With 17 blood samples of the 81 slaughtered pigs testing positive for Japanese encephalitis (JE), the alarmed brass of the Delhi government and MCD on Friday decided to identify the source of the infection in pigs before initiating more drastic measures to check the spread of the disease.

Since JE has already killed more than 500 people in Uttar Pradesh and its spread in the Capital is a scary possibility, the decision was taken at an emergency meeting between senior officials of the MCD and the health department.

Health minister Dr A. K. Walia said: "The first thing we will investigate before the next meeting is the source of the infection. The samples of another 100 pigs are being tested. Since this is the winter season, even the number of mosquitoes - which are the primary carriers of the disease from animals to humans - is quite less."

The MCD had sent the samples for testing to the National Research Centre for Equines at Hisar, Haryana, in late November. Eight of the 17 samples that tested positive had been collected from the Civil Lines area of the Capital, six from Shahdara South and three from Sadar Paharganj.

One of the key instructions issued by the jittery government brass to the MCD authorities was about regular fogging and checking the presence of mosquitoes, particularly in the resettlement and unauthorised colonies. Pigs are known hosts of JE, which spreads from them to humans via mosquitoes.

Based on the preconditions that help the disease spread, the authorities have already identified the "high risk" zones.

Most of these are resettlement colonies with poor hygiene conditions and the presence of pigs, mosquitoes and birds in close proximity to one another. These include Raghubir Nagar, Mangolpuri, Shastri Park, Rohini, Bawana and Trilok Puri, among others.

Though the culling of pigs isn't allowed in the national Capital, the state government's health officials said on the condition of anonymity that it was "the best and the safest option" to check the spread of the disease.

"But since most of these areas have a high population density, the culling of pigs by the government/ civic administration could become a significant political issue in the forthcoming civic elections. Such a move will most likely affect a certain votebank. Therefore, it'll be a tricky decision to take for the political parties," a senior health department official said.

In fact, the issue of compensation to the owners of pigs that may ultimately have to be slaughtered across the city would also be discussed at the crucial meeting on JE, which is scheduled for next week.

Walia confirmed that the state government was aware of the financial aspect of such a decision. "We will discuss a range of issues, including the financial ramifications, at the meeting next week," Walia said.

JE had surfaced in the Capital for the first time this year in October, when four persons tested positive for it. Since then, 14 persons have tested positive for the virus. The areas from where these cases were reported included Gole Market, Bawana and Jahangirpuri .