Building the Future of Biodefense

Recommendation: Sporadic cases of locally acquired dengue have been reported in California, but it is generally rare. The peak mosquito season in Los Angeles County is from June to November, with warm weather prolonging the season. Organizations should 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: Health officials confirmed a locally acquired case of dengue in a resident of the San Gabriel Valley, Los Angeles County, with no history of domestic or international travel. This is the 1st locally acquired case reported in Los Angeles County this year. Enhanced vector surveillance activities were implemented, including increased mosquito trapping and monitoring activities. The overall risk of sustained local dengue transmission in the county remains low, but this case highlights the presence of infected mosquitoes in the area. In 2024, 14 locally transmitted dengue cases were identified in the county. [Confidence: Very High]

Recommendation: Local chikungunya transmission is very rare in the mainland US, with 13 cases detected in Florida and Texas in 2014-15, though it more commonly occurs in some US territories. Before this detection, no cases had been reported in the US states and US territories since 2019. Organizations in Nassau County, New York, should reduce mosquito populations at their facilities by eliminating standing water. Employees can prevent mosquito bites by wearing protective clothing, using insect repellent, and eliminating standing water near their homes.

Situation: New York confirmed its 1st ever locally acquired chikungunya case this week, an update to the PHC alert on 9/26. The individual resides in Nassau County on Long Island. The exact location of exposure is not known at this time, but it was classified as locally acquired based on current information. The Aedes albopictus mosquito, a vector of chikungunya, is present in downstate New York. For chikungunya transmission to occur, the mosquito must first bite an infected individual before transmitting the disease to others. 3 and 8 imported chikungunya cases were reported in the state (outside of New York City) and in New York City, respectively, so far this year. Chikungunya has not been detected in any New York mosquito samples yet. Health officials stated the current risk is very low, especially as mosquito activity is on the decline with decreasing temperatures. [Confidence: Very High]

Recommendation: China reports avian influenza H9N2 human cases sporadically. Historically, the risk of an outbreak has been extremely low since human-to-human transmission does not usually occur. Employees in or traveling to China should avoid live-animal markets and not have contact with or consume diseased poultry.

Situation: Hong Kong health officials reported 2 new H9N2 human cases in mainland China as of 10/11, with onset dates in September. The H9N2 cases were detected in Hunan and Jiangxi Provinces. One case was in a 2-year-old, and the other was in a 70-year-old. 17 cases and no deaths have been reported in the past 6 months. [Confidence: Very High]