An outbreak of dengue fever has been declared in a Pacific country beloved by Australian travellers.

The Cook Islands Ministry of Health declared the outbreak last week, with a total of seven cases of the illness in the past 18 days now confirmed.

So far, the ministry said, the cases were confined to the main isle of Rarotonga, with none in the outlying islands of the Pa Enua.

Outbreaks in Australia are largely confined to north Queensland.

Indicators of the illness may start with a rapid fever, headache, chills, swollen lymph nodes, muscle and joint aches, exhaustion, stomach discomfort, nausea, vomiting, and a light red rash.

The severity can range from mild to severe.

Most people with dengue fever recover in about a week, according to Health Direct, but other cases can require hospital case.

Occasionally, dengue fever has proven fatal.

In cases of severe dengue, symptoms might progress a few days after the first symptoms, showing signs such as repeated vomiting, vomiting blood, and unexpected bleeding.

People who have any dengue fever symptoms and are concerned for their health should contact their doctor.

Anybody feeling extremely unwell should contact Triple Zero in Australia, or emergency health services overseas.