The Northern Territory of Australia

(NT) is currently regarded as free of the vectors of dengue [1]. The vector Aedes aegypti was present prior to the 1950s, but disappeared some time between 1956 and 1974, primarily as a result of the widespread reticulation of water during and soon after WorldWar II, and the coincidental removal of rainwater tanks [2–4]. Entomologists in the Department of Health operate an exotic mosquito surveillance program to detect any importation or establishment of either Ae. aegypti or Ae. albopictus [5], and recent incursions of Ae. aegypti in two locations within the NT (Tennant Creek in 2004 and on Groote Eylandt in 2006) were soon eliminated [1]. We present a case of dengue acquired in a region assumed to be free of dengue vectors. On 20 July 2010, a 34-year-old man presented to the public hospital in Darwin on the north coast of the NT with a one day history of rash and fever, retro-orbital headache, and prominent myalgia. He denied any travel outside the Northern Territory in the previous month. On examination he was febrile (38.3uC) and had an extensive blanching erythematous rash on his trunk, back, and upper and lower limbs. A serum sample referred to PathWest Laboratory Medicine WA and tested for NS1 antigen by a commercial enzyme immunoassay (Bio-Rad Platelia Dengue NS1 Ag) was strongly positive. Dengue virus (DENV) was detected using a type-specific semi-nested polymerase chain re-action (PCR). The first round used consen-sus outer primers that detect all four dengue serotypes, followed by a second round using type-specific inner primers [6]. A later sample showed a rise in haemagglutination inhibition antibody titre to.1:640, and was positive for IgM to DENV. Samples were also sent to a secon