Isolation of Burkholderia pseudomallei from a goat in New Caledonia: implications for animal and human health monitoring and serological tool comparison

BACKGROUND

Melioidosis is a serious bacterial infection caused by Burkholderia pseudomallei, a gram-negative bacterium commonly found in soil and water. It can affect both humans and animals, and is endemic in regions such as Southeast Asia and Northern Australia. In recent years, there have been reports of an emergence of human melioidosis in other areas, including New Caledonia.

RESULTS

During standard laboratory analysis in New Caledonia in 2021, a strain of B. pseudomallei was isolated from a goat. The strain was characterized using both MLST and WGS techniques and was found to cluster with previously described local human strains from the area. In parallel, several serological tests (CFT, ELISA, Luminex (Hcp1, GroEL, BPSS1840), arrays assay and a latex agglutination test) were performed on animals from the farm where the goat originated, and/or from three other neighboring farms. Using two commercial ELISA kits, seropositive animals were found only on the farm where the infected goat originated and tests based on recombinant proteins confirmed the usefulness of the Hcp1 protein for the diagnosis of melioidosis in animals.

CONCLUSIONS

Despite the regular reports of human cases, this is the first confirmed case of melioidosis in an animal in New Caledonia. These results confirm the presence of the bacterium in the region and highlight the importance of vigilance for both animal and human health. It is critical that all health partners, including breeders, veterinarians, and biologists, work together to monitor and prevent the spread of the disease.

Influence of an oral health promotion program on the evolution of dental status in New Caledonia: A focus on health inequities

New Caledonia is a sui generis collectivity of overseas France situated in the south Pacific Ocean. Geographical and social inequalities are superimposed on ethnic disparities with high prevalence of chronic diseases such as oral diseases. In 2012, the health agency has evaluated the children's health status. Then, an oral health promotion program was developed in 2014. Another study was conducted in 2019 in New Caledonia to appreciate the evolution of children's oral health. A sample of 488 9-years-old children was randomly selected. Dental status was clinically recorded, families and children answered questionnaires about oral health determinants. The methodology (sampling, study variables…) was similar to the one used in the 2012 study. Multivariate mixed-models were conducted to compare 2012 and 2019 dental status and to explore the determinants of caries experience in 2019. Results indicated that caries prevalence and experience decreased between 2012 and 2019, with nonetheless various trends depending on the province or type of indexes. The number of carious lesions (d3t + D3T) in 2019 was used as an outcome variable in four models. Model 1 integrated social variables; ethnicity was found to be the only significant determinant. Model 2 was related to oral health care; participation in the program & and access to oral health care was found to be significant. For oral health behaviours (model 3), tooth brushing frequency and consumption of sugary snacks were significant risk factors. In a final model with significant variables from the previous models, ethnicity, accessibility of oral health care, number of sealed molars, consumption of sugary snacks remained explanatory factors. Five years after the implementation of the oral health promotion program, positive changes in oral health have been observed. However, health equity is still an issue with varying health status depending on ethnicity, behavioural factors and accessibility to oral health care.

Genomic Epidemiology of Corynebacterium diphtheriae in New Caledonia

An increasing number of isolations of Corynebacterium diphtheriae has been observed in recent years in the archipelago of New Caledonia. We aimed to analyze the clinical and microbiological features of samples with C. diphtheriae. All C. diphtheriae isolates identified in New Caledonia from May 2015 to May 2019 were included. For each case, a retrospective consultation of the patient files was conducted. Antimicrobial susceptibility phenotypes, tox gene and diphtheria toxin expression, biovar, and the genomic sequence were determined. Core genome multilocus sequence typing (cgMLST), 7-gene MLST, and search of genes of interest were performed from genomic assemblies. Fifty-eight isolates were included, with a median age of patients of 28 years (range: 9 days to 78 years). Cutaneous origin accounted for 51 of 58 (87.9%) isolates, and C. diphtheriae was associated with Staphylococcus aureus and/or Streptococcus pyogenes in three-quarters of cases. Half of cases came either from the main city Noumea (24%, 14/58) or from the sparsely populated island of Lifou (26%, 15/58). Six tox-positive isolates were identified, associated with recent travel to Vanuatu; 5 of these cases were linked and cgMLST confirmed recent transmission. Two cases of endocarditis in young female patients with a history of rheumatic fever involved tox-negative isolates. The 58 isolates were mostly susceptible to commonly used antibiotics. In particular, no isolate was resistant to the first-line molecules amoxicillin or erythromycin. Resistance to tetracycline was found in a genomic cluster of 17 (29%) isolates, 16 of which carried the tetO gene. There were 13 cgMLST sublineages, most of which were also observed in the neighboring country Australia. Cutaneous infections may harbor nontoxigenic C. diphtheriae isolates, which circulate largely silently in nonspecific wounds. The possible introduction of tox-positive strains from a neighboring island illustrates that diphtheria surveillance should be maintained in New Caledonia, and that immunization in neighboring islands must be improved. Genomic sequencing uncovers how genotypes circulate locally and across neighboring countries. IMPORTANCE The analysis of C. diphtheriae from the tropical archipelago of New Caledonia revealed a high genetic diversity with sublineages that may be linked to Polynesia, Australia, or metropolitan France. Genomic typing allowed confirming or excluding suspected transmission events among cases and contacts. A highly prevalent tetracycline-resistant sublineage harboring the tetO gene was uncovered. Toxigenic isolates were observed from patients returning from Vanuatu, showing the importance of improving vaccination coverage in settings where it is insufficient. This study also illustrates the importance for diphtheria surveillance of the inclusion of isolates from cutaneous sources in addition to respiratory cases, in order to provide a more complete epidemiological picture of the diversity and transmission of C. diphtheriae.

A fusidic acid-resistant (PVL+) clone is associated with the increase in methicillin-resistant Staphylococcus aureus in New Caledonia

OBJECTIVES

Since 2014, Staphylococcus aureus methicillin resistance is rapidly increasing in New Caledonia and is associated with potential serious clinical repercussions. In the present study, we investigated the epidemiology of Methicillin-Resistant S. aureus (MRSA) in New Caledonia and the possible emergence of a particular clonal strain.

METHODS

An overview of the distribution of MRSA in New Caledonia in 2019 is presented. We collected and analysed 171 clinical MRSA isolates from New Caledonia medical laboratories during August and September 2019. Among this collection, 49 representative isolates were analyzed by the French National Reference Center for Staphylococci using StaphyType DNA microarray allowing genetic characterization of the isolates.

RESULTS

Among the 1144 S. aureus isolated over the year 2019, 442 isolates (39%) were resistant to methicillin and 62% of these isolates were resistant to fusidic acid (FA). During the inclusion period, FA resistance rate was similar (60%). Genetic characterization evidenced CC6 as the predominant clonal complex (70%) with 26 isolates (53%) identified as CC6-MRSA-[IV+fus] (PVL+).

CONCLUSIONS

These findings demonstrated a low diversity of MRSA in New Caledonia with the dominance of a clonal complex not reported previously. The frequent fusidic acid (FA) resistance in MRSA was associated with a high prevalence of fusC, suggesting that FA misuse contributed to driving the selection of this clone. Our findings suggest the recommendation to stop the topical use of FA to control the emergence of this severe MRSA clone and decrease the rate of MRSA in New Caledonia.

Modeling present and future climate risk of dengue outbreak, a case study in New Caledonia

BACKGROUND

Dengue dynamics result from the complex interactions between the virus, the host and the vector, all being under the influence of the environment. Several studies explored the link between weather and dengue dynamics and some investigated the impact of climate change on these dynamics. Most attempted to predict incidence rate at a country scale or assess the environmental suitability at a global or regional scale. Here, we propose a new approach which consists in modeling the risk of dengue outbreak at a local scale according to climate conditions and study the evolution of this risk taking climate change into account. We apply this approach in New Caledonia, where high quality data are available.

METHODS

We used a statistical estimation of the effective reproduction number (R_t) based on case counts to create a categorical target variable : epidemic week/non-epidemic week. A machine learning classifier has been trained using relevant climate indicators in order to estimate the probability for a week to be epidemic under current climate data and this probability was then estimated under climate change scenarios.

RESULTS

Weekly probability of dengue outbreak was best predicted with the number of days when maximal temperature exceeded 30.8°C and the mean of daily precipitation over 80 and 60 days prior to the predicted week respectively. According to scenario RCP8.5, climate will allow dengue outbreak every year in New Caledonia if the epidemiological and entomological contexts remain the same.

CONCLUSION

We identified locally relevant climatic factor driving dengue outbreaks in New Caledonia and assessed the inter-annual and seasonal risk of dengue outbreak under different climate change scenarios up to the year 2100. We introduced a new modeling approach to estimate the risk of dengue outbreak depending on climate conditions. This approach is easily reproducible in other countries provided that reliable epidemiological and climate data are available.

