A study published late last week in Nature Communications details the evolution and spread of a strain of extensively drug-resistant (XDR) Shigella.

Using genomic epidemiology, a team of researchers led by the United Kingdom Health Security Agency (UKHSA) analyzed a collection of more than 3,000 isolates from a strain of XDR Shigella sonnei that has caused shigellosis outbreaks in the United Kingdom and several other countries (Australia, Belgium, France, and the United States) since late 2021. The analysis revealed an internationally connected outbreak with a most recent common ancestor in 2018 that has been primarily associated with spread among men who have sex with men (MSM).

Although shigellosis is commonly associated with exposure to food or water that has been contaminated by human feces and is known to spread in settings with overcrowding and poor sanitation, oral and anal sex has become a major route of transmission, particularly among MSM.

While earlier versions of the S sonnei strain were resistant to the first-line (ciprofloxacin) and second-line (azithromycin) treatments recommended by the World Health Organization for treatment of shigellosis, the emergent XDR strain carries an additional resistance gene that confers resistance to ceftriaxone and a plasmid that can share the gene with other enteric bacteria. The study authors suggest the resistance to ceftriaxone is likely being driven by bystander resistance resulting from the use of ceftriaxone for treatment of gonorrhea.

"Treatment for ongoing high rates of gonorrhoea in the UK thus likely contributed to the acquisition of resistance to third-generation cephalosporins into this circulating ciprofloxacin resistant lineage of S. sonnei," they wrote. "It is also possible that plasmid fitness cost played a role in the emergence of this XDR strain."

The authors say active surveillance of microbiota among MSM receiving antibiotic treatments for sexually transmitted infections could potentially help mitigate the further development of XDR or pan–drug-resistant strains of Shigella. They also call for open international sharing of genomic surveillance data to help identify early indicators of antimicrobial resistance threats.

A meta-analysis of 23 studies reveals that the psychiatric symptoms of long COVID were, from most to least prevalent, anxiety, depression, post-traumatic stress disorder (PTSD), poor sleep, hyperfocus on symptoms (somatic disorder), impaired cognition, and obsessive-compulsive disorder (OCD). Women and those with a history of psychiatric diagnoses were at greater risk for these symptoms.

The investigation was published late last week in PLoS One.

Padjadjaran University researchers in Indonesia analyzed the results of 23 studies published from January 2020 to October 2021 involving adult COVID-19 patients with psychiatric symptoms lasting more than 4 weeks after infection. Of the 23 studies, 15 were cohort, 5 were cross-sectional, and 3 were case-control. They were conducted in 13 countries in Europe, Asia, and North and South America.

Physical, mental symptoms may be bidirectional

Nineteen studies reported anxiety prevalence rates of 6.8% to 47.8%, 17 studies identified depression rates of 4.4% to 35.9%, 7 found PTSD rates of 13.0% to 42.8%, and 13 showed rates of poor sleep, sleep disturbances, and insomnia in 4.4% to 50.0%. One article found a 35.2% cognitive-deficit rate, one showed a 73.2% rate of impaired cognition, and one identified an OCD rate of 26.0%.

The researchers said the physical and psychiatric symptoms may have a reciprocal relationship. "Mental health issues in Long COVID patients were known to be associated with persistent physical symptoms, such as myalgia and shortness of breath," the researchers wrote. "This may be bidirectional. The physical symptoms could result in psychiatric symptoms and the psychiatric symptoms may show as physical symptoms."

These COVID-related psychiatric complications could become a long-term public health burden, the authors said. "This condition should be regarded as the potential cause of a delayed pandemic in the medium to long term," they wrote. "Therefore, it is recommended to closely monitor people experiencing Long COVID in the long term."

Most studies included in the meta-analysis relied on self-report questionnaires, and the authors noted the heterogeneous nature of study designs and outcomes, both of which they said may complicate interpretation of the results.

Three countries—Chad, the Democratic Republic of the Congo (DRC), and Mozambique—reported more polio cases last week, all involving vaccine-derived strains, the Global Polio Eradication Initiative (GPEI) said in its latest weekly update.

Chad reported a circulating vaccine-derived poliovirus type 2 (cVDPV2) case from Logone Occidental, bringing its 2023 total to five.

The DRC reported nine more cVDPV2 cases, eight included in its 2023 total and one added to its 2022 total. The cases were from six different provinces. Also, the country reported 12 cases involving circulating vaccine-derived poliovirus type 1 (cVDPV1), eight included in its 2023 total and four included in its 2022 total. The infections are from three provinces.

Also, Mozambique reported one cVDPV1 case from Zambezia, its first case involving the strain of 2023.

More details about Peru's polio investigation

In March, Peru reported a vaccine-derived poliovirus type 1 (VDPV1) case involving an unvaccinated child with no travel history whose paralysis symptoms began in December. In an Apr 7 update, the Pan American Health Organization (PAHO) posted an update on the investigation, which notes that health officials are waiting on test results for another suspected case as well as those for the first patient's asymptomatic contacts.

PAHO said a genetic analysis done at the Oswaldo Cruz institute suggests the virus isn't related to any other detected VDPV1 strains, signifying a new strain. Health officials are testing nine fecal samples, including that from a child younger than 18 months from Atahualpa native community who developed paralysis symptoms. The samples also include four contacts and four unvaccinated children as part of community surveillance.