A new study in The Lancet Infectious Diseases shows the Oropouche virus may be more widespread in Latin America than previously thought, and as many as 1 in 10 people living in the region have likely experienced a prior infection with the pathogen.

First identified in the 1950s, the virus causes nonspecific symptoms that are usually mild, including fever, chills, headache, pain in the limbs and, in some cases, nausea and skin rashes. The virus is mainly spread by biting midges and possibly some Culex mosquitoes.

But since a large outbreak began in 2023, more case reports of severe complications of infection in pregnant women and at least two deaths have been reported among more than 20,000 cases seen in Latin and Caribbean countries. 

Climate, rain behind uptick 

To understand the shift, researchers from Berlin’s Charite Hospital analyzed more than 9,400 blood samples collected from healthy and sick people in Bolivia, Brazil, Colombia, Costa Rica, Ecuador and Peru between 2001 and 2022. Antibodies against the virus were present in 6.3% of the samples. Samples taken from people living in the Amazon region showed a 10% prevalence of antibodies, while only 2% of samples from Costa Rica showed antibodies. 

Moreover, rain and weather patterns had a direct influence on the number of Oropoche virus infections, suggesting it was climate and environment — and not viral changes — fueling the current outbreak. 

We therefore assume that the current Oropouche outbreak has been fueled by weather phenomenons like El Niño.

“We therefore assume that the current Oropouche outbreak has been fueled by weather phenomenons like El Niño,” said Jan Felix Drexler, PhD, head of the virus epidemiology laboratory at Charite said in a press release from Charite. "By contrast, we have not found evidence that changing properties of the virus could provide an alternative explanation for the high case count at present. I think it’s possible that Oropouche virus will become even more widespread in the future as climate change progresses.”

Chronic wasting disease (CWD) has been found in five more Iowa counties, the Iowa Department of Natural Resources (IDNR) told the Cedar Rapids–based Gazette.

The newly affected counties, identified during the April 2024 to March 2025 CWD surveillance season, include Cedar, Davis, Shelby, Story, and Wapello. The new detections bring the CWD-positive county total in Iowa to 29. Cases in Pottawattamie and Fremont counties were reported in January 2025.

The season case total was 135 of 5,493 (2.5%) deer tested, up from 128 in 2023-24, 96 in 2022-23, 52 in 2021-22, and 21 in 2020-21. In total, 521 of the 106,000 (0.5%) Iowa deer tested for CWD since 2022 have had the fatal neurologic disease of cervids such as deer, moose, and elk.

Officials advise against eating CWD-positive venison

CWD is a transmissible spongiform encephalopathy—the same disease group as bovine spongiform encephalopathy, or "mad cow" disease. These diseases are caused by abnormally folded infectious proteins called prions. 

Human CWD cases haven't been reported, but health officials recommend not consuming the meat of CWD-positive animals and advise hunters who harvest deer in CWD-endemic areas to have their deer tested before eating the venison. 

A study of infants hospitalized in US neonatal intensive care units (NICUs) shows that low–birth-weight infants are highly vulnerable to invasive Staphylococcus aureus infections, researchers reported yesterday in JAMA Pediatrics.

Using data from a national convenience sample of 315 US NICUs from 2016 through 2021, researchers from Johns Hopkins University School of Medicine found that 1,724 (0.4%) of 468,201 infants experienced a late-onset invasive S aureus infection during their NICU admission, with a total of 1,762 events, most of which were bloodstream infections (85.4%). 

Most infants with invasive infections were 32 weeks' gestational age or younger (80.9%), very low birth weight (VLBW) (76.5%), and/or had a central line during their hospital stay (87.5%). 

The incidence rate was 37.6 infections per 10,000 hospitalized infants, and 12.1% of infected infants died. Birth weight was inversely correlated with incidence, with VLBW infants—who comprised only 12.7% of the total cohort—experiencing a more than 20-fold higher incidence relative to infants born weighing at least 1,500 grams (3.3 pounds; 227.1 vs 10.1 infections per 10,000 infants). In addition, most deaths following invasive infection (90.4%) occurred in VLBW infants.

The estimated absolute difference in 7-day all-cause mortality in infants with an invasive S aureus infection compared with matched controls was 5.3% (95% confidence interval [CI], 3.8% to 6.8%). 

Novel approaches needed to reduce incidence in VLBW infants

The study authors note that the incidence rate of invasive S aureus infection in US NICUs has declined from the previous estimate of 44.8 infections per 10,000 hospitalized infants, which was based on data from 1997 to 2012. They attribute the decline to an expansion of S aureus prevention programs in US NICUs. But the incidence rate among VLBW infants has remained relatively stable. 

"Late-onset invasive S aureus is an important contributor to disease burden in hospitalized infants, especially among infants with VLBW," they wrote. "Future research directions for infection prevention and control in the NICU should focus on investigating novel approaches to limit disease burden in infants with VLBW to decrease S aureus–attributable morbidity and mortality."

China has detected three more H9N2 avian flu cases, which involved two children and one adult from three different provinces, according to a weekly avian flu update from Hong Kong’s Centre for Health Protection (CHP).

The virus is known to circulate in poultry in China and other parts of Asia, and sporadic human infections continue to be reported, mainly from China. Infections are typically reported in children who usually experience mild infections. However, infections can be severe.

Illness onsets in February and March

One of the patients is a 7-year-old girl from Henan province whose symptoms began on February 11. Another infection also involved a child, a 5-year-old boy from Guangxi province who became ill on March 3. 

The third patient is a 35-year-old woman from Guizhou province who got sick on March 10. The CHP report didn’t note how the patients contracted the virus, but many H9N2 infections in the past were linked to exposure to poultry or poultry environments. The report didn’t list the conditions for the patients.

The new cases lift China’s H9N2 total for the year to five. In 2024, the country reported 11 cases.