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.

WASHINGTON – Climate change could increase exposure to water-borne diseases originating in oceans, lakes and coastal ecosystems, and the impact could be felt within 10 years, US scientists told a conference here Saturday.Several studies have shown that shifts brought about by climate change make ocean and freshwater environments more susceptible to toxic algae blooms and allow harmful microbes and bacteria to proliferate, researchers from the National Oceanic and Atmospheric Administration said.In one study, NOAA scientists modeled future ocean and weather patterns to predict the effect on blooms of Alexandrium catenella, or the toxic “red tide,” which can accumulate in shellfish and cause symptoms, including paralysis, and can sometimes be deadly to humans who eat the contaminated seafood.”Our projections indicate that by the end of the 21st century, blooms may begin up to two months earlier in the year and persist for one month later compared to the present-day time period of July to October,” said Stephanie Moore, one of the scientists who worked on the study.But the impact could be felt well before the end of this century — as early as 2040, she said at the annual meeting of the American Association for the Advancement of Science (AAAS).”Changes in the harmful algal bloom season appear to be imminent. We expect a significant increase in Puget Sound (off the coast of Washington state where the study was conducted) and similar at-risk environments within 30 years, possibly by the next decade,” said Moore.In another study, NOAA scientists found that desert dust that is deposited into the oceans from the atmosphere could also lead to increases of harmful bacteria in seawater and seafood.Researchers from the University of Georgia found that adding desert dust, which contains iron, to seawater significantly stimulated the growth of Vibrios, a group of ocean bacteria that can cause gastroenteritis and infectious diseases in humans.”It is possible this additional input of iron, along with rising sea surface temperatures, will affect these bacterial populations and may help to explain both current and future increases in human illnesses from exposure to contaminated seafood and seawater,” the researchers said.”Within 24 hours of mixing weathered desert dust from Morocco with seawater samples, we saw a huge growth in Vibrios, including one strain that could cause eye, ear and open wound infections, and another strain that could cause cholera,” said Erin Lipp, who worked on the study.the amount of iron-containing dust that is deposited in the sea has increased over the last 30 years and is expected to continue to rise, based on precipitation trends in western Africa which are causing desertification.meanwhile, researchers at the University of Wisconsin-Milwaukee warned that an increase in severe rainstorms could cause more sewage overflows, which would release disease-causing bacteria, viruses and protozoa into drinking water and onto beaches.the researchers in this study used climate models to show that spring rains are expected to increase in the next 50 years, and with that increase, ageing sewer systems are more likely to overflow because the ground is frozen and rainwater can’t be absorbed.