THIRUVANANTHAPURAM: Kerala reported a spike in Covid-19 cases on Tuesday with 19 people testing positive, after a decline in the numbers in the past few days, as the total infections touched 423 in the southern state.Kannur recorded 10 cases, Palakkad four, Kasaragod three and Malappuram and Kollam one each, chief minister Pinarayi Vijayan told reporters here.The number of those getting infected were in single digits over the past few days.Of the 10 positive cases from Kannur, nine of them had come from abroad and one had been infected through contact, he said.Pointing out that the positive cases in Palakkad, Malappuram and Kollam had come from neighbouring Tamil Nadu, Vijayan said there is need to enforce strict vigilance in places bordering neighbouring states.Sixteen people tested negative on Tuesday, while the total active cases 117, he added.At least 32,000 people are under observation.Of the around 20,000 samples sent, 19,440 had returned negative, Vijayan said.