In Alice Springs, the Ilparpa Swamp is the most productive mosquito breeding site for the common banded mosquito, Culex annulirostris. The swamp is of major public health concern due to potential outbreaks of Murray Valley encephalitis (MVE), with the virus transmitted by this mosquito. In 2001, extensive flooding and two MVEV disease cases led to the first aerial control of Ilparpa Swamp, with aerial control also carried out in 2010. In January 2015, Alice Springs again received heavy rainfall associated with monsoonal activity in the north-east, indicating a possible MVEV disease risk. DoH responded by carrying out another aerial control operation in Ilparpa Swamp, with the successful operation jointly funded by the Power and Water Corporation and the Department of Lands & Planning.

Australian encephalitis (AE) is an arboviral (ie arthropod borne or in this case more specifically mosquito borne) disease caused predominantly by Murray Valley encephalitis virus, and occasionally by Kunjin virus. The disease was initially recognised as occurring in epidemics chiefly centred about the Murray-Darling system, but now is known to occur Australia-wide. The last major epidemic was in 1974; 58 people were affected, including five from the Northern Territory (NT).

Sentinel chicken flocks are used to monitor flavivirus activity in Australia. The main viruses of concern are Murray Valley encephalitis (MVE) and Kunjin which cause the potentially fatal disease encephalitis, in humans. Currently 30 flocks are maintained in the north of Western Australia, 9 in the Northern Territory, 12 in New South Wales and 10 in Victoria. The flocks in Western Australia and the Northern Territory are tested year round but those in New South Wales and Victoria are tested only from November to March, during the main risk season. Results are coordinated by the Arbovirus Laboratory in Perth and reported bimonthly.

The Northern Territory Government proposes to convert Berrimah Farm on the southern outskirts of Darwin, NT into an urban residential subdivision. Areas of Berrimah Farm are located within 1.5km of tidal mangrove areas, and were expected to experience seasonal populations of pest biting midges. Seasonally flooded areas located within and adjacent to Berrimah Farm were also expected to be sources of pest and disease carrying mosquitoes. Due to the potential for significant populations of biting insects, the Department of Planning and Infrastructure (DPI) commissioned Medical Entomology (ME), of the Department of Health and Families (DHF) to conduct a biting insect assessment of the Berrimah Farm site.

A biting insect assessment was conducted at the Andranangoo Creek West and Lethbridge Bay West mining prospects from the 29th September to the 1st of October 2005. This included detailed ground surveys for actual and potential mosquito breeding sites, assessment of aerial photography for potential mosquito and biting midge breeding sites, and initial adult biting insect trapping at both mining prospects. The early report production meant that information from subsequent peak season adult biting insect trapping in November 2005, and January and May 2006 had to be produced in a separate supplementary report. Therefore some conclusions in the first report were drawn based on field inspections and desktop observations, and not on trap data. The following report highlights the findings of the supplementary trapping, with new conclusions in regards to mosquitoes and biting midges. Trapping conducted for the Andranangoo Creek West and Lethbridge Bay West Biting Insect Assessment Report (Warchot & Whelan 2005) is referred to as ‘initial trapping’ in this supplementary report.

Burnside Operations Pty Ltd plan to commence mining at the North Point and Princess Louise mine sites, located in the East Burnside Project Area approximately 130km south-east of Darwin. The mining method will be open cut, with ore to be transported to Union Reefs Gold Mine for processing. Workers are to be housed at the mine camp at Cosmo Village. Mine sites have the potential to create or exacerbate mosquito breeding, potentially from the creation of water dams, wetland filters, borrow pits, sediment traps, dry season water discharge, waste water disposal, as well as the construction of roads and mine waste dumps. Mine sites also have the potential to introduce new mosquito species into the Northern Territory, such as the dengue mosquito Aedes aegypti from North Queensland, if equipment was to be sourced from this area. As part of the environmental process, all major development in the NT is required to consider mosquitoes during the preparation of Environmental Impact Statements or Public Environmental reports, to ensure new development does not create new mosquito breeding sites, and also to protect the health of workers.

