Patients with persistent symptoms of depression and cognitive impairment after a mild to moderate COVID-19 infection had elevated levels of a protein indicating inflammation of the brain, finds a Canadian case-control study published yesterday in JAMA Psychiatry.

The team led by researchers from the Centre for Addiction and Mental Health in Toronto used positron emission tomography (PET) to compare levels of translocator protein, a marker for gliosis (inflammation of the brain), in 20 participants with persistent symptoms of depression and cognitive impairment with those of 20 healthy controls.

The study was conducted from April 1, 2021, to June 30, 2022. Average participant age was 32.9 years, and roughly 60% were women.

Greatest difference in 2 brain regions

Translocator protein volume in the brain regions of interest was higher in participants with depressive and cognitive symptoms than in controls (mean difference, 1.51; 1.51 divided by 9.20, 17%).

The difference was most pronounced in two regions of the brain: the ventral striatum (mean difference, 1.97; 1.97 divided by 8.87, 22%) and dorsal putamen (mean difference, 1.70; 1.70 divided by 8.37, 20%).

"Gliosis may be consequent to inflammation, injury, or both, particularly in the ventral striatum and dorsal putamen, which may explain some persistent depressive and cognitive symptoms, including slowed motor speed, low motivation or energy, and anhedonia [reduced ability to experience pleasure]," the authors wrote.

In a related commentary, Alexander Gerhard, MD, of the University of Manchester in England, said the study was limited by PET's signal, which is not restricted to microglial cells.

"To target neuroinflammatory changes therapeutically, we will need a much more detailed understanding of microglial activation at different time points of neurological disorders," Gerhard wrote. "Not surprisingly, relatively simplistic attempts to suppress microglial activation have so far not resulted in clinical meaningful results."

Cats can become infected with COVID-19 through contact with other infected animals or contaminated pens and should be considered part of the household dynamics of the virus, according to a new study in Microbiology Spectrum.

"SARS-CoV-2 transmission between cats is efficient and can be sustained," said study author Wim van der Poel DVM, PhD, of Wageningen University and Research, in the Netherlands, in a press release. "Infections of cats via exposure to a SARS-CoV-2-contaminated environment cannot be discounted if cats are exposed shortly after contamination." 

The experiment involved 16 cats placed in different exposure groups. They were swabbed multiple times over the course of 3 weeks after exposure to either an infected cat or to a pen in which an infected cat was housed. Environmental samples were also taken.

Of the eight cats exposed to the contaminated pens, only one got infected, but three of four animals exposed to another infected animal became infected. The cats displayed mild symptoms, including nasal discharge.

"We found that the infectiousness of contaminated surfaces would decay within 8.8 (95% CI [confidence interval] = 1.5 to 31.2) hours, making transmission via contaminated surfaces alone inefficient," the authors wrote.

What about spread to people?

"We did not expose humans to the infectious cats. Our animal handlers were always fully protected," van der Poel said in the release. "We must assume that cat owners can be infected by SARS-CoV-2 infected cats since these cats excrete infectious virus." In fact, Thai scientists reported such an occurrence in June 2022.

"We should see our cat as part of the family regarding virus transmission," van der Poel added.

Mexican health officials have identified Fusarium solani, a common soil fungus, in cerebrospinal fluid samples from five American women who got sick after undergoing cosmetic surgery procedures performed under spinal anesthesia at two private clinics in Matamoros, Mexico, from January to April, the World Health Organization (WHO) said today.

The illnesses were the subject of a US Centers for Disease Control and Prevention (CDC) Health Advisory Network notice on May 17. The WHO said that, as of May 26, 20 cases have been reported in people who have signs and symptoms compatible with central nervous system infection. The CDC has reported two deaths.

An investigation found that 547 people had procedures at the clinics during the time people got sick, 304 from Mexico and 237 from the United States, the WHO said. In an update this week, the CDC said 220 people in the United States have known exposure, with 11 listed as having probable infections, meaning tests were positive for fungal infection markers, and 14 are listed as having suspected cases, meaning their symptoms are consistent with meningitis. Some of the US patients seen at the clinic didn't have epidural anesthesia.

State health officials in Mexico closed the two clinics on May 13, and investigations into the illnesses are ongoing. So far the fungus source, vehicle, and transmission route are unknown.