Testing wastewater for Samoa brings benefits

Researchers in New Zealand and Australia say testing wastewater for COVID-19 is an ideal early warning system for Samoa, and that in around six months it could be a widespread surveillance method globally.

Published studies reveal the COVID-19 identified in the wastewater finds the virus’s R.N.A. (Ribonucleic acid) two days earlier than it manifests physically in people, meaning clusters might be stopped before they have even started.

University of Otago Geneticist, Professor Neil Gemmel, said sewage systems and septic tank systems are already used to test for known diseases, and most laboratories already carry the equipment and know-how to begin testing for the virus that causes COVID-19, SARS-CoV-2, right away.

“This could be a really good early warning system that you could put in place in a variety of places but I imagine airports and ports would be really useful to screen for incoming residents,” he told the Samoa Observer. “We think it’s really powerful, I wish we were doing more of it in this country (New Zealand).”

Professor Gemmell has been working with a team of researchers from the Institute of Environmental Science and Research in New Zealand. They have an NZ$1.65 million grant for this research. 

With much of the world under some form of lockdown since February or March, a World Health Organisation doctor has recently called for countries to stop using lockdowns to control the virus, saying all they achieve is poverty.

"Lockdowns just have one consequence that you must never ever belittle, and that is making poor people an awful lot poorer,” Dr. David Nabarro said this week. 

Dr. Nabarro is one of six special envoys working on the W.H.O. COVID-19 response.

Professor Gemmell said that while Samoa is in a great place having kept the virus out so far, pressure will come to open up the country to tourists and there will need to be a more efficient virus surveillance method in place to make that possible. 

And while he acknowledged the sewage sampling work is expensive, costing thousands of dollars per sample at the moment, it is a worthwhile investment to do alongside testing new arrivals at the border and having them quarantine.

Here in Samoa, outspoken exporter Papalii Grant Percival called for Samoa to start testing its wastewater in a letter published in the Samoa Observer, saying the country needs to protect itself using the “latest and cheapest” methods.

“We should be asking Auckland Airport, the airlines and the Airport Authority to institute daily waste testing protocols at the airport and on the aircraft that fly here,” he said.

“Science has progressed beyond blanket population testing and the traveller is the vector and therefore if not infected may become infected through transiting an infections zone like an airport and an aircraft.

“The managers of these facilities have a primary [occupational health and safety] responsibility to protect their staff and should as a matter of course introduce these measures as a social and ethical responsibility to their staff and their guests.”

Professor Gemmell said one of the best examples of the wastewater surveillance system working was in Arizona State University, which tested sewage from the residential college of about 300 people, and found a positive sample of the virus.

They then tested the 300 people using the nasal swab tests and found two asymptomatic people, and were able to manage the group to avoid any further spread.

Just this month, Australian testing did the same, predicting the latest outbreak in Sydney by several days.

Australia’s Commonwealth Scientific and Industrial Research Organisation (C.S.I.R.O.) have been investigating this option for several months now.

Project lead microbiologist Dr. Warish Ahmed said the wastewater surveillance could allow countries to open up their economies.

“Among the impacted sectors, tourism requiring international travel has suffered a tremendous loss due to stringent measures, including complete lockdowns, border closures, and social distancing to suppress transmission of the SARS-CoV-2,” he said.

“If you can detect the virus early, it gives you three to five days so that you can implement contact tracing, more testing done and ask community to be vigilant to the chance of a community transmission can be minimized. 

“Many countries such as [the United Kingdom], Australia, South Africa and N.Z. have on-going wastewater surveillance program to fight against COVID-19. 

“This can be great tool in addition to clinical testing that may provide valuable information to the public health units.”

Samples can be collected from urban wastewater treatment plants, pumping stations, hospitals, prisons, aged care facilities and residential areas with limited testing abilities, he said. 

“This is more useful because you can potentially screen thousands of people by testing wastewater than individuals and should be performed in conjunction with clinical testing.

“Application of this technique nationally requires a co-ordinated effort by researchers, public health units, utilities and communities.”

As well as testing the wastewater from quarantine sites, hotels and the border entry points like the airport and port, testing from within the community is important so that false negatives or cases of extremely long virus incubation can be caught.

In New Zealand, a new cluster of cases started from a person that could not be linked back to the border as either a border worker or a recent arrival. Professor Gemmell said water testing could identify cases like these quickly.

The testing work requires sample filtration equipment, a real-time P.C.R. machine (which Samoa acquired earlier this year) and centrifuges for “spinning down” the waste and separating it into its testable parts.

Professor Gemmell said the work is neither pretty nor pleasant and fairly laborious. But if a result can be turned around in 24 hours it could be hugely effective.

Experienced laboratories in New Zealand report they can process between 30 and 35 samples a week. 

C.S.I.R.O. published its paper reporting on successfully finding COVID-19 in wastewater in August, and this month has published their study on virus concentration methods.

“The isolation of the virus from wastewater can be tricky especially when the case number is low,” Dr. Ahmed explained.

“For this reason, we need to have a good concentration method. In a recent study, we have evaluated several concentration methods that can recover SARS-CoV-2 from wastewater effectively.”

While identifiable in wastewater, there is no evidence that COVID-19 can spread to people from wastewater. 

The Samoa Water Authority has been approached for comment. 

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