Imported malaria cases at the Northern Immigration Detention Facility, Berrimah, Northern Territory

There have been no endemic cases of malaria recorded in the Northern Territory (NT) since 1962, and in 1981 the World Health Organisation declared the whole of Australia to be malaria free.1 Due to favourable environmental conditions and the presence of competent vectors of the disease, the area north of the 19? parallel in the NT is considered to be receptive to the re-introduction of malaria.2,3 Small outbreaks involving local transmission have been recorded in Queensland in 1986 and 2002.4 These illustrate the potential for malaria to be re-introduced into North Australia, and the importance of monitoring all imported malaria cases. Cases of imported malaria are diagnosed in the NT every year and public health procedures are in place to manage these, including entomological investigations and control protocols.5,6 Entomological investigations are usually triggered if a malaria patient has infective stages (gametocytes) of the malaria parasite in the blood. A patient with gametocytes can potentially infect a vector mosquito which, in turn, could potentially transmit the parasite to another person. Entomological investigations involve analysing historical trapping data from any nearby routine adult trap sites, and setting adult traps at the case house and the nearest mosquito harbourage site. These determine the levels of potential malaria vectors present in the area.7 If high numbers of vectors are detected in the traps, and the patient has been exposed to mosquito bites, a precautionary fogging operation may be recommended. The aim of the fogging operation is to knock down any adult malaria vectors that may be infective, thereby preventing the development of a local malaria transmission cycl