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NSW Arbovirus Surveillance & Vector Monitoring Program |  |
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NSW Arbovirus Surveillance & Vector Monitoring Program | |
 2000 - 2001
Annual Report  |
Albury: collections from both sites were well above average, especially at the Sewage Treatment Works (STW), during the early part of the season in December. Thereafter, mosquito numbers declined with the warmer drier weather and were below the long-term average for the remainder of the mosquito season. There were five isolates; one Sindbis from Culex annulirostris trapped 16/Jan at the STW, one Sindbis from Culex annulirostris trapped on 15/Feb also at the STW, and three unknowns from the 12/Dec.
Brewarrina: trapping occurred only twice, and collections were dominated by Aedes theobaldi during late November, with a ‘high’ collection. No viruses were isolated.
Bourke: mosquito trapping was very inconsistent and began only in March with the one site of the STW, and numbers were mostly ‘high’. No arbovirus isolates were made. The bleeding of the sentinel flock occurred more regularly and there was one MVE seroconversion from 5/Mar, six Kunjin seroconversions (one 20/Feb, four 5/Mar and one 12/Mar) and one dual MVE/KUN seroconversion from the 5/Mar.
Condobolin: mosquito collections were very irregular this year and mainly occurred from mid-February to early March. Numbers during this time were mostly below average and no arboviruses were isolated from the trapped mosquitoes. No sentinel flock operated at Condobolin this year.
Deniliquin: the general trend of well above average mosquito numbers during the early part of the season from southern inland also occurred at Deniliquin. Collections were ‘very high’ through December and up to ten times greater than average at the Island Sanctuary. The hot and dry conditions in January resulted in a general decline in mosquito numbers, which were mostly below average after January. There were three unknown arbovirus isolates and one sentinel chicken seroconversion to Kunjin on the 4/Mar.
Forbes: collections were very regular and except for some ‘high’ numbers in November, numbers were mostly below average. No viruses were isolated and there were no flavivirus seroconversions in the sentinel chickens.
Fords Bridge: mosquito trapping was extremely irregular this year and occurred on only six occasions. The ‘extreme’ collections from early 2000 did not reoccur. Numbers in December were ‘high’ but thereafter declined to be mostly ‘low’. Unlike the previous season, no isolates were made from the trapped mosquitoes. Bleeding of the sentinel flock was undertaken from most weeks during the season and there were three Kunjin seroconversions: two from 27/Mar and one from 11/Mar.
Griffith: the trapping site and sentinel flock at Barren Box were discontinued this year, and the sentinel flock located at Hanwood was moved to the more appropriate location of Willbriggie. Like the other southern inland localities, Griffith had mosquito numbers that were well above average during the early part of the season, with a series of ‘very high’ collections. From January onwards, numbers declined to be average to below average for the remainder of the season. There were 18 isolates from the mosquitoes: one Ross River, 13 Sindbis and four unknowns. There were two Kunjin seroconversions in the sentinel chickens, one each on the 28/Feb and 12/Mar.
Lake Cargelligo: mosquito numbers were well above average from late November through December and peaked with a ‘very high’ collection of 1,672 on 17/Dec. Numbers thereafter declined with the drier conditions and mostly were well below average. No isolates were made from the mosquitoes. There were two seroconversions to Kunjin in the sentinel chicken flock, one each on the 6/Mar and on the 20/Mar.
Leeton: numbers as elsewhere in southern inland were well above average in December, especially at Almond Rd where collections in late December were 14 times greater than normal. Numbers during January declined to be average and then peaked in February with an ‘extreme’ collection of over 10,000 mosquitoes at Mountford Park. There were nine isolates from the mosquitoes: four RR (all from 12/Feb), two SIN (30/Jan & 28/Feb), one KOK (28/Feb) and two KUN (12/Feb). There were nine Kunjin seroconversions in the sentinel chickens, four on 5/Mar and five on the 13/Mar.
Macquarie Marshes: ‘very high’ mosquito collections were made early in the season from late November through December, with a peak of over 9,000 mosquitoes in mid-December. As the weather became hot and dry from January onwards, mosquito collections declined. From the big December collection there was five SIN isolates, another SIN isolate was made from 21/Jan and there were two unknowns from the 18/Dec. There were several flavivirus seroconversions in the sentinel chicken flock, including four MVE (two from the 24/Jan, one 7/Jan, one 7/Feb), ten KUN (one 24/Jan, three 21/Feb, four 8/Mar, two 12/Mar) and one dual MVE/KUN infection (21/Jan).
Menindee: there were four seroconversions in the sentinel chickens, all on the 18/Jan. This included two MVE, one KUN and one dual MVE/KUN seroconversion. Mosquito traps were not routinely operated this season at Menindee, the only collection occurred in mid-February, well after the positive chickens.
