A study today of viral shedding dynamics in 101 children who had COVID-19 during the Omicron surge in Toronto shows that 40% were still infectious on the day after their symptoms resolved.

Moreover, rapid antigen tests (RATs) were often negative early in the course of illness, and thus cannot be relied on to exclude infection, they authors say. The study is published in Clinical Infectious Diseases.

The prospective study was conducted from February 1 to March 14, 2022, and included children ages 18 and younger with confirmed COVID-19. Researchers conducted daily SARS-CoV-2 testing based on saliva samples for 10 days, and 50 of the participants also completed daily RATs. All testing began within 72 hours of symptoms.

In total, 66 participants (65%) were positive for BA.1 and 33 (33%) were positive for BA.2. The mean age of participants was 10.2 years. Sixty-three percent of participants had two doses of mRNA vaccine, and 18% were unvaccinated.

Three-fourths non-infectious by day 7

The median time to symptom resolution was 6 days, and 12% of participants still had symptoms at day 10. Overall, the median time to non-infectious virus load was 5 days after symptom onset, with 75% of participants meeting the non-infectious threshold by 7 days, and 90% by 10 days. Ten participants were still infectious at 10 days, but only one was symptomatic, with a cough.

"On the day of symptom resolution, 43 of 87 (49%) had met the threshold of non-infectiousness, with 52 (60%) having reached the threshold as of the first day post symptom resolution," the authors wrote.

These findings support the consideration for infection prevention and control interventions for up to 10 days.

Among the 50 participants using RATs, positivity at symptom onset and on the day after symptom onset was 67% and 75%, respectively. On the first day where the non-infectious threshold was met, 61% of participant RAT results were positive.

"These findings support the consideration for infection prevention and control interventions for up to 10 days post symptom onset to reduce residual transmission risk around vulnerable or immunocompromised populations," the authors said.

A cross-sectional study identified several racial differences in the clinical presentation and treatment of Lyme disease, researchers reported today in JAMA Network Open.

The study by researchers with Johns Hopkins University School of Medicine found that, among 1,395 Lyme disease patients (50.4% men, median age 48 years) treated at a specialty clinic in suburban Maryland, Black patients had 4.93 times (95% confidence interval [CI], 2.02 to 12.02) the odds of being diagnosed as having disseminated disease compared with patients who only had signs of the erythema migrans (EM) rash—the most common early sign of infection. The EM rash typically occurs within days or weeks of a deer tick bite.

Among 1,325 patients, Black patients (odds ratio [OR], 2.07; 95% CI, 1.12 to 3.84), women (OR, 1.39; 95% CI, 1.09 to 1.77), and younger patients (per 10 years: OR, 1.12; 95% CI, 1.04 to 1.20) all independently had higher odds of being in the symptoms-only group.

Analysis of 1,295 patients also found that Black patients had a significantly longer median time to appropriate antibiotic treatment (35 days) compared with White patients (7 days). This was significant among patients with EM (Black, 26 days; White, 4 days) but not those with disseminated disease or symptoms only. Initial inappropriate antibiotics were found in 6 of 37 Black patients (16.2%) and 90 of 1,165 White patients (7.7%)

When administered early, antibiotics cure Lyme disease in more than 99% of cases. Untreated infection can lead to complications involving the joints, heart, and nervous system.

Gaps in access, implicit bias may play a role

Although this is one of the few large, clinic-based studies to examine racial differences in Lyme disease treatment, the study authors note that the findings are consistent with prior surveillance and insurance-claims studies. They suggest EM under-recognition could be attributed to EM images on Black patients being underrepresented in medical literature, gaps in healthcare access, racial discrimination, and implicit bias.

"Efforts are needed to increase patient and clinician awareness to ensure equitable reductions in disease burden," the authors wrote.

The Wyoming Game and Fish Department (WGFD) yesterday announced that chronic wasting disease (CWD) was detected in a hunter-harvested cow elk in Elk Hunt Area 122 in early November, County 17 News reports. 

