Indicating that the chances of monkeypox case cannot be ruled out in the country, the Tamil Nadu Health Department on Tuesday advised international airports in the state to step up their surveillance with regard to the disease and directed the respective health officer to collect samples of passengers who show symptoms on arrival from the affected countries. The Director of Public Health and Preventive Medicine T S Selvavinayagam said the health officer at the international airports may isolate the sick travelers on arrival and send their samples to the National Institute of Virology, Pune for further investigation.