Summer is finally here, but unfortunately so are the mosquitos. Whilst most of us recognise these small flies for their annoying swarming and painful bites, mosquitoes can carry dangerous diseases. Taking steps to avoid being bitten is therefore important to properly enjoy the outdoors this summer. Dr Rob Norton, Clinical Microbiologist and Director of Microbiology at Townsville Hospital explains some of the more serious diseases associated with mosquitos in Australia.
“Any disease that is spread from mosquito to human is known as a 'mosquito-borne disease. These are diseases which can make people ill and, in some severe cases, can even cause death. The main diseases transmitted by mosquitoes in Australia include Australian encephalitis, Ross River (RR) virus disease and Barmah Forest (BF) virus disease.
“Whilst there are a number of other mosquito-borne diseases that occur in Australia, these are introduced by people arriving from places such as South East Asia or the Pacific Islands. This can include the various forms of malaria, a number of the flaviviruses such as chikungunya, the zika virus, and rarer types such as Japanese encephalitis. As there is no endemic Dengue fever in Australia, that also falls into this category, however if it is introduced in a Dengue receptive area then it can be locally transmitted,” said Dr Norton.
Dengue fever is a disease which has important public health implications for Northern Australia. Whilst the disease is usually found in tropical and sub-tropical countries in Africa, Asia and South America, outbreaks of the disease still occur in North Queensland every year. Outbreaks such as this occur when someone becomes infected overseas, then is bitten by a mosquito in Australia and that mosquito spreads the virus to others.
“In terms of its effects on human society, dengue is one of the most important mosquito-borne viral disease of humans. However, recently dengue has been virtually prevented from spreading in Australia by the introduction of Wolbachia infected mosquitos into areas affected by the mosquito-borne disease,” said Dr Norton.
Wolbachia are extremely common bacteria that occur naturally in 60 per cent of insect species, including some mosquitoes, fruit flies, moths, dragonflies and butterflies. The World Mosquito Program discovered that when certain mosquitoes carry Wolbachia, the bacteria compete with viruses like dengue, Zika, chikungunya and yellow fever. This makes it harder for viruses to reproduce inside the mosquitoes. The mosquitoes are therefore much less likely to spread viruses from person to person. 
“The only way to prevent infection from diseases transmitted by mosquitoes is to avoid being bitten. To protect against mosquitoes and reduce the risk of diseases they transmit it is best to cover-up with a loose-fitting long-sleeved shirts and long pants; apply mosquito repellent to exposed skin; and take special care during peak mosquito biting hours, especially around dawn and dusk,” said Dr Norton.