Matilda Minerals Limited (Matilda) proposes to develop sand mining operations at Andranangoo Creek West (Andranangoo) and Lethbridge Bay West (Lethbridge), Melville Island, Tiwi Islands, Northern Territory. The proposed operation will extract high grade heavy minerals (HM), specifically zircon and rutile, for export to China. It is estimated that a total of 99,000 t of zircon and rutile will be exported during the anticipated sand mining operation over three and half years. A proposal to mine both sites was submitted to the NT Government in the form of a Notive of Intent Document (URS, 2005). The NT Government determined the project is to undergo formal environmental assessment in the form of an Environmental Impact Assessment (EIS). Part of the EIS process is to conduct a biting insect assessment of the general project areas to determine any public health risks to workers and the potential for mining activities to alter the natural environment and create further biting insect breeding sites. The Medical Entomology Branch was commissioned by URS Australia on behalf of Matilda Minerals to undertake a biting insect assessment at both proposed sandmining sites.

Darwin Clean Fuels Pty Ltd plan to establish and operate a Condensate Processing Facility in Section 5720 and part Section 5633 at the Darwin Business Park at East Arm. The Condensate Processing Facility will produce a range of products, principally unleaded petrol, diesel and kerosene/jet fuel. It is anticipated that the condensate would be sourced principally from the Bayu Undan field in the Timor Sea and North West Shelf off Western Australia. Surface water ponding and mosquito breeding has been an issue in the East Arm area, primarily due to reclamation works conducted for the development of Darwin Business Park and the port facility. Water ponding and mosquito breeding has also been located in Section 5720 and part Section 5633 by the Medical Entomology Branch during previous surveys. The Darwin Business Park is also located adjacent to extensive mangrove areas of Bleesers Creek, Elizabeth River and Hudson Creek, which are expected to be large sources of pest biting midges. Due to the proposed development site and adjacent areas containing potential mosquito breeding sites, and the close proximity of mangrove areas, which are potentially large sources of pest biting midges, the Medical Entomology Branch (MEB) was commissioned by URS Australia Pty Ltd on behalf of Darwin Clean Fuels Pty Ltd to conduct a Biting Insect Assessment for the proposed facility.

A Hazchem Storage Facility is proposed at Section 4239, Hundred of Bagot. Section 4239, Hundred of Bagot is located at Hidden Valley adjacent to extensive mangrove areas of Bleesers Creek and Reichardt Creek in Frances Bay, Darwin Harbour. Section 4239 is proposed to be subdivided in future, with the proposed Hazchem Storage Facility to be built within a 4ha site in Section 4239. The areas adjacent to the proposed development area were also identified as being subject to seasonal pest problems from the salt marsh mosquito Ochlerotatus vigilax (Whelan et al 1994). Other mosquito species of potential significance in the proposed development area include Culex annulirostris and Coquillettidia xanthogaster (Whelan et al 1994). Ochlerotatus vigilax is a vector of Ross River virus (RRV) disease and Barmah Forest virus (BFV) disease, while Culex annulirostris is a vector of RRV, BFV, Murray Valley encephalitis virus (MVEV) disease and Kunjin virus (KUNV) disease. The numbers of these species of mosquitoes in this area indicated there are seasonal risks for mosquito borne disease transmission in the development area. The Medical Entomology Branch (MEB) has been asked to identify any biting insect pest or potential human health problems in the development area, and provide advice on the magnitude of the problem. To do this MEB has referred to past biting insect investigations in the development area (Whelan et al 194), as well as examined the proposed plans for the potential of the development to create or exacerbate existing biting insect problems.

The Blacktip Project consists of both offshore and onshore components. The onshore components include the construction and operation of an onshore processing plant, construction and operation of 3km of buried onshore pipeline, and the construction of access roads and construction camp. There were potential biting insect concerns associated with these onshore components of the Blacktip Project. EcOZ Environmental Services was commissioned by Woodside Energy Limited (Woodside) to assist in the preparation of a Draft Environmental Impact Statement (EIS) for the Blacktip Project. EcOZ Environmental Services then commissioned the Medical Entomology Branch of the Department of Health and Community Services to provide information on biting insects likely to affect the Blacktip Project.

