Argentina reports rare human Western equine encephalitis infection

News brief

Argentina has reported a rare human case of Western equine encephalitis (WEE), the first in more than two decades, the World Health Organization (WHO) said yesterday. The announcement follows a recent warning from the Pan American Health Organization (PAHO) about the potential threat to human health following detections of WEE in horses in several Argentina locations as well as some sites in Uruguay.

Culex tarsalis
Don Loarie/Flickr cc

Birds are the main hosts of the virus, which can pass to horses and, occasionally, humans through infected mosquitoes. In humans, WEE infections range from the asymptomatic or moderate level to a severe form that includes aseptic meningitis and encephalitis. People who work or recreate outdoors in areas where the disease is endemic or outbreaks are occurring in animals are at higher risk of disease.

Argentina's last cases occurred in 1982 and 1983 in equine outbreak settings. It reported an isolated case in 1996.

The latest patient is man from Santa Fe province whose symptoms, such as headache, myalgia, dizziness, and fever, began on November 19. He was hospitalized on November 24 and was admitted to the intensive care unit and placed on mechanical ventilation during the 12-day stay. He was discharged to home monitoring on December 20.

An investigation into the source of his illness found that the man was a rural worker in an area where horses had tested positive for WEE infection.

Increased incidence of invasive S aureus seen more in Black patients during COVID

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CDC / Meredith Newlove

A population-based study in Atlanta highlights the impact of community COVID-19 incidence on racial disparities in invasive Staphylococcus aureus infections, researchers reported this week in Infection Control & Hospital Epidemiology.

Using data from the Georgia Emerging Infections Program, which conducts active population-based surveillance for invasive S aureus infections in the eight-county Atlanta metropolitan area, researchers from Emory University estimated race- and ethnicity-specific incidence rates of S aureus and COVID-19 for mutually exclusive groups of Hispanic, Black, White, and other non-Hispanic groups.

Their aim was to determine whether the well-documented racial and ethnic disparities in COVID-19–related outcomes influenced invasive S aureus incidence, which is higher among Black patients than White patients.

Statistically significant increase in Black patients

From March 2020 through December 2021, there were 4,062 4,062 invasive S aureus infections (including methicillin-resistant and methicillin-susceptible S aureus [MRSA and MSSA]) and 454,489 COVID-19 cases across all counties.

While the correlation between county-level monthly COVID-19 incidence and invasive S aureus incidence was weak, it retained statistical significance among Black patients. The researchers estimated an 8% increase in the rate of invasive S aureus incidence per quartile increase in county-specific COVID-19, but for Black patients, the increase was 9%, compared with a 5% increase among White patients. Hospital-onset cases increased most, at 16% per quartile increase in COVID-19.

"Our data expand on previous findings and suggest that community COVID-19 infection burden is associated [with] not only hospital-onset MRSA bloodstream infection risk but also MSSA bloodstream infection risk, as well as community-onset S. aureus bloodstream infection risk," the study authors wrote. "Moreover, this increased rate affected Black residents 60% more than White residents."

Indonesia and Mauritania report vaccine-derived polio cases

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Two countries reported new polio cases this week, including Mauritania, which reported its first circulating vaccine-derived poliovirus type 2 (cVDPV2) case of the year, according the latest weekly update from the Global Polio Eradication Initiative (GPEI).

Indonesia's patient is from Central Java province on the island of Java, and the illness marks the country's fourth such case of the year.

Meanwhile, the cVDPV2 case from Mauritania was detected in the Nouakchott Nord region in the southwest of the country. The area includes the country's capital and largest city, Nouakchott.

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