The painstaking detective work of contact tracing usually starts with an infected person and works forward, asking who has that person seen since they became potentially contagious with COVID-19.
But that mainstay of public health has a less high-profile cousin that’s become instrumental in spotting superspreader events quickly — working in reverse.
“Instead of asking who did that person potentially give the virus to, you’re asking where did that person get the virus?” said Dr. Trevor Arnason, associate medical officer of health with Ottawa Public Health.
“It makes you become better at finding people who have COVID-19 who you might not have known about.”
COVID-19 tends to spread explosively in situations where the virus can infect a bunch of people all at once, public health experts say, which is where what’s known as backward tracing comes in handy.
Ottawa Public Health cottoned on to the benefits of backward tracing when emerging evidence from Japan showed how focusing on where a person got COVID-19 and going back to that location helped to find many more who were infected.
“We started more systematically asking everybody, ‘Where do you think you got it? Or who do you think you got this from? And then we started working back from those places. You start to notice these patterns, which we’ve put together in infographics that we’ve shared with the public,” Arnason said.
Another Ottawa example of community transmission. In September, an individual with mild symptoms attended a wedding. 15 days later, 207 people were self-isolating & needed testing. Kids missed school, their parents couldn’t work & testing lines were longer. Our. Actions. Matter. <a href=”https://t.co/QUgqAL7C8O”>pic.twitter.com/QUgqAL7C8O</a>
Infographics tracing how many were affected from one indoor wedding allowed the public to see how seemingly disparate locations tied together, resulting in 22 people from eight households being affected in two weeks.
“Backward contact tracing is used to find the superspreading events. That’s the main goal.”
Ashleigh Tuite, an infectious diseases epidemiologist in Toronto, said most people who are infected don’t pass it to others.
But the instances where an individual goes on to transmit to many others likely reflect how coronavirus transmission clusters at a particular location or environment.
An indoor gym where those working out are unmasked, breathing heavily in what may not be the best ventilated conditions is one example.
“It’s clear that telling people to wear masks when they move around a gym, but not when they’re exercising, which I think has been the protocol in a lot of places, wasn’t enough,” Tuite said.
WATCH | Day in the life of COVID-19 contact tracers [May 2020]:
The National’s Adrienne Arsenault spends a day with contact tracers in London, Ont., who help figure out where someone caught COVID-19 and determine who else may be at risk. 3:43
Suppressing variants
Backward contact tracing is a lot of work for public-health staff facing down outbreaks, said Tuite, but also potentially high yield.
It can be particularly helpful at the early stages an epidemic — which is long-gone for normal coronavirus, but the introduction of more-transmissible variants of concern is like a do-over, said Tuite, an assistant professor at the University of Toronto’s Dalla Lana School of Public Health.
“It’s an effective way of suppressing the growth of the variants of concern amongst this larger epidemic that’s happening,” she said.
“Overall, we have declining case counts and so if we can control sparks that are happening with the variants of concern, there is the potential to really keep it under control and at least keep case counts declining.”
This May 13, 2020, photo taken with a fisheye lens shows a list of the confirmed COVID-19 cases in Salt Lake County. The white board remains in the office as a reminder of how quickly the coronavirus spread. (Rick Bowmer/Associated Press)
Declining case counts mean hospital and health-care capacity can accommodate more surgeries and preventative care and allow the economy underpinning society to recover, too.
For now, Tuite said case counts will only decline if people restrict their interactions.
For Dr. Susy Hota, an infectious diseases specialist at Toronto’s University Health Network, keeping the variants of concern at bay is another goal of vaccinating as many people as quickly as possible.
“If we continue to allow transmission to occur, [the variants] will take over a larger and larger proportion of the market, so to speak,” said Hota, an associate professor of medicine at the University of Toronto.
Stopping spread fast
Regardless of variants, forward contact tracing to identify high-risk contacts and possible cases as aggressively as possible so they know to isolate quickly will always be a key public health tool.
For instance, a Manitoba spokesperson said they routinely collect information on where a COVID-positive case may have been exposed. But the focus is on forward contact tracing to stop spread as quickly as possible.
WATCH | Workplace physical distancing innovation:
A Calgary tech company’s device is in big demand as manufacturing companies look for ways to keep employees physically distanced while maintaining productivity. 3:09
Hota cautioned there are even more recall challenges with backward contact tracing than forward, using herself as an example.
“Do you think you were more than two metres away when you talked to that person? I think so. But I didn’t have a yardstick with me. And how long do you think you were talking? Oh, I’m terrible at that. I’ll tell you, like, five minutes. I have no idea.”
The recall problem gets amplified because to do backward contact tracing effectively means going back the full 14-day incubation period of the coronavirus. Hota does see a role for backward contact tracing in trying to pin down if there’s a single source of multiple cases, say at a meat-packing plant.
“The truth often doesn’t emerge until the epidemic is over,” Hota said.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
