Quick takes: Genetic clusters in E-11 cases, Americas dengue rise, African disease surveillance

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  • In an update today on severe enterovirus-echovirus 11 (E-11) infections in newborns in some European countries, the European Centre for Disease Prevention and Control said viruses isolated from some of Italy's cases belong to the same genetic cluster as those isolated from France and are part of a new divergent lineage. It added that more data are needed to assess if the new lineage is linked to more severe disease.
  • The number of dengue cases in the Americas this year, nearing 3 million, has already passed the total for 2022, with Brazil, Peru, and Bolivia among the hardest-hit countries, the World Health Organization (WHO) said today in an update. Though activity is now declining in much of South America, the risk to the region is still high owing to the wide distribution of Aedes mosquitoes and the expansion outside of historical transmission areas, where populations may not be aware of warning signs. Some countries in the region, especially in Central America and the Caribbean, could see increased incidence in the second half of the year due to increased rainfall. The WHO urged member states to be prepared to ramp up prevention, case detection, and mosquito control.
  • The Africa Centres for Disease Control, the WHO, and Germany's Robert Koch Institute yesterday announced the launch of a partnership to strengthen infectious disease surveillance in Africa. In a WHO statement, the groups said the first phase will launch in Gambia, Mali, Morocco, Namibia, Tunisia, and South Africa. The project is funded by the Canadian government and aligns with health security objectives of the G7-led Global Partnership Against the Spread of Weapons and Materials of Mass Destruction.

Preventive TB treatment could avert close to 1 million deaths, study finds

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Dispensing tuberculosis medication

A modeling study estimates that scaling up preventive tuberculosis (TB) treatment for people with HIV/AIDS and household contacts of newly diagnosed TB patients could save nearly 850,000 lives by 2035, researchers reported yesterday in The Lancet Global Health.

To estimate the health impact, cost, and cost-effectiveness of implementing short-course TB preventive treatment (TPT) and contact investigation in four populations (people living with HIV/AIDS and household contacts in three age groups [under 5 years, 5 to 14, and over 15]) in 29 high-incidence countries, researchers from Johns Hopkins University, South Africa's Aurum Institute, and Switzerland-based Unitaid developed decision-tree and state-transition models to simulate the delivery of the intervention at a country level.

The team modeled scenarios in which coverage increased from 0% in 2022 to 90% in 2032 and remained at 90% through 2035.

We’ve lagged behind in keeping family members—especially children—free of the disease when a parent becomes sick.

The model estimated that scaling up TPT from 2023 through 2035 would prevent 0.9 people from developing TB and 0.13 TB deaths per 100 people living with HIV/AIDs, at an incremental cost of $15 per person. For household contacts, TPT would avert 1.1 cases and 0.7 deaths per 100 contacts for $21 per person. Cost-effectiveness was most favorable for household contacts under 5 years ($22 per disability-adjusted life year [DALY] averted) and contacts aged 5 to 14 ($104 per DALY averted).

If TPT is not scaled up for these populations, nearly 850,000 preventable TB deaths are projected to occur, including 700,000 among household contacts under 15.

Clear justification for cost

The study authors say that while the cost of scaling up TPT to such a large population would be substantial, the findings provide a clear justification for policy change.

"Although progress has been made in preventing TB among people living with HIV, we’ve lagged behind in keeping family members—especially children—free of the disease when a parent becomes sick," study author and Aurum Institute CEO Gavin Churchyard, PhD, said in a press release.

"This new study, we hope, provides the evidence needed to massively scale up the use of TB preventive treatment among those individuals at risk of developing TB."

Study highlights elevated mortality linked to C diff infection

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C difficile bacteria

A population-based cohort study in Sweden found that Clostridioides difficile infection (CDI) was associated with elevated all-cause and cause-specific mortality, researchers reported yesterday in Clinical Microbiology and Infection.

For the study, a team of Swedish and Belgian researchers compared individuals diagnosed as having at least one episode of CDI from 2006 through 2019 to the entire Swedish population using standardized mortality ratios (SMRs). Each CDI patient was matched to 10 controls, and SMRs were computed for all-cause and cardiovascular- and cancer-related mortality, which were selected based on the prevalence of the causes of death in Sweden. The analysis made adjustments for chronic comorbidities.

The study included 43,150 individuals with CDI (74.8% aged 65 and older, 91.6% with hospital-acquired CDI, and 16.8% with recurrent CDI) and 355,172 controls.

Overall, 61.6% of the CDI group died during the study period, compared with 28.8% of the controls. CDI was associated with a 3- to 7-fold increased mortality rate (incident rate ratio [IRR], 3.5; 95% confidence interval [CI], 3.3 to 3.6; SMR, 6.8; 95% CI, 6.7 to 6.9) compared to the matched controls and Swedish background population, respectively. Mortality rates were highest for hospital-acquired CDI (IRR, 2.4; 95% CI, 1.9 to 3.2) and during the first CDI episode (IRR, 0.2; 95% CI, 0.2 to 0.3 for recurrent versus first CDI).

Mortality risks were, however, still significantly increased when we restricted our analyses to those without comorbidities.

Individuals with CDI had more chronic comorbidities than controls, yet mortality remained higher among CDI cases even after adjustment and stratification for comorbidity; CDI was associated with increased mortality, particularly among those without chronic comorbidities (IRR, 6.1; 95% CI, 5.5 to 6.8).