Viral evolution sustains a dengue outbreak of enhanced severity

Compared to the previous 2013-2014 outbreak, dengue 2016-2017 outbreak in New Caledonia was characterized by an increased number of severe forms associated with hepatic presentations. In this study, we assessed the virological factors associated with this enhanced severity. Whole-genome sequences were retrieved from dengue virus (DENV)-1 strains collected in 2013-2014 and from severe and non-severe patients in 2016-2017. Fitness, hepatic tropism and cytopathogenicity of DENV 2016-2017 strains were compared to those of 2013-2014 strains using replication kinetics in the human hepatic cell line HuH7. Whole-genome sequencing identified four amino acid substitutions specific to 2016-2017 strains and absent from 2013-2014 strains. Three of these mutations occurred in predicted T cell epitopes, among which one was also a B cell epitope. Strains retrieved from severe forms did not exhibit specific genetic features. DENV strains from 2016-2017 exhibited a trend towards reduced replicative fitness and cytopathogenicity in vitro compared to strains from 2013-2014. Overall, the 2016-2017 dengue outbreak in New Caledonia was associated with a viral genetic evolution which had limited impact on DENV hepatic tropism and cytopathogenicity. These mutations, however, may have modified DENV strains antigenicity, altering the anti-DENV immune response in some patients, in turn favoring the development of severe forms.Trial registration: ClinicalTrials.gov identifier: NCT04615364.

Erection of Euterranova n. gen. and Neoterranova n. gen. (Nematoda, Anisakidae), with the description of E. dentiduplicata n. sp. and new records of two other anisakid nematodes from sharks off New Caledonia

Helminthological examinations of three species of sharks, Galeocerdo cuvier, Triaenodon obesus (both Carcharhinidae, Carcharhiniformes) and Stegostoma fasciatum (Stegostomatidae, Orectolobiformes) from New Caledonian waters, carried out during 2003-2005, revealed the presence of three species of adult anisakid nematodes referable to Terranova Leiper et Atkinson, 1914. However, this genus can no longer be considered valid, because its type species has been designated a species inquirenda. Therefore, the present nematodes are assigned to two newly established genera, Euterranova n. gen. [type species E. dentiduplicata n. sp.] and Neoterranova n. gen. [type species N. scoliodontis (Baylis, 1931) n. comb.], based mainly on different labial structures. Euterranova dentiduplicata n. sp. from the stomach of S. fasciatum is mainly characterized by the presence of lips with two rows of denticles. Innominate specimens of Euterranova (a female and a third-stage larva) were collected from the digestive tract of T. obesus. Specimens of N. scoliodontis were recorded from G. cuvier. The two named species are described based on light and scanning electron microscopical examinations. Neoterranova scoliodontis has previously been recorded in New Caledonian waters from the same host species. Species previously attributed to Terranova are transferred to Euterranova (5 species), Neoterranova (4 species) or considered species inquirendae (10 species). Since Pseudoterranova Mozgovoy, 1950 was found to be a nomen nudum according to the International Code of Zoological Nomenclature (ICZN), the available name of this genus is Pseudoterranova Mozgovoy, 1953. A key to Porrocaecum-like nematode genera (Porrocaecum, Pseudoterranova, Pulchrascaris, Euterranova, and Neoterranova) is provided.

Living in Rural and Urban Areas of New Caledonia: Impact on Food Consumption, Sleep Duration and Anthropometric Parameters Among Melanesian Adolescents

BACKGROUND

Food consumption, sleep duration and overweight were assessed in rural and urban Melanesian adolescents.

METHODS

A cross-sectional survey of 312 rural and 104 urban adolescents (11-16 years old) was conducted. Food intakes were assessed by a 26-item food frequency questionnaire and then categorised into the number of serves from each of the three recommended Pacific food groups (energy foods, protective foods, bodybuilding foods), with two additional categories for foods and drinks to be avoided i.e., processed foods and sugary drinks. Number of food serves were compared with the guidelines of 50% serves from energy foods, 35% serves from protective foods and 15% serves from bodybuilding foods. Sleep duration as hours per day was self-reported and body mass index (BMI) was calculated from measured weight and height.

RESULTS

Approximately 17.9% of rural and 26.9% of urban adolescents met the guidelines for energy foods; 61.5% rural and 69.2% urban met the serves for protective foods and 88.5% and 94.2% met the serves for bodybuilding foods. Less than 6.4% rural and 1.9% urban adolescents avoided processed foods but 61.5% rural and 56.7% urban avoided sugary beverages. Sleep duration for school days was below the international recommendations and did not significantly differ between rural and urban groups: respectively, 8.16 ± 1.10 and 8.31 ± 1.29 h. Overweight/obesity percentage was 38.1% for rural and 31.7% for urban adolescents.

CONCLUSIONS

Although traditional foods, including protective food, are still part of the adolescents' diet, low consumption of the energy food group and high consumption of processed food occurs regardless of location. As poor eating habits and insufficient sleep may contribute to overweight/obesity, educational nutrition programs should target these lifestyle variables.

Vector competence of Aedes aegypti from New Caledonia for the four recent circulating dengue virus serotypes

In New Caledonia (NC), Aedes aegypti is the only proven vector of dengue virus (DENV), which is the most prevalent arbovirosis in NC. Since World War II, the four DENV serotypes have circulated regularly in NC. The epidemiological profile, however, has evolved over the last ten years, with the persistence of DENV-1 circulation and the co-circulation of several DENV serotypes. The current study evaluated the ability of Ae. aegypti from NC to transmit four DENV serotypes (and two DENV-1 genotypes) isolated during recent outbreaks in NC. An Ae. aegypti F1 generation was twice independently orally challenged with each DENV strain (10⁷ FFU/ml). Infection, dissemination and transmission rates and transmission efficiency were measured at day 7 and 14 post-exposure, as well as the quantity of infectious virus particles. Mosquito infection was observed as early as 7 days post-infection. Infection rates between 18 and 58% were measured for all DENV serotypes/genotypes tested. Although dissemination rates ranged from 78 to 100%, transmission efficiencies were low, with values not exceeding 21% at 14 days post-infection for all DENV strains. This study shows that NC Ae. aegypti are moderately competent for DENV in laboratory conditions. In link with epidemiological data, these results suggest implication of other factors in the sustained circulation of DENV-1 in New Caledonia.

Aedes aegypti is the only known vector for dengue virus (DENV) in New Caledonia (NC). DENV are divided into four serotypes (DENV-1 to -4), based on their antigenic properties, these being subdivided into different genotypes. All four DENV serotypes have regularly circulated in New Caledonia in the past. An unusual persistence of DENV-1 has been observed during the last ten years, suggesting a possible preferential transmission of this DENV serotype by Ae. aegypti. In this study, we examine for the first time the ability of Ae. aegypti from New Caledonia to transmit the four circulating DENV serotypes, and more precisely two genotypes of DENV-1. Our results demonstrate that this vector is moderately competent for DENV, with slight differences observed between DENV serotype/genotype in terms of transmission. These findings suggest that other factors are at play in the sustained circulation of DENV-1 and that further vector-virus interactions studies should be undertaken to better understand the DENV epidemiological profile in NC.

Body image, body dissatisfaction and weight status of Pacific adolescents from different ethnic communities: a cross-sectional study in New Caledonia

Objective(s): The prevalence of adolescent obesity is high among the various ethnic groups native to the Pacific region (European, Melanesian and Polynesian). An important factor of weight gain or loss is body size satisfaction; however, little is known about adolescent body self-perception in the Pacific region.Design: Body dissatisfaction was evaluated using the Stunkard Figure Rating Scale in a sample of 699 adolescents from rural and urban areas of New Caledonia. The socio-demographic factors associated with higher body dissatisfaction were determined by multiple linear regression modeling.Results: Our results showed a high rate of body dissatisfaction (over 70%) in the adolescents. Body dissatisfaction was strongly related to the body mass index z-score. Melanesians boys had higher body dissatisfaction scores when they felt 'too thin' while Melanesian girls showed lower body dissatisfaction when they felt 'too fat.'.Conclusion: These results showed that social pressure for thinness or musculature may be different among adolescents living in New Caledonia. These results should be taken into account in education overweight prevention programs.

Nutrition behaviors and sociodemographic factors associated with overweight in the multi-ethnic adolescents of New Caledonia

Objectives: New Caledonia is a multi-ethnic French territory in the Pacific, characterized by communities with widely varying nutritional habits. Little is currently known about adolescent food behaviors and habits and their association with overweight. This study therefore determined the sociodemographic factors and food behaviors associated with overweight and underweight in this population, as well as the factors associated with skipping breakfast. Methods: A cross-sectional survey was conducted among New Caledonian adolescents using a self-administered questionnaire; anthropometric measurements were also taken. Weight status was determined using international cutoffs, and the factors associated with overweight and underweight were identified with multiple logistic regression analysis. The factors associated with breakfast skipping were also determined. Results: Skipping breakfast, being Melanesian, living in a rural area and having low economic status were positively associated with overweight in these adolescents. Skipping breakfast was relatively infrequent, reported by 18% and 13% of the males and females, respectively. Logistic regression models found that the main factors associated with breakfast consumption habits were gender, weight status and ethnicity. Conclusions: Several factors are associated with overweight status in New Caledonian adolescents. Breakfast education should be improved for adolescents living in rural areas and from low socioeconomic status.

