COVID-19 virus in Palm Springs' wastewater surged more than 700% in November, report says

The amount of COVID-19 virus measured in the Palm Springs Wastewater Treatment Plant increased by more than 700% throughout November, according to new data published by the city. And samples collected this week suggest that about 5,800 people in Palm Springs could currently be infected with the virus.

According to Riverside County, Palm Springs has had 1,626 coronavirus cases confirmed via diagnostic tests since the start of the pandemic and 67 deaths. The city has about 48,000 people.

The company that does the wastewater testing for Palm Springs estimated that the viral load in its sewage over the 24 hours from 9 a.m. Dec. 7 to 9 a.m. on Dec. 8 meant there could be as few as 3,093 cases or as many as 13,720, although it said testing via wastewater "is not yet an exact science."

The data, however, highlighted how other, more traditional testing measures will miss cases. It remains unclear exactly how sensitive wastewater testing is to people who may no longer be contagious. 

Riverside County data do show that cases have been surging in Palm Springs. From Dec. 1 to Dec. 7, 73 cases were reported via diagnostic tests. From Tuesday through Thursday, 167 cases were confirmed. County data indicate there may be about 455 active cases in Palm Springs currently. 

The wastewater testing suggests the virus is more widespread.

"Recent testing at the Palm Springs Wastewater Treatment Plant supports community guidance to take the state’s regional shelter-in-place order seriously to slow the spread of the virus," according to documents shared by Mayor Geoff Kors prior to the presentation at Thursday night's city council meeting.

The report included a comparison to Burlington, Vt., which has about the same population and saw the amount of COVID-19 found in its wastewater also rise substantially in November. Meanwhile, the Massachusetts Water Resources Authority is similarly testing for COVID-19 around the Boston metro area, and its growth of observed viral particles in wastewater had a similar trendline to the rise in cases detected via other methods.

Tracking the coronavirus through wastewater can help public health officials identify changes in its spread between three days and a full week earlier than person-by-person testing, according to Palm Springs' presentation. Although the commonly relied upon diagnostic tests that use nasal or cheek swabs are highly accurate, they take several days to process and can be even further delayed when demand surges.

Additionally, they only represent the population that actually gets tested. This means that testing centers need to be well-dispersed and that there should be a concerted public outreach campaign to ensure a representative sample of people gets tested.

But, as the saying goes, everybody poops.

If levels of the virus are high, they can be accurately analyzed in samples of wastewater as small as a single milliliter — about 20 drops of water — according to the Centers for Disease Control and Prevention.

This type of community level testing has been used for other diseases and is being rolled out in other parts of the country and the globe, according to the World Health Organization, although it is primarily available in high-income areas. Public health officials could face additional obstacles to using this in parts of the eastern Coachella Valley, for example, where many communities are not hooked up to a centralized sewage system.

Riverside County reported more than 18,000 new COVID-19 cases from Tuesday to Thursday. From Dec. 1 to Dec. 7, it reported about 7,400.

Palm Springs officials said at the city council meeting Thursday night that Riverside County's ICU capacity was at 4.1% and that there were only 7 ICU beds available in the Coachella Valley. Those beds were at Eisenhower Health and JFK Memorial hospital in Indio. 

Desert Sun reporter Mark Olalde can be reached at molalde@gannett.com or on Twitter at @MarkOlalde.