"Survival bias and underlying comorbidities may play a role, and although we adjusted for chronic comorbidities, residual confounding by comorbidities and frailty is likely," the study authors wrote. "Mortality risks were, however, still significantly increased when we restricted our analyses to those without comorbidities."

H5N1 avian flu strikes more Finnish fur farms, second fox species

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Silver fox
zoofanatic / Flickr cc

The Finland Food Authority today announced that H5N1 avian flu has been detected on 5 more fur farms, including one housing a second fox species, raising the total to 10.

Of the five additional farms, four are located near Kausti in the south central part of the country where two earlier outbreaks were reported. Those four farms housed blue foxes.

One of the new outbreaks was reported from Evijarvi, about 25 miles south of Kausti. That farm housed silver foxes, a variant of the red fox (Vulpes vulpes). Most of the earlier outbreaks involved blue foxes, a variant of the Arctic fox (Vulpes lagopus). One of the earlier affected farms also detected the virus in minks raised at its facility.

Regulatory changes, safety measures

In related developments, Finnish government officials yesterday announced regulatory changes that would give them jurisdiction regarding avian flu outbreaks on fur farms, according to a statement translated and posted by Avian Flu Diary, an infectious disease news blog. Today they announced safety measures for feed operators. Investigators are working to determine the source of the outbreaks, with contact with infected wild birds or their environments and contaminated food among the possibilities.

The initial outbreaks at the fur farms were first reported last week, marking the country's first such events in the facilities and the world's second involving fur farms. Officials have said the virus is related to the one affecting wild birds in Finland, with detections continuing over the summer, along with mass deaths in sea gulls from different parts of the country.

Increasing numbers of H5N1 detections in mammal species have raised concerns about whether the virus is changing to more easily infect humans.

Obstructive sleep apnea linked to severe COVID-19

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Woman using CPAPYesterday in PLOS One, Israeli researchers report that a high risk of obstructive sleep apnea is associated with severe COVID-19 and longer hospitalization.

The study was based on medical records and outcomes seen among 119 COVID-19 patients who were given questionnaires about sleep quality in the 6 to 8 weeks following hospitalization for the novel coronavirus.

Among the 119 patients, 37 (31.1%) had a documented risk of obstructive sleep apnea (OSA). All patients were seen at the Shaare Zedek Medical Center in Jerusalem from June to November 2020.

Quadruple the risk for severe COVID

Patients with OSA were more likely to be male or older or have a higher body mass index (BMI), higher rate of high blood pressure, and more frequent snoring than patients with low OSA risk. The percentage of patients with severe COVID-19 disease at risk for OSA was significantly higher than that of patients with mild disease (50% vs 22.9%).

After adjusting for BMI, age, high blood pressure, and chronic disease, the odds ratio for severe COVID-19 and OSA was 4.3 (95% confidence interval, 1.2 to 16.0).

Some COVID-19 patients who have not been diagnosed with OSA [obstructive sleep apnea] could still be at high risk for OSA.

"The suggested mechanisms by which OSA increases the risk of poor outcomes from COVID-19 include exacerbation or endothelial dysfunction, inflammation, oxidative stress, microaspiration, and lung injury," the authors said. "We recommend that clinicians be aware that some COVID-19 patients who have not been diagnosed with OSA could still be at high risk for OSA, thus making them prone to severe COVID-19."

Study: Most COVID cases in Danish schools didn't cause clusters in fall 2021

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Mask wearing in classroom

Most COVID-19 cases in Danish K-9 schools in fall 2021 didn't trigger clusters, but when they did, they were large, suggests a study published today in Epidemiology & Infection.

A team led by Serum Institut researchers in Copenhagen conducted a register-based, observational study linking student-level data on COVID-19 test results and vaccination status of children aged 6 to 15 years with grade-level and school-specific information from August 9 to December 19, 2021.

The SARS-CoV-2 Delta variant was dominant throughout the study, public health restrictions were minimal, and school COVID-19 testing was in place. The researchers defined clusters as three or more cases in a grade within 14 days of a primary case.

42% of cases tied to clusters

By study end, 2.5% of children in grades 0 to 4 and 63.1% in grades 5 to 9 were vaccinated. Almost all children (94.4%) were tested at least once.

A total of 75,225 COVID-19 infections were detected among 75,168 children (12.1% of all children). Overall, 5.7% of children were infected before the study. One or more infections were detected in 96.2% of schools, and 76.5% of 1,300 schools reported at least one cluster.

Overall, 21,497 case introductions and 7,518 clusters consisting of 55,912 cases were identified. More cases and clusters were identified in lower (4,239) than in higher grades (3,281). Of 21,497 case introductions, 41.6% produced a cluster. Overall, 74.4% of cases were linked to clusters of 3 to 65 infections.

Overall, more cases and clusters had been seen in the lower class levels, where children were mainly unvaccinated.

A higher assumed within-grade immunity level due to vaccination or previous infection appeared to significantly lower the likelihood of a link between a case introduction and a cluster (eg, immunity of at least 80% vs less than 20%; odds ratio [OR], 0.28). A previous infection in the primary case protected against clusters (OR, 0.58).

"Overall, more cases and clusters had been seen in the lower class levels, where children were mainly unvaccinated, than in higher class levels," the study authors wrote. "It further indicates that vaccination of children markedly reduces the risk of secondary infections."

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