Nickel and associated metals in New Caledonia: Exposure levels and their determinants

The ultramafic massifs of the New Caledonian archipelago contain about 10% of the world's nickel reserves, which also contain significant but lower amounts of cobalt, chromium, and manganese. Natural erosion of these massifs and mining activities may contribute to the exposure of local populations to these metals through contamination of air, food, and water resources. We conducted a biomonitoring survey to evaluate exposure to these four metals and its main determinants by constructing a stratified sample of 732 adults and children (>3 years old) from visitors to 22 health centers across the archipelago. Urine was collected and analyzed by inductively-coupled plasma mass spectrometry to determine metal concentrations. A face-to-face interview was conducted to document sociodemographic characteristics, lifestyle and dietary habits, and residence-mine distance. Environmental samples (soil, house dust, water, and foodstuffs) were collected from two areas (one with and one without mining activity) to delineate determinants of exposure in more detail. Nickel and chromium were metals with the highest concentrations found in urine, especially in children, at levels exceeding reference values derived from representative national surveys elsewhere throughout the world (for children: 4.7 μg/g creatinine for nickel and 0.50 μg/g creatinine for chromium): 13% of children exceeded the reference value for nickel and 90% for chromium. Large variations were observed by region, age, and sex. In this geological setting, urinary and environmental nickel concentrations appear to be driven mainly by soil content. This is the first archipelago-wide survey of metal exposure in New Caledonia. The potential health consequences of this chronic high exposure need to be assessed.

Introduction of the Anopheles bancroftii Mosquito, a Malaria Vector, into New Caledonia

In June 2017, an Anopheles mosquito species was detected in New Caledonia. Morphologic identification and genomic sequencing revealed that the specimens tested belong to An. bancroftii genotype A1. This introduction underscores the risk for local malaria transmission and the vulnerability of New Caledonia to vector introduction.

Overweight and obesity in New Caledonian adults: Results from measured and adjusted self-reported anthropometric data

AIMS

To estimate the overweight (OW) and obesity (Ob) prevalence and associated socio-demographic risk factors in New Caledonian adults aged 18-67years.

METHODS

From a randomly selected cross-sectional population survey, self-reported (n=2513) and measured (n=736) height and weight data were collected. Separate linear regression analyses for measured weight and height were performed, using cases with both self-reported weight and height and socio-demographic variables. The final weight and height assigned to each case was either measured or predicted from the regression (n=2075). OW prevalence was defined as: Body Mass Index (BMI) ≥25 and <30kg/m^-2; and Ob: BMI ≥30kg/m^-2. Samples were weighted to the general adult population. Prevalence and Odds ratios (ORs) were calculated by gender, and adjusted for socio-demographic variables, to assess differentials in OW, Ob and OW-Ob, using multinomial and logistic regressions.

RESULTS

Male (M) OW was 35% (95% CI: 31-38), Ob 29% (95% CI: 26-32) and OW-Ob 64% (95% CI: 60-67); female (F) OW was 26% (95% CI: 23-28), Ob 34% (95% CI: 31-37) and OW-Ob 60% (95% CI: 57-63). Compared to Melanesians (OR=1.0) for male/female: Polynesians had the highest prevalence of OW (1.7/1.5), Ob (4.7/3.5), and OW-Ob (3.0/2.5); New Caledonian-born Europeans had greater OW, Ob and OW-Ob (0.3/0.4) than immigrant Europeans (0.2/0.2).

CONCLUSIONS

Findings contribute to obesity comparisons with other Pacific Islands, and they establish trends in New Caledonia for targeting policies and strategies of prevention.

Socioeconomic and environmental determinants of dengue transmission in an urban setting: An ecological study in Nouméa, New Caledonia

Background

Dengue is a mosquito-borne virus that causes extensive morbidity and economic loss in many tropical and subtropical regions of the world. Often present in cities, dengue virus is rapidly spreading due to urbanization, climate change and increased human movements. Dengue cases are often heterogeneously distributed throughout cities, suggesting that small-scale determinants influence dengue urban transmission. A better understanding of these determinants is crucial to efficiently target prevention measures such as vector control and education. The aim of this study was to determine which socioeconomic and environmental determinants were associated with dengue incidence in an urban setting in the Pacific.

Methodology

An ecological study was performed using data summarized by neighborhood (i.e. the neighborhood is the unit of analysis) from two dengue epidemics (2008–2009 and 2012–2013) in the city of Nouméa, the capital of New Caledonia. Spatial patterns and hotspots of dengue transmission were assessed using global and local Moran’s I statistics. Multivariable negative binomial regression models were used to investigate the association between dengue incidence and various socioeconomic and environmental factors throughout the city.

Principal findings

The 2008–2009 epidemic was spatially structured, with clusters of high and low incidence neighborhoods. In 2012–2013, dengue incidence rates were more homogeneous throughout the city. In all models tested, higher dengue incidence rates were consistently associated with lower socioeconomic status (higher unemployment, lower revenue or higher percentage of population born in the Pacific, which are interrelated). A higher percentage of apartments was associated with lower dengue incidence rates during both epidemics in all models but one. A link between vegetation coverage and dengue incidence rates was also detected, but the link varied depending on the model used.

Conclusions

This study demonstrates a robust spatial association between dengue incidence rates and socioeconomic status across the different neighborhoods of the city of Nouméa. Our findings provide useful information to guide policy and help target dengue prevention efforts where they are needed most.

Dengue virus is rapidly spreading throughout tropical and subtropical regions worldwide, possibly aided by environmental change, urbanization and/or increase in human mobility. Already present in 120 countries, dengue virus causes extensive disease burden and generates large economic costs. As dengue is mosquito-borne, its transmission pattern is strongly influenced by climate. However, dengue cases are not always distributed evenly throughout cities, where climate can be assumed to be homogenous. This suggests that other factors which are heterogeneously distributed in cities could play a role in dengue transmission, such as socioeconomic status and environmental factors (both natural and built). Identifying those factors is crucial to develop and target dengue prevention interventions, such as mosquito control and education. Our study uses dengue incidence statistics from two large epidemics in Nouméa, the capital of New Caledonia, to investigate which socioeconomic or environmental factors correlate with dengue incidence in an urban setting. Dengue incidence was consistently higher in neighborhoods where socioeconomic status was lower (i.e. lower revenue or higher unemployment) and often higher where the proportion of single-family houses in all buildings was higher. Our data suggest that, if resources are limited, prevention measures should be targeted in priority towards neighborhoods of lower socioeconomic status.

Seeking the environmental source of Leptospirosis reveals durable bacterial viability in river soils

Background

Leptospirosis is an important re-emerging infectious disease that affects humans worldwide. Infection occurs from indirect environment-mediated exposure to pathogenic leptospires through contaminated watered environments. The ability of pathogenic leptospires to persist in the aqueous environment is a key factor in transmission to new hosts. Hence, an effort was made to detect pathogenic leptospires in complex environmental samples, to genotype positive samples and to assess leptospiral viability over time.

Methodology/Principal findings

We focused our study on human leptospirosis cases infected with the New Caledonian Leptospira interrogans serovar Pyrogenes. Epidemiologically related to freshwater contaminations, this strain is responsible for ca. 25% of human cases in New Caledonia. We screened soil and water samples retrieved from suspected environmental infection sites for the pathogen-specific leptospiral gene lipL-32. Soil samples from all suspected infection sites tested showed detectable levels of pathogenic leptospiral DNA. More importantly, we demonstrated by viability qPCR that those pathogenic leptospires were viable and persisted in infection sites for several weeks after the index contamination event. Further, molecular phylogenetic analyses of the leptospiral lfb-1 gene successfully linked the identity of environmental Leptospira to the corresponding human-infecting strain.

Conclusions/Significance

Altogether, this study illustrates the potential of quantitative viability-PCR assay for the rapid detection of viable leptospires in environmental samples, which might open avenues to strategies aimed at assessing environmental risk.

Leptospirosis is an emerging zoonotic disease caused by infection with pathogenic strains of Leptospira. Most human infections arise from environmental exposure to contaminated freshwater environments or watered soils where pathogenic Leptospira are considered as able to survive for prolonged periods. Therefore, a good understanding of Leptospira survival strategy in the environment is a key step to identifying crucial factors amenable to interventions and public health actions to lower leptospirosis burden. In this study, we investigated the environmental presence and survival of pathogenic leptospires in areas where recent human leptospirosis cases had been reported. Although detection of Leptospira from complex environmental samples is difficult, we successfully detected the presence of pathogenic Leptospira in soils of suspected infection sites. In addition, we showed that these pathogenic leptospires were alive and present in soils several weeks after the infecting event. Typing of leptospiral DNA retrieved from the environment revealed identities between environmental pathogenic Leptospira and the causative strains involved in human leptospirosis index cases. Interestingly, we also identified yet unreported genotypes. Altogether, our work illustrates the potential of quantitative molecular assays for the rapid detection and typing of viable leptospires in environmental samples, which could prove useful to assess the risk of environmental exposure.

