Three locally acquired cases of dengue fever have been confirmed
in Cairns, Australia. Dengue serotype 2 has been confirmed in one of the cases
(Brian Montgomery, Scientific Officer, Tropical Public Health Unit, Queensland
Heath, personal communication, 5 March 2003).
All three patients are residents of Cairns and became ill in mid February
2003. One of them also had a connection with Mareeba (approximately 40 km
west of Cairns) during the infectious period (1). The primary case has not
yet been identified, and there is a possibility that more people may be
infected in Cairns or Mareeba. The Dengue Action Response Team (DART) is
carrying out extensive mosquito surveillance and eradication in line with
the protocols established in the Dengue Fever Management Plan for North
Queensland 2000-2005 (2).
Dengue is not endemic in Queensland but the mosquito vector Aedes aegypti,
is common in north Queensland. Sporadic outbreaks occur when the virus is
introduced via international travellers or residents returning from endemic
countries, most typically, Asia and the south Pacific. There have been three
large outbreaks of dengue in north Queensland since 1992, all originating
from imported cases; one in Townsville (1992-3), involving 900 cases, one
in the Torres Strait and Cairns (1996-7), involving 208 cases, and the third
in Cairns, Mossman, and Port Douglas (2000), involving 498 cases (2).
Prevention of dengue focuses around avoidance of mosquito bites. Advice
to European travellers to Queensland would include the use of an appropriate
insect repellent (containing Diethyltoluamide (DEET)) and to wear long sleeved
shirts and long trousers to limit skin available for bites. Aedes aegypti
mosquitoes bite during the day (particularly around dawn and dusk) and may
be found both outdoors and indoors. Spraying rooms with a knockdown insecticide
and using an electrical pyrethroid vaporiser will help to control mosquitoes
indoors. Air conditioning also tends to make mosquitoes less active. Sleeping
under an impregnated mosquito net will minimise mosquito bites from dawn
All travellers to Australia should take measures to prevent bites to protect
themselves against other mosquito-borne diseases such as Ross River virus,
Barmah Forest virus, Kunjin virus, and Murray Valley Encephalitis.