Published Date: 2012-03-25 00:03:17
Subject: PRO/EDR> Ross River virus - Australia (02): (WA, TA)
Archive Number: 20120325.1079874

ROSS RIVER VIRUS - AUSTRALIA (02): (WESTERN AUSTRALIA, TASMANIA)
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Date Fri 23 Mar 2012
Source: Wanderlust [edited]
http://www.wanderlust.co.uk/magazine/news/warning-ross-river-virus-rise

The number of people contracting the mosquito-spread infection has dramatically increased in Western Australia and Tasmania

Although not fatal, many health authorities are warning travellers to be aware of mosquitoes and the Ross River virus (RRV). A significant rise in people contracting the disease, has reportedly been caused by recent flooding and consequent swarms of mosquitoes in Western Australia.

The Australian Medical Association (AMA) has already reported 632 cases in Western Australia and Tasmania this year [2012] – more than double for the same period last year.

Due to heavy rainfall in several states and severe flooding in New South Wales and Queensland, vast areas of stagnant water have formed – acting as the perfect breeding grounds for mosquitoes.

Health authorities are urging travellers in the affected regions to be vigilant in protecting themselves against mosquito bites.

Dr Jane Wilson-Howarth told Wanderlust a bit more about RRV: "It is spread by mosquito bites and the only way to prevent it is by avoiding bites, especially between late afternoon and about 3 hours after sundown. The symptoms can persist for months so bite-avoidance is crucial."

"Ross River virus [infection] is never fatal. However there is great variability in the severity of the symptoms: about 1/3 of people are unaware that they are infected. Any symptoms tend to start 3 - 11 days after an infective bite, when people feel weak, fatigued, they develop aches and pains, and there may be swelling and stiffness of the joints. Some experience a rash on the arms legs and body which settles in 7 - 10 days,” she added.

Travellers should be wary that the virus is not restricted to Australia. RRV cases have been reported in Indonesia, Papua New Guinea and some Pacific Islands.

Advice to travellers:

The virus is transmitted via an infected mosquito. There is no vaccination available, so travellers should avoid being bitten by using insect repellent containing 50 per cent DEET, wearing lose fitting clothes, sleeping in mosquito nets and trying to avoid stagnant bodies of water around dusk and dawn when mosquitoes are most active.

If you experience the following symptoms, Dr Wilson-Howarth advises that you should take paracetamol to relieve the symptoms. If it has little effect, you should consult a doctor. The virus is diagnosed with a simple blood test.

Although signs of the RRV [infection] vary from person to person, often people experience a red spotty rash, flu like-symptoms, including fever, chills and headaches, as well as stiffness of joints or muscles.

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[The number of reported Ross River virus infections have increased from 511 on 1 Mar 2012 to 632 just 3 weeks later as noted above. This year (2012) has been one of the worst for RRV infections. RRV is an alphavirus transmitted mainly by _Aedes_ and _Culex_ mosquitoes. A candidate RRV vaccine has been tested in humans. The adjuvanted, inactivated whole-virus Vero cell-derived RRV vaccine is highly immunogenic in RRV-naive adults and well tolerated at all dose levels. Since this vaccine is not commercially available, avoidance of mosquito bites, as indicated in the report above, is the only preventive measure available currently.

Reference:
Aichinger G, Ehrlich HJ, Aaskov JG, Fritsch S, Thomasser C, Draxler W, Wolzt M, Müller M, Pinl F, Van Damme P, Hens A, Levy J, Portsmouth D, Holzer G, Kistner O, Kreil TR, Barrett PN. Safety and immunogenicity of an inactivated whole virus Vero cell-derived Ross River virus vaccine: a randomized trial. 2011. Vaccine 29(50):9376-84.

A HealthMap/ProMED-mail interactive map showing the location of Western Australia state can be accessed at http://healthmap.org/r/00co and Tasmania at http://healthmap.org/r/00Kt. - Mod. TY]

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