Queensland Health (QH) says it is concerned that the latest outbreak of dengue fever in far north of Queensland could get worse.

Four more people have contracted locally-acquired type two dengue in the Tully area south of Cairns, bringing the total to seven since February.

Series of checks and spraying are being conducted for possible breeding sites by the dengue mosquito control teams.

QH spokesman Dr Jeffrey Hanna says recent heavy rain has provided the perfect breeding ground for aedes aegypti mosquitos.

He says dengue control teams are spraying the affected areas.The two teams of mosquito control staff in Tully and the local governments are doing a major cleanup on blocks, streets and houses.

Dr Hanna said that the teams will stay in Tully until the mosquito numbers go down.

We thought we had knocked this on the head but that's clearly not the case and we are concerned that it's slipped away from us to a certain extent, he said.

He further adds that the cooler months in June and July will hopefully slow down the breeding of the dengue mosquito.