The US Food and Drug Administration (FDA) today issued warning letters to nine manufacturers and distributors of products for animals containing unapproved and misbranded antimicrobial drugs.

The products, which are marketed and labeled for minor species such as aquarium fish and birds, contain medically important antibiotics such as amoxicillin, penicillin, tetracycline, and erythromycin. The FDA says the companies are violating federal law, because the products have not gone through the main legal pathways for animal drugs to reach the marketplace and are being sold over the counter illegally. FDA-approved animal drugs containing medically important antibiotics—those that are also used in human medicine—require a prescription from a licensed veterinarian.

The FDA says the products pose a "two-fold" risk to public health.

"First, these products haven't been through the FDA drug review process, and we don't know whether they're safe or effective, or even contain what the label states," Tracey Forfa, JD, director of the FDA's Center for Veterinary Medicine, said in a press release. "Second, inappropriate use of medically important antimicrobials contributes to the development of antimicrobial resistance, which affects both human and animal health."

The warning letters were sent to American Aquarium Products, Aquanest Biotic, Aquarium Pharmacy LLC, California Veterinary Supply, Chewy Inc., Kraft Drug, Midland Veterinary Services LLC, Silver Lease LLC, and Valley Veterinary Clinic LTD.

The FDA says anyone currently using the products included in the warning letters should safely dispose of them. The agency has given the companies 15 days to respond.

An experimental study that involved cockroaches highlights the dynamics of antimicrobial resistance (AMR) transmission, Danish researchers reported today in mSystems.

In the study, a team of researchers from the Technical University of Denmark set up an experiment in which they separated 250 Pycnoscelus surinamensis cockroaches into two groups to explore AMR transmission within symbiotic microbiomes across hosts. One group (terrarium B) was treated daily with tetracycline, and the other (terrarium A) went untreated. They then sampled cockroaches and soil from both terraria for metagenomic sequencing.

Sequencing analysis revealed that the gut microbiome of the treated cockroaches contained decreased microbial diversity and an elevated abundance of tetracycline resistance genes compared with the untreated group.

When the researchers transferred some of the treated cockroaches into terrarium A and sampled cockroaches and soil from the mixed population, they found that untreated cockroaches also had elevated tetracycline resistance, as did the soil. The levels of resistance differed based on the magnitude and frequency of population mixing.

Valuable insight, but more research needed

The researchers say the study is noteworthy because while mathematical models have been used to predict the potential trajectories and outcomes of AMR transmission, "there remain major gaps in our understanding when it comes to actual, real-world transmission events." They chose cockroaches because they harbor a diverse microbiome, which makes them a good model for microbiome research. In addition, P surinamensis is a highly social species known to live in closely knit, clonal colonies and is a good model for testing microbial transmission.

"Of course, insect models are only the first step in testing modeling hypotheses, as the physiological differences between cockroaches and mammals might result in some variations in microbial interactions and immunity," the study authors wrote.

"Hence, while cockroaches provide valuable insights into the basic mechanisms of AMR transmission, extrapolating findings to human population dynamics should be approached with caution and complemented by other animal models or clinical observations."

Bangladesh has reported 14 Nipah virus cases this year, 10 of them fatal, scientists from the country's Institute of Epidemiology, Disease Control, and Research (IEDCR) said this week at a discussion at the group's headquarters, according to the Business Standard, a daily newspaper based in Dhaka. The IEDCR said deaths from the disease are at the highest level in 7 years.

The cases were reported from 7 of the country's 64 districts, according to IEDCR data.

Scientists also revealed that the virus has been detected for the first time in breast milk. Nipah virus, a paramyxovirus that can cause severe encephalitis, has a high case-fatality rate, between 45% and 75%. People are typically exposed to the virus through direct contact with infected animals, drinking contaminated palm sap, or eating contaminated fruit. The virus can also spread from person to person. The natural reservoir is fruit bats.

In Bangladesh, Nipah infections can follow a seasonal pattern, from December through May. The period tracks with the harvesting of palm sap and festivities surrounding the practice. Health officials urged people to avoid drinking date sap, which can be contaminated by bat droppings, unless it is processed in a way that kills the virus.

There are no vaccines or treatments for Nipah virus, designated as one of the World Health Organization's priority diseases for research and development. It is also one of the Coalition for Epidemic Preparedness Innovations' top priorities for countermeasure development.

Yesterday the Centers for Disease Control and Prevention (CDC) announced that its investigation into a multistate Salmonella outbreak tied to onions has ended.

Seven more people, for a total of 80, have been sickened in the Salmonella Thompson outbreak linked to fresh-diced onions. Cases have been reported in 23 states, including 1 death in Wisconsin, and 18 case-patients have been hospitalized.

The death is new since the CDC's previous update on the outbreak, on October 24.

Gill's Onions recalled

The outbreak is tied to contaminated fresh diced Gill's Onions brad products, which were recalled on October 23. Products had use-by dates from August 8, 2023, to August 28, 2023, and were sold or sent to institutions, stores, and restaurants throughout the United States and Canada.

"Recalled onions are no longer available for sale and the use-by dates have passed," the Centers for Disease Control and Prevention said in an update on the outbreak.

Illnesses-onset dates range from August 2, 2023, to November 11, 2023, and an early cluster of cases were identified in a long-term care facility.

In epidemiologic investigations, 84% of people reported eating or likely eating onions in the week prior to illness.

A meta-analysis of 12 studies shows that 30% of COVID-19 survivors have persistent symptoms 2 years after infection, the most common of which are fatigue, cognitive problems, and pain.

For the study, published yesterday in the Journal of Infection, an international team led by a researcher from Universidad Rey Juan Carlos in Madrid, Spain, searched the literature for observational and case-control studies of long COVID 2 years after infection. The studies, published up to October 1, 2023, were from Europe, China, and the United States.

The sample included 7,912 hospitalized and non-hospitalized COVID-19 survivors; the average age was 59.5 years, and 50.7% were women. Up to 54% of patients had at least one underlying medical condition, with high blood pressure (34.0%) and obesity (22.4%) the most common. Long-COVID symptoms were evaluated at an average follow-up of 723 days.

Psychologic problems also prevalent

The most common post-COVID symptoms 2 years post-infection were fatigue (28.0%), cognitive impairment (27.6%), and pain (8.4%). Psychologic problems such as anxiety (13.4%), depression (18.0%), and disturbed sleep (20.9%) were also prevalent.

The most common respiratory and general symptoms were fatigue (28.0%), runny nose (8.2%), and shortness of breath (5.7%). Prevalent neurologic and cognitive symptoms were dizziness and vertigo (6.7%) and impaired sense of smell (5.3%) and taste (4.9%).

This plethora of post-COVID symptoms can be explained by several mechanisms attributed to SARS-CoV-2 such as viral persistence, long-lasting inflammation, autoimmunity, reactivation of latent infections, alteration in gut microbiota, microvascular thrombosis, or others.

Stomach pain was the most common gastrointestinal symptom (6.7%); headache (8.9%) and muscle pain (8.1%) were the most prevalent pain symptoms; and hair loss was the most common dermatologic symptom (7.4%).

"This plethora of post-COVID symptoms can be explained by several mechanisms attributed to SARS-CoV-2 such as viral persistence, long-lasting inflammation, autoimmunity, reactivation of latent infections, alteration in gut microbiota, microvascular thrombosis, or others," the study authors wrote.

They added that population-based studies using homogeneous data-collection procedures are needed to further refine estimates of the prevalence of long COVID.