Structural changes in the brain may explain the persistent fatigue and neuropsychiatric complications associated with long COVID, finds an observational study published yesterday in eClinicalMedicine.

Universitatsmedizin Berlin researchers in Germany enrolled 47 adults aged 18 to 69 years who had moderate to severe fatigue and visited post-COVID neurologic outpatient clinics from Apr 15 to Nov 30, 2021; 83% were women. They were compared with 47 uninfected control patients and 47 multiple sclerosis patients with fatigue. The average age of all participants was 43 to 44 years.

The team conducted magnetic resonance imaging (MRI) and neuropsychiatric and cognitive testing at a median of 7.5 months after COVID-19 infection.

Poor sleep quality, depression

MRI revealed abnormal structural changes in the thalamus, the part of the brain responsible for relaying motor and sensory signals and regulating sleep and wakefulness. The changes have been correlated with physical fatigue severity, fatigue-related daily functional impairment, and daytime sleepiness, the authors noted.

The shape deformations and reduced volumes of the thalamus and other areas of the brain overlapped with the changes seen in the MS patients and were tied to impaired short-term memory.

Poor sleep quality and depression—but not fatigue—were tied to infection severity and co-occurred with heightened anxiety and daytime sleepiness.

We provide an insight into the brain changes related to post-COVID syndrome.

"By showing that the subjective symptom of fatigue has an underlying structural correlate in the brain, we provide an insight into the brain changes related to post-COVID syndrome and report a potential longitudinal biomarker for recovery," the researchers wrote. "In the context of further increasing numbers of SARS-CoV-2 infections, a precise characterisation of post-COVID fatigue is a prerequisite to understand the involved pathomechanisms and improve patient care."

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) added 10 more H5N1 avian flu detections in mammals to its running list, which adds reports from four states and includes five different species.

Seven of the detections were in Colorado, where the virus was found in three mountain lions, a bobcat, two red fox, and a black bear.

Kansas and Oregon both reported detections in striped skunks, and North Carolina reported a detection in a black bear.

The new H5N1-positive samples bring the number of known US detections in mammals to 131.

Health officials are closely monitoring continuing reports of H5N1 spillovers to mammals, which have been reported from the Americas and Europe. The Eurasian H5N1 clade currently hitting birds and poultry in multiple world regions has a mutation that makes it more recognizable to mammal airway cells, including humans.

Human infections have been rare and have occurred in people who had close contact with poultry. Of the handful of cases that have been reported, some were severe or fatal, with others thought to represent environmental contamination rather than true infections.

The health ministry in Equatorial Guinea reported 2 more deaths in people with symptoms of Marburg virus infection, which would raise the outbreak total to 11 cases, all fatal.

On Twitter and in an official statement, officials also said there are four other suspected cases, involving three people with mild symptoms in hospital isolation and one person in the community. Overall, 48 contacts have been identified, and 15 samples from suspected cases have been collected for lab testing.

The country announced its first outbreak of Marburg virus, a close relative of Ebola, earlier this month. A few days ago, the World Health Organization (WHO) posted an update on the investigation, which was triggered by a cluster of suspicious deaths between early January and early February in eight people from the same district, some of whom had participated in a burial of a patient with similar symptoms.

Marburg virus, like Ebola, spreads through contact with an infected patient's body fluids. It has a fatality rate as high as 88%, and there are no approved vaccines or treatments, though some vaccines are in clinical trials.