The spread of COVID-19 in wastewater could devastate certain species of marine mammals

Some endangered species of whales, seals and other marine mammals could fall victim to COVID-19 infection from sewage and sewage that infiltrates their marine habitats, researchers from Dalhousie in a new study which found that some of the animals are very susceptible to the virus.

In a study published in Total environmental science, the team describes how they used genomic mapping to determine which marine mammals would be vulnerable to SARS-CoV-2, the virus responsible for COVID-19. They looked at the key amino acids that the virus binds to and found that there were striking similarities between those in humans and several marine mammals, including dolphins, beluga whales, seals and sea otters.

Graham Dellaire (pictured left), director of research in the Department of Pathology at Dalhousie, led research using a modeling approach to predict the susceptibility of a marine mammal to SARS-CoV-2. The team found that at least 15 species of marine mammals were susceptible to infection with SARS-CoV-2 due to their ACE2 receptors – the essential protein required for the virus to enter and infect the cell. .

Above all, more than half of the species considered vulnerable to SARS-CoV-2 are already at risk in the world.

“Many of these species are threatened or critically endangered,” says Dr Dellaire. “In the past, these animals have been infected with related coronaviruses which have caused both mild illness as well as potentially fatal liver and lung damage.”

Same or greater susceptibility to virus than humans

The team predicts that the majority of whale, dolphin and porpoise species – 18 out of 21 – have a susceptibility to the virus equal to or greater than that of humans, while eight out of nine seal species are also expected to be highly susceptible to SARS -CoV- 2.

“Our main concern is in developing countries, where there is already a disparity in public health and the wastewater treatment infrastructure needed to manage the COVID-19 crisis,” says Saby Mathavarajah, pre- Killam doctoral research in the laboratory of Dr Dellaire who co-authored the report. “Surveillance of susceptible species in these high risk areas around the world will be relevant to protect wildlife during and after the pandemic.”

Studies have shown that SARS-CoV-2 is excreted in feces and can survive in water for up to 25 days, raising the possibility that sewage provides a distinct mode of spread for this coronavirus, such as this has happened in Spain, Italy and France where the virus has been detected in untreated wastewater.

For example, in Italy, SARS-CoV-2 was recently detected in untreated wastewater, while in Paris it was shown that high concentrations of SARS-CoV-2 RNA in wastewater between March and April 2020 were correlated with a peak in COVID deaths. -19 about seven days later. In June, SARS-CoV-2 was also detected in river water in Ecuador, where untreated wastewater is piped directly into natural waters.

Reversal of wastewater from lagoons, ponds

Many jurisdictions have at least primary waste treatment, but sewage systems can be overwhelmed under certain conditions, causing raw sewage to overflow directly into waterways that are home to vulnerable mammals. Even wastewater treated by primary means has been shown to have detectable levels of SARS-CoV-2 RNA. Primary treated wastewater can be discharged from settling ponds or lagoons, a risk that researchers have identified as a potential problem in Alaska, where beluga whales could be infected by sewage flowing into backyards. local water from the state lagoon system.

“Over the past few months, our lab has focused on detecting SARS-CoV-2 in wastewater to help understand public health outcomes,” says Graham Gagnon (pictured right), professor in the Department of Dal’s civil engineering and resources who also worked on the study with colleague Dr. Amina Stoddart.

“However, this study has shed light on a potentially significant environmental concern of untreated wastewater.”

There have been no documented cases of SARS-CoV-2 in marine mammals to date, but dolphins and belugas have been infected with related coronaviruses in the past. And since most marine mammals are social, it’s also possible for coronaviruses to be spread between animals through close contact. Thus, an infected animal could threaten entire populations.

The authors suggest that susceptible animals could be monitored for infection through innovations such as drone sampling of mucus from whale’s blowholes – called SnotBot – and even propose to vaccinate these animals.

They also recommend limiting interactions between people and animals in zoos to protect them from potential exposure to the virus.

Finally, they say wastewater treatment systems should be evaluated to make sure they can stem the transmission of the virus through wastewater into natural water systems.

“Given the proximity of marine animals to high-risk environments where viral overflows are likely, we must act with foresight to protect marine mammal species that are expected to be at risk and mitigate the environmental impact of the COVID pandemic. -19 “, the States document.