Eosinophilic meningitis due to Angiostrongylus cantonensis (AC) is an emerging parasitic disease worldwide but remains endemic in the Pacific region. In New Caledonia, sporadic cases occur each year, and the route of transmission is often unclear. In January 2023, an unusual cluster of three cases occurred in a village on Lifou Island following week-long community festivities, leading to an epidemiological investigation to determine the outbreak scope, the source of contamination, and inform public health interventions. We conducted a retrospective epidemiological and environmental investigation in one month after the suspected exposure. Cases were defined according to international criteria and classified as confirmed, probable, or suspected. Clinical data, attendance at the festivities and food exposures were collected from medical records and interviews. Environmental observations focused on potential contamination sources in food preparation areas. Serological analyses were performed in symptomatic and asymptomatic exposed individuals. Descriptive statistics were used to summarize demographic, clinical, and exposure characteristics. Nineteen cases were identified, including three confirmed and sixteen suspected cases; no probable cases were identified. Headache was the predominant symptom, often associated with vomiting or paresthesias. All cases attended festivities on December 27, 2022 suggesting a common exposure during that day. The median incubation period was 3 weeks (IQR: 2–4). Two exposure hypotheses were identified: beverages diluted with rainwater and contamination of blended fruit juice. Environmental investigations revealed rats and gastropods around rainwater reservoirs and food preparation areas, including on utensils left to dry outdoors. No AC DNA was detected in water samples. Serology for AC was positive in all confirmed cases (3/3), in 13 of 14 tested suspected cases, and in all ten exposed asymptomatic individuals tested 9 months after the outbreak. This investigation highlights the diagnostic and epidemiological challenges of neuroangiostrongyliasis in endemic areas, where mild presentations often remain unconfirmed and where the value of serological testing is limited by the lack of baseline seroprevalence data. The findings support the hypothesis of accidental incorporation of a heavily infected gastropod into blended fruit juice during preparation, potentially facilitated by open-air kitchen practices in rural Pacific settings.
Introduction Le plus souvent bénigne, la méningite à éosinophiles se manifeste par des céphalées persistantes, voire des déficits sensitivo-moteurs et un syndrome méningé. La maladie est causée par un nématode Angiostrongylus cantonensis dont l'adulte parasite les artères pulmonaires du rat, son hôte définitif. Les gastéropodes sont les hôtes intermédiaires primaires. Les humains qui sont des hôtes accidentels et dits paraténiques sont infectés principalement lors de la consommation d’escargots crus ou insuffisamment cuits. Début janvier 2023, sur l’île de Lifou en Nouvelle-Calédonie, un cluster a été suspecté après la consultation médicale de 18 patients symptomatiques et originaires de la même tribu. Objectif L’étude a pour but de décrire l’épidémie à Angiostrongylus cantonensis, de confirmer le cluster et d’identifier la source de contamination. Méthode Il s’agit d’une étude observationnelle rétrospective, descriptive et environnementale qui repose sur une enquête épidémiologique, comprenant notamment le recueil des symptômes et des bilans biologiques réalisés, et une enquête environnementale pour déterminer la source de contamination. Résultats Nous avons identifié un cluster comprenant 3 cas confirmés par PCR et 14 patients suspects, dont 5 qualifiés de « fortement suspects ». Une patiente a été écartée de la cohorte initiale après 2 sérologies successives négatives. La contamination s’est produite le 27 et/ou 28 décembre 2022 lors d’un rassemblement religieux protestant réunissant environ 60 personnes. La consommation de jus de fruits mixés a été probablement responsable de l’épidémie: une limace ou une planaire contenant des larves d’Angiostrongylus cantonensis serait parvenue à rentrer dans le mixeur qui sert habituellement à la fabrication des jus. La symptomatologie et la période d’incubation correspondent aux données déjà publiées dans la littérature médicale. Conclusion Il s’agit du plus important cluster de méningite à éosinophiles décrit en Nouvelle-Calédonie avec 17 patients concernés. La consommation de jus de fruits mixés a été probablement responsable de l’épidémie.
Aedes albopictus is a mosquito vector of arboviruses that is native to southeast Asia. However, this invasive species has spread worldwide. It arrived in the Caribbean in 1993, but had never been recorded in the French Territories of the Americas. We report here the first detection of Aedes albopictus in Saint Barthélemy, Guadeloupe confirmed by morphological criteria, matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS), and cytochrome c oxidase 1 (cox1) gene barcoding. The presence of this invasive mosquito species in Saint Barthélemy, an island with daily aerial or maritime connections to the French Departments of the Americas, raises concerns about the risk of its introduction into these territories, as well as into other Caribbean countries. It also emphasizes the urgent need to locally reinforce vector surveillance and control measures to prevent the further spread of this mosquito vector.
The global burden of mosquito-transmitted diseases, including malaria, dengue, West Nile, Zika, Usutu, and yellow fever, continues to increase, posing a significant public health threat. With the rise of insecticide resistance and the absence of effective vaccines, new strategies are emerging that focus on the mosquito's microbiota. Nevertheless, the majority of symbionts remain resistant to cultivation. Characterizing the diversity and function of bacterial genomes in mosquito specimens, therefore, relies on metagenomics and subsequent assembly and binning strategies. The obtention and analysis of Metagenome-Assembled Genomes (MAGs) from separated organs can notably provide key information about the specific role of mosquito- associated microbes in the ovaries (the reproductive organs), the midgut (key for food digestion and immunity), or the salivary glands (essential for the transmission of vector-borne diseases as pathogens must colonize them to enter the saliva and reach the bloodstream during a blood meal). These newly reconstructed genomes can then pave the way for the development of novel vector biocontrol strategies. To this aim, it is required to isolate mosquito organs while avoiding cross-contamination between them or with microorganisms present in other mosquito organs. Here, we describe an optimized and contamination-free dissection protocol for studying mosquito microbiome at the organ level.
The Scutellaris Group of Aedes comprises 47 mosquito species, including Aedes albopictus. While Ae. albopictus is widely distributed, the other species are mostly found in the Asia–Pacific region. Evolutionary history researches of Aedes species within the Scutellaris Group have mainly focused on Ae. albopictus, a species that raises significant public health concerns, neglecting the other species. In this study, we aimed to assess genetic diversity and estimate speciation times of several species within the Scutellaris Group. Mosquitoes were therefore collected from various Asia–Pacific countries. Their mitochondrial cytochrome c oxidase subunit 1 (cox1) and subunit 3 (cox3) sequences were analyzed alongside those of other Scutellaris Group species available in the GenBank database. To estimate the divergence time, we analyzed 1849 cox1 gene sequences from 21 species, using three species (Aedes aegypti, Aedes notoscriptus and Aedes vigilax) as outgroups. We found that most of the speciation dates occurred during the Paleogene and the Neogene periods. A separation between the Scutellaris Subgroup and the Albopictus Subgroup occurred approximately 64–61 million years ago (MYA). We also identified a split between species found in Asia/Micronesia and those collected in Melanesia/Polynesia approximately 36–35 MYA. Our findings suggest that the speciation of Aedes species within the Scutellaris Group may be driven by diversity in mammalian hosts, climate and environmental changes, and geological dynamics rather than human migration.
