Investigation of the First Case of Dengue Virus Infection Acquired in Western Australia in Seven Decades: Evidence of Importation of Infected Mosquitoes?

Abstract

In October 2013, a locally-acquired case of dengue virus (DENV) infection was reported in Western Australia (WA) where local dengue transmission has not occurred for over 70 years. Laboratory testing confirmed recent DENV infection and the case demonstrated a clinically compatible illness. The infection was most likely acquired in the Pilbara region in the northwest of WA. Follow up investigations did not detect any other locally-acquired dengue cases or any known dengue vector species in the local region, despite intensive adult and larval mosquito surveillance, both immediately after the case was notified in October 2013 and after the start of the wet season in January 2014. The mechanism of infection with DENV in this case cannot be confirmed. However, it most likely followed a bite from a single infected mosquito vector that was transiently introduced into the Pilbara region but failed to establish a local breeding population. This case highlights the public health importance of maintaining surveillance efforts to ensure that any incursions of dengue vectors into WA are promptly identified and do not become established, particularly given the large numbers of viraemic dengue fever cases imported into WA by travellers returning from dengue-endemic regions.

A Survey of Knowledge, Attitudes, and Practices in Relation to Mosquitoes and Mosquito-Borne Disease in Western Australia

“…All notified malaria cases and all except one dengue case were reported in travelers who acquired the infection overseas and were diagnosed after returning to WA (Department of Health, unpublished data). The first case of dengue believed to be locally acquired in WA for over 70 years was notified in October 2013 from Point Sampson in the Pilbara region ( 17 ). This was thought to have resulted from the temporary incursion of an infected dengue vector mosquito that failed to establish a local population ( 17 ).…”

“…The first case of dengue believed to be locally acquired in WA for over 70 years was notified in October 2013 from Point Sampson in the Pilbara region ( 17 ). This was thought to have resulted from the temporary incursion of an infected dengue vector mosquito that failed to establish a local population ( 17 ). The majority of the overseas acquired dengue cases were from individuals who traveled to Bali and Indonesia, and the majority of cases of malaria were among travelers to, and refugees from, African countries (Department of Health, unpublished data).…”

Assessing the Risk of Exotic Mosquito Incursion through an International Seaport, Newcastle, NSW, Australia

“…There have been recent examples of “airport dengue” in the Northern Territory, where an infected mosquito thought to have arrived in an aircraft infected an individual working in an industrial area adjacent to Darwin airport [ 63 ]. Similarly, a case of DENV was reported in a resident without overseas travel that was suspected to have been caused by an infected mosquito arriving from overseas in an aircraft and transported in personal belongings [ 64 ]. There is likely to be a lower risk of infected mosquitoes arriving with vessels at the Port of Newcastle but with the potential that crew, infected prior to departure, are viraemic during travel, there is a small possibility that infected mosquitoes may be present on arrival.…”

Predicting arboviral disease emergence using Bayesian networks: a case study of dengue virus in Western Australia

“…After the Second World War, dengue was successfully eradicated due to the introduction of reticulated water systems and the reduction of open rainwater tanks, among several other public health initiatives [34]. Currently, diagnoses of dengue infection in WA are only in travellers who had been infected elsewhere [35]. Nonetheless, DENV and its vectors have the potential of returning to WA should conditions allow.…”