News Scan for Oct 19, 2022

News brief

Prolonged COVID test positivity in symptomatic, Omicron BA.2 infections

Among a group of vaccinated college athletes who tested positive for COVID-19 and underwent rapid antigen testing 7 days later, 27% were still positive—a proportion that climbed to 35% in symptomatic athletes and 40% in those infected with the Omicron BA.2 subvariant.

The findings, published yesterday in JAMA Network Open, suggest that rapid antigen testing may help prevent still-positive people from leaving isolation while still infectious, the Stanford University authors said. The US Centers for Disease Control and Prevention (CDC) currently recommend 5 days of isolation followed by 5 days of wearing a well-fitting mask after a COVID-19 diagnosis.

The researchers studied Stanford athletes who tested positive for COVID-19 from Jan 3 to May 6, 2022, and had received the primary series of the Pfizer/BioNTech, Moderna, or Johnson & Johnson vaccines at least 2 weeks earlier. Seven days later, the athletes began rapid antigen testing to determine if isolation was still needed. They also completed symptom questionnaires.

According to campus wastewater data, 68% of infections occurred when the BA.1 variant was dominant, and 32% occurred during BA.2 dominance.

A total of 264 athletes had 268 infections, with 66% of them symptomatic. Average age was 20.1 years, and 53% were women. Most students (representing 248 infections) underwent rapid antigen testing on day 7, and 27% of them were still positive. Students were significantly more likely to test positive on day 7 if they had COVID-19 symptoms (35% vs 11% of asymptomatic students) and if they were infected with Omicron BA.2 (40% vs 21% with BA.1 infections).

On day 8, 47% of 76 tests were negative, as were 35% of 43 tests on day 9. The 28 athletes who tested positive on day 9 were allowed to leave isolation the next day without further testing.

"These findings could call into question the current guidelines allowing for exit of isolation after 5 days without requiring additional testing to prevent further spread, particularly in the setting of newer variants, such as BA.4 and BA.5," the researchers wrote.
Oct 18 JAMA Netw Open study


Study finds extensive antibiotic use on poultry farms in Bangladesh

A cross-sectional survey revealed extensive antibiotic use in commercial chicken production in Bangladesh, researchers reported this week in PLOS One.

To assess antibiotic use on chicken farms in Bangladesh, where commercial chicken production has been expanding to meet rising demand, an international team of researchers surveyed chicken farms across the country. They collected data on demographics, poultry species, antibiotic use preceding the interview, and type of antibiotics used. They also measured the association between antibiotic use and factors related to the characteristics of the farms and farmers.

Among the 768 farms surveyed, 41% reported using antibiotics within the previous 24 hours, 45% reported antibiotic use within the previous 72 hours, and 86% reported antibiotic use within the previous 2 weeks. In all timeframes, antibiotic use was more common among broiler and Sonali (a crossbreed chicken) farms than layer farms. Almost all farms (98%) had used antibiotics since the start of their production cycle. Oxytetracycline, doxycycline, ciprofloxacin, and amoxicillin were the most frequently used antibiotics.

Antibiotics were reported to be used for both treatment and prophylactic (disease prevention) purposes on most farms (57% to 67%), with many farmers saying they used antibiotics for fattening purposes. Antibiotic usage was mainly advised by veterinary practitioners (45% to 71%, depending on production type), followed by feed dealers (21% to 40%) and farmers (7% to 13%).

Multivariable analysis indicated that the use of antibiotics in the 24 hours preceding an interview was significantly associated with the occurrence of any illnesses in broilers (adjusted odds ratio [aOR], 41.22 ; 95% confidence interval [CI], 13.63 to 124.62), layers (aOR, 36.45; 95% CI, 9.52 to 139.43), and Sonali chickens (aOR, 28.47; 95% CI, 4.97 to 162.97).

"The findings from this study emphasize that the improvement of chicken health through good farming practices can help to reduce antibiotic use and the consequential development of antimicrobial resistance," the study authors wrote. "Regular monitoring of antibiotic usage, educating farmers, drug sellers, and feed dealers about effective use of antibiotics, and restricting ease of access to antibiotics, may also be useful to reduce unnecessary use of antibiotics in commercial chicken production systems."
Oct 17 PLOS One study


Unprecedented outbreaks prompt shift to 1-dose cholera vaccine strategy

An unprecedented rise in cholera outbreaks straining the global cholera vaccine supply has prompted the International Coordinating Group (ICG), which manages emergency cholera vaccine supplies, to temporarily suspend the standard two-dose regimen, the World Health Organization (WHO) announced today. To stretch vaccine supplies, outbreak response campaigns for now will use a single dose.

Since January, 29 countries have reported outbreaks, including Haiti, Malawi, and Syria, which are experiencing large outbreaks. For comparison, the WHO said that over the previous 5 years fewer than 20 countries on average reported outbreaks. The WHO said cholera outbreaks are becoming more numerous, widespread, and severe due to floods, droughts, population movements, and other fators that limit access to clean water.

The WHO said the one-dose strategy is known to be effective, though evidence is limited on the duration of protection. Also, protection with one dose appears to be much lower in children. Officials added that the benefit of supplying one dose still outweighs no doses and will allow more people to be protected in the near term.

In a press release today, Daniela Garone, MD, international medical coordinator for Doctors Without Borders (MSF) said, "This last-resort decision is a way to avoid making the impossible choice of sending doses to one country over another. Single dose vaccination will provide shorter protection, but it is the fair and equitable way to try to protect as many people as possible as we face simultaneous cholera outbreaks."

Of 36 million doses expected to be produced in 2022, 24 million have already been shipped for reactive (83%) and preventive (17%) campaigns. The International Coordinating Group (ICG) has approved an additional 8 million doses for the second round of emergency vaccination in four countries, underscoring the dire shortage of the vaccine. Producers are already making vaccine at maximum capacity, leaving no short-term solutions to increase production.
Oct 19 WHO press release
Oct 19 MSF press release


Two new multistate Salmonella outbreaks linked to bearded dragons

The CDC yesterday said it and its state health partners are investigating two multistate Salmonella outbreaks linked to pet bearded dragons. The outbreaks involve two different subtypes that have sickened 23 people in 15 states since the end of March. Ten of the illnesses are from Salmonella Vitkin, and 13 are linked to Salmonella IIIb 61:z52:z53.

Pet bearded dragons have been the source of several Salmonella outbreaks in the past, including one announced in January that was due to Salmonella Uganda and sickened 56 people from 26 states.

In the latest outbreak, the CDC has used PulseNet, the national sequencing database, to identify related cases. Of people who were sick with Salmonella Vitkin, six reported contact with bearded dragons. Of those, four had purchased them from different pet stores. Investigators are exploring if there is a common supplier. Officials are investigating a similar source of the animals bought by five people infected with the other strain.

Utah officials have identified the outbreak strain from samples collected from a sick patient's pet and its habitat.

Of the 23 patients, 10 are children younger than 1 year old. Of 17 people with available information, 8 were hospitalized. No deaths have been reported. The latest illness onset was Sep 13. Sequencing from 22 patient samples predicted resistance to ciprofloxacin.

The CDC said it working with the bearded dragon industry and the pet industry to reduce the bacteria in bearded dragons. It urged people to wash their hands after handling the animals and to avoid kissing or snuggling with them. Also, the CDC advised pet owners to keep the dragons out of the kitchen and limit young children's contact with the animals.
Oct 18 CDC outbreak announcement
Jun 16 CDC Salmonella
Uganda outbreak information

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