Rise in dengue fever outbreaks across the Pacific driven by the climate crisis, experts say | Pacific islands

The climate crisis leads to a sharp increase in dengue cases in the Pacific islands, according to experts, while infections reach their highest level in a decade and several countries declare emergencies.

The countries and territories of the Pacific Island have reported 16,502 confirmed cases and 17 deaths since the beginning of 2025, according to the Pacific Sytromic Surveillance System (PSSS), which collaborates with the World Health Organization (WHO) and other agencies. Infections through the region have been at the highest level since 2016, WHO said. Fiji, Samoa and Tonga are among the most affected.

Dr. Paula Vivili, deputy director general of the Pacific Community (SPC), said that the historically dengue’s epidemics were seasonal.

“However, due to climate change, the transmission seasons are getting longer and certain regions present a risk of dengue all year round,” said Vivili.

Dengue, a viral difficulty is propagated by Aedes mosquitoes, causes a high fever, serious headaches, joint and muscle pain, a rash and in serious cases can be fatal. The increase in temperatures, precipitation and increased humidity create ideal breeding conditions for AEDE mosquitoes, even in areas previously unsuitable for transmission.

“Dengue is one of the first real phenomena linked to the diseases we can put at the foot of climate change,” said Dr. Joel Kaufman, epidemiologist and director of the Center for Exhibitions, Diseases, Genomics and Environment at the University of Washington.

“Precipitation increases the flotation line on mosquito eggs laid just above the surface, which then hatch-this is part of the natural reproduction cycle. Strong rains can also increase stagnant water sources, creating more opportunities for mosquitoes to reproduce,” he said.

Kaufman warned that these epidemics have highlighted a wider public health challenge.

“It is at the forefront of what will certainly be many types of human diseases that become more common and more serious as the planet warms up.”

Since he declared an epidemic in April, The Samoa confirmed six deaths linked to dengue, including two brothers and sisters and more than 5,600 cases. This year, Fiji recorded eight deaths and 10,969 cases. The Tonga reported more than 800 cases and three deaths since declared an epidemic in February.

These epidemics highlight the vulnerability of the region to climate -sensitive diseases, which should intensify as global temperatures increase.

Pacific island countries produce only 0.03% of global greenhouse gas emissions, according to the Intergovernmental Panel on Climate Change (IPCC), but confront some of the most serious health threats, including vector transmission diseases.

The last months have brought extreme precipitation in certain parts of the Pacific, notably the Palaos, the Papua New Guinea and the Solomon Islands, while the Secheresse Severe has seized parts of the Marshall Islands, the Papua Nouvelle-Guinée, Nauru and Fiji, according to the New Zealand National Institute of Water and Atmospheric Research Research (Niwa). Forecasts show that these contrasts will continue until October.

Although higher precipitation has been assigned to ideal conditions for mosquito breeding, Kaufman said that extreme weather events can also increase the transmission of mosquito origin diseases. Serious or very dry conditions have been recorded on large parts of the Pacific in the first half of the year, according to Niwa.

“We might have thought that drought would reduce the infections behind mosquitoes, but it seems that it does not go,” Kaufman said. “Instead, there is an acceleration of the transmission.” In the Pacific, national responses have varied. The Samoa, the Cook Islands and the American Samoa have declared emergencies. The Cook Islands have done cleaning on the island, intensified surveillance and targeted spray. The Tonga worked with the WHO to strengthen its response to the epidemic in its most affected islands, while Tuvalu turned to social media and health campaigns to promote preventive measures. The Samoa organized school cleanings and stimulated public health messaging. New Zealand has sent a clinical team and $ 300,000 NZ ($ 178,000) of medical supplies to Samoa, alongside the staff in the field and continuous coordination with Samoane health officials.

But experts say that these measures are undermined by inadequate surveillance.

“Current disease surveillance systems are rarely sufficient to manage dengue, as evidenced by continuous growth of dengue in the region, and more generally worldwide,” said Dr. Bobby Reiner, an ecologist of the disease at the Institute for Measures and Health Assessment at Washington University.

Mosquito control tools are methods used to reduce the population of Aedes mosquitoes that spread dengue, such as the elimination of reproductive sites, the application of lags or the spraying of insecticides. They can also include organic controls, personal protective measures and community cleaning campaigns to prevent mosquito bites and transmission.

However, Reiner said that many mosquito control tools had never been proven to reduce transmission, most reactive responses and often “in search of the epidemic, applying for too late efforts”.