A Novel Human T-lymphotropic Virus Type 1c Molecular Variant in an Indigenous Individual from New Caledonia, Melanesia

BACKGROUND

Human T-Lymphotropic Virus type 1 (HTLV-1) is endemic among people of Melanesian descent in Papua New Guinea, Solomon Islands and Vanuatu, and in Indigenous populations from Central Australia. Molecular studies revealed that these Australo-Melanesian strains constitute the highly divergent HTLV-1c subtype. New Caledonia is a French overseas territory located in the Southwest Pacific Ocean. HTLV-1 situation is poorly documented in New Caledonia and the molecular epidemiology of HTLV-1 infection remains unknown.

OBJECTIVES

Studying 500 older adults Melanesian natives from New Caledonia, we aim to evaluate the HTLV-1 seroprevalence and to molecularly characterize HTLV-1 proviral strains.

STUDY DESIGN

Plasma from 262 men and 238 females (age range: 60-96 years old, mean age: 70.5) were screened for anti-HTLV-1 antibodies by particle agglutination (PA) and indirect immunofluorescence assay (IFA). Serological confirmation was obtained using Western blot assay. DNAs were extracted from peripheral blood buffy coat of HTLV-1 seropositive individuals, and subjected to four series of PCR (LTR-gag; pro-pol; pol-env and tax-LTR). Primers were designed from highly common conserved regions of the major HTLV-1 subtypes to characterize the entire HTLV-1 proviral genome.

RESULTS

Among 500 samples, 3 were PA and IFA positive. The overall seroprevalence was 0.6%. The DNA sample from 1 New Caledonian woman (NCP201) was found positive by PCR and the complete HTLV-1 proviral genome (9,033-bp) was obtained. The full-length HTLV-1 genomic sequence from a native woman from Vanuatu (EM5), obtained in the frame of our previous studies, was also characterized. Both sequences belonged to the HTLV-1c Australo-Melanesian subtype. The NCP201 strain exhibited 0.3% nucleotide divergence with the EM5 strain from Vanuatu. Furthermore, divergence reached 1.1% to 2.9% with the Solomon and Australian sequences respectively. Phylogenetic analyses on a 522-bp-long fragment of the gp21-env gene showed the existence of two major clades. The first is composed of strains from Papua New Guinea; the second includes strains from all neighboring archipelagos (Solomon, Vanuatu, New Caledonia), and Australia. Interestingly, this second clade itself is divided into two sub-clades: strains from Australia on one hand, and strains from Solomon Islands, Vanuatu and New Caledonia on the other hand.

CONCLUSIONS

The HTLV-1 seroprevalence (0.6%) in the studied adult population from New Caledonia appears to be low. This seroprevalence is quite similar to the situation observed in Vanuatu and Solomon Islands. However it is very different to the one encountered in Central Australia. Taken together, these results demonstrated that Australo-Melanesia is endemic for HTLV-1 infection with a high diversity of HTLV-1c strains and a clear geographic clustering according to the island of origin of HTLV-1 infected persons.

Zika Virus, a New Threat for Europe?

BACKGROUND

Since its emergence in 2007 in Micronesia and Polynesia, the arthropod-borne flavivirus Zika virus (ZIKV) has spread in the Americas and the Caribbean, following first detection in Brazil in May 2015. The risk of ZIKV emergence in Europe increases as imported cases are repeatedly reported. Together with chikungunya virus (CHIKV) and dengue virus (DENV), ZIKV is transmitted by Aedes mosquitoes. Any countries where these mosquitoes are present could be potential sites for future ZIKV outbreak. We assessed the vector competence of European Aedes mosquitoes (Aedes aegypti and Aedes albopictus) for the currently circulating Asian genotype of ZIKV.

METHODOLOGY/PRINCIPAL FINDINGS

Two populations of Ae. aegypti from the island of Madeira (Funchal and Paul do Mar) and two populations of Ae. albopictus from France (Nice and Bar-sur-Loup) were challenged with an Asian genotype of ZIKV isolated from a patient in April 2014 in New Caledonia. Fully engorged mosquitoes were then maintained in insectary conditions (28°±1°C, 16h:8h light:dark cycle and 80% humidity). 16-24 mosquitoes from each population were examined at 3, 6, 9 and 14 days post-infection to estimate the infection rate, disseminated infection rate and transmission efficiency. Based on these experimental infections, we demonstrated that Ae. albopictus from France were not very susceptible to ZIKV.

CONCLUSIONS/SIGNIFICANCE

In combination with the restricted distribution of European Ae. albopictus, our results on vector competence corroborate the low risk for ZIKV to expand into most parts of Europe with the possible exception of the warmest regions bordering the Mediterranean coastline.

Prevalence and Sequence-Based Identity of Rumen Fluke in Cattle and Deer in New Caledonia

An abattoir survey was performed in the French Melanesian archipelago of New Caledonia to determine the prevalence of paramphistomes in cattle and deer and to generate material for molecular typing at species and subspecies level. Prevalence in adult cattle was high at animal level (70% of 387 adult cattle) and batch level (81%). Prevalence was lower in calves at both levels (33% of 484 calves, 51% at batch level). Animals from 2 of 7 deer farms were positive for rumen fluke, with animal-level prevalence of 41.4% (29/70) and 47.1% (33/70), respectively. Using ITS-2 sequencing, 3 species of paramphistomes were identified, i.e. Calicophoron calicophorum, Fischoederius elongatus and Orthocoelium streptocoelium. All three species were detected in cattle as well as deer, suggesting the possibility of rumen fluke transmission between the two host species. Based on heterogeneity in ITS-2 sequences, the C. calicophorum population comprises two clades, both of which occur in cattle as well as deer. The results suggest two distinct routes of rumen fluke introduction into this area. This approach has wider applicability for investigations of the origin of rumen fluke infections and for the possibility of parasite transmission at the livestock-wildlife interface.

Socio-economic and Climate Factors Associated with Dengue Fever Spatial Heterogeneity: A Worked Example in New Caledonia

BACKGROUND/OBJECTIVES

Understanding the factors underlying the spatio-temporal distribution of infectious diseases provides useful information regarding their prevention and control. Dengue fever spatio-temporal patterns result from complex interactions between the virus, the host, and the vector. These interactions can be influenced by environmental conditions. Our objectives were to analyse dengue fever spatial distribution over New Caledonia during epidemic years, to identify some of the main underlying factors, and to predict the spatial evolution of dengue fever under changing climatic conditions, at the 2100 horizon.

METHODS

We used principal component analysis and support vector machines to analyse and model the influence of climate and socio-economic variables on the mean spatial distribution of 24,272 dengue cases reported from 1995 to 2012 in thirty-three communes of New Caledonia. We then modelled and estimated the future evolution of dengue incidence rates using a regional downscaling of future climate projections.

RESULTS

The spatial distribution of dengue fever cases is highly heterogeneous. The variables most associated with this observed heterogeneity are the mean temperature, the mean number of people per premise, and the mean percentage of unemployed people, a variable highly correlated with people's way of life. Rainfall does not seem to play an important role in the spatial distribution of dengue cases during epidemics. By the end of the 21st century, if temperature increases by approximately 3 °C, mean incidence rates during epidemics could double.

CONCLUSION

In New Caledonia, a subtropical insular environment, both temperature and socio-economic conditions are influencing the spatial spread of dengue fever. Extension of this study to other countries worldwide should improve the knowledge about climate influence on dengue burden and about the complex interplay between different factors. This study presents a methodology that can be used as a step by step guide to model dengue spatial heterogeneity in other countries.

Prevalence and sociodemographic risk factors of chlamydia, gonorrhoea and syphilis: a national multicentre STI survey in New Caledonia, 2012

OBJECTIVES

To estimate prevalence and identify sociodemographic risk factors for Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT) and Treponema pallidum infections in New Caledonia.

METHOD

A national cross-sectional survey was undertaken using a three-stage random sampling of general practice surgeries and public dispensaries. Participants were included through opportunistic screening and using a systematic step for selection. The study sample was weighted to the general population aged 18-49 years. Prevalence and risk factors were calculated by logistic regression.

