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A Covid-19 wastewater test pilot is being rolled out across the country as a safety net for catching the virus in the community.
The eight-week ESR pilot will see wastewater sampled in managed quarantine and isolation facilities, as well as in communities that do not have MIQ hotels, including Gisborne, Dunedin, Queenstown, Taupō and Whangārei.
People with Covid-19 can shed the virus for weeks, so a positive sewage test would mean that health authorities could target testing in a community to contain the spread.
“When the work started, there were dreams that you could look at the sewage and say, ‘This relates to five people or 500, or some people,'” said Dr. Brent Gilpin of ESR. Control.
“I think that, as we are realizing, people can spread the virus from a few hundred per ml of whatever it is they are looking at, to potentially trillions of viruses.
“What can really be said about the detection in sewage is that there is at least one person shedding the virus at some point in the past period. Some of the things that we are really learning is about how long people shed the virus.
“People generally shed the most virus around the time they show symptoms and two to five days afterward. But people can pass the virus up to five weeks later, in their feces or in other ways.
“When we look at the sewage, we also look at what you spit out. So everything that goes into the sewer system, you brush your teeth, you spit, you wipe your nostrils, you hit the shower, and what comes out through the numbers one. and two.
“So both the fecal deposits and what it might be spitting out will contribute to the sewer.
“Sewage detections for viral fragments: The answer to this is to provoke additional testing in people. In Australia, there have been several detections in sewage, and most of them have not found people in the community who so there certainly hasn’t been an outbreak, which may mean someone who was previously infected and is no longer contagious was spreading some virus, and then when they looked at it again, it had stopped spreading.
“Or in some of those situations it may have been a case where someone passed by, the truck driver who stopped at one of these places, left a deposit in the sewer system and then continued.
“It is unlikely that you can really get to say definitively that it is about one or five people.
“What I think we can say is that it is someone or several people who are more likely to be infectious based on the levels of virus present.
“And then the other part that we are looking to develop is the genotyping approach: being able to take what we detect in the search and compare it to the known strains of the SARS-COV2 virus.
“It’s amazing when you think about the hundreds of millions of liters of wastewater a day. We are taking 24 composite samples, we will take a few ml of water every 15 minutes, combining them into one sample.
“And then there is a rather complicated extraction process of concentrating that wastewater, extracting the viral fragments from everything that is there. Then we use the same PCR-type detection to look for these fragments.”
“We’re really looking at extreme detection limits, when you get into sewage, but we can get viruses that could be from just one person. But that person could be spreading trillions of viruses, if ‘you’re a highly contagious person.”
