Mosquitos and Dengue Fever

Mosquitos, spreading Dengue Fever and other tropical diseases throughout Airlie Beach. Health authority warnings say the insect borne disease is spreading through the tropics, with 100 dengue cases reported in Cairns in late 2008. Tourist industry fear endemic dengue threatens tourism in Cairns.

There were 417 cases of dengue or bonebreak fever in Australia in 2008 to the end of November. However a traveller brought type 3 dengue to Cairns, resulting in hospitals being under strain from dengue, with 100 extra cases in December and 150 by mid January 2009. Meanwhile, Townsville experienced 5 cases of type 1 dengue, increasing to 9 in mid January. The mid January flooding will increase mosquito numbers. Before the end of January there were 200 cases in Cairns, 20 in Townsville, and two infected travellers in Mackay. Innisfail now has dengue, imported from Vanuatu, for the first time. In addition, there were fears the usual 12 day virus breeding cycle was now as low as five days.

One major danger of being infected with any of the four types of dengue is that a subsequent infection with a different variety (the four varieties were previously associated with different geographical areas) is typically far more harmful. In March 2009, all four strains of dengue had been found in tropical north Queensland, for the first time ever.

Fipronil (also used for tick and flea control in pets) has been used by Queensland Health. However this poison is under investigation by the Australian Veterinary Pesticides and Medicines Authority (AVPMA) for potential risk to humans. This poison is being used because mosquitos have built up immunity to another pesticide.

There is no drug treatment nor cure for Dengue. Experiments to shorten the lifespan of the Aedes aegypti mosquito (only older females spread dengue) using Wolbachia bacteria are encouraging. There are suggestions in the press that dengue mosquitos are resistant to pesticide. Unfortunately, the Asian tiger (ades albopictus) mosquito is out of control on Prince of Wales Island in the Torres Strait. This mosquito handles cooler climates, targets humans, and breeds in forests and woodlands. In addition to dengue, it can spread the related chikungunya disease. This new threat is serious.

Attempts at a dengue vaccine are also proceeding, but may not cover all varieties.

Council Warning and Advice

You can read a PDF of Whitsunday Regional Council warnings about mosquito disease threats on the council web site. They warn about Dengue Fever, Ross River Virus, Barmah Forest Virus and Encephalitis. Basically stay indoors, use insect repellent and insect sprays, wear long loose clothing, and swelter. Right, real likely.

Water Tanks

Which reminds me, the insane quest for home water tanks encourages mosquitos and similar insect vectors for tropical diseases. I would expect any competent health department in the tropics (or any warm area) to outright ban the sale and installation of home water tanks in built up areas. Instead we have government subsidies! This is insane, and I fully expect after the next disease outbreak, that the governments involved will be sued.

Unless there is a competent, regularly scheduled inspection of insect control measures built into water tanks, they are a health menace. Tanks should only be permitted where the nearest neighbour is at a distance greater than 200 metres (the approximate maximum flight range of a mosquito). I notice tanks sold by local hardware stores essentially have no insect control filters. They also lack first flush diverters. Leave water tanks to farmers who are used to operating them safely. Water tanks are dangerous in suburban areas.

ABC news way back on 16 Oct 2007 warns. Water tanks spark killer mozzie warning. SBS on 30 December 2008 saying NSW warned of mosquito threat from Ross River virus and Barmah Forest virus by Dr Jeremy McAnulty of NSW Health. Central Queensland News 26 Jan 2008 Rainwater tanks could see mozzies return reports on an article in British Ecological Society's journal Functional Ecology by Dr Michael Kearney of the University of Melbourne. I see in the 26 January 2009 Courier Mail. Rain tanks spark spread of dengue fever mozzie risk. I warned this was a risk long ago. In 2009, Professor Stephen Prowse said backyard water tanks provided good breeding sites for aedes aegypti mosquitos, which have spread as far as Gympie. He expects dengue outbreaks in SouthEast Queenland. Professor Brian Kay was concerned about the spread of ades albopictus mosquitos from the Torres Straits into mainland Australia.