It sounded like the plot of a suspense novel, but a letter from Knesset Director-General Dan Landau Sunday confirmed that a worker in the parliament has been diagnosed with swine flu. The letter went on to instruct Knesset employees to remain alert in order to prevent further incidents of the disease from spreading throughout the parliament staff. Landau confirmed that "in recent days, a case of H1N1 influenza (swine flu) had been discovered in the Knesset." Landau emphasized that the infected worker - who was not a permanent Knesset employee or an MK - had been treated and was in good health, and that no additional cases had been identified among Knesset staff or visitors. The Knesset rumor mill immediately sprung into fifth gear, and word on the street indicated that the infected person was a parliamentary aide. The Knesset infirmary received detailed instructions from the head of public health at the Health Ministry - Dr. Itamar Gruto - regarding proper identification of potential additional cases as well as guidelines for those who may have come into contact with the infected person. Knesset workers who received Landau's letter were instructed to turn to the Knesset infirmary if they felt that they had any of the symptoms that could indicate that they had been infected with the disease. Those who came into contact with the infected employee were instructed to continue with their planned activities, and only report to the doctor if symptoms appeared. So far, 26 cases of the virus have been diagnosed in Israel.