This article summarises the 2013-14 wet season in Darwin urban in relation to rainfall, mosquito numbers and notified Ross River virus cases.

Ross River virus (RRV) causes the most common human arbovirus disease in Australia. Although the disease is nonfatal, the associated arthritis and postinfection fatigue can be debilitating for many months, impacting on workforce participation. We sought to create an early-warning system to notify of approaching RRV disease outbreak conditions for major townships in the Northern Territory. By applying a logistic regression model to meteorologic factors, including rainfall, a post-estimation analysis of sensitivity and specificity can create rainfall cut-points. These rainfall cut-points indicate the rainfall level above which previous epidemic conditions have occurred. Furthermore, rainfall cut-points indirectly adjust for vertebrate host data from the agile wallaby (Macropus agilis) as the life cycle of the agile wallaby is intricately meshed with the wet season. Once generated, cut-points can thus be used prospectively to allow timely implementation of larval survey and control measures and public health warnings to preemptively reduce RRV disease incidence. Cut-points are location specific and have the capacity to replace previously used models, which require data management and input, and rarely provide timely notification for vector control requirements and public health warnings. These methods can be adapted for use elsewhere.

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.

This report describes the epidemiology of mosquito-borne disease in Australia for the mosquito-borne disease season 1 July 2004 to 30 June 2005. Ross River virus (RRV) infections (45%), Barmah Forest virus (BFV) infections (30%) and malaria (19%) were the most common mosquito-borne diseases reported in 2004-05. The Northern Territory had the highest rate of RRV notifications and the peak notification rate (in February 2005) was 54 per cent less than the previous season. The Northern Territory also reported the highest BFV notification rate this season, peaking in April 2005, which was the second highest reported BFV notification rate since 1998. National RRV and BFV notification rates were highest in the 45-49 year age group. There were 799 notifications of malaria in 2004-05 of which none were reported as locally acquired. This was the third highest reporting season for malaria notifications since 1998. In contrast to previous years in which Plasmodium vivax was the predominant species, Plasmodium falciparum was reported as the infecting species in 57 per cent of the malaria notifications and Plasmodium vivax for 34 per cent of cases. Children in the 5-9 year age group had the highest number of cases compared to previous years in which the peak number of cases tended to be in young adult age groups. There were four cases of Kunjin virus (KUNV) and two cases of Murray Valley encephalitis virus (MVEV) reported in 2004-05. Sentinel chicken surveillance data for flaviviruses and sentinel pig surveillance data for Japanese encephalitis virus are reported. There were 188 notifications of dengue virus infection (DENV) in 2004-05, of which 46 per cent (n=86) were reported as having been acquired overseas. Dengue serotype 4 was the most frequently reported type, accounting for 32 per cent of cases (n=60).

This report describes the epidemiology of mosquito-borne disease in Australia for the mosquito-borne disease season 1 July 2005 to 30 June 2006, in which the second largest number of notifications since 1995-96 was reported. Ross River virus (RRV) infections (66%), Barmah Forest virus (BFV) infections (23%) and malaria (9%) were the most common mosquito-borne diseases reported in 2005-06. National RRV notifications were the fifth largest on record. The Northern Territory had the highest rate of RRV notifications and the peak notification rate (in January 2006) was the third highest since 2000. National BFV notification rates were the highest on record. The Northern Territory also reported the highest BFV notification rate this season, peaking in February-March 2006, which was the highest reported BFV notification rate on record. BFV notification rates were significantly higher in teenagers compared to previous seasons. There were 731 notifications of malaria in 2005-06 of which none was reported as locally acquired. This was the third highest reporting period for malaria notifications since 2000. In contrast to previous years in which Plasmodium vivax was the predominant species, Plasmodium falciparum was reported as the infecting species in 45 per cent of the malaria notifications and Plasmodium vivax for 42 per cent of cases. Young adults in the 20-24 year age group had the highest number of cases and children in the 5-9 year age group accounted for 22 per cent of notifications. There were two cases of Kunjin virus (KUNV) infection and one case of Murray Valley encephalitis virus (MVEV) infection reported in 2005-06, all from Western Australia. Sentinel chicken surveillance data for flaviviruses and sentinel pig surveillance data for Japanese encephalitis virus are reported. There were 200 notifications of dengue virus (DENV) infection in 2005-06, of which 46 per cent (n=92) was reported as having been acquired overseas. Dengue serotypes 2 and 3 were detected in two outbreaks of locally-acquired dengue in Queensland this season.

