In French Polynesia, semi-closed atolls of the eastern Tuamotu Archipelago are home to fisheries and mariculture activities based on giant clam resources. These activities are increasingly vulnerable to global warming, as evidenced by the mass bleaching event observed in Reao atoll in March 2024, triggered by the most intense and prolonged Marine Heatwave (MHW) ever recorded in this lagoon. The GAIA project (manaGement strAtegy evaluatIon for small-scale fisheries in Atoll lagoons) was launched to address this issue and aimed to explore the sustainability of giant clam fisheries under climate change, with a particular focus on processes driving thermal exposure during MHWs. To achieve this, spatial and temporal temperature fluctuations, lagoon circulation, and water exchange dynamics between ocean and lagoon across the atoll rim were monitored using moored autonomous oceanographic sensors. A total of 6 monitoring periods took place between December 2016 and May 2025, with the most extensive instrumentation covering the entire February–March 2024 MHW event. The strength of these observations lies not only in their coverage of a unique and poorly sampled ecosystem, but also in their comprehensive documentation of an exceptional MHW event, from its onset and peak to its dissipation, providing an unprecedented record of the full life cycle of a major thermal anomaly in a tropical semi-closed atoll lagoon. This dataset also supports future modelling efforts to simulate temperature dynamics and identify thermal refugia in atoll lagoons under changing climate scenarios. All data were post-processed, quality-controlled, and formatted into interoperable NetCDF files. The full dataset is openly accessible through the SEANOE marine data platform: https://doi.org/10.17882/105885 (Le Gendre et al. 2025a).
Importance:Chikungunya virus has reemerged in some French overseas territories and mainland France, raising concern for its reintroduction in French Polynesia. Objective:To assess current population immunity to chikungunya virus and estimate future outbreak risk. Design, Setting, and Participants:This cross-sectional study included data from 2 serosurveys and used a modeling approach that integrated seroprevalence, contact matrices, and demographic characteristics. The first serosurvey was conducted on the island of Tahiti (June 2018) among schoolchildren aged 6 to 16 years. The second serosurvey (November 2019 to December 2021) included adults aged 18 to 69 years across French Polynesia, a French overseas territory in the Southeast Pacific that comprises 75 inhabited islands grouped into 5 subdivisions with 279 000 people according to the 2022 census. Data analysis was conducted from April to June 2025. Main Outcomes and Measures:Main outcomes were seroprevalence rates and factors associated with seropositivity; age-stratified infection proportions for the 2014 to 2015 outbreak, pre-outbreak the basic reproduction number (R0), the effective reproduction number (Reff) for 2025, and Reff projections were estimated. Results:Serological data were available for 2363 participants (457 schoolchildren; median [IQR] age, 11 [8-13] years; 244 [53.3%] female, and 1906 adults; 38 [28-52] years; 1003 [52.6%] female). Seroprevalence was 62.8% (95% CI, 58.0%-67.0%) in schoolchildren, and the weighted seroprevalence was 67.6% (95% CI, 64.8%-70.3%) in adults. In adults, lower odds of seropositivity were associated with male sex (adjusted odds ratio [aOR], 0.71; 95% CI, 0.55-0.92), age groups 30 to 44 years and 45 to 69 years compared with 18 to 29 years (ages 30-44 years: aOR, 0.46; 95% CI, 0.32-0.66; ages 45-69 years: aOR, 0.33; 95% CI, 0.22-0.48), living in the Austral subdivision (aOR, 0.38; 95% CI, 0.27-0.55), and higher education (ie, university or more education: aOR, 0.51; 95% CI, 0.32-0.81). Living in larger households and being unpartnered were associated with higher odds of seropositivity (larger households: aOR, 1.69; 95% CI, 1.12-2.56; being unpartnered: aOR, 1.95; 95% CI, 1.03-3.69). Modeled infection rates for 2014 to 2015 ranged from 52.6% (95% credible interval [CrI], 43.6%-60.0%) in children aged 0 to 4 years to 80.8% (95% CrI, 73.3%-86.2%) in those aged 10 to 14 years. Inferred pre-outbreak R0 was 1.78 (95% CrI, 1.73-1.82), and Reff for 2025 was estimated at 0.95 (95% CrI, 0.85-1.04). Assuming assortative mixing, projections suggest Reff would exceed 1 (lower 95% CrI >1) by 2028, but assuming random mixing, Reff would exceed 1 in 2051, more than 20 years later than the other estimate. Conclusions and Relevance:In this cross-sectional study, high chikungunya seroprevalence was observed, with heterogeneity between subdivisions, age groups, and other sociodemographic characteristics. Modeling analysis estimated Reff near 1 in 2025, suggesting sustained transmission could occur if chikungunya is reintroduced. These findings suggest that incorporating contact matrices could improve outbreak risk assessments, while assuming random mixing might underestimate reemergence timing.
