Kerala recorded 42 fresh COVID-19 cases on Friday, the highest after the first ever case in the state, and also the country, was reported on January 30. It is now almost two months since the number of daily fresh cases came close; on March 27, Kerala had recorded 39 cases.

But then, 34 of the 39 cases were in Kasaragod alone. On Friday, the cases were distributed among 10 districts.

Except for two who were declared positive on Friday, the remaining 40 had come from outside; 17 from foreign countries, 21 from Maharashtra and one each from Andhra Pradesh and Tamil Nadu.

The influx is pushing up cases, and Chief Minister Pinarayi Vijayan warned that the daily tally would go up even further in the coming days. Post the influx of Malayalis stranded in other countries and states, the progression of active cases has been dizzyingly swift.

In the last seven days, the number of fresh cases was 156. In the preceding seven days, the number was 73. And in the seven days before that, the fresh cases reported was just six. A classic example of exponential growth.

Signs of community transmission, yet again

Equally worrisome are the two non-imported cases. One a health worker in Kozhikode, and the other a pregnant tribal woman in Kannur. Both their sources of infection remain a mystery.

The tribal woman was admitted to the Kannur District Hospital on May 12 after her blood pressure shot up. On May 20, when she developed fever and sore throat, she was shifted to the Pariyaram Medical College. There, her sample was taken and it was declared positive on Friday morning.

The woman lives in a tribal colony, Ambedkar Colony, in Kannur's Ayyankunnu panchayat. Sources said she could have been infected by someone in the colony or a patient or health worker in the district hospital.

The colony has been virtually ruled out as a source of infection. No positive case has ever been recorded in the colony. No one in the colony has a travel history either. Moreover, the houses are spaced far apart. "Social distancing is in-built, and they work in their own lands," said Thomas Valiyathottiyil, the vice president of Ayyankunnu panchayat.

Therefore, it looks highly likely the woman was infected while at the Kannur District Hospital.

The other non-imported case is a health worker in Kozhikode, picked up as part of the sentinel surveillance done among high-risk groups to check the presence of community transmission.

Already five samples among the 7072 collected so far under the sentinel surveillance project have tested positive. Of this, four are health workers associated with government hospitals. A sign that the virus is crouching unseen in persons with high social exposure.

Surge in North Kerala

At the moment, reflecting the migratory nature of districts, active cases are accumulating more in northern districts. Malappuram, with the most number of expats in Kerala, has the highest number: 39; four of this were added today.

Kannur has 31, and 12 were added today. Kasaragod and Palakkad have 26 each; seven and five respectively were added today. The spike in Palakkad is mostly on account of the influx from Tamil Nadu.

Thrissur has 18, four of which were added today and it included Khadeeja Kutty who died on May 20 and whose sample was declared positive late on May 21, and also a one-year-old child.

Kozhikode has 16, five were added today. Wayanad has 12, one person was added today.

In the south, Kollam has the highest number: 10 (there was just one addition today). Pathanamthitta, Alappuzha, Kottayam and Thiruvananthapuram have eight cases each. (Pathanamthitta had one and Kottayam two cases today.)

Ernakulam (4) and Idukki (2) had no fresh cases today.

Emergence of delayed positives

Most of the returnees are testing positive within two days of return. But there are also quite a significant number returning positive after a week or even 10 days of their return.

This opens up two possibilities. The first is more probable and also less scary: they got infected by carriers during the return journey.

The alternative possibility is of them getting the infection from someone within the state. If this is true in at least some cases, it hints at the existence of community transmission in Kerala. The chances cannot be ruled out fully because since May 7, after he influx began, over 500 cases have been charged for quarantine violation.

Indications of internal spread

A 31-year-old woman, a native of Nendoor in Kottayam, was declared positive on May 21. She had reached Kochi from Kuwait on May 9. A 29-year-old woman in the same flight had tested positive on May 12. It can be safely assumed she go infected from the 29-year-old woman.

But an Alappuzha native who had arrived in the same flight on May 9 turned positive only on May 21, which is 11 days after arrival. Sources, however, said he had minor symptoms even at arrival and this was why he was taken directly to the Government Medical College in Kalamassery, Ernakulam.

Take two more people who were declared positive on May 21, an 83-year-old woman of Manganam in Kottayam and a 42-year-old man from Thrikkodithanam. Both had come from Dubai on May 11, and had as co-passenger a Pathanamthitta native who had tested positive on May 14. Again, the link is established.

But no such link could be found for the infection of a 21-year-old Malappuram who had arrived on May 10 from Kuala Lumpur and was declared positive on May 21, had arrived on May 10. He developed symptoms only 10 days after arrival, on May 20.

Curiously, no passenger who came with him was declared positive.

Time-consuming mystery

Arrivals have been puzzling in other ways, too. At the latest count, 11 persons who arrived in the Abu Dhabi-Thiruvananthapuram flight on May 16, but unconnected to each other, had tested positive, almost at the same time.

Did the infection come from a single source or were there multiple carriers in the aircraft, or did all the 11 of them board the plane infected? At least two had claimed that they were infected while in the Gulf but had recovered. Authorities, however, are not convinced saying they had no documents to back their claims.

This is a mystery epidemiologists have wisely decided not to waste their dear time on. Instead, they have opted for quick practical preventive measures.

Samples of 60 others in the same aircraft, some now lodged in a COVID Care Centre and others in room isolation, have now been taken.

Indian Council of Medical Research (ICMR), in its latest guidelines, has mandated that contacts of a confirmed case, even if asymptomatic, should be tested twice, on the 5th and the 10th day of coming into contact.

Significantly, all the 11 who had tested positive are asymptomatic.