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Catching Dengue in Florida
Abstract & Commentary
By Stan Deresinski, MD, FACP, Clinical Professor of Medicine, Stanford University; Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center. 1Dr. Deresinski serves on the speaker's bureau for Merck, Pharmacia, GlaxoSmithKline, Pfizer, Bayer, and Wyeth, and does research for Merck.This article originally appeared in the August 2010 issue of Infectious Disease Alert. It was peer reviewed by Timothy Jenkins, MD. Dr. Jenkins is Assistant Professor of Medicine, University of Colorado, Denver Health Sciences Center; he reports no financial relationships relevant to this field of study.
Synopsis: Autochthonous transmission of dengue virus infection has been detected in Florida.
Source: CDC. Locally acquired dengue Key West, Florida, 2009-2010. MMWR. 2010;59:577-581.
A physician in New York notified relevant county and state public health authorities in August 2009, of a patient from Rochester with suspected dengue, subsequently confirmed by CDC, whose only travel had been to Key West, FL. Confirmation at the CDC included both serum antibody testing and detection of dengue virus serotype 1 in cerebrospinal fluid. The patients subsequently completely recovered. Within two weeks, two residents of Key West who had not traveled were found to have dengue. Increased truck and aerial spraying and an intense door-to-door campaign to detect and eliminate mosquito breeding sites were instituted. Since enhanced and active surveillance was implemented by April 13, 2010, a total of 28 cases had been identified.
A serosurvey of residents found that 13 of 240 (5.4%) had evidence of recent dengue infection. Of 21 specimens from patients with suspected dengue submitted from Sept. 23, 2009-Nov. 27, 2009, nine (42.9%) were positive. An additional two cases were detected by review of medical records from three Key West Health facilities. The median age was 47 years (range, 15 -73 years), and approximately two-thirds were male. Fever occurred in all, and most had headache and myalgia, with or without arthralgia. Fifty percent had ocular pain and 54% had a skin rash. Six patients reported bleeding, including hematuria (4), gingival bleeding (2), vaginal bleeding (1), and epistaxis (1).
This is the first evidence of acquisition of dengue virus infection in the continental U.S. (dengue has occurred in Hawaii) since cases along the Texas-Mexico border in 1945 and the first in Florida since 1934. Dengue is endemic in Puerto Rico, the U.S. Virgin Islands, and U.S. territories in the Pacific. In 2007, more than 10,500 cases of dengue were reported among American citizens in the continental United States and its territories, mostly in Puerto Rico.1 These cases, and the serosurvey data, indicate that dengue has established a footlhold in Florida. The widespread presence of Aedes aegypti throughout the southern U.S. and Aedes albopictus in the southeastern U.S. provide continuing cause for concern regarding its reemergence throughout these areas.
Dengue was added to the National Notifiable Diseases Surveillance System list of nationally notifiable infectious diseases in 2009.1 Laboratory confirmaton of cases require one or more of the following:
Direct identification of the virus by culture or PCR (requires collection of the specimen within the first five days of illness).
Seroconversion between acute and convalescent serum specimens obtained within 30 days of symptom onset.
Detection of NS-1 antigen (the test is, however, not FDA-approved).
Virus-specific IgM antibody in cerebrospinal fluid.
The presence of dengue-specific IgM antibody in serum, in the presence of a compatible clinical picture, can only be considered probable (not confirmed) evidence of dengue because of the possibility of false-positive tests.
By the way, kudos to the anonymous infectious disease specialist in New York who made the diagnosis in the first case!