RESULTS

CT was the most common sexually transmitted infection, with a prevalence of 9% (95% CI 6.6% to %11.4), followed by NG 3.5% (95% CI 1.9% to 5.1%), previous or latent syphilis 3% (95% CI 1.7% to 4.3%), NG and CT co-infection 2.1% (95% CI 0.8% to 3.3%) and active syphilis 0.4% (95% CI 0.0% to 0.9%). Being from a young age group (18-25 years), being single, having a low level of education and province of residence were all associated with higher prevalence of all three STIs. Being of Melanesian origin was associated with higher prevalence of both CT and NG. There was a significant interaction between ethnic group and province of residence for prevalence of CT. Female gender was associated with higher prevalence of CT.

CONCLUSIONS

The prevalence of CT was similar to estimates from other healthcare-based surveys from the Pacific, but higher for NG and lower for active syphilis infection. All sexually transmitted infections estimates were much higher than those found in population-based surveys from Europe and the USA. The sociodemographic risk factors identified in this study will help guide targeted prevention and control strategies in New Caledonia.

Dental status of new caledonian children: is there a need for a new oral health promotion programme?

BACKGROUND

Before implementing a new oral health promotion program in the French overseas territory of Nouvelle Calédonie, the health authorities needed recent data about dental status of the New Caledonian child population.

OBJECTIVES

This study aimed to describe the dental status of 6, 9 and 12-yr-old New Caledonian children and to investigate the environmental and behavioural risk factors related to oral health.

METHODS

A randomly selected sample of 2734 children (744 6-yr-olds, 789 9-yr-olds, and 1201 12-yr-olds) was examined clinically by seven calibrated investigators and participants responded to a questionnaire. The main variables were objective criteria about dental status and subjective criteria about experience of dental care, dental fear, self-perception of oral health, cultural or ethnic identity and environmental and behavioural risk factors.

RESULTS

Overall, most of the children had infectious oral diseases: more than 50% had gingivitis, and 60% of 6- and 9 yr-olds had at least one deciduous or permanent tooth with untreated caries. The mean 12-yr-old number of decayed missing and filled teeth (DMFT) was 2.09±2.82. The number of carious lesions was related to the unfavourable lifestyle, deprived social status and no preventive dental care. Kanak, Polynesians and Caledonians (respectively 27%, 18% and 45% of the study sample) were more affected by caries than metropolitan French and Asian children. Children with many untreated carious lesions had negative perceptions of their oral health; they complained of chewing difficulty and had higher scores for dental anxiety.

CONCLUSION

This study highlights the need for new strategies aimed at improving oral health and at reducing inequalities in New Caledonia. An oral health promotion program would need to be developed in connection with other health programmes using the common risk factor approach within the context of the local environment.

El Niño Southern Oscillation and leptospirosis outbreaks in New Caledonia

Leptospirosis is an important cause of seasonal outbreaks in New Caledonia and the tropics. Using time series derived from high-quality laboratory-based surveillance from 2000-2012, we evaluated whether climatic factors, including El Niño Southern Oscillation (ENSO) and meteorological conditions allow for the prediction of leptospirosis outbreaks in New Caledonia. We found that La Niña periods are associated with high rainfall, and both of these factors were in turn, temporally associated with outbreaks of leptospirosis. The sea surface temperature in El Niño Box 4 allowed forecasting of leptospirosis outbreaks four months into the future, a time lag allowing public health authorities to increase preparedness. To our knowledge, our observations in New Caledonia are the first demonstration that ENSO has a strong association with leptospirosis. This association should be tested in other regions in the South Pacific, Asia or Latin America where ENSO may drive climate variability and the risk for leptospirosis outbreaks.

Effect of persistent patent ductus arteriosus on mortality and morbidity in very low-birthweight infants

AIM

Because New Caledonia is geographically isolated from the nearest cardiac surgical centre, surgical closure of ductus arteriosus is not performed in very low-birthweight (VLBW) infants who have a persistent patent ductus in spite of having undergone treatment with ibuprofen. This study aimed at investigating the possible effect of persistent patent ductus in VLBW infants.

METHODS

The study included 177 VLBW infants born at 25-31 weeks of gestation from January 2006 to May 2011. Mortality and major morbidities were compared between infants with a persistent patent ductus (n = 33) and those without it (n = 104). Statistical associations between potential neonatal risk factors and significant morbidities were identified using multivariate regression analyses.

RESULTS

Rates of mortality and major morbidities, including the rate of bronchopulmonary dysplasia, necrotizing enterocolitis, intraventricular haemorrhage grades I-II and III-IV, periventricular leucomalacia, late-onset infections and failure of hearing screening, were insignificantly higher in VLBW infants with a persistent patent ductus than in those without it.

CONCLUSION

This study adds further evidence that persistent patent ductus arteriosus has no significant effect on mortality and morbidity in VLBW infants born at ≥25 weeks' gestational age.

Rodent abundance dynamics and leptospirosis carriage in an area of hyper-endemicity in New Caledonia

Background

Widespread but particularly incident in the tropics, leptospirosis is transmitted to humans directly or indirectly by virtually any Mammal species. However, rodents are recognized as the most important reservoir. In endemic regions, seasonal outbreaks are observed during hot rainy periods. In such regions, hot spots can be evidenced, where leptospirosis is “hyper-endemic”, its incidence reaching 500 annual cases per 100,000. A better knowledge of how rodent populations and their Leptospira prevalence respond to seasonal and meteorological fluctuations might help implement relevant control measures.

Methodology/Principal Findings

In two tribes in New Caledonia with hyper-endemic leptospirosis, rodent abundance and Leptospira prevalence was studied twice a year, in hot and cool seasons for two consecutive years. Highly contrasted meteorological situations, particularly rainfall intensities, were noted between the two hot seasons studied. Our results show that during a hot and rainy period, both the rodent populations and their Leptospira carriage were higher. This pattern was more salient in commensal rodents than in the sylvatic rats.

Conclusions/Significance

The dynamics of rodents and their Leptospira carriage changed during the survey, probably under the influence of meteorology. Rodents were both more numerous and more frequently carrying (therefore disseminating) leptospires during a hot rainy period, also corresponding to a flooding period with higher risks of human exposure to waters and watered soils. The outbreaks of leptospirosis in hyper-endemic areas could arise from meteorological conditions leading to both an increased risk of exposure of humans and an increased volume of the rodent reservoir. Rodent control measures would therefore be most effective during cool and dry seasons, when rodent populations and leptospirosis incidence are low.

In this study, we surveyed rodents and their Leptospira carriage in an area where human leptospirosis is hyper-endemic. We evidenced the well-known associations between specific rodent species and particular leptospires in both mice and rats. Overall, the observed Leptospira prevalence was in the range 18–47% depending on species, similar to other descriptions. However, significant variations were observed both in the abundance of rodents and their Leptospira carriage, one hot period with heavy rain being associated with both a highest abundance and an increased prevalence. Similar meteorological conditions could lead to increased leptospires dispersal by the rodent reservoir and increased exposure of humans to risk situations (e.g. flood, mud). Because rodent control measures were demonstrated elsewhere to be cost-effective if correctly planned and implemented, this contribution to a better knowledge of rodent and leptospires dynamics provides useful information and may in turn allow to develop relevant rodent control actions aimed at reducing the burden of human leptospirosis.

A campaign to eradicate bovine babesiosis from New Caledonia

In December 2007, Babesia bovis was introduced to New Caledonia through the importation of cattle that had been vaccinated with a live tick fever (babesiosis and anaplasmosis) vaccine. Although the tick Rhipicephalus (Boophilus) microplus is common in New Caledonia, the territory had previously been free of tick-borne diseases of cattle. This paper describes the initial extent of the outbreak, the measures and rationale for disease control, and the progress to date of the eradication campaign. Initially, 22 properties were affected involving approximately 2300 cattle in 'high risk' zones and 1600 in adjoining 'suspect' zones. Rather than slaughtering infected herds or attempting to eliminate the tick vector, the campaign was based on quarantine of affected properties, and aggressive tick control in conjunction with 3-monthly treatments of the high risk cattle with the antiprotozoal drug imidocarb dipropionate. Subsequent surveillance by ELISA and PCR showed a progressive and dramatic decline in seroprevalence among infected herds and the absence of new infections. All 22 properties were considered to be free of Babesia within 12 months of the start of the disease control program. These results indicate that the strategy was effective in eliminating Babesia from infected herds and feasible as an eradication strategy on a moderately large scale. Unfortunately, early in the campaign, babesiosis spread to a herd of feral cattle on a property in the 'suspect' zone, and this reservoir of infection subsequently resulted in the infection (or reinfection) of cattle on several neighbouring commercial farms. The eradication campaign in New Caledonia is currently focussed on destocking the feral cattle - extensive surveillance suggests that this is the only remaining nidus of infection.

Pooled analysis of two case-control studies in New Caledonia and French Polynesia of body mass index and differentiated thyroid cancer: the importance of body surface area

BACKGROUND

New Caledonia and French Polynesia have among of the world highest thyroid cancer incidence rates. Studies have demonstrated a relationship between anthropometric parameters and the prevalence of cancer. In this study we evaluated further the relationship between body mass index (BMI) and other anthropometric parameters on the incidence of thyroid cancer in the New Caledonia and French Polynesia populations.

