Thiruvananthapuram, Sep 15 : With a 39-year-old man turning Nipah positive on Friday morning at Kozhikode, the total positive cases in Kerala has risen to four, and extra vigil is being maintained at all border checkposts of the state bordering Tamil Nadu and Karnataka. All the four cases have been reported from Kozhikode.The person who tested positive on Friday was a direct contact of the first positive Nipah case who passed away on August 30. State Health Minister Veena George after chairing a meeting at Kozhikode said the decision to conduct testing on all the high-risk contacts has been decided. "Testing has started in Kozhikode, including in a mobile testing centre as all high-risk contacts will have to undergo a test. The condition of the person who turned positive on Friday is stable and the nine-year-old positive patient, who is undergoing treatment, is also stable," said George. So far, two deaths have been reported of patients who tested positive. The central team, which has arrived at Kozhikode, will be visiting the villages where the positive cases have been reported. Extra vigil is being kept at checkposts of the state bordering Tamil Nadu and Karnataka and every vehicle passing by is being checked for people with fever symptoms. All schools in Kozhikode district have been asked to go into online mode till Saturday. A separate ward has also been opened at the Kozhikode Medical College hospital. /IANS