Moree: mosquito collections began in December and were mostly average to below average for the season. There were no isolates from the mosquitoes. A sentinel chicken flock was established in March following the flavivirus activity elsewhere, and there were no seroconversions.
Tamworth: the majority of collections were below average, except for some ‘high’ numbers in January. There were no isolates from the mosquitoes.
Wanaaring: the ‘very high’ numbers that occurred during March of 2000 did not recur. Collections were mostly ‘high’ from November through December. Thereafter no further trapping was undertaken until mid-February and the collections that followed were all ‘low’. Seroconversions to flaviviruses occurred on the 24/Jan (one MVE and one dual MVE/KUN infection) and on the 12/Mar (1 KUN).
Wee Waa: a sentinel chicken flock was established in March following the flavivirus activity elsewhere, and there were no seroconversions. No mosquito traps were operated at Wee Waa.
Wentworth:
no collections were made this season.
Coastal Locations
Ballina: mosquito numbers were mostly average to below average up until late February. Heavy rainfall in February, coupled with king tides lead to ‘very high’ collections with numbers around four times greater than normal at Greenfield Rd. Interestingly, it was Aedes funereus rather than Aedes vigilax which dominated these collections. Both sites continued to collect large numbers of freshwater breeding mosquitoes. No virus isolation was undertaken.
Batemans Bay: no collections were made this season.
Gosford: only the one trapping site of Empire Bay was operated. Numbers were generally close to average except for a ‘very high’ collection in mid-February, which was around ten times the average, and again in early April when collections were ‘very high’ and likewise about ten times greater than average. Aedes notoscriptus was the most common species collected. No virus isolation was undertaken.
Newcastle: no collections were made this season.
Port Stephens: for most sites, mosquito numbers were around average from November to early January and there was a small peak in numbers with several ‘high’ collections in mid-January. This followed the high tides that occurred from the 8-14 January. Numbers declined and another peak occurred in late February (again following the high tidal patterns). The highest mosquito densities occurred during the last week of March/first week of April when several sites had ‘very high’ collections (over 3,700 mosquitoes at Heatherbrae in one week) and these numbers were much greater than the average. The Heatherbrae site continued to trap the majority of mosquitoes from Port Stephens, where the collections were dominated by freshwater species such as Culex annulirostris and Coquillettidia linealis. For the other sites, Aedes vigilax and Aedes procax were the dominant species. No virus isolation was undertaken.
Tathra: no collections were made this season.
Tweed Heads: both sites consistently yielded below average numbers for the season, with ‘low’ to ‘medium’ trap collections. No virus isolation was undertaken.
Wyong: only one site, Ourimbah, undertook
trapping this season. Numbers were mostly around average, with Aedes notoscriptus being the species
most commonly captured. No virus isolation was undertaken.
Blue Mountains: two sites undertook trapping; the Sewage Treatment Plant, which had consistent ‘low’ collections and the Glenbrook Lagoon, where numbers were ‘medium’ to ‘high’ and dominated by Aedes notoscriptus. There were no mosquito isolates.
Concord: collections were broadly ‘low’ to ‘medium’ throughout the season, with a large peak during mid-January to Mid-February of ‘very high’ numbers with 988 mosquitoes in one week’s trap. The collections were dominated by Aedes vigilax. The Powell’s Creek site yielded the majority of the mosquitoes and had the highest number for the Concord/Parramatta/Ryde area. No virus isolation was undertaken.
Hawkesbury: collections were ‘low’ to ‘medium’, although Wheeney Creek produced some ‘high’ numbers. Aedes Marks sp. no.51 and Culex annulirostris dominated the mosquito catches. No viruses were isolated.
Parramatta: the insecticide treatments of Aedes vigilax breeding sites at Homebush Bay continued this season, ensuring that the big collections of 1997-1998 were not repeated. Over the season, collections were ‘low’ to ‘medium’, with a notable peak in late February/early March of some ‘high’ numbers, comprising mainly Culex sitiens, Culex annulirostris, Aedes notoscriptus and Aedes vigilax. George Kendall Reserve continued to yield the highest mosquito numbers from Parramatta. There were no isolates from the mosquitoes.
Penrith: following heavy rainfall in January, collections were consistently ‘high’ from mid-February to late March for most trapping sites, and included the highest collections over the three years of monitoring. The collections were dominated by the noted vector, Culex annulirostris. No isolates were made from the mosquitoes.
Ryde: collections varied substantially between sites. At Wharf Road, the saltmarsh species Aedes vigilax and Culex sitiens dominated the catches, and numbers were mainly ‘low’ up until late January and thereafter ‘high’ for the rest of the season. At the other sites, the domestic mosquito, Aedes notoscriptus, was the main species trapped and these collections were generally ‘low’ to ‘medium’. Only the Lambert Park collections were processed for viruses, and none were isolated.