METHODS

We performed a pooled analysis of two case-control studies in New Caledonia and French Polynesia. We included a total of 554 cases (65 men and 489 women) of differentiated thyroid cancers and 776 population control subjects matched on sex, age, and study. Anthropometric factors (height, weight, BMI, body fat percentage [BF%], and body surface area [BSA]), at age 18 and before diagnosis, were analyzed by conditional logistic regression, adjusting for other independent risk factors.

RESULTS

A high proportion of cases (73%) were overweight (25-29.9 kg/m(2)) or obese (≥30 kg/m(2)) before diagnosis of thyroid cancer (against 57% of control subjects). An increased risk of thyroid cancer was observed with greater height, weight, BMI, BF%, and BSA. The association of thyroid cancer risk with height, weight, BMI, and BF% did not remain when adjustment was made for BSA. By comparison, the odds ratios for the highest versus the lowest quartile of BSA at age 18 were 3.97 (95% confidence interval, 2.57-6.15; p < 0.001) for women and 4.06 (95% confidence interval, 1.03-16.06; p = 0.04) for men. The association between thyroid cancer risk and each of anthropometric factors did not depend on tumor size or menopausal status before diagnosis.

CONCLUSION

Among anthropometric factors, BSA plays a dominant role in thyroid cancer risk and explains the apparent role of BMI.

Natural attenuation of dengue virus type-2 after a series of island outbreaks: a retrospective phylogenetic study of events in the South Pacific three decades ago

Dengue is an expanding arboviral disease of variable severity characterized by the emergence of virus strains with greater fitness, epidemic potential and possibly virulence. To investigate the role of dengue virus (DENV) strain variation on epidemic activity we studied DENV-2 viruses from a series of South Pacific islands experiencing outbreaks of varying intensity and clinical severity. Initially appearing in 1971 in Tahiti and Fiji, the virus was responsible for subsequent epidemics in American Samoa, New Caledonia and Niue Island in 1972, reaching Tonga in 1973 where there was near-silent transmission for over a year. Based on whole-genome sequencing and phylogenetic analysis on 20 virus isolates, Tonga viruses were genetically unique, clustering in a single clade. Substitutions in the pre-membrane (prM) and nonstructural genes NS2A and NS4A correlated with the attenuation of the Tongan viruses and suggest that genetic change may play a significant role in dengue epidemic severity.

Childhood sexual abuse and adult sexual health among indigenous Kanak women and non-Kanak women of New Caledonia

OBJECTIVES

Few studies have addressed the long-term consequences of adverse childhood experiences among women in Oceania, in particular among indigenous women. This paper aims to report prevalences of childhood sexual abuse (CSA) and to asses the negative sexual health consequences in adulthood by comparing indigenous Kanak to non-Kanak women in New Caledonia.

METHODS

Data come from a population survey on violence against women and health. Face-to-face interviews were conducted in 2002-2003 with adult women randomly selected from the electoral list. Separate models for Kanak (n=329) and non-Kanak women (n=426) were performed. Regression models adjusted for relevant socio-demographics factors were conducted to estimate the odds ratios for the associations between childhood sexual abuse and adult sexual health outcomes.

RESULTS

A non-significant difference between Kanak (11.8%) and non-Kanak women (14.4%) was found for the prevalence of CSA. Among Kanak women, CSA increases the risk of sexually transmitted infections, of non-desired sexual intercourse with an intimate partner and of experience of adult sexual violence. However, use of modern contraception as an adult was more frequent among CSA Kanak victims, as compared to other Kanak women. Among non-Kanak women, only abortion appeared significantly associated with CSA.

CONCLUSIONS AND PRACTICE IMPLICATIONS

The findings show that in all ethnic communities of New Caledonia, a history of child sexual abuse is not rare among women. They also shed light on the long-term consequences of CSA, suggesting that the effect of CSA may differ according to ethnic membership and subsequent social stratification and gender norms. Efforts to break the silence around violence against girls and establish a stronger foundation are required in New Caledonia. Prevention programs on violence against women and sexual health that take into account the cultural and social heterogeneity are needed.

Invasive serotype 1 Streptococcus pneumoniae outbreaks in the South Pacific from 2000 to 2007

In New Caledonia, Wallis and Futuna, and French Polynesia, an active surveillance system was established to monitor pneumococcal serotype prevalence between 2000 and 2007. The most prevalent serotype was serotype 1, which belonged to the major clonal complex sequence type 306 (ST306) and was responsible for invasive pneumococcal disease outbreaks.

[Laboratory based hepatitis A surveillance in New Caledonia: from an endemic to an epidemic pattern (1986-2007)]

This study aimed at describing the evolution of the epidemiological pattern of hepatitis A in New Caledonia since 1986 and the recent epidemic which occurred in 2005-2006, regarding particularly its demographic and virological aspects and the public health response implemented. The annual or monthly activity records for Hepatitis A sero-diagnostic performed at the Pasteur Institute of New Caledonia were processed in a retrospective analysis (9723 samples tested for the detection of IgM to hepatitis A). Over the 2004-2006 period, a phylogenetic study of representative strains from New Caledonia and other Pacific islands was carried out by the French National Reference Laboratory for hepatitis A (Paul-Brousse hospital, Villejuif, France).

RESULTS

The continuous improvement of hygiene that occurred in New Caledonia during the last two decades led to a dramatic drop in the frequency of hepatitis A among patients tested, ranging from an average value of 79 cases (14%) for the 1986-1999 period to 0 case from 2002. However, in 2005, a strong increasing number of confirmed cases was notified, mainly among young people (78% were under the age of 20). In 2006, this epidemic reached the island of Futuna where it involved more than 1% of the total population (56 cases). The phylogenetic study has confirmed the clonality of the virus circulating during this epidemic, not related to other regional strains (Fiji, Vanuatu, New Zealand) nor with a New Caledonian strain from the previous endemic period. This transition situation, with persistence of a high epidemic risk, should encourage the health authorities to implement adapted response strategies, based in particular on systematic case declaration and targeted immunisation programmes.

Genotyping as a tool for antibiotic resistance surveillance of Neisseria gonorrhoeae in New Caledonia: evidence of a novel genotype associated with reduced penicillin susceptibility

Antibiotic resistance in Neisseria gonorrhoeae continues to be a major concern in public health. Resistance of N. gonorrhoeae bacteria to penicillin G is widespread in most developed countries, which has necessitated a change to newer drugs for treatment of gonococcal infections. Recent reports indicate that resistance to these newer drugs is increasing, highlighting the need for accurate therapeutic recommendations. In some countries or communities, however, N. gonorrhoeae isolates are still susceptible to penicillin, so the use of this antibiotic for single-dose treatments of medically under-resourced patients is beneficial. In order to evaluate the adequacy and sustainability of this treatment approach, we explored the presence and prevalence of chromosomally mediated resistance determinants in N. gonorrhoeae isolates collected from 2005 to 2007 in New Caledonia. We developed two new real-time PCR assays targeting the penB and mtrR determinants, to be used together with a previously described duplex assay targeting the penA and ponA determinants. The results of this study provided evidence that neither the most-common mtrR determinants nor the most-resistance-associated penB alleles are currently circulating in New Caledonia, suggesting that penicillin should still be considered a valuable treatment strategy. Additionally, using our genotyping assay, we observed an unexpected penB genotype at a relatively high frequency that was associated with a decreased susceptibility to penicillin (average MIC, 0.15 mug/ml). Sequencing revealed that this genotype corresponded to an A102S mutation in the penB gene. The molecular tools developed in this study can be used successfully for prospective epidemiological monitoring and surveillance of penicillin susceptibility.

Alcohol drinking, tobacco smoking, and anthropometric characteristics as risk factors for thyroid cancer: a countrywide case-control study in New Caledonia

Exceptionally high incidence rates of thyroid cancer are observed in New Caledonia, particularly in Melanesian women. To investigate further the etiology of thyroid cancer and to clarify the reasons of this elevated incidence, the authors conducted a countrywide population-based case-control study in this multiethnic population. The study included 332 cases with histologically verified papillary or follicular carcinoma (293 women and 39 men) diagnosed in 1993-1999 and 412 population controls (354 women and 58 men) frequency matched by gender and 5-year age group. Thyroid cancer was negatively associated with tobacco smoking and alcohol drinking, but no inverse dose-response relation was observed. Height was positively associated with thyroid cancer, particularly in men. Strong positive associations with weight and body mass index were observed in Melanesian women aged 50 years or more, with an odds ratio of 5.5 (95% confidence interval: 1.5, 20.3) for a body mass index of 35 kg/m2 or greater compared with normal-weight women, and there was a clear dose-response trend. This study clarifies the role of overweight for thyroid cancer in postmenopausal women. Because of the high prevalence of obesity among Melanesian women of New Caledonia, this finding may explain in part the exceptionally elevated incidence of thyroid cancer in this group.

