In a new report published in Eurosurveillance, Dutch investigators describe an outbreak of COVID-19 in gorillas and lions at the Rotterdam Zoo in late 2021, despite the use of personal protective equipment (PPE) by their zookeepers.

SARS-CoV-2 has been detected in several zoo animals, likely caused by human-to-animal transmission. Such transmission has also been documented among domesticated and wild animals. Transmission dynamics must be understood, the authors of the study said, to assess spillover risk and protect animals from SARS-CoV-2 from a One Health perspective.

The Rotterdam outbreak occurred during a 6-day period in November 2021, when multiple western lowland gorillas and Asiatic lions experienced fever, coughing and lethargy. Zookeepers had been wearing PPE since 2020, when the COVID-19 pandemic began, and zoo visitors were required to show proof of vaccination, or a negative COVID test result to gain admission.

Animal-to-animal spread likely, too

Extensive testing of the animals and 19 staff deemed direct contacts and 21 staff deemed indirect contact suggested human-to-animal transmission. Genomic data of two zookeepers and the lions and gorillas clustered, which may indicate transmission between the animals and their zookeepers, the authors said.

"We considered one or multiple asymptomatic infectious zookeepers, who may have had contact with each other in private settings or in the changing rooms, as the most likely outbreak source," the authors said. "Subsequent animal-to-animal transmission is likely given the high attack rate among the animals and the consistent PPE use of the zookeepers."

Subsequent animal-to-animal transmission is likely given the high attack rate among the animals.

Strict measures should be taken in zoos to protect against SARS-CoV-2 spillover events, the authors conclude. "It is crucial to adopt stringent prevention and control strategies to avoid introduction of respiratory pathogens in animal populations," they write.

A systematic review and meta-analysis shows that influenza vaccination is associated with significantly reduced antibiotic use, while the effect of pneumococcal vaccination is less pronounced, Dutch researchers reported today in Antimicrobial Resistance and Infection Control.

Reviewing literature published from 1998 through 2021, researchers from the Netherlands Institute for Health Services Research included 29 randomized controlled trials (RCTs) and 69 observational studies in their meta-analysis. Most studies were performed in high-income countries in Europe and the Americas, and outcome measures included the proportion of people receiving antibiotics, the number of antibiotic courses or prescriptions per person, and days of antibiotic use. Results were stratified by global region and age-group.

The RCTs showed that the effect of influenza vaccination on the number of antibiotic prescriptions or days of antibiotic use (ratio of means [RoM], 0.71; 95% confidence interval [CI], 0.62 to 0.83) is stronger compared to the effect of pneumococcal vaccination (RoM, 0.92; 95% CI, 0.85 to 1.00) and confirmed a reduction in the proportion of people receiving antibiotics after flu vaccination (risk ratio [RR], 0.63; 95% CI 0.51 to 0.79). The effect of flu vaccination in Europe and the Americas ranged from 0.63 and 0.87 RoM to 0.70 and 0.66 RR, respectively. The evidence from observational studies supported these findings but presented a less consistent picture.

These interventions need to be integrated into a multi-pronged strategy that takes into account all of the other factors that can reduce antibiotic use over time.

The study authors say the stronger effect of the flu vaccine on antibiotic use is surprising, given that flu should not be treated with antibiotics and that the vaccine effectiveness (VE) of pneumococcal vaccines is considerably higher than the VE of influenza vaccines. Still, they say that both vaccines should be used as a possible public health intervention to address antimicrobial resistance.

"These interventions need to be integrated into a multi-pronged strategy that takes into account all of the other factors that can reduce antibiotic use over time, such as antibiotic stewardship policies, raised awareness about rational antibiotic use through antibiotic campaigns and/or access to antimicrobials," they wrote.

After 26 cases and 4 hospitalizations in six states, the Centers for Disease Control and Prevention (CDC) yesterday declared its investigation over into a Salmonella outbreak tied to raw cookie dough sold at Papa Murphy's pizza outlets. The CDC noted an increase of 8 cases and 2 hospitalizations since it first reported the outbreak in May.