The hunt area, which is in the Casper area, is bordered by three hunt areas with previous CWD detections. The disease was found to the north in Hunt Area 129 in 2021 and to the south in Hunt Areas 19 and 7 in 2008 and 2001, respectively.

In 2022, WGFD tested 6,701 cervid (eg, elk, deer, moose) lymph node samples, mainly hunter-submitted, for CWD.

CWD is a fatal disease caused by infectious misfolded proteins called prions. While CWD is not yet known to infect humans, the Centers for Disease Control and Prevention advises hunters to not consume meat from any animal that is obviously ill or tests positive for CWD.

A University College London–led study reveals that the percentage of children younger than 5 years hospitalized for respiratory syncytial virus (RSV) infection rose significantly after the first year of the COVID-19 pandemic, as did disease severity in infants.

The researchers analyzed hospitalization trends and illness severity in preschoolers admitted to Nationwide Children's Hospital in Columbus, Ohio, during eight RSV seasons: November to April 2012 to 2018 (prepandemic), June to December 2021 (pandemic), and September 2022 to January 2023 (postpandemic). In 2020, there was no RSV season.

The findings were published yesterday in JAMA Pediatrics.

Illness more severe in infants

During the study period, 6,986 children younger than 5 were hospitalized for RSV (55.1% boys), including 5,143 in 2012 to 2018, 908 in 2021, and 935 in 2022 to 2023. The median age at admission jumped from 5.3 months before the pandemic to 6.3 months in 2021 and 8.2 months in 2022 to 2023.

The increase in age was mainly seen among children aged 1 to 4 years, making up 30.0% of all RSV hospitalizations from 2012 to 2018, compared with 37.0% in 2021 and 42.0% in 2022 to 2023.

Compared with before the pandemic, illness severity (need for supplemental oxygen, pediatric intensive care unit [PICU] admission, and length of stay [LOS]) climbed during and after the pandemic.

As RSV preventive strategies with vaccines and monoclonal antibodies are implemented, continued surveillance of RSV burden is essential.

Age-stratified analyses showed that disease severity gradually rose from before the pandemic to 2021 and 2022 to 2023; the increases were significant among children younger than 6 months and 6 months to 1 year, separately or combined (oxygen administration, 68.2% to 75.1% and 88.3%; PICU admission, 36.4% to 47.3% and 52.7%; invasive mechanical ventilation, 11.8% to 9.6% and 16.0%; LOS, 2.6 to 3.0 and 3.8 days).

The increase in RSV hospitalizations may be linked to waning immunity rather than the emergence of new RSV strains or increases in chronic conditions. "As RSV preventive strategies with vaccines and monoclonal antibodies are implemented, continued surveillance of RSV burden is essential," the study authors concluded.

Five African countries—Kenya, Malawi, Uganda, Zambia, and Zimbabwe—are experiencing anthrax outbreaks, the World Health Organization (WHO) said yesterday. So far the countries have reported more than 1,100 suspected cases and 20 deaths this year.

Zambia is seeing the most cases, with 684 suspected and 25 confirmed cases and 4 deaths. It has surpassed its previously largest outbreak. In 2011, the country reported 511 suspected cases.

Though anthrax is endemic in these countries, the Bacillus anthracis bacterium usually causes only small seasonal outbreaks. Humans are exposed to the bacteria most often through infected animal carcasses or contaminated animal products, especially those of cows, sheep, and goats.

To end these outbreaks we must break the cycle of infection by first preventing the disease in animals.

The WHO said the recent uptick in cases is caused by a number of factors, including climate change, food insecurity, and a low perception of risk when handling animal products.

"To end these outbreaks we must break the cycle of infection by first preventing the disease in animals. We are supporting the ongoing national outbreak control efforts by providing expertise as well as reinforcing collaboration with partner agencies for a common approach to safeguard human and animal health," said Matshidiso Moeti, MD, WHO regional director for Africa. 

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