A systematic review yesterday in PLOS Medicine found that antibiotics significantly reduced bacterial diversity and altered the gut microbiome of infants in low- and middle-income countries (LMICs).

Conducted by researchers from the University of Amsterdam and the Centre for Infectious Disease Research in Zambia, the systematic review examined studies that reported on the effects of antibiotics on the gut microbiota of children under age 2 in LMICs and profiled resistance genes. Of 92 studies assessed, 10 met the eligibility criteria, all of which were randomized controlled trials comparing children who received antibiotics with those who received placebo.

The studies were conducted in South Africa (1), Niger (4), Burkina Faso (3), India (1), and Malawi (1) and assessed a limited number of antibiotics, including cotrimoxazole (3 studies), azithromycin (9 studies), and amoxicillin (2 studies).

Overall, the studies showed that the children who received antibiotics had reduced gut microbiome diversity and increased antibiotic-specific resistance gene abundance, particularly the children who received azithromycin, in whom macrolide resistance was seen as early as 5 days post-treatment and persisted for up to 6 months. Studies on children who participated in biannual mass azithromycin distribution, a strategy that has been used in several African countries, also had a greater abundance of non-macrolide resistance determinants.

Research initiatives are urgently needed to understand how antibiotic perturbations on the microbiome translate into health benefits or risk of disease.

The authors say the findings are limited by the paucity of studies, and that several questions remain. Among them are whether depletion of commensal microbiota renders children more susceptible to infections, whether antibiotic use puts children at risk for infection with antimicrobial-resistant (AMR) pathogens, and whether disruption of the infant microbiome translates into short- and long-term health issues.

"Given the vulnerability of children in LMIC to infections, the frequency of antibiotic consumption in their early lives, and the growing global threat of infections with AMR, harmonized research initiatives are urgently needed to understand how antibiotic perturbations on the microbiome translate into health benefits or risk of disease," they wrote.

Flu activity remains mixed in the Southern Hemisphere, with increasing activity in a region that includes Australia and some declines in South America's temperate countries, the World Health Organization (WHO) said this week. The update covers roughly the first half of June.

In Australia, clinic visits for flu increased overall, but with differences across states and territories. In South America, flu declined in Chile but rose to a moderate level in Argentina, with smaller increases in Paraguay and Uruguay. In tropical parts of South America, flu activity declined in multiple countries, including Brazil and Bolivia.

Flu activity increased in some Central American countries, including El Salvador, Guatemala, Honduras, Nicaragua, and Panama.

South Africa's flu levels trended downward, with pneumonia still tracking at a moderate level. Flu activity remained low or stable in other regions, though levels rose in the Philippines.

At national flu labs over the reporting period, 62.9% of positive respiratory samples were influenza A, and, of subtyped influenza A samples, 73.6% were the 2009 H1N1 virus. All influenza B viruses that were subtyped belonged to the Victoria lineage.

Following Brazil's first detection of highly pathogenic H5N1 avian flu in wild birds in early May, the country has now reported its first outbreak involving poultry, a pattern that has played out in multiple countries as the virus continues its southward spread.

The virus struck backyard chickens and ducks in the city of Serra in Espirito Santo state in southeastern Brazil, the same area where H5N1 first turned up in seabirds, Merco Press reported, citing agriculture officials. The detection didn't affect a commercial operation, so it doesn't diminish Brazil's trade status. The country is the world's largest poultry producer.

More H5N1 in Polish cats, US wild birds, US mammals

Following the detection of H5N1 in 9 cat deaths in Poland, the country's chief veterinarian today announced several more detections in more cities, raising the total at least 16 in six cities, according to an official statement translated and posted by Avian Flu Diary, an infectious disease news blog.

Tests are under way to further characterize the virus, after preliminary results suggested it was different from the one infecting wild birds in the nation. Also, the source of the virus infecting cats isn't clear, and a media report posted by FluTrackers, an infectious disease news message board, said two of the affected cats had been kept indoors.

In US developments, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) reported 7 more H5N1 detections in wild birds, bringing the total to 7,105. They included terns, gadwalls, a gull, and a red-tailed hawk. Also, APHIS reported 2 more H5N1 detections in mammals, raising the total to 198. Both involved red foxes, one in Michigan and the other in Maine.

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  The Colorado Department of Public Health (CDPH) and its partners in Montezuma County are investigating plague activity following a report of a Yersinia pestis infection in an adult from the county, the groups said in a statement. The exposure likely occurred on private property. Montezuma County is located in the southwest corner of Colorado. Sporadic cases are reported from the state each year, and officials urged the public to take precautions, including protecting pets from fleas and staying out of areas where wild rodents live.
• The World Health Organization's (WHO's) annual report on diseases from unsafe water, sanitation, and hygiene shows improvements over the past decade, but it is uneven and insufficient, Maria Neira, MD, who directs the WHO department of environment, climate change, and health, said in a statement. The new report said half of the world's population lacks access to safe water, sanitation, and hygiene, and that improvement could have prevented at least 1.4 million deaths and 74 million disability-adjusted life-years in 2019. Much of the burden comes from diarrheal diseases, with two regions—Africa and Southeast Asia—most affected.
• Blue Water Biotech, a Cincinnati-based pharmaceutical company, today announced promising preclinical trial results for its new mpox vaccine candidate, which is made on a norovirus-like particle platform. Initial data show that mice were able to mount an immune response after vaccination and that antibodies neutralized the vaccina virus. In a statement, the company said it will move forward with further preclinical development.