Wastewater monitoring of norovirus can be a useful monitoring system and can provide an earlier signal than other surveillance methods, researchers from the University of Michigan reported yesterday in PLOS Water.

Monitoring wastewater as an early virus activity indicator has become more common following the emergence of SARS-CoV-2, and the researchers wanted to see if it could bolster surveillance of norovirus, which causes a substantial medical burden. They said current surveillance relies on syndromic surveillance, such as school and emergency department data on gastrointestinal illnesses, which sometimes isn't specific to norovirus and isn't easily available to the public.

For the study, they sampled wastewater samples from five communities in southeastern Michigan, mostly between July 2021 and July 2022. Communities included Ann Arbor, Flint, Jackson, Tecumseh, and Ypsilanti. They compared the detections with syndromic surveillance findings as well as digital epidemiologic sources such as search term data.

Wastewater RNA detections were highest in the winter and spring and were comparable across all five sampling sites. Norovirus wastewater signals typically led syndromic, outbreak, and search-term trend data.

Researchers said when used alongside other monitoring methods, wastewater sampling for norovirus can provide an early and accessible warning system that has the advantage of detecting virus from people who have mild or asymptomatic infections. Unlike other monitoring methods, wastewater tracking doesn't depend on healthcare seeking, clinical testing, or inference based on other patterns, they said.

CDC reports first 2024 cruise ship norovirus outbreak

In other norovirus developments, the Centers for Disease Control and Prevention (CDC) recently reported the first cruise ship norovirus outbreak of 2024. The outbreak involved the Celebrity Cruises Celebrity Constellation that sailed from January 2 to 12. Of 2,056 passengers, 92 got sick. The virus also sickened 8 of 948 crew members.

Yesterday in Emerging Infectious Diseases, scientists describe a 2021 COVID-19 outbreak at a beaver farm in Mongolia.

Located in the Bayanzurkh district in Ulaanbaatar, the farm raised 32 adult beavers and 16 kits in 2021 for conservation purposes. The animals lived in a large indoor area separated by waist-high walls.

On August 6, one of the seven farm employees tested positive for COVID-19 after experiencing flu-like symptoms. Three days later, the farm reported the death of two beavers aged 6 months and 2 years after they exhibited cough, nasal discharge, rasping sounds in the lungs and chest, sluggishness, and food aversion.

On August 13, investigators collected nasal swabs, saliva, and tissue from the two dead beavers and obtained nasal samples, saliva, and blood from seven other beavers exhibiting cough and nasal discharge with pus. Later that week and on September 12, the researchers collected more samples from the same animals and from two healthy beavers.

Four unique mutations spark concern

Nearly all (46 of 48) specimens from nine beavers with clinical signs, including the two dead animals, tested positive for COVID-19 on polymerase chain reaction (PCR) testing. Serologic testing of 23 samples revealed the presence of SARS-CoV-2 antibodies in 15. One beaver that didn't show signs of infection also had antibodies.

An alarming aspect of SARS-CoV-2 infection in animals is that host animals can maintain the virus and contribute to the emergence in humans of new variants that have accumulated multiple mutations.

Five random SARS-CoV-2–positive samples were shipped to Austria for whole-genome sequencing, which identified the Delta variant. The Delta and Alpha variants were circulating among people in Mongolia at the time, and the closest related sequences in the beaver samples were from human SARS-CoV-2 in Mongolia, although they contained four novel mutations not found in any public databases as of November 2023.

"An alarming aspect of SARS-CoV-2 infection in animals is that host animals can maintain the virus and contribute to the emergence in humans of new variants that have accumulated multiple mutations," the study authors wrote. "Because the emergence of viruses with mutations not targeted by current SARS-CoV-2 vaccines is a credible possibility, more active surveillance of SARS-CoV-2 infection in animals should be encouraged to identify the appearance of mutated viruses."

A new report from the Government Accountability Office (GAO) urges the US Food and Drug Administration (FDA) to finalize its plan to implement new rules to help identify sources of foodborne illness outbreaks.

The FDA's final rule on food traceability, introduced in November 2022, established a list of certain foods for which enhanced recordkeeping is required, including additional traceability records to track certain points in the item's supply chain—known as critical tracking events. Products that contain dairy, eggs, nuts, prepared food, produce, and seafood are covered by the rule's recordkeeping requirements if that ingredient remains in the form in which it appears on the list, according to the FDA. Examples include fresh lettuce used in a bagged salad mix and a sandwich containing a tomato.

Concerns about complexity, cost

While the FDA says they identified items on the list based on previous outbreaks and the risks they pose to human health, some stakeholders interviewed by the GAO said the list is overly inclusive and have expressed concerns about compliance costs. Although the FDA has taken steps to help industry and non-federal regulators prepare for compliance and has begun the planning process for implementing the rule, which has a compliance date of January 20, 2026, the GAO found that the FDA has not finalized or documented its implementation plan.

The GAO says the finalized plan should address the challenges identified by stakeholders and included additional guidance, training, and tools.

"By finalizing and documenting an implementation plan, FDA will have better assurance it is well positioned to make progress toward its regulatory goals and address the various challenges that stakeholders identified to achieving compliance by the deadline," the GAO said.

Chad, Ivory Coast, the Democratic Republic of the Congo (DRC), Mozambique, Nigeria, and South Sudan all reported new polio cases this week, according to an update yesterday from the Global Polio Eradication Initiative. All involved circulating vaccine-derived poliovirus type 1 (cVDPV1) or type 2 (cVDPV2) and were confirmed in 2023.

Chad confirmed 1 cVDPV2 case in Mandoul, bringing its number of 2023 cases to 51. The DRC reported 4 cVDPV1 cases in Tanganyika, bringing its 2023 cases to 101, and 1 cVDPV2 case in Tshopo, raising the 2023 total to 118. Ivory Coast reported 1 cVDPV2 case in Haut-Sassandra, bringing the country's 2023 cases to 6.

Mozambique had 1 cVDPV1 case in Zambezia, for a total of 4 for 2023. Nigeria confirmed 6 cVDPV2 cases, 1 in Kano and five in Katsina, bringing its 2023 total to 70. And South Sudan recorded 1 cVDPV2 case in Central Equatoria, which doubled its 2023 total.

Afghanistan and Pakistan reported no new wild poliovirus type 1 cases but did report several positive environmental samples.