COVID-19 Scan for Nov 25, 2020

News brief

Loss of taste/smell, stomach upset, headache may predict COVID in kids

A study of SARS-CoV-2–positive Canadian children in CMAJ yesterday showed that 64.1% of children were symptomatic, with loss of taste or smell, stomach upset, headache, and fever most predictive of infection.

Researchers analyzed reverse-transcriptase polymerase chain reaction (RT-PCR) results and self-reported symptoms for children who tested positive for SARS-CoV-2 in Alberta from Apr 13 to Sep 30. Of 2,463 children tested, 1,987 had a positive result, with fever (25.5%), cough (24.5%), and runny nose (19.3%) the most commonly reported symptoms in infected patients.

Cough and runny nose were also common in SARS-CoV-2–negative patients and were not predictive of a positive result; neither were sore throat, nasal congestion, or diarrhea.

Loss of taste or smell, however, was highly predictive, with a likelihood of test positivity more than seven times higher than that for patients without this symptom (positive likelihood ratio [LR], 7.33, 95% confidence interval [CI], 3.03 to 17.76). Other symptoms predictive of a positive result included nausea and vomiting, headache, sneezing, and fever (LR values ranging from 1.68 to 5.51).

When the researchers combined loss of taste/smell, nausea/vomiting, and headache symptoms, the overall likelihood was highly predictive of a positive result (LR, 65.92; 95% CI, 49.48 to 91.92), but the infrequency of loss of taste/smell in children may limit its predictive value.

"Administrators of screening questionnaires for schools or daycares may wish to consider reassessing the symptoms they screen for to include only those that are most strongly associated with positive results for swabs for SARS-CoV-2 infection," the authors advise.

"Because more than one-third of pediatric patients who test positive for SARS-CoV-2 infection exhibit no symptoms, identifying children who are likely to be infected is challenging," said lead author Finlay McAlister, MD, MSc, in a Canada Hospital News press release.

As a result of that, Canadian hospital experts caution in an accompanying commentary, that symptom screening is unlikely to prevent every infected child from entering school. "School-based health and safety measures beyond screening—including physical distancing, hand hygiene, masking, improved ventilation and outdoor learning opportunities—play an essential role in preventing the spread of infection," they note.
Nov 24 CMAJ study
Nov 24 CMAJ commentary
Nov 24 Canada Hospital News news release


Chilblains skin lesions noted in some COVID-19 patients

A French study in JAMA Dermatology today found chilblains-like skin lesions in COVID-19 patients, suggesting a heightened virus-induced immune response associated with SARS-CoV-2 infection.

Chilblains—shiny, bluish-red discolorations of the skin caused by inflammation of small blood vessels—typically occur on fingers and toes, are often accompanied by burning and itching sensations, and can lead to blisters, skin ulcers, infection, and occasionally necrosis—tissue death.

The study authors identified 40 outpatients suspected of having COVID-19 who presented with chilblains at Nice University Hospital from Apr 9 to Apr 17. Chilblains occurrence is unusual in temperate areas, and the incidence corresponded with the spread of SARS-CoV-2 in the region.

None of the chilblains patients tested positive for SARS-CoV-2 via RT-PCR, but 60% had contact with possible COVID-19 cases, and 11% met the definition for a possible COVID-19 infection in the 6 weeks before developing chilblains. Despite negative RT-PCR tests and the lack of a clear causative link between infection and chilblains, 30% of patients tested positive for SARS-CoV-2 antibodies.

Most of the patients were otherwise healthy adolescents and young adults. Symptoms resolved in all patients, but some experienced slow recovery—35% still had cold or discolored toes at 1-month follow-up.

Laboratory findings in chilblains patients showed elevated levels of type I interferon alpha (IFN-α), which are a class of cytokines, or immune proteins, that act to inhibit virus replication and are crucial in the early response to viral infections. IFN-α production is higher in young people and decreases with age, and previous studies have shown an association between severe COVID-19 in older populations and a defective IFN-α response.

