Southern Saltmarsh Mosquito Suspected

Southern Saltmarsh Mosquito Suspected South Of Gisborne

THE Ministry of Health is advising all public health services to recheck all potential mosquito breeding sites, following the discovery of mosquitos south of Gisborne, suspected to be the exotic southern saltmarsh mosquito.

A national exotic mosquito surveillance programme has been in place since last year, when the southern saltmarsh mosquito, Aedes camptorhynchus, was first identified in Hawke's Bay. The mosquito larvae found at the Wherowhero Lagoon near Muriwai, 20 kilometres south of Gisborne were detected during routine sampling. The southern salt marsh mosquito has been declared an unwanted organism in New Zealand. In Australia is thought to be the main carrier of Ross River Virus.

Deputy Chief Technical Officer (Health) Dr Bob Boyd said Australian experts will be examining the samples next week to confirm the species identity.

"In the meantime an intensive survey is underway in the surrounding area to determine the extent of potential habitat and identify where the mosquitos are located. The results of the survey will be presented to a Technical Advisory Group late next week which will advise what action should be taken."

Dr Boyd said if the mosquito is confirmed as being Aedes camptorhynchus, it is not know how or when the mosquito arrived in Gisborne. However, it was unlikely that the mosquito would have flown from Hawke's Bay.

"We have not found any evidence of the mosquito between Napier and Muriwai as would have been expected if it had flown north. Furthermore, no adult mosquitos have been found in Hawke's Bay since May, and no larvae has been found after two recent heavy rainfall despite a sampling programme involving over 28,000 samples."

Dr Boyd said the southern saltmarsh larvae relies on saline water for its survival. Recent rainfall in Gisborne at the end of September, after a dry period, may have activated larvae laid earlier in the year.

Meanwhile, all other public health services have also been advised to recheck potential breeding sites in their areas and repeat again after the next heavy rainfall.

Dr Boyd said the first samples which raised suspicion were taken in July. Further samples were taken this week after further heavy rain.

Dr Boyd said the southern saltmarsh mosquito was known to be an "aggressive" biter. He advised that people in the Gisborne area should avoid being bitten by any mosquitos. Mosquitos are most active around dawn, late afternoon and just after dusk. By screening open doors and windows, using insect sprays or mosquito coils indoors, wearing long clothing and repellent when outdoors, the possibility of being bitten can be reduced.

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For more information contact: Selina Gentry, Media Advisor, ph: 04-496-2483 or 025-277-5411 Internet address: http://www.moh.govt.nz/media.html

Background Information

A southern saltmarsh mosquito eradication programme is currently underway in Napier, Hawke's Bay. A total of $6-million over four years has been allocated to eradication programme in Hawke's Bay which began in 1999.

To date there have been no confirmed cases of Ross River Virus in Napier or Gisborne.

Mosquitos breed in water. The public can help discourage the breeding of mosquitos for example by checking gutters and drains around their house and ensuring they are clear of leaves and blockages, getting risk of old tyres, and also drill holes in tyre swings to allow water to drain free. Swimming pools should be well chlorinated, and boats and canoes on land overturned so they don't accumulate water.

Selina Gentry Media Liason Communications DDI: 496 2483 Fax: 496 2010 mailto:selina_gentry@moh.govt.nz Ministry of Health

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