Bengaluru, Dec 5 : The Karnataka health department has increased vigilance on prevailing Covid situation in four districts of the state as the union government in a letter has warned of rising cases in these districts and urged the state government to initiate action. Union Ministry of Health and Family Welfare Secretary, Rajesh Bhushan in his letter to the state, said that Tumakuru district has seen 152 per cent spike in Covid cases which have witnessed a jump from 46 on November 19 to 116 on December 2. Dharwad saw a rise of 21 per cent, Bengaluru Urban 19 per cent and Mysuru 16.5 per cent. The letter says steps have to be taken to contain the infection and reduce the fatality. It also emphasised to adopt test, track, treat and vaccinate method and follow Covid appropriate behaviour. The letter has also directed the state health department to send all positive samples for genomic sequencing quickly. It also talks about enhanced surveillance of international arrivals, monitoring of emerging hotspots, prompt contact tracing and monitoring for 15 days. The state health department is worried as Covid cases exploded in colleges and educational institutions of these districts. However, swift actions by district authorities have prevented Covid infections from spreading further. Sources say, though in small proportion, increasing cases of Covid-19 in the state has become a cause of worry for the health authorities. /IANS