Ciguatoxins (CTXs) are produced by marine microbial eukaryotes (Gambierdiscus/Fukuyoa, Dinophyta: Alveolata) that live epiphytically on macroalgae and other substrates. When CTXs accumulate in seafood they cause Ciguatera Poisoning (CP), which affects ca. 20-50,000 people p.a. and is likely worsened by climate change. CTXs in fish are highly variable with diet, ecology, size, age and phylogeny. Chemical identification of CTXs is difficult, and while detection of Gambierdiscus is simple, often no clearly CTX-producing Gambierdiscus are known from CP sites. Here, we coupled custom deep metabarcoding with quantitative PCR, CTXs in both Gambierdiscus and a sentinel fish (Ctenochaetus striatus) with limited home range, in the Cook Islands, an endemic CP area. Using neuroblastoma cell assays and liquid chromatography-tandem mass spectrometry, CTXs were present in fish species from six families. Dinoflagellate α-diversity was dominated by nine Gambierdiscus/Fukuyoa spp., the highest diversity yet reported from a single location. Sites where the rare species, G. polynesiensis, were detected on artificial substrates and macroalgae were more closely aligned with concentrations of P-CTX3B in C. striatus, unrelated to fish age or size, than with overall Gambierdiscus abundance. Of newly isolated Gambierdiscus strains, only the three G. polynesiensis produced P-CTXs. We show rare Gambierdiscus spp. and sentinel fish can map site-specific CP risk to address a growing climate change-related public health threat.
SUMMARY Ross River virus (RRV) causes the most mosquito-borne disease notifications in Australia and a considerable burden of non-fatal, yet frequently prolonged rheumatic illness across the Australia-Pacific region, reflected in thousands of notifications each year and notable economic and quality-of-life losses. Research on RRV spans multiple disciplines, encompassing viral genomics, immunopathology, transmission ecology, epidemiology, entomology, and environmental science. This review synthesizes two decades of cross-disciplinary investigations to present an integrated perspective on the biological, clinical, ecological, and environmental dimensions of RRV infection. By consolidating findings from diverse fields, the review enhances understanding of the complex factors influencing RRV transmission and disease outcomes throughout its endemic range.
BACKGROUND:Vector-borne diseases cause morbidity and mortality globally. However, some areas are more impacted than others, especially with climate change. Controlling vectors remains the primary means to prevent these diseases, but new, more effective tools are needed. The World Health Organization (WHO) prioritized evaluating novel control methods, such as sterile insect technique (SIT) for control of Aedes-borne diseases. In response, a multiagency partnership between the U.S. Centers for Disease Control and Prevention (CDC), the Special Programme for Research and Training in Tropical Diseases (TDR), WHO, and the International Atomic Energy Agency (IAEA) supported the operational implementation and evaluation of SIT against Aedes aegypti and arboviral diseases in the Pacific through a consortium of regional partners (PAC-SIT Consortium). MAIN TEXT:A workshop was held from 2 to 6 May 2023, during which PAC-SIT country participants, researchers, and stakeholders in SIT, scientific advisory committee members, and organizational partners came together to review the principles and components of SIT, share experiences, visit field sites and the SIT facility, and officially launch the PAC-SIT project. Working in groups focused on entomology, epidemiology, and community engagement, participants addressed challenges, priorities, and needs for SIT implementation. CONCLUSIONS:The PAC-SIT workshop brought together researchers and stakeholders engaged in evaluating SIT for arboviral diseases in the Pacific region and globally. This training workshop highlighted that many countries are actively engaged in building operational capacities and phased testing of SIT. The workshop identified a key need for robust larger-scale studies tied with epidemiological endpoints to provide evidence for the scalability and impact on mosquito-borne diseases.
