While large number of COVID-19 cases being reported in Tiruvarur and Nagapattinam districts in recent days is being seen as a cause of concern, officials in the districts say that aggressive testing strategies and contact tracing have led to number of patients testing positive for the viral infection.

In Nagapattinam, the spike in cases is due to scaled-up testing, A. Liakath Ali, District Epidemiologist, told The Hindu. Nearly 2,000 throat swab samples were lifted over the last week, especially from contacts of patients who tested positive. “If 10 patients test positive in an area, at least 500 more samples are lifted from the locality,” he said.

According to Thursday's bulletin released by the Department of Health and Family Welfare, Nagapattinam had so far recorded 3,716 COVID-19 cases. The patients who are testing positive are predominantly index cases with no history of travel or contacts and primary contacts of those who test positive, Dr. Ali said. A total of 80% of these patients continue to be asymptomatic, he added.

The fever camps conducted across the district, especially in remote areas and among high-risk groups has helped in identifying more cases, Dr. Ali added.

In Tiruvarur, 90% of the patients who test positive are primary contacts and asymptomatic carriers of the virus, P. Vijayakumar, Deputy Director of Health Services said. These patients are identified through fever camps and door-to-door testing in containment areas, he said.

A total of 70 fever camps are conducted on a daily basis across the district from where at least 1,500 nasopharyngeal swabs are lifted a day. At least 500 more swabs are lifted at the seven government hospitals in the district, Dr. Vijayakumar said.

Of the 2,000 swabs, at least 100 test positive per day, among which only 10 are patients with symptoms for COVID-19 he added. “When we trace contacts for each of the 100 patients, we trace at least 200 people among whom at least 10 more test positive. A similar pattern is noted among patients with Influenza-Like Illnesses (ILI). When one patient with ILI symptoms tests positive for the viral infection, seven of their contacts, including family members, test positive. The ratio is one ILI patient to seven primary contacts,” he said.

Active contact tracing has helped in keeping the spread of the infection at bay in the district, Dr. Vijayakumar said. The positivity rate is around 7.5% while the death rate is 1.6% in the district. The district has reported 4,816 COVID-19 cases so far and this, he said,was due to focussed contact tracing.