cross the region, using the reported mean values of actual cases for the three periods for which we have data (1,762 for 1973–1983; 2,844 for 1989–1992 (South Pacific Epidemiological and Health Information Services data); and 3,607 for 1998–2008 (current study)) and using a conservative under reporting rate of 80%, we estimate that since 1973 approximately 500,000 PICT inhabitants have had ciguatera.
It is possible that there might be a reporting bias in the data because of increased research and interest in ciguatera compared to the 1973–1983 time period. However, our data demonstrate high variability of ciguatera reporting from 1998–2008 across the PICTs. It is beyond the scope of this study to ascertain the effect of immigration and translocation of people to and from some of these PICTs, with different dietary habits than the local inhabitants, on ciguatera incidence. Given the variability in the change of incidence across the region demonstrated in this study, it is clear that the overall ciguatera trend cannot be extrapolated from data for a single PICT.
We elicited a relatively poor response rate from questions relating to coral bleaching, cyclones, and degraded reef conditions. Such environmental disturbance generally occurs at finer scales, so it might be appropriate to perform a more detailed field surveys in collaboration with environmental, fisheries, and meteorology agencies in the future to better understand such effects. However, despite the methodological limitations, we have shown that there is a trend for ciguatera incidence to be higher where bleaching, cyclones, and poor reef condition have been reported.
Stronger relationships were identified between ciguatera incidence and social impacts of ciguatera outbreaks. We found a marginally significant positive relationship between changing diet and the incidence of ciguatera, and associated medical problems and incidence of