Dengue fever outbreak closes schools in Western Samoa

According to media reports, the government of Western Samoa has closed schools to allow for the fumigation of mosquito breeding sites.

More than 5,500 cases of dengue fever have been clinically diagnosed between January and August this year (2025). Many cases have been hospitalised and there have been at least 4 confirmed deaths.

Escalating case numbers and spread

The dengue outbreak in Samoa has recently intensified with 1,446 clinically diagnosed cases in a reporting week. Most of the initial notifications came from the capital city, Apia and northwest Upolu but cases are now being reported countrywide.

Seventy percent of cases are in children under 15 years. This age group is more likely to have no previous immunity.

Den-1 and Den-2 have been identified as the circulating serotypes.

NZ assists Samoa in dengue outbreak response

The outbreak has drawn regional support from New Zealand, which intends to send a small medical team to Apia to provide clinical assistance and work with Samoan authorities to determine further medical support needs.

It will also source and fund medical supplies to help manage the outbreak.

Large case numbers across the Pacific

The current outbreak in Western Samoa is not unexpected given the recent outbreaks in the Cook Islands and French Polynesia. The large numbers of people travelling between island groups contribute to spread.

Large case numbers have also been reported in Kiribati and Tonga. Our previous report, Dengue Fever Across the Pacific Region, outlines these outbreaks and the factors contributing to their spread.

Understanding dengue fever and prevention measures for travellers

Dengue fever is a vector-borne disease. The virus is transmitted to humans by a mosquito bite. Humans are the only known reservoir of infection.

Travellers should be reminded of the risk of dengue fever and other mosquito-borne diseases when travelling to areas of risk. This may even include northern Australia.

Expatriate workers in dengue prone areas should take extra care as they have cumulative risk for the disease. They are also less likely to be immune to dengue. It is very important they participate with local populations to reduce breeding sites for mosquitoes around their housing. Rubbish should be attended to and watercraft such as dinghies and canoes upturned to avoid any water collection. Pot plant saucers are a common breeding site, and these should be either drained or removed.

Holidaymakers on cruise ships should take particular care when undertaking day trips to affected areas. The dengue fever mosquito (primarily Aedes aegypti) is most active early in the morning and just before sunset. These are the times when people are leaving and returning to ships in port areas. Litter can often be seen in dock areas and rubbish provides excellent breeding sites.

Personal mosquito avoidance measures should be observed in high-risk locations.

Dengue cases in Australia

More than 2,100 cases of dengue fever have been reported in Australia over the past 12 months (to July 20, 2025). Most of these cases are most likely short-term travellers returning from Indonesia and other countries in Asia and the Pacific.

One hundred and thirty-four cases of Chikungunya have also been reported.