the Aedes aegypti mosquito is a pest for all the usual reasons, but it can also be a carrier of dengue fever and yellow fever. Picture: Supplied. Source: Supplied

A RETURN of La Niña weather heralds an explosion of bugs and disease.

Forecasters are predicting another long, wet and humid summer - and those warm, sticky days could mean all sorts of potential health problems.what is known as a La Niña weather pattern is tipped to bring plenty of rain and humidity over summer. this weather is a haven for bacteria and insects, and food poisoning and gastroenteritis are more common. An explosion of flies and mosquitoes expected in the coming months is also set to lift the risk of viral infections.

Be on guard:“if it is hot, people tend to be outside a bit more, so they are more exposed and of course people get relaxed and less vigilant,’’ says Dr Liz Hanna, convenor of the Climate Change Adaptation Research Network - Human Health. “if we are facing another long, hot summer, we have to be on guard.’’ Experts are currently analysing data from last year’s La Niña, which brought extreme temperatures and flooding along Australia’s east coast. it is expected the figures will show an increase in various illnesses caused by the extreme weather.it is already known that last summer’s downpours saw the largest outbreak of mosquito-borne diseases in the past decade in western NSW and parts of inland Queensland.Dr Cameron Webb, an entomologist from the University of Sydney, says if current conditions continue we could see a repeat, with large numbers of mosquitoes expected. “As soon as you add all that water to areas that were once drought-affected, you start getting big populations of mosquitoes,’’ Dr Webb says. “when we get hot weather combined with rain these insects can live longer, so the problems can persist for longer.”

Once bitten:in Australia, mosquitoes carry two main infections - Ross River virus and Barmah Forest virus. Other potentially deadly mosquito-borne illnesses include dengue fever and Murray Valley encephalitis. there are about 5000 notified cases of Ross River/Barmah Forest infection every year but the true figure could be higher, says Dr Webb, who suspects mild cases are often not reported. Both viruses cause a rash, fever and joint pain lasting from a few days to weeks or even months. Both diseases can also leave victims with extreme tiredness and weakness. Birgit Bradtke, 43, from Kununurra in Western Australia, says she still has relapses almost five years after being bitten by a mosquito infected with Ross River fever. “the first six to 12 months were the worst, but all the symptoms, especially the tiredness, can come back.”

Watch out for fleas:Fleas and ticks also thrive in the predicted muggy conditions, says Dr Bob Rees, a veterinarian with Bayer Healthcare.such parasites are likely to be brought into the home by pets and can cause more than just nasty bites or allergic reactions.the Australian Medical Journal this year reported on the first known case of cat flea typhus, after four members of a Melbourne family fell ill from a flea-infested kitten. the illness had not previously been seen in Australia. it is possible there have been other cases, but until recently the pathology to prove it was not available, Dr Rees says.Flea bites transmit the bacterium to humans. it causes a rash, flu, high temperatures and lethargy and sometimes serious complications such as pneumonia. “it is relatively easy to treat in humans with standard antibiotics,’’ Dr Rees says.Researchers from Murdoch University are also investigating whether Lyme disease exists in Australia. the bacterium, transmitted by tick bites, is well known in North America and Europe. Lyme disease starts off as a rash but, if left undiagnosed, can cause permanent arthritic conditions, chronic fatigue and heart damage. it can also be treated with antibiotics.

Staying safe:As a precaution against ticks, long-coated animals should be clipped in the warmer months, Dr Rees warns. Lawns should also be mowed regularly.Clearing puddles and other stagnant water around the home will help ward off mosquitoes, as will insect screens and using a good insect repellent.With the number of cases of food-borne illnesses also increasing as temperatures rise, extra precautions, including vigilance over food temperatures  and better hand hygiene, need to be taken when preparing food or eating outdoors.