Mosquito-associated Dengue Virus, Key West, Florida, USA, 2010

outbreak of extended-spectrum beta-lacta-mase (ESBL)–producing Shigella sonnei at a day care nursery in Sakai City, 2006.tre study of Shigella diarrhoea in six Asian countries: disease burden, clinical manifestations, and microbiology.ing picture of shigellosis in southern Vietnam: shifting species dominance, an-timicrobial susceptibility and clinical presentation. profi les and growing fl uoroquinolone resistance in Shigella from Kolkata, In-dia (2001–2007): a hospital-based study. To the Editor: Except for sporadic cases along the Texas– Mexico border, local transmission of dengue virus (DENV) has not occurred in the contiguous United States since 1946. In 2009, DENV was diagnosed in a vacationer to Key West, Florida (1). Subsequently, 25 other cases were reported that year, transmission was confi rmed by detection of DENV serotype 1 (DENV-1) in local mosquitoes, and a random serosurvey showed evidence of recent DENV infection in 5.4% of Key West residents (1). Transmission continued in 2010, and an additional 63 cases were confi rmed (2). We used PCR amplifi cation and sequence analysis of virus identifi ed from mosquito collections during 2010 to identify the closest relatives, probable geographic origin, and divergence time of the Key West DENV. A total of 1,178 pools of Aedes aegypti mosquitoes were collected light traps, and stored at −80°C. Reverse transcription PCR was conducted on each pool by using primers designed to amplify all 4 DENV serotypes, followed by seminested PCR with serotype-specifi c primers (3). Results from 2 Key West mosquito pools collected on June 25 and 30 showed a positive fi rst-round reverse transcription PCR and a positive second-round PCR specifi c for DENV-1. A third Key West pool collected on August 27 showed only a positive second-round PCR specifi c for DENV-1. No other DENV serotypes were detected. DENV-1–specifi c primers (5′-GG GCCTTGAGACACCCAGG-3′ and 5′-CCTCCCATGCCTTCCCAAT GGC-3′) were used to amplify products encompassing the envelope (E) gene region and parts of the premembrane and nonstructural 1 genes from the pools collected on June 25 and 30. PCR products were sequenced by using amplifi cation and internal primers to provide double or triple coverage (Functional Biosciences, Madison, WI, USA). The sequences from these 2 pools were identical (GenBank accession no. JF519855). We used ClustalX (4) to align the Key West sequences with 175 nonredundant American DENV-1 sequences from the National Center for Biotechnology Information Virus Variation database (5) and 9 additional DENV-1 subgenomic E sequences from GenBank, which provided a comprehensive set of American DENV-1 …