As part of the biting insect assessment for the Blacktip Project, traps were required to be set during the peak pest biting midge season months of either August, September, October or November. The month of September was to sample peak season numbers of the main human pest biting midge in coastal areas of Northern Australia, Culicoides ornatus. Peak abundance of C. ornatus occurs around the time of the full moon each month, with numbers generally elevated over a four-five day period. Numbers of C. ornatus can vary dramatically over this four-five day period, although previous studies have shown highest numbers generally occur one day before the full moon and on the day of the full moon. To define the peak numbers of C. ornatus in September, trapping was proposed to occur over a three day period around the full moon, which was to include trapping one night before the full moon, the night of the full moon, and the night after the full moon. This trapping was also likely to indicate peak mosquito numbers for this month, with the exception of Ochlerotatus vigilax, which generally occur 10 days after the monthly high tide. The ensuing report discusses the new findings and recommendations derived from the September 2004 trapping period, and is to be used as a supplement to the Biting Insect Survey and Assessment report for the Blacktip Project, which was produced in July 2004. The new findings provided in this report can supersede the equivalent findings in the July 2004 report.

Milingimbi is an Aboriginal community in Arnhem Land, 206 km West from Nhulunbuy. The population is 920 (NT government intranet, 30/6/2003). The community is located on Milingimbi Island. Near the end of February 2003 the Milingimbi community council expressed concerns over increased mosquito numbers to Environmental Health, who requested the Medical Entomology Branch to visit the community, assess the situation and advise on strategies to reduce mosquito problems. Two MEB officers visited Milingimbi on 7-9 April 2003 and carried out a comprehensive biting insect survey, including biting insect trapping, larval mosquito surveillance and a receptacle survey. The results of this survey and the assessment are presented in this report. A mosquito survey had previously been carried out in Milingimbi in 1983, and was documented in a MEB branch report.

There are many examples of development in the Darwin region that have led to enormous populations of a range of mosquito species, severely effecting residents in nearby areas and requiring costly rectification. To aid planners in their design of the proposed Newton development, the Medical Entomology section of the department of Health and Families has made collections of biting midges and mosquitoes form march 1984 to April 1985 in and around the proposed development area between the Elizabeth and Blackmore Rivers, south-west of Palmerston. Additional surveys of biting midge breeding areas were made in late 1987. This report analyses the result and suggest methods of minimising the adverse effects of the biting insect present in the proposed development area, and outlines some construction guidelines to avoid exacerbating the problem.

Compass Resources NL is proposing the development of the Browns Oxide mine, located in the Northern Territory approximately 65km south of Darwin and 7km north-west of Batchelor (Figure 1).The project is currently under construction. Compass Resources NL proposes to utilise open cut mining methods and a conventional hydrometallurgical process to extract approximately 3.9 million tonnes of oxide ore and produce copper, cobalt and nickel over a four year period (Public Environmental Report (PER) - Enesar Consulting Pty Ltd 2005). Mine sites have the potential to create or exacerbate mosquito breeding, from the creation of water dams, wetland filters, borrow pits, sediment traps, pit water discharge, waste water disposal, as well as the construction of roads and mine waste dumps. Mine sites also have the potential to introduce new mosquito species into the Northern Territory, such as the dengue mosquito Aedes aegypti from North Queensland, if equipment is sourced from this area. Therefore, all major development in the NT is required to consider mosquito breeding during the Environmental Assessment process, to ensure development does not create new mosquito breeding sites.

In an effort to reduce the high incidence of Murray Valley encephalitis in remote communities across the NT, DoH launched a radio campaign, with MVE risk messages delivered in eight Indigenous languages.

