Ciguatera poisoning in French Polynesia: A review of the distribution and toxicity of Gambierdiscus spp., and related impacts on food web components and human health

Ciguatera Poisoning (CP) is a seafood poisoning highly prevalent in French Polynesia. This illness results from the consumption of seafood contaminated with ciguatoxins (CTXs) produced by Gambierdiscus, a benthic dinoflagellate. Ciguatera significantly degrades the health and economic well-being of local communities largely dependent on reef fisheries for their subsistence. French Polynesia has been the site of rich and active CP research since the 1960's. The environmental, toxicological, and epidemiological data obtained in the frame of large-scale field surveys and a country-wide CP case reporting program conducted over the past three decades in the five island groups of French Polynesia are reviewed. Results show toxin production in Gambierdiscus in the natural environment may vary considerably at a temporal and spatial scale, and that several locales clearly represent Gambierdiscus spp. "biodiversity hotspots". Current data also suggest the "hot" species G. polynesiensis could be the primary source of CTXs in local ciguateric biotopes, pending formal confirmation. The prevalence of ciguatoxic fish and the CTX levels observed in several locales were remarkably high, with herbivores and omnivores often as toxic as carnivores. Results also confirm the strong local influence of Gambierdiscus spp. on the CTX toxin profiles characterized across multiple food web components including in CP-prone marine invertebrates. The statistics, obtained in the frame of a long-term epidemiological surveillance program established in 2007, point towards an apparent decline in the number of CP cases in French Polynesia as a whole; however, incidence rates remain dangerously high in some islands. Several of the challenges and opportunities, most notably those linked to the strong cultural ramifications of CP among local communities, that need to be considered to define effective risk management strategies are addressed.

Quantifying the burden of premature mortality at national level in France in 2016

Background

Efforts to accurately measure premature mortality are important to monitor the impact of diseases and injuries on population health and to set policy priorities. This is an ongoing study with a strong collaboration between Santé Publique France and the French National Health Insurance, whose main objective is to provide the first national estimates of Years of Life Lost (YLLs) for all causes of death in France.

Methods

The French national health data system (SNDS) contains detailed nationwide causes of death data, reported using ICD-10 codes. We used the underlying cause, as defined by the Center for Epidemiology on Medical Causes of deaths, of all deaths for year 2016 (the last year available). For this preliminary study without redistribution of ill-defined deaths (IDDs), national sex-specific life expectancy tables were used to estimate YLLs by age class, sex, and cause of death categories at national level. We identified and quantified IDDs and also compared YLLs to crude mortality.

Results

In 2016, we estimated approximately 7.3 million YLLs (586,519 registered deaths), of which 35.1% were due to neoplasms, 17.8% to cardiovascular diseases (respectively 34.5% and 17.3% in men; 35.8% and 18.4% in women) and 10.3% to injuries (4.9% among people aged 65 or more at time of death; 34.5% among people aged 25-44). Approximately 27% of the deaths registered were IDDs, representing approximately 1.8 million YLLs.

Conclusions

These preliminary results confirm the importance of YLLs as a metric to target preventive strategies according to age. Moreover, by quantifying IDDs, we highlight that data gaps are important even in settings with highly developed health information systems. Next steps include applying an IDD redistribution methodology, aspirational life table and computing subnational YLLs. The French collaborative initiative should address those gaps and propose national and subnational burden metrics in the following months.

Key messages

Methodological and data requirements to compute YLLs constitute a challenge even in settings with developed health information systems, highlighting the need of national institutional collaborations. Highlight data gaps in terms of ill-defined deaths in mortality database.

Hollow CoFe₂O₄ nanospheres as a high capacity anode material for lithium ion batteries

Hollow structured CoFe₂O₄ nanospheres were synthesized by a hydrothermal method. The uniform hollow nanosphere architecture of the as-prepared CoFe₂O₄ has been confirmed by field emission scanning electron microscopy and transmission electron microscopy analysis, which give an outer diameter of 200-300 nm and a wall thickness of about 100 nm. CoFe₂O₄ nanospheres exhibited a high reversible capacity of 1266 mA h g⁻¹ with an excellent capacity retention of 93.6% over 50 cycles and an improved rate capability. CoFe₂O₄ could be a promising high capacity anode material for lithium ion batteries.

