For the fourth consecutive day, nopositive cases of COVID-19 infection were reported in Dakshina Kannada and Udupi districts in Karnataka, officials said on Wednesday.The two districts had not reported coronavirus positive cases since April 5.Seven samples from DK, sent on Tuesday for tests at the new virology lab set up at Wenlock hospital here, turned out negative.Currently eight patients are under treatment in DK district.Four have been discharged from hospital after recovery, while 15 others are under observation.In Udupi district also, all the samples of suspected cases sent to the laboratory were found to be negative after tests on Wednesday.