Virus can be detected 39 days after initial negative result, says study

A new study by Kenyan pathologists shows that the coronavirus can be detected in faeces up to 39 days after an initial throat swab sample tests negative.

This is according to global research studies that the Kenya Association of Clinical Pathologist (KACP) has put together so far to understand the coronavirus.

According to KACP, the highest viral load of the disease is detected between the fourth and sixth day of a person developing symptoms, but after the seventh day, the viral load reduces as one keeps shedding it off.

This viral shedding, however, can happen anytime between the eighth and 37th day of developing symptoms, with the average being 20 days.

These dates explain the protocols provided by the Ministry of Health on when to test suspected cases or contacts of those who have been confirmed to have Covid-19, in addition to when a person can be discharged from isolation.

The clinical pathologists added that the best place to obtain a sample for testing for the coronavirus disease is up a person’s nose, but because of the level of discomfort of doing so, they recommend using a swab with a thin and flexible shaft, especially for children.

“Detection of the viral RNA (ribonucleic acid, or one of the three major biological macromolecules) doesn’t necessarily indicate the presence of the virus,” Abubakar Abdillahi, a member of KACP, said.

Data on asymptomatic patients — those showing no symptoms of the disease — published in two journals has suggested that they can transmit infections for up to three days before they develop symptoms, raising concerns about the effectiveness of isolation.

“Severely ill persons confirmed to have the virus might transmit the disease for a longer duration,” Dr Abdillahi said, adding that it is not yet clear if the virus can still cause the coronavirus disease even after it has run its course, or when an oral swab tests negative.

Patients discharged

This interval during which an individual with the virus is infectious is uncertain.

“The challenge in managing suspected cases is deciding whether they may be de-isolated or if further isolation and repeat testing is necessary,” he said.

Different countries have had different protocols for the discharge of a person confirmed to have the coronavirus, from one no longer showing any symptoms to evidence through testing that the person has no more viruses.

And where testing is either not available or practical, others have relied on timelines.

Kenya’s protocols involve two negative swab sample taken at least 24 hours apart. The country’s Patient Zero, for example, was discharged 19 days after being admitted for isolation and registering two consecutive negative results.

One of the patients discharged after recovery had her second-last swab done on March 31 and her last one on April 4. This came up negative upon which she was declared recovered.

“I went home three days later because I was informed that the results had to be announced to the media first before I could be discharged,” she said.

While at Mbagathi’s isolation unit, her symptoms cleared within four days of being admitted. She had a fever of 38 degrees Celsius, sneezing, a running nose and a mild headache which she likened to a headache after having one’s hair braided too tight.

“The entire time I was just listening to music and sleeping. There is nothing else you can do in there. It is very depressing,” she said.

Recovery is defined as when one’s fever has gone down without medication, and symptoms of coughing and shortness of breath have resolved. This is in addition to it being more than seven days since the symptoms first appeared or more than 14 days since the last possible exposure.

What doctors are still grappling with is whether these clinical criteria alone for discharge is enough, and for how long after discharge should one be in quarantine. Because of this, the ministry is expected to release protocols for home-based care for mild cases of the disease.

Where resources allow, one should spend 14 days in quarantine or isolation centres, with the test done to determine the presence of the virus being done on the 14th day.

The ministry plans to increase its options for mass testing of Kenyans by exploring rapid test kits that are easy to use and interpret for quick detection of the coronavirus. Currently, automated testing can be carried out in five Kenya Medical Research (Kemri) laboratories and the National Influenza Centre.

At least 187 Gene Xpert machine with a capacity to process at least 20 samples a day are expected to be activated.