"The exaggerated type I interferon response might also explain the relatively low rate of seropositivity in patients with chilblains because those patients could clear SARS-CoV-2 infection before humoral immunity occurs," the authors wrote.
Nov 25 JAMA Dermatol study

News Scan for Nov 25, 2020

News brief

Different CWD strains in North America, Europe, researchers conclude

While both North America and Europe have detected chronic wasting disease (CWD) in cervids such as deer, the two continental strains are distinct, reports a study yesterday in Proceedings of the National Academy of Sciences (PNAS).

To compare CWD strains in Canada and Norway, the researchers experimentally infected bank voles to observe phenotypes across three serial passages. (A 2013 bank vole phenotype study showed Canadian and US CWD had identical transmission and phenotypes.) Not only did Canadian strains have faster replication—suggesting they would have outcompeted the Norwegian strains if they had emigrated to Europe—but they caused spongiform degeneration in different areas of the brain.

Although all three Norwegian moose isolates transmitted easily to bank voles, only one of two Norwegian reindeer isolates transmitted and all corresponding bank vole strains were distinct. This could mean Norwegian CWD does not transmit between cervid species, unlike North American CWD.

"Since the CWD strains in Europe are different from [North America] CWD, the present knowledge is not easily transferrable to the European situation, and a reevaluation of the transmissibility and the zoonotic potential of the new CWD strains here identified is needed," the researchers write.

CWD is a fatal neurologic disease transmitted from cervid to cervid through shed prions, and, according to the study, both North American and Norwegian CWD caused spongiform degeneration, neuronal loss, and gliosis in bank voles. European CWD was first detected in Norwegian reindeer and moose in 2016, almost 60 years after the first North American case in captive deer in Colorado in the 1960s.

The study adds that, in Europe, CWD has been found in 1 red deer and 7 moose in Norway as well as 3 moose in Finland and 1 in Sweden.
Nov 23 PNAS study


WHO: Flu detections remain low as both influenza A and B detected

Flu activity across the globe remains at lower levels than expected for this time of year, likely due to COVID-19 impacts, though some countries in temperate parts of the Northern Hemisphere are reporting sporadic detections from both influenza A and influenza B, the World Health Organization (WHO) said in its latest regular update.

Saudi Arabia and Haiti are among the countries to report sporadic influenza B cases in recent weeks, and co-circulation of influenza A and B strains has been reported in a few West African countries, including Burkina Faso, Ivory Coast, and Togo.

In tropical Asia, India reported sporadic H3N2 cases, while Afghanistan detected some influenza B viruses, and H3N2 was reported in southeast countries, including Laos, Vietnam, and Thailand.

Globally, of nearly 109,000 respiratory samples tested at WHO affiliated labs in late October through early November, only 100 were positive for flu. Of those, 63% were influenza A, and of the subtyped influenza A samples, 88.7% were H3N2.
Nov 23 WHO global flu update


Nigeria battles new yellow fever clusters in multiple states

Nigeria has reported a new yellow fever clusters in three states, Delta, Enugu, and Bauchi, the WHO said yesterday. Yellow fever is endemic in Nigeria, with widespread outbreaks occurring over a wide geographic area since 2017.

In Delta state, officials reported a cluster on Nov 2, and an investigation identified 65 suspected cases, 33 of them fatal. So far, 7 have been confirmed through polymerase chain reaction (PCR) testing.

A probe into a 10-person death cluster in Enugu state found that 6 were positive for yellow fever based on PCR testing. Health officials in Bauchi state reported that 8 samples were positive for yellow fever, based on PCR tests, and investigations are still under way. And finally, 3 recent samples from Benue state were also PCR-positive.

The WHO said the new outbreaks are occurring in areas that hadn't reported cases earlier this year, suggesting sustained high transmission with spillover to human populations. It said the disease activity poses a risk of spread to other states with underimmunized populations, including large urban centers including Lagos.

The agency added that Nigeria is grappling with multiple public health emergencies, including polio, measles, monkeypox, Lassa fever, cholera, and COVID-19. Currently, the yellow fever risk is high within Nigeria, but low at regional and global levels.
Nov 24 WHO statement

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