Patients range in age from 14 to 81 years, with a median age of 48. Of the 26 patients, 21 (81%) are female. Illness-onset dates range from February 24 to May 28. None of the illnesses proved fatal. Oregon reported the most cases (8) followed by Washington (6), Idaho (5), Utah (4), California (2), and Missouri (1).

The true number of sick people in this outbreak was likely much higher.

"The true number of sick people in this outbreak was likely much higher than the number reported, and the outbreak may not have been limited to the states with known illnesses," the CDC said. "This is because many people recover without medical care and are not tested for Salmonella."

Dough should not be eaten raw

Of the 22 case-patients interviewed, 17 reported eating food from Papa Murphy's. Of those, 15 ate Papa Murphy's raw chocolate chip cookie dough or raw s'mores bars dough, and 1 person ate baked chocolate chip cookies made from Papa Murphy's dough.

Papa Murphy's temporarily stopped selling its raw dough on May 23 in response to the outbreak. And the CDC said that, as of July 13, the chain has not restarted sales of cookie dough and is reviewing its dessert labels to make it clear to customers that such products are not intended to be eaten raw.

Surveillance at a large school district in Kansas City, Missouri, found that 25% of nasal swabs from students and staff tested positive for common non-COVID respiratory viruses, according to a study today in Morbidity and Mortality Weekly Report.

To determine the prevalence of respiratory viruses in school students and staff members, researchers tested samples from a large school district in Kansas City that includes 33 pre-kindergarten (pre-K) through grade 12 schools during the 2022-23 school year.

Among the 894 study participants, 639 (71.5%) were students (representing 3.0% of total district enrollment), and 255 (28.5%) were staff members (representing 7.1% of the total). Researchers tested 3,232 surveillance specimens, including 872 (27.0%) from staff and 2,360 (73.0%) from students. Among 2,393 completed surveys, pre-K students reported the highest prevalence of having one or more symptoms—41.1%—compared with 14.0% among high school students.

Rhinovirus, enterovirus most common

Overall, 805 specimens (24.9%) tested positive for any virus (95% confidence interval, 23.4% to 26.4%). A substantially higher percentage of pre-K specimens tested positive (40.0%) compared with staff member specimens (14.1%). Among all samples, rhinovirus or enterovirus was most common (found in 12.1% of samples), followed by seasonal coronaviruses (5.6%).

It is important to implement strategies to prevent and reduce the spread of infectious diseases.

The study authors conclude, "It is important to implement strategies to prevent and reduce the spread of infectious diseases, including staying up to date with recommended vaccinations, including COVID-19 and influenza vaccines, practicing good hand hygiene and respiratory etiquette, staying home when sick, and improving indoor ventilation."

• In an update on global mpox activity today, the World Health Organization (WHO) said it received reports of 316 more cases, along with 2 more deaths, since its last update on June 24. Cases for the week ending July 9 were up 9.2% compared to the week before. Though cases continue at a low level in most of the world, Southeast Asia is experiencing a significant rise linked to activity in Thailand. The WHO also noted that the Democratic Republic of the Congo has reported a steady rise in suspected and confirmed infections since 2022, with sequencing suggesting that all viruses are related to clade 1, which is different than the clade 2 virus fueling the global outbreak. Tests on 156 samples from wild animals this year show that 64% were positive, though none were linked to zoonotic spillovers.
• Measles cases in the United Kingdom have risen steadily this year, with 126 infections reported so far, compared with 54 for all of 2022, the UK Health Security Agency said today. In a new risk assessment, it said modeling suggests that London is at most risk and without increases in measles, mumps, and rubella (MMR) vaccination rates, the city faces the risk of an outbreak that could reach 40,000 to 160,000 cases.
• Four African countries reported more polio cases this week, all involving circulating vaccine-derived poliovirus type 2 (cVDPV2), the Global Polio Eradication Initiative (GPEI) said in its latest weekly update. The countries are Benin, the Central African Republic (CAR), Kenya, and Niger. Benin's cases were added to its 2022 total, which is now at 13. The CAR cases were from three locations, pushing its total for the year to 10. Kenya's has 3 new cases, which are its first of the year and are genetically related and linked to a virus circulating in neighboring Somalia. Niger had 1 case that was added to its 2022 total, which is now 16.