The two doctors who tested Covid positive on Sunday include a paediatrician and a physician who have had close contacts with their patients.
The list of 20,000 suspected contacts have been prepared and it includes all those who came in contact with them since June 5.
The paediatrician's contact list includes 10,000 out patients and those who came with them and another 160 in-patients and their by-standers.
In the list of the physician, 5,500 patients who have come in close contact with him have been identified and all of them have been asked to remain in isolation at their homes.
At an emergency meeting on Monday with health authorities, State Higher Education Minister K.T. Jaleel asked them to conduct random testing of around 1,500 and if required more suspects will be tested.
Malappuram district is home to a huge number of diaspora, who have returned from various Middle East countries since May 7.
The district at present has 224 Covid positive cases, the second largest among the 14 districts of the state and over 24,000 people are under isolation at homes, corona care centres and hospitals.