Mumbai's Dharavi slum has recorded a third coronavirus case in as many days. A 35-year-old doctor has tested positive for Covid-19. He has been quarantined and contact tracing has begun to isolate all those who came in contact with him. The doctor's family has also been quarantined and will be tested for infection. The building he was living in had been sealed by health department officials. More than a million people live in Dharavi, which is Asia's largest slum.