Ciguatera risk assessment in two toxic sites of French Polynesia using the receptor-binding assay

Ciguatera Fish Poisoning (CFP) is a tropical syndrome well known in remote archipelagos where the population is still dependent on fish resources. In order to assess the ciguatera risk in two islands of French Polynesia, Tubuai (Australes) and Nuku Hiva (Marquesas), a study was carried out on both Gambierdiscus populations as well as on various fish species using the receptor-binding assay (RBA) to detect and quantify ciguatoxins. Relationship between RBA data and size or weight of fish was evaluated, and when only few individuals for a particular species were available the trophic level was used to help comparisons between studied areas. According to epidemiological data, toxic versus safe areas were explored and compared in both islands. In Tubuai Island, Gambierdiscus cells were surprisingly absent in the north area, considered as a toxic area, but almost 94% of fishes were classified as RBA+. In contrast, the south area, supposed to be safe, was evolving to be a risky area because of the presence of Gambierdiscus cells and 74% of fishes being RBA+. In Nuku Hiva Island, Gambierdiscus cells were present in the toxic areas, Anaho, Taiohae and Taipivei, with two toxic blooms in Anaho Bay, but none in Terre Déserte, the fishing area of this island. With RBA data, fishes were analyzed to be RBA+ at a high percentage in Anaho and Taiohae, higher than in Taipivei and Terre Déserte areas. In general, our findings were congruent with epidemiological data and the knowledge of local people only for risky fish species.

[An experimental model of pulmonary valve implantation: a percutaneous and transventricular approach without cardiopulmonary bypass]

Pulmonary valve replacement by a catheter procedure remains a therapeutic challenge. In this report, the authors demonstrate the possibility of implantation of a porcine xenograft specially prepared on an auto-expanding stent (valved stent) in a sheep model. The porcine xenograft was prepared with hypotonic non-enzymatic solutions. It was sewn onto an auto-expanding stent (Luminex Bard) and inserted into an introduction sheath of 22-24 F (Gore) calibre. In a preliminary approach, the catheter was inserted through the jugular vein. Out of 6 attempts, it was possible to position the valved stent in the pulmonary position in two cases but all the animals died of different causes: tamponade, arrhythmias, air embolism. Following this experience, two valves were implanted through the superior and inferior vena cavae. This first percutaneous approach has been modified to a mixed medico-surgical approach with a transventricular introduction without cardiopulmonary bypass. This was performed through a left thoracotomy with puncture of the pulmonary infundibulum using the same systems of introduction and valved stent. Three implantations were successfully performed. In addition, a reduction of the size of the pulmonary artery was realised to prevent embolisation of the valved stent to the pulmonary artery or one of its branches. The transventricular approach is feasible for implantation of pulmonary valve prosthesis on a stent. This technique could be adapted for correction of pulmonary regurgitation after correction of Tetralogy of Fallot associated with reduction of the pulmonary infundibulum.

Spectrofluorometers are not adequate for aging Aedes and Culex (Diptera: Culicidae) using pteridine fluorescence

Attempts were made to use pteridine fluorescence levels as a tool for aging individual Aedes polynesiensis Marks and Culex quinquefasciatus Say mosquitoes. Fluorescent pigments were extracted and quantified with techniques and apparatus (i.e., a spectrofluorometer) that can be used in developing countries or in field laboratories, and that has already given consistent results in similar studies on other insect groups. However, for Ae. polynesiensis as well as Cx. quinquefasciatus, individual fluorescence measurements were mostly below the spectrofluorometer white noise level. With batches of Aedes or Culex of the same age, significant fluorescence levels were recorded but not in relation to their calendar ages. The low content of pteridines in mosquitoes suggests that standard spectrofluorometry is not sufficiently sensitive for such studies.

Soluble interleukin 2 receptor levels and cervical neoplasia: results from a population-based case-control study in Costa Rica

Progression from infection with human papillomavirus (HPV) to cervical cancer in some women is thought to involve a permissive host environment, one in which immune response is mobilized in an inappropriate manner. In a previous study (A. Hildesheim et al., Cancer Epidemiol. Biomark. Prev., 6: 807-813, 1997), increasing levels of soluble interleukin 2 receptor (sIL-2R), a known proxy for general immune activation, was found to be positively associated with increasing levels of cervical neoplasia. We attempted to confirm this finding by conducting a nested case-control study of 478 women within a 10,000-woman population-based cohort in Costa Rica. We selected for the study all of the women diagnosed (at enrollment into the cohort) with: (a) low-grade squamous intraepithelial lesions (LSIL, n = 191); (b) high-grade squamous intraepithelial lesions (HSIL, n = 130); or (c) cancer (n = 37). Controls were 120 cytologically normal, HPV-negative women selected from a random sample of the entire cohort. A questionnaire was administered to participants to elicit information on cervical cancer risk factors. All of the women received a pelvic examination during which cervical cells were collected and used for HPV DNA testing by PCR. Blood samples were also collected. Plasma obtained from the blood samples was tested for sIL-2R levels by ELISA. Results indicated that sIL-2R levels increased with age. Among controls, we observed that 44.3% of women over the age of 50 had high levels of sIL-2R (defined as >735 units/ml) compared with 15.8% of women <30 years of age (P = 0.008). When women with cervical disease (LSIL+) were compared with controls, women in the upper quartile of the sIL-2R distribution had an age-adjusted odds ratio (OR) of 2.1 [95% confidence interval (CI), 1.1-4.1]. Comparing each advancing state of neoplasia with its precursor, we found that women with LSIL had higher sIL-2R levels than controls (OR for upper quartile of sIL-2R, 2.3; 95% CI, 1.1-5.2; comparing LSIL cases with controls); women diagnosed with HSIL were similar to the LSIL group (OR for upper quartile of sIL-2R, 1.1; 95% CI, 0.5-2.4; comparing HSIL cases with LSIL cases); and those with cancer had higher sIL-2R levels than subjects with an HSIL diagnosis (OR for upper quartile of sIL-2R = 1.8; 95% CI, 0.5-7.1; comparing cancer cases with HSIL cases). These data suggest that among our study subjects, sIL-2R levels most likely rise as a response to the events of infection and cancerous invasion, but that sIL-2R levels are unlikely to be predictive of disease progression among women with LSIL.

