Northern Territory Government
NT Health Mosquito-borne disease alert following monsoonal rains
18 January 2022
Territorians and visitors are being urged to protect themselves from mosquitoes bites, with mosquito numbers expected to increase following recent heavy monsoonal rainfall.
Some mosquito species can transmit viruses including the Ross River and Barmah Forest viruses, as well as the potentially fatal Japanese encephalitis and Murray Valley encephalitis viruses.
The high risk period for the Ross River and Barmah Forest viruses is December to March, and for Murray Valley encephalitis and Japanese encephalitis, it is from January to June.
Mosquito numbers usually increase around 10 days following heavy rainfall.
Nina Kurucz, Director of Medical Entomology, NT Health, said heavy rainfall or flooding associated with monsoonal activity creates environmental conditions favourable for mosquitoes to breed in high numbers.
Ms Kurucz said three cases of Japanese encephalitis have been diagnosed in the Northern Territory (NT), with the first detected in in 2021. All cases were found in the Top End however, infected mosquitoes and birds may be able to carry the virus into other regions with favourable monsoonal conditions.
“We are in the midst of the high-risk period for mosquito-borne viruses, and so expect to see an increase in the number of common banded mosquitoes which transmit diseases.
“The recent rainfall is a timely reminder for Territorians and visitors to protect themselves against mosquito bites, especially while outdoors,” Ms Kurucz said.
To minimise the chance of being bitten by mosquitoes, people should:
• wear protective light-coloured clothing with long sleeves, long trousers, and ankle protection with socks, in areas where mosquito bites are likely
• avoid outdoor exposure near wetlands and flooded areas, especially between dusk and dawn when mosquitoes are most active
• use a protective repellent containing DEET, picaridin or oil of lemon eucalyptus (PMD) and other mosquito protection devices as a supplement to protective clothing when outdoors in areas of mosquito activity
• ensure infants and children are adequately protected against mosquito bites
• consider getting vaccinated against Japanese encephalitis if residing in a high risk area
• consider bifenthrin insecticide barrier treatments by pest control companies for use around residential grounds
• ensure windows and doors have screens to prevent mosquitoes from entering houses.
