As authorities in northern Greece stepped up plans yesterday to spray pesticide across several prefectures, officials repeated calls for calm amid fears of mosquitoes spreading the West Nile virus in northern Greece after two elderly people who contracted the disease died. Health authorities said that 20 people were being treated in the hospital yesterday for brain inflammation or a form of meningitis after contracting the virus. Of these, an elderly man in Thessaloniki is in the most serious condition, as the virus has attacked his central nervous system. Meanwhile, a 65-year-old woman hospitalized in Larissa, central Greece, with a brain inflammation triggered by the virus is the first person outside of the northern part of the country to contract the virus. The Center for Disease Control and Prevention (KEELPNO) has issued instructions to hospitals to keep anyone suffering from brain inflammation or meningitis under observation for 10 days before they are discharged, as it attempts to get an accurate picture of how widespread the virus is. The Imathia Prefecture in central Macedonia, where most of the cases have been reported, decided yesterday to begin an awareness campaign in a bid to ensure citizens do not panic about the spread of the virus. Officials also said they would begin spraying pesticide in all 12 of the prefecture’s municipalities. The spraying will not take place from the air but at ground level. Efforts will concentrate on areas where there is a lot of standing water, which attracts mosquitoes that carry the virus. Two elderly people have died since last Friday after contracting the West Nile virus, which is transmitted by mosquitoes and was discovered in 1937 in Uganda. Sporadic cases of the disease in humans have occurred in Europe since the 1960s. KEELPNO has recommended that, to help ward off mosquitoes, people wear light-colored clothing and long sleeves and pants. They also recommend using insect repellent and draining any standing water.