Familial and sporadic cases of nasopharyngeal carcinoma in Taiwan

BACKGROUND

Nasopharyngeal carcinoma (NPC) has a striking geographic/ethnic distribution, with especially high rates among southern Chinese. Previous studies have indicated that a family history of NPC is associated with increased risk and noted familial clustering in low-risk populations.

MATERIALS AND METHODS

We investigated differences between sporadic and familial cases of NPC in a case-control study of 375 histologically confirmed NPC cases (99% response rate) and 328 age-, sex-, and geographically-matched controls (88% response rate). All participants answered a detailed risk factor interview and donated blood for EBV and CYP 2E1 testing.

RESULTS

Subjects with a first degree relative with NPC had on odds ratio (OR) of 7.6 (95% confidence interval (CI) = 2.3-25), while those with a family history of any other cancer had only a slightly elevated risk of disease (OR = 1.4; 95% CI = .93-2.2). Of the cases, 25 (6.7%) were familial--having at least one first degree relative with NPC. No significant difference was seen between familial and sporadic cases with respect to sex, age, ethnicity, histology or stage. There was a nonsignificant (p = 0.16) increase in T1N2 tumors among familial cases, suggesting a more aggressive tumor. Family history of other cancers, EBV serologies, or the distribution of the RsaI c2 form of the allele of cytochrome P450 2E1 were also not significantly different between the two groups.

CONCLUSIONS

In conclusion, while genetic factors are likely to play an important role in NPC pathogenesis, our results provide little evidence that a familial form of NPC exists with characteristics notably distinct from sporadic cases.

Variation in the vector competence of Aedes polynesiensis for Wuchereria bancrofti

The vector competences of 6 geographic strains of Aedes polynesiensis for Wuchereria bancrofti were studied using two types of experimental infections. Experimental infection of laboratory-bred mosquitoes fed on the carriers' forearms with different levels of microfilaraemia showed that microfilariae (mf) uptake was directly proportional to the carrier's mf density and, as mf densities decreased, concentration capacity of Ae. polynesiensis increased. It was also shown that infection has an important effect on mosquito mortality, and that the mortality rate differed among mosquito strains. In infections using artificial feeders, the mf uptake was closely regulated, thus showing differences in the vectorial efficiency of Ae. polynesiensis related to the geographic origin of the mosquito strain. The mosquitoes from the Society archipelago were more efficient intermediate hosts than geographically distant strains when infected with W. bancrofti from an island within the archipelago (Tahiti). Mosquito strains from the Society archipelago developed the highest proportion of infective-stage larvae and exhibited the lowest mortality rate when infected with sympatric Tahitian W. bancrofti.

Insecticide susceptibility in mosquitoes (Diptera: Culicidae) from French Polynesia

Susceptibility to six organophosphate (OP), two pyrethroid (PY), and one carbamate (C) insecticides was investigated in Culex pipiens quinquefasciatus Say, Aedes aegypti (L.), and Aedes polynesiensis Marks larvae from the island of Tahiti. Cx. p. quinquefasciatus and Ae. aegypti were compared with susceptible reference strains treated simultaneously. A low, but significant, resistance to bromophos (4.6x), chlorpyrifos (5.7x), fenthion (2.4x), fenitrothion (5.0x), temephos (4.3x) and permethrin (2.1x) was found in Cx. p. quinquefasciatus, and to malathion (1.5x), temephos (2.3x), permethrin (1.8x) and propoxur (1.7x) in Ae. aegypti. Cx. p. quinquefasciatus was shown to possess over-produced esterases A2 and B2, which are known to be involved in resistance to OPs in other countries. Ae. polynesiensis was less resistant than the Ae. aegypti reference strain to all insecticides except temephos (1.8x) and permethrin (6.7x). To determine whether Ae. polynesiensis had developed resistance to these insecticides in Tahiti, a geographical survey covering 12 islands of the Society, Tuamotu, Tubuai, Marquesas, and Gambier archipelagoes was undertaken with three insecticides (temephos, deltamethrin, and permethrin). Two- to threefold variations in LC50S were observed among collections. Results are discussed in relationship to the level of insecticide exposure on the different islands.