West Nile virus Kunjin subtype (WNV/KUNV)is enzootic across the tropical north of Australia, with epizootic spread into other jurisdictions. The clinical spectrum of illness in humans is poorly described. We report a clinical case of WNV/KUNV encephalitis and performed a retrospective chart audit of all cases of WNV/KUNV notified in the Northern Territory from 1992 to 2010. Thirteen cases of WNV/KUNV disease were identified; case notes were available for 10 of these presentations. Six of these patients had confirmed infection and presented with neuroinvasive illness,whereas the other four suspect cases comprised three cases with arthralgia, myalgia, and/or rash and one case with fever alone. On the available evidence, WNV/KUNV is of lower virulence compared with the New York 1999 strain. Difficulties in serological diagnosis, especially when paired acute and convalescent sera are not available, may adversely impact the accuracy of the epidemiological and clinical understanding of this virus.

West Nile virus Kunjin subtype (WNV/KUNV) is enzootic across the tropical north of Australia, with epizootic spread into other jurisdictions. The clinical spectrum of illness in humans is poorly described. We report a clinical case of WNV/KUNV encephalitis and performed a retrospective chart audit of all cases of WNV/KUNV notified in the Northern Territory from 1992 to 2010. Thirteen cases of WNV/KUNV disease were identified; case notes were available for 10 of these presentations. Six of these patients had confirmed infection and presented with neuroinvasive illness,whereas the other four suspect cases comprised three cases with arthralgia, myalgia, and/or rash and one case with fever alone. On the available evidence, WNV/KUNV is of lower virulence compared with the New York 1999 strain. Difficulties in serological diagnosis, especially when paired acute and convalescent sera are not available, may adversely impact the accuracy of the epidemiological and clinical understanding of this virus.

A 58 year old male from Batchelor (Miles Rd) was admitted to Royal Darwin Hospital on 10/3/09 with suspected MVE (suspected onset date 8/3/09). A RDH doctor informed Medical Entomology (ME) of the suspected case on 13/3/09 but advised that test results were still pending. The patient remained in ICU for 10 days and passed away on 20/3/09. ME received the Flavivirus Disease Case Investigation Form from CDC on 24/3/09. Later test results indicated a significant rise in antibodies in the HI test and MVE IgM in the CSF, with MVE-RNA detected in multiple postmortem brain samples on 1/4/09. According to the patient’s wife, her husband was bitten by mosquitoes on his rural property but had not been to Litchfield Park or any other rural areas.

A Kunjin virus (KUN) case with encephalitis symptoms was reported from the Darwin area, Northern Territory on 17 June 2010. The diagnosis was confirmed on 5 August. Adult mosquito trapping showed high vector mosquito numbers at the time originating from large swamps in the Howard Springs area. The sentinel chicken program across the Top End indicated probable KUN activity in the area, but no arboviruses were isolated from the mosquitoes collected. With an incubation period for KUN of between 7 – 12 days and an onset date of 15 June, the patient most likely contracted the KUN around 5 June at his Howard Springs residence.

A 83 year old non-indigenous male was admitted to Royal Darwin Hospital on 8/5/09 with suspected MVE (suspected onset date 4/5/09). A RDH doctor informed Medical Entomology (ME) of the suspected case on 11/5/09 but advised that test results were still pending. The first tests were conducted on 9/5/09, showing a weakly positive MVE IgM in CSF (negative for Kunjin and West Nile), a positive PCR, and a weak positive arbovirus serology HI result for MVE (titre 40). Further tests were conducted on 11/5/09 and 15/5/09, but the MVE HI titre did not rise. Tests were also conducted for other viruses including Dengue, Stratford, Kokobera, Edge Hill and Alfuy, but the test results were negative. MVE was confirmed on 19/5/09. The patient remained in ICU showing symptoms of encephalitis, including confusion, fever and fitting, until he passed away on 23/5/09. ME received the Flavivirus Disease Case Investigation Form from CDC on 20/5/09. The patient’s fishing partner reported that the patient had been fishing at Wranglers Creek and other areas at Channel Point for three and a half weeks since Easter, experiencing moderate mosquito numbers at dawn and dusk only. The patient has not been to any other areas, and there was anecdotal evidence that the patient did not usually practice personal protection, such as using insect repellent.