The use of fish parasites as biological indicators of anthropogenic influences in coral-reef lagoons: a case study of Apogonidae parasites in New-Caledonia

Parasite species have been widely used as fish host migration tag or as indicators of local pollution. In this paper our approach is to consider the entire parasite community as a biological indicator of the fish environmental conditions. Seven fish species belonging to the Apogonidae, Apogon bandanensis, A. cookii, A. doderleini, A. norfolkensis, A. trimaculatus, Cheilodipterus quinquelineatus and Fowleria variegata, were sampled on six stations in two bays (Grand-Rade and Sainte-Marie) around Nouméa (New-Caledonia). The two bays are submitted to urban wastewater inputs alone or combined with additional industrial inputs which influences decrease from the inner part to the entrance of each bay. A total of 592 fish were dissected for macro parasite examination. Parasites were grouped according to their taxonomical rank and development stage for the analysis. We found an inconsistent effect of the confinement between the two bays, revealing that the parasite community is not the same in the two bays. Moreover, the encysted metacercariae found in the pericardic cavity were found to be significant indicators of the specific anthropogenically impacted environmental conditions prevailing in the inner parts of the two bays. Other parasite taxa were found to be significant indicators of specific environmental conditions in one or two stations among the six sampled. Results on parasite specificity and biological life cycle of the parasite taxa found in sampled Apogonid were further compared with environmental parameters.

Accumulation of acaricide resistance mechanisms in Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) populations from New Caledonia Island

Rhipicephalus (Boophilus) microplus has been pesticide-controlled for several decades in the pacific island of New Caledonia. Since 1996, pesticide-control has been based on either deltamethrin (Butox) or amitraz (Taktic) in herds harbouring deltamethrin-resistant ticks. In this island, the first R. microplus deltamethrin- and amitraz-resistances were detected in 1992 and 2003, respectively. Using LPT bioassays, we have undertaken to update data regarding the geographical distribution and the physiological diversity likely to be involved in these resistances. We confirmed that after 17 years of intensive use of deltamethrin, several resistances of moderate levels (<30-fold) have evolved and/or diffused in any part of the island. We also evidenced that amitraz-resistant phenotypes have recently evolved in diverse western tick populations, although none has reached fixation in any tick population yet. According to synergists bioassays, the physiological changes involved in amitraz-resistance in New Caledonia would involve target modification and detoxifying P450 cytochrom oxydase(s). It may also involve detoxifying esterase(s) although this later point will need confirmation on samples bearing higher frequency of resistant phenotypes. Results are discussed with regard to the local evolutionary dynamics of resistance.

Nanophthalmos in a Melanesian population

PURPOSE

To characterize the ophthalmic features and causes of visual loss in a cohort of Melanesians living in New Caledonia with nanophthalmos.

METHODS

In this observational study, axial length, visual acuity (VA), cycloplegic autorefraction were assessed and dilated fundus examination was performed. Visual impairment was defined as VA<6/12 in the better eye, hypermetropia as >+1.0 dioptre (D), astigmatism as >or=1.0 D and anisometropia as >or=1.0 D difference between both eyes. Unilateral amblyopia was defined as at least a two-line difference in VA between both eyes and bilateral amblyopia as VA<6/12 in both eyes which was not adequately explained by refractive error and macular folds.

RESULTS

Seventeen community-dwelling participants (aged 1.1-45.3 years) with short axial length (range from 16.1 to 21.6 mm) were identified. Of the 17 subjects, 14 were found to have crowded optic discs, three with papillomacular folds, three with a papillomacular band and three with macular radial folds. Further, all subjects demonstrated bilateral hypermetropia (range from +1.3 D to +15.1 D). A high proportion of subjects had astigmatism (12) and anisometropia (nine) in at least one eye. Visual impairment was found in nine subjects: five bilateral and four unilateral. Causes of visual impairment included amblyopia (seven), ametropia (seven) and macular folds (two). Amblyopia was attributed to several factors, including hypermetropia, anisometropia, astigmatism and esotropia.

CONCLUSIONS

In this sample of Melanesians with nanophthalmos, a spectrum of ophthalmic features that was consistent with intraocular crowding was found. Over half of the subjects were visually impaired, mostly due to amblyopia and ametropia. Further characterization of the underlying genetic cause of nanophthalmos in this cohort will be the focus of future studies.

Time trends and geographic variations for thyroid cancer in New Caledonia, a very high incidence area (1985-1999)

Thyroid cancer incidence in New Caledonia is the highest reported in the world and is approximately 10-fold higher than in most developed countries. We describe the incidence patterns in this country according to histological and sociodemographic characteristics to give clues about potential etiologic factors. Another objective is to see whether the incidence figures are related to enhanced detection of small size carcinomas. The study included all 498 cases of thyroid cancer diagnosed in 1985-1999. Pathology reports were systematically reviewed to determine the histological type of the tumor and the size of the cancerous nodules. The incidence of carcinomas < or =10 mm was taken as an indicator of enhanced detection due to improved screening procedures. The age-standardized incidence rates in 1985-1999 were exceptionally high in Melanesian women (71.4/100,000) and men (10.4/100,000). The incidence increased three-fold in women from 1995 onwards. The increase in incidence was more striking for papillary carcinomas < or =10 mm than for large size carcinomas, but an increased incidence of carcinomas >10 mm was also observed among women. The analysis by municipality of residence in Melanesian women showed that the incidence was twice as high in 1995-1999 in the Loyalty Islands as in the rest of the country. The sharp increase of thyroid cancer incidence in 1985-1999 in New Caledonia was partly related to enhanced detection of small size carcinomas. The elevated incidence of thyroid cancers, as well as the ethnic and geographic disparities, may result from common environmental or lifestyle risk factors that need to be identified.

Pleural mesothelioma in New Caledonia: An acute environmental concern

BACKGROUND

In 1991, a relationship was established between excess cases of pleural cancer in New Caledonia and a traditional lime, called "Pö", to cover houses. Our study aimed to determine whether the Pö is the only cause of mesothelioma in New Caledonia.

METHODS

Eligible cases were pleural tumor diagnosed between 1984 and 2002 with histological diagnosis of mesothelioma. For each case, two controls were selected from the cancer registry. Cases and controls were compared for the ethnic groups and the places of residence. To identify environmental risk factors, we used first a qualitative analysis comparing villages with and without mesothelioma cases, then a linear regression including Pö, mining activity and serpentinite in surface soil.

RESULTS

Sixty-eight cases were included: 37 men and 31 women. Melanesians had the highest risk (OR=16.18; 95% CI=[5.68; 49.64]) and 30% of the cases lived in Houailou (OR=119). Mining activity and Pö were not significant risk factors. The existence of a significant relationship between soil containing serpentinite and mesothelioma was demonstrated (p=0.017). The sex ratio close to 1 and the number of young cases are consistent with environmental exposure.

CONCLUSION

Pö did not explain all cases; only serpentinite in the soil was identified as a significant risk factor. A research project has been initiated in the area around Houailou, with the objective of constructing a model taking into account: exposure to the Pö, exposure to airborne pollution by asbestos fibres at the place of residence, and occupational exposure. Epidemiological and geological investigations are underway.

Relationships between glycaemic abnormalities, obesity and insulin resistance in nondiabetic Polynesians of New Caledonia

OBJECTIVE

Polynesians in New Caledonia have an increased risk for developing diabetes, compared to Melanesians or Europeans. They are also more prone to obesity. The aim of this study was to analyse differences in the pre-diabetic state that may explain the varying susceptibility to diabetes between these three ethnic groups, focusing on the balance between insulin resistance and capacity of pancreatic cells to secrete insulin.

DESIGN AND SUBJECTS

The CALDIA Study is a population-based cross-sectional survey of diabetes prevalence conducted in New Caledonia. All participants who did not have diabetes, according to the results of a 0-2 h oral glucose tolerance test (n=392), were selected for analysis.

RESULTS

Compared to Europeans, Polynesians and Melanesians had significantly higher body mass indices (BMI) and waist-to-hip ratios (WHRs). Polynesians had higher fasting plasma glucose values than Europeans or Melanesians (6.03 mmol/l, vs 5.78 and 5.46, respectively; P<0.0001). Fasting plasma insulin level and the estimate of insulin resistance by homeostasis model assessment were not significantly different between the three ethnic groups. Homeostasis model assessment estimate of beta-cell secretory capacity was lower in Polynesians compared to the two other ethnic groups (83.1 mU/mmol, vs 119.3 and 125.2, respectively; P<0.02).

CONCLUSION

Despite a high prevalence of central obesity, as judged by high BMI and WHR, in Polynesians of New Caledonia, their high risk of diabetes may be more strongly related to a defect in insulin secretion capacity than to insulin resistance.

