Yesterday, Mexico confirmed a case of New World screwworm (NWS) in Sabinas Hidalgo, in a cow in Nuevo Leon state, less than 70 miles from the US-Mexico border.

The flesh-eating parasitic infection, carried by the Cochliomyia hominivorax fly, a type of blowfly, is causing a large outbreak in Central America. NWS can infect any warm-blooded animal, but human cases are rare. So far this year, US officials haven't confirmed any cases in animals.

"This is now the northernmost detection of NWS during this outbreak, and the one most threatening to the American cattle and livestock industry," the US Department of Agriculture (USDA) said in a news release. "Sabinas Hidalgo is located near the major highway from Monterrey, Nuevo Leon, to Laredo, Texas, which is one of the most heavily trafficked commercial thoroughfares in the world."

Closest previous detection 370 miles south

Preliminary reports from Mexico's National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) indicate that the latest infected animal, an 8-month-old cow, had recently been moved to a certified feedlot in Nuevo Leon from a southern Mexico area with active NWS cases. The previous northernmost identification was reported on July 9 in Veracruz, roughly 370 miles south of Sabinas Hidalgo.

We are firmly executing our five-pronged plan and will take decisive action to protect our borders, even in the absence of cooperation.

US ports remain closed to imports of cattle, bison, and horses from Mexico.

"We are firmly executing our five-pronged plan and will take decisive action to protect our borders, even in the absence of cooperation," the USDA said. "Furthermore, we will pursue aggressive measures against anyone who harms American livestock."

The United States and Mexico have been monitoring nearly 8,000 traps in Texas, Arizona, and New Mexico since July. More than 13,000 screening samples have been submitted, without detection of NWS flies. 

Among other efforts, the USDA said it has dedicated $100 million to enhance sterile-fly production and develop tools such as advanced traps, lures, and therapeutics. The US Animal and Plant Health Inspection Service (APHIS) has updated its national disease-response registry and is training federal, state, tribal, and veterinary partners, according to the release.

A new study by Chinese researchers describes the burden and historic trends of antimicrobial resistance (AMR) in China over the past three decades. The findings were published last week in BMC Medicine.

Using data collected for a study on the global burden of AMR from 1990 to 2021, researchers from Huazhong University of Science and Technology conducted the first nationwide assessment of the AMR burden in China, covering 12 infectious syndromes and 22 bacterial pathogens. To estimate deaths directly attributable to resistant bacteria, they considered a scenario in which those infections were replaced by antibiotic-susceptible infections. To estimate associated deaths, they considered a scenario in which resistant infections were replaced by no infection.

In 2021, 160,268 deaths were attributable to AMR and 711,852 were associated with AMR, accounting for 14% of global deaths attributable to AMR and 15% of deaths associated with AMR. Among the 12 infectious syndromes analyzed, bloodstream infections accounted for the most AMR-attributable deaths in 2021 (74,119), followed by lower respiratory infections (60,839) and peritoneal and intra-abdominal infections (11,827). 

Bloodstream infections were also the infectious syndrome with the greatest increase in deaths over the study period. The pathogen-drug with highest number of AMR-attributable deaths in 2021 was methicillin-resistant Staphylococcus aureus.

Deaths declining in young kids, rising in elderly

Over the 31-year study period, two trends became clear: The number of AMR-attributable deaths in children under 5 declined by 95%, while AMR-attributable deaths among people aged 65 and over rose by 68%. 

The study authors say the reduction in AMR mortality in young children can be attributed in part to the introduction and expansion of pneumococcal vaccination since 1998, along with improvements in water, sanitation, and hygiene in China. The increased mortality among those 65 and older, on the other hand, is likely a reflection of chronic health issues and weakened immune systems among China's fast-aging population.

"Therefore, regardless of whether the causative pathogens are drug-sensitive or drug-resistant, the elderly are particularly vulnerable to infectious diseases," they wrote.

The authors conclude that vaccines, reducing antibiotic misuse, and developing new antibiotics should be combined to address the health threat of AMR.