The biggest outbreak of dengue fever in decades has had scientists and health officials from more than 20 countries buzzing during an annual conference aiming to limit the spread of the debilitating disease.
The PacMOSSI gathering - the acronym stands for Pacific Mosquito Surveillance Strengthening for Impact - gathered this week in Nadi, Fiji in the sobering wake of one of the worst seasons on record.
More than 20,000 cases of dengue swept through at least 10 Pacific Island countries in 2025, the highest regional confirmed case counts in over a decade, with at least 21 confirmed deaths.
The worst-hit countries were Fiji, French Polynesia, Samoa and Tonga, with more than 94 per cent of the cases and children under 18 the most impacted age group.
The figure almost certainly underestimates the total health burden, given ongoing gaps in diagnostic capacity across the region - one of the reasons why PacMOSSI was established, according to director Tessa Knox.
The consortium includes The Pacific Community, QIMR Berghofer Medical Research Institute, Papua New Guinea Institute of Medical Research, Institut Pasteur New Caledonia and Beyond Essential Systems.
Prof Knox, an expert in public health at James Cook University, says the group was established in 2020 in recognition of the fact vector-borne disease was increasing in the Pacific due to climate change.
Mosquitoes love warm, humid environments and a warmer, wetter Pacific naturally means more mozzies and longer dengue seasons, Prof Knox says.
"When you have mosquitoes proliferating because of environmental conditions and human activity, then there's a high likelihood those mosquitoes will bite someone who has the virus," she explains to AAP.
The disease is not spread directly from person to person. Two species "yellow fever" mosquitoes, Aedes aegypti and Aedes albopictus, act as carriers or vectors, rather than the source.
"The virus will go through their bodies and eventually be transmitted on to someone else, so more mosquitoes means a higher risk transmission will continue and increase in the human population," she says.
Dengue is a potentially fatal illness that causes severe headaches, joint and muscle aches and pains, and rashes.
The disease is difficult to control due to Aedes preference for human habitation, where it is attracted to water storage containers, pot plant bases and discarded tyres.
"We've got a real challenge ahead of us to change what's in the environment directly around us to reduce the production of mosquitoes," Prof Knox said.
With the US-based National Oceanic and Atmospheric Administration officially declaring an El Nino event for the Pacific on Friday, the situation is likely to worsen, she says.
She saysid an El Nino could affect different countries in the Pacific in different ways, with some areas receiving less rainfall than others.
While an increase in rain might increase the amount of water available for the mosquitoes to breed in, a reduction might also mean more people storing water around their houses.
Delegates at PacMOSSI examined a range of regional challenges, from mosquito resistance to insecticides to the scramble to access control supplies during a crisis.
They also looked at how to engage communities for spraying operations, digital tools for tracking and sharing surveillance and control data, and new technologies that use mosquitoes' own biology against them.
Prof Knox says the aim is to provide tailored support to Pacific ministries of health to promote preparedness and support responses to vector-borne diseases.
Lesieli Mahe, from Tonga's ministry of health, says the initiative is life-saving.
"For a small country like ours, being part of these regional initiatives means we're not starting from scratch every time there's an outbreak," according to a statement she provides to AAP.
"There are protocols in place and colleagues in other countries we can call on for advice.
"We have baseline mosquito data to help us understand what we're seeing and how and where to best respond."
Prof Knox says Australia needs to also be vigilant, despite reduced incidence of dengue in far north Queensland due to successful control measures.
She says incursions of Aedes albopictus, which have not previously been found on the Australian mainland, pose a greater risk because current controls do not apply to the species.
But Prof Knox also notes controls that have been developed in Australia have been successfully exported to other countries in the Pacific, including Kirabati, Vanuatu, Fiji and New Caledonia.
She says the culturally, geographically and ecologically diverse nature of island nations in the Pacific means mitigation measures have to be locally tailored to maximise limited regional resources.