Factors of severity at admission during an epidemic of dengue 1 in New Caledonia (South Pacific) in 2003

We report a retrospective study of an epidemic of dengue in New-Caledonia (South Pacific) in 2003 among adult inpatients. The aim was to establish clinical and biological criteria for the severity of the infection at the time of admission. During 7 months, all inpatients older than 15 y having a laboratory-confirmed diagnosis of dengue fever (IgM or PCR) were included (n=170). Two groups were defined: severe cases (death and/or transfer to intensive care unit, n=24) and benign cases (n=146). Data were analysed using Epi-Info software. Univariate analysis showed that shock, haemorrhage and neurological complications were significantly more frequent in serious cases, respectively 37.5% vs 0.7%, 62.5% vs 32.2%, 25% vs 9.6% (p<0.05). Relevant biological criteria were: creatinine > 140 micromol/l (OR 12 (95% CI 3.93-37.44)), free bilirubin > 18 micromol/l (OR 12.69 ( 95% CI 2.88-59.5)), amylase > 220 UI/l (OR 27.34 (95% CI 4.57-210)) and platelets < 45,000/mm3 (OR 4.35 (95% CI 1.43-14.2)) with p<0.005 (VPP = 100% for association of 3 criteria). We suggest this combination of 4 biological criteria inclines to severity.

Distribution of Streptococcus pneumoniae serotypes responsible for penicillin resistance and the potential role of new conjugate vaccines in New Caledonia

Invasive pneumococcal disease is a significant cause of morbidity and mortality worldwide. The aim of this study was to establish the serotypes responsible for pneumococcal disease and the serotypes responsible for penicillin resistance in Noumea, New Caledonia. Isolates of Streptococcus pneumoniae from all body sites referred to the Microbiology Department of the Pasteur Institute in New Caledonia between May 1999 and May 2001 had serotyping and susceptibility testing performed. Basic demographic data on patients were also collected. A total of 298 isolates were included in the study. The most common serotypes were types 1 (20%), 23F (10%), 12F (8%), 19F (8%), and 6B (5%). The serotype distribution differed significantly with age, site of collection, and ethnicity. Overall, 280 of 298 (94%) of the isolates had serogroups that are included in the 23-valent vaccine. However, only 14 of 20 (70%) of the isolates associated with invasive disease from children younger than 5 years of age and 26 of 113 (23%) of invasive isolates from patients more than 5 years of age were included in the new 7-valent conjugate vaccine. Overall, reduced susceptibility to penicillin was found in 43 of 298 (14.4%) of the isolates, with 13% falling into the intermediate resistance category and only 5 (2%) being high-level resistant. A higher prevalence of penicillin resistance occurred in younger age groups and in European patients and involved specifically certain serotypes. The 7-valent conjugate pneumococcal vaccine has potential benefit for the New Caledonian population under 5 years of age and should be considered for future vaccines schedules.

Melioidosis in New Caledonia

Recognized melioidosis-endemic areas are widening. In the South Pacific, melioidosis is endemic in New Caledonia, northern Australia, and Papua New Guinea. We report the first 4 documented cases of human melioidosis from New Caledonia. Molecular typing of 2 Burkholderia pseudomallei isolates suggests a link to Australian strains.

WHO Western Pacific Gonococcal Antimicrobial Surveillance Programme. Surveillance of antibiotic resistance in Neisseria gonorrhoeae in the WHO Western Pacific Region, 2005

The World Health Organization Western Pacific Region Gonococcal Antimicrobial Surveillance Programme examined about 8,700 isolates of Neisseria gonorrhoeae from 15 countries for resistance to antibiotics in 2005. High to very high rates of resistance to penicillins and quinolones persisted in most centres. Increasing numbers of gonococci with decreased susceptibility to third generation cephalosporins were found in several countries. There were infrequent instances of spectinomycin resistance.

Laboratory-based influenza surveillance in New Caledonia, 1999-2003

We aimed to evaluate the annual incidence of influenza in New Caledonia and to identify the circulating viral types and subtypes in order to gather information for the local vaccination programme and regional influenza surveillance. A surveillance network was set up in 1999; it included sentinel practitioners in Noumea and the virology department of the Pasteur Institute. Influenza circulated in New Caledonia every year, regularly during the southern hemisphere winter and occasionally during March-May. Isolates were generally consistent with world surveillance, except in 1999, when a new A/H1N1 variant was identified. This study emphasises the need for regular influenza surveillance, even when performed on a limited scale. Importantly the optimal time for local vaccination was found to be in December or January each year.

Role of goiter and of menstrual and reproductive factors in thyroid cancer: a population-based case-control study in New Caledonia (South Pacific), a very high incidence area

Exceptionally high incidence rates of thyroid cancer have been reported for Melanesian women in New Caledonia (South Pacific). To investigate the occurrence of thyroid cancer in that country and to clarify the role of goiter and hormonal factors in that disease in women, a countrywide population-based case-control study was conducted in 1993-1999. The study included 293 cases, identified through pathology registers and whose thyroid cancer was verified histologically, and 354 population controls. Thyroid cancer was associated with goiter, age at menarche, irregular menstruation, and hysterectomy. There was a dose-response trend with number of full-term pregnancies (p = 0.01), with an odds ratio of 2.2 (95% confidence interval: 1.1, 4.3) for women with eight or more pregnancies. Miscarriage, particularly as an outcome of the first pregnancy, was also indicated as a risk factor. The association between voluntary abortion and thyroid microcarcinoma could be explained by enhanced medical surveillance and improved cancer detection in women undergoing abortion. Oral contraceptives and hormone replacement therapy were unrelated to thyroid cancer. The very high birth rate among Melanesian women in New Caledonia, as well as late age at menarche, may explain, in part, their elevated incidence of thyroid cancer.

HLA class-I and class-II allele frequencies and two-locus haplotypes in Melanesians of Vanuatu and New Caledonia

HLA class-I and class-II allele frequencies and two-locus haplotypes were examined in 367 unrelated Melanesians living on the islands of Vanuatu and New Caledonia. Diversity at all HLA class-I and class-II loci was relatively limited. In class-I loci, three HLA-A allelic groups (HLA-A*24, HLA-A*34 and HLA-A*11), seven HLA-B alleles or allelic groups (HLA-B*1506, HLA-B*5602, HLA-B*13, HLA-B*5601, HLA-B*4001, HLA-B*4002 and HLA-B*2704) and four HLA-C alleles or allelic groups (HLA-Cw*04, HLA-Cw*01, HLA-Cw*0702 and HLA-Cw*15) constituted more than 90% of the alleles observed. In the class-II loci, four HLA-DRB1 alleles (HLA-DRB1*15, HLA-DRB1*11, HLA-DRB1*04 and HLA-DRB1*16), three HLA-DRB3-5 alleles (HLA-DRB3*02, HLA-DRB4*01 and HLA-DRB5*01/02) and five HLA-DQB1 alleles (HLA-DQB1*0301, HLA-DQB1*04, HLA-DQB1*05, HLA-DQB1*0601 and HLA-DQB1*0602) constituted over 93, 97 and 98% of the alleles observed, respectively. Homozygosity showed significant departures from expected levels for neutrality based on allele frequency (i.e. excess diversity) at the HLA-B, HLA-Cw, HLA-DQB1 and HLA-DRB3/5 loci on some islands. The locus with the strongest departure from neutrality was HLA-DQB1, homozygosity being significantly lower than expected on all islands except New Caledonia. No consistent pattern was demonstrated for any HLA locus in relation to malaria endemicity.

Sustained transmission of dengue virus type 1 in the Pacific due to repeated introductions of different Asian strains

Outbreaks of dengue due to dengue virus type 1 (DENV-1) occurred almost simultaneously in 2001 in Myanmar and at multiple sites almost 10,000 km away in the Pacific. Phylogenetic analyses of the E protein genes of DENV-1 strains recovered from Asia and the Pacific revealed three major viral genotypes (I, II, and III) with distinct clades within each. The majority of strains from the Pacific and Myanmar, and a number of other Asian strains fell into genotype I. Genotype II comprised a smaller set of Asian and Pacific strains, while genotype III contained viruses from diverse geographical localities. These analyses suggested that the continuing outbreak of dengue in the Pacific has been due to multiple, direct, introductions of dengue viruses from a variety of locations in Asia followed by local transmission. There was no evidence that the introduction of these viruses into the Pacific was associated with any adaptive changes in the E protein of the viruses.

[Evaluation of toxoplasmosis seroprevalence among 2416 women of childbearing age followed at the Pasteur Institute of New Caledonia]

Evaluation of Toxoplasmosis seroprevalence was conducted in 2416 women of childbearing age by Pasteur Institute of New-Caledonia. The estimated seroprevalence was 56.7%, significantly higher in the North-East part of the territory (79.1%), area characterized by strong precipitations, and in the Melanesian ethnic group (62.1%). The habits of this population could enhance contamination by ingestion of oocysts during childhood or adolescence, particularly in the North-East territory. Melanesian women living in the North-East and being not immunized against toxoplasmosis represent the population with the highest risk for Toxoplasma gondii infection.