virus is “in the air” and the strategy will no longer focus on enumeration and targeted surveillance.

It will instead involve information, education and communication (IEC) activities to sensitise the public and doctors on symptoms and treatment protocol. Also, any suspicion that someone has caught the virus will be enough to put that person on Tamiflu; doctors have been advised not to wait for test results.

“Last year it was clear that the virus came to India from a group of students returning from abroad. Thus we had a thread to follow and so we could conduct targeted screenings in specific areas. But this is the second wave; the virus is no longer localised,” said Dr Pradeep Awate, head of the state’s swine flu control room.

Mumbai does not have “the luxury of focusing on localised areas any more,” agrees Dr Daksha Shah, head of the BMC’s epidemiology cell. “We are getting swine flu patients from everywhere in the city. We have to maintain vigilance all over.” In fact, she says, last year too, a target-based strategy could be adopted only in the initial stages of the crisis.

The cases this year aren’t evenly distributed, with slums reporting a higher number than less congested areas, and some wards showing more cases than others, but the BMC still ruled out targeted surveillance. “Like all infectious diseases, the occurrence of swine flu too is higher in congested areas,” said the BMC’s executive health officer, Dr GT Ambe. The BMC’s Arogya Abhiyaan includes efforts to check malaria in slums, but not swine flu. Screening the estimated 80-90 lakh slum population for H1N1 “ is just not practical”, Ambe said. “Taking swabs for H1N1 is a specialised activity.”

About ward-wise cases, Dr Shah said: “The number of cases reported is directly proportional to the number of available test centres. Thus, relatively more cases were reported in the F ward.” Most wards have had between one and five cases, but wards A, B and C have reported none, while ward G-North has had 18, K-West-16, and F-North 10. G-North includes the heavily populated Dharavi.

Another reason cited for the high count is that all private practitioners are now authorised to take swabs and screen for swine flu. Last year, only 12 centres were authorised to conduct swine flu tests; this year, private centres screened 205 people between April 1 and July 7, and admitted 68 of them.