Building the Future of Biodefense

Recommendation: Usutu virus is a mosquito-borne virus similar to West Nile virus, which primarily causes disease in birds but can infect people. The emergence of the Usutu virus in Europe does not require new actions. Organizations should continue to take actions to reduce mosquito populations and habitats at their facilities. This includes eliminating sources of standing water and applying insecticides to outdoor water storage containers. Employees can reduce infection risk by wearing clothing that covers skin, using mosquito repellents, and emptying standing water.

Situation: The Blood and Tissue Bank of the Balearics (BSTIB) identified Spain’s 1st indigenous case of Usutu virus in a blood donor. Detected in July 2024 in Mallorca, Spain, the initial sample showed reactivity in routine tests for West Nile virus. After being sent to the National Reference Laboratory for Arboviruses, specific and neutralization tests confirmed infection as Usutu virus, an emerging arbovirus in Europe transmitted by mosquitoes of the Culex genus. Two additional cases were later confirmed in Catalonia. All 3 cases had no recent travel, indicating local virus circulation. The findings, published in Transfusion, highlight that standard West Nile virus screening can also detect Usutu virus, enhancing transfusion safety during periods of high mosquito activity. [Confidence: Very High]

Recommendation: This death serves as a reminder that influenza can be a severe disease. Influenza and other respiratory diseases are expected to impact employee absenteeism due to illness or caregiving duties. Organizations in California should provide flexible work schedules to support employees making vaccine appointments for themselves or family members.

Situation: Los Angeles County health officials confirmed their 1st influenza-related death of the 2025-2026 respiratory season. This individual was an older resident with underlying health conditions and had not received an influenza vaccination this season. Influenza activity in the county is currently low but is expected to increase as the holidays approach, with more travel and indoor gatherings. Health officials advised the public to review their vaccination status and to get vaccinated, as well as practice respiratory hygiene. [Confidence: Very High]

Recommendation: Infection of free-living amoebas in warm freshwater can cause amebic meningoencephalitis, which can present as 2 highly fatal types: primary amebic meningoencephalitis or granulomatous amebic encephalitis. Free-living amoebas can include Naegleria fowleri, Acanthamoeba (several species), Sappinia pedata, and Balamuthia mandrillaris. Organizations in Kerala, India, should ensure employees have access to potable water. Employees working or living in Kerala should avoid drinking, swimming, or bathing in stagnant freshwater.

Situation: The 2-month-long annual Sabarimaya pilgrimage started this week in Kerala, India. An aspect of the pilgrimage includes ritual purifying baths in the Pamba River. Media sources reported that both Kerala and Karnataka issued health advisories ahead of the pilgrimage, cautioning pilgrims to avoid letting river water enter their noses. This advice follows an atypical rise in amebic meningoencephalitis cases in Kerala over recent months. 170 cases were confirmed, including 40 deaths, in Kerala so far this year. Local officials implemented bans in August and September on swimming in untreated water as well as state-wide water chlorination drives to minimize the risk of further cases (see PHC alerts on 9/9 and 8/26). [Confidence: Very High]

Recommendation: Peak dengue season usually spans June to November in Florida, but cases can occur all year, with warm weather prolonging the season. Organizations should continue to reduce mosquito populations at their facilities by eliminating standing water. Employees can take steps to prevent mosquito bites by wearing protective clothing, using insect repellent, and eliminating standing water near their homes.

Situation: Florida reported 2 new locally acquired dengue cases this week, totaling 58 human cases this year. Most cases were reported in Brevard County (35), followed by Miami-Dade (21), Hillsborough (1), and Pasco (1) Counties. Additionally, 355 imported dengue cases were reported so far this year, mostly from Cuba (252). Florida also reported its 1st travel-associated Oropouche fever case this year, involving a Miami-Dade resident who had recent international travel to Cuba. Cuba is experiencing high mosquito-borne disease activity in recent weeks and months (see PHC 11/13). [Confidence: Very High]