Police personnel look on as two young women get on ambulance in Kochi, Kerala. (PTI)

Kochi: As few cases have been reported wherein persons exhibiting no symptoms have been tested positive for the novel coronavirus infection, the Kerala health authorities have initiated a study on such silent cases of infection.

Three such cases were reported from Pathanamthitta district where the medical team will begin the study. As similar cases were reported from other districts, those cases will also be studied.

An 18-year old girl from Pathanamthitta who had no symptoms was tested positive, four days after completing her home quarantine period. The girl arrived from Delhi by train. Her swab samples were tested only because she boarded the train from Nizamuddin, one of the major hotspots.

Two other persons, a Keralite returned from abroad and an Italian national, were also tested positive, without having any symptoms.

A medical team of four doctors and two postgraduate medicos has begun detailed study on silent carriers of the virus.

Regarding the silent cases, the medical experts stress the need for close monitoring of all those who returned from abroad or disease cluster areas, even if they exhibit no symptoms.

The authorities have started conducting testing of close contacts of such asymptomatic persons and even those who are not in the high risk category as part of preventing spread of silent cases.

Usually foreign-returned persons are being tested only if they have symptoms like higher than normal body temperature, cough or throat pain.

The State health authorities are keeping tight vigil as the silent carriers pose high threat of rapid spread of the virus. If large number of foreign-returnees are silent virus carriers with no symptoms, it poses a big risk. Hence, the health department has initiated the study.