This report describes the epidemiology of mosquito-borne disease in Australia for the mosquito-borne disease season 1 July 2006 to 30 June 2007, which was moderately low compared to previous seasons. Ross River virus (RRV) infections (55%), Barmah Forest virus (BFV) infections (29%) and overseas acquired malaria (11%) were the most common mosquito-borne diseases reported in 2006–07. The number, proportion and rate of national BFV notifications were the second highest on record since 1998-99. The Northern Territory reported the highest BFV notification rate this season. BFV notification rates were the highest in the 40-59 year age groups when compared to other age groups. National RRV notifications were the fifth largest on record. The number, proportion and rate of RRV notifications were moderately low this season compared with previous seasons. The highest RRV rate was reported by Western Australia from the Kimberley region. The highest age-specific RRV notification rate was observed in the 40-59 year age groups. Locally acquired dengue virus notifications were low this season compared to previous seasons, with a small outbreak of dengue serotype 3 in 39 cases confined to the greater Townsville region. There were 640 notifications of malaria in 2006–07 of which none were reported as locally acquired. This was the third highest number of malaria notifications since 2001. Plasmodium falciparum was reported as the infecting species in 47 per cent of the malaria notifications and Plasmodium vivax for 40 per cent of cases. Young adolescent and adults in the 15–29 year age group had the highest number of cases accounting for 32 per cent of notifications. Sentinel chicken surveillance data for flaviviruses and sentinel pig surveillance data for Japanese encephalitis virus are also reported.

There have been a number of cases of epidemic polyarthritis reported from Alice Springs over the last few years, but few have been confirmed as acquired in Alice Springs. This report confirms a case of Ross River virus infection that was acquired by a 48 year old female in mid March on the outskirts of Alice Springs.

The towns of the "Top End" of the Northern Territory are to various degrees adjacent to tropical wetlands, localised swamps, or wet season flooded areas, which can produce seasonally high numbers of a range of pest and potential vector mosquito species. These towns are both receptive and vulnerable to a number of endemic mosquito borne virus diseases including epidemic polyarthritis. Barmah Forest disease, and Australian encephalitis. Due to the proximity of some residential areas of Darwin to extensive wetlands and the large number of residents potentially exposed to mosquito attack, this city has the most comprehensive mosquito control program. The other towns in the Northern Territory have mosquito control programs that are appropriate to their locality, their specific mosquito problems and the practicality of various control methods. This paper outlines an overview of current insecticide mosquito control programs in the Northern Territory, with details of the extensive aerial larval control program and prospects for future control.

Energy Resources of Australia (ERA) Ranger Mine is located in Kakadu National Park, adjacent to several arms of the Magela Creek and within flight range of mosquitoes from the extensive Magela Swamp. Weekly routine adult mosquito trapping in and adjacent to the nearby town of Jabiru consistently reveals very high numbers of pest and disease carrying mosquito species, generally in the post wet season and dry season months of April to August, and during a short period of a few weeks in the mid wet season. Low to moderate numbers of pest and disease carrying mosquito species are also encountered during most other months of the year. The presence of extended periods of high mosquito numbers translates to a significant potential for mosquito borne disease transmission in the Jabiru locality.The following report presents the results of brief field investigations in September and December 2005, a critical review of the nature and extent of natural mosquito breeding sites likely to affect Ranger Mine, outlines potential breeding sites at the mine site, outlines the adult mosquito and ovitrap program, and provides recommendations on how to manage potential mosquito issues at the mine site.

Lee Point, at the northern end of Casuarina Coastal Reserve in Darwin, Northern Territory, has historically been a productive breeding area for the northern salt marsh mosquito, Aedes vigilax. The main breeding habitats for this mosquito at Lee Point are coastal interdunal depressions. Sand deposition can form new mosquito breeding sites in the area, with the most recent site to the east of the tip of Lee Point found to be breeding mosquitoes in 2015. Coastal depressions at Lee Point usually breed Ae. vigilax after heavy wet season rainfall, with some sites also breeding after high tides during the wet season. However, the most recently formed interdunal depression was found to breed high numbers of Ae. vigilax larvae following a high tide in the late dry season, indicating the formation of the first dry season Ae. vigilax breeding site at Lee Point. Aedes vigilax is a major pest mosquito and can carry Ross River virus and Barmah Forest virus. This new area of mosquito breeding will be added to the routine larval mosquito control program for Casuarina Coastal Reserve. However, the new site and other interdunal depressions at Lee Point should be investigated for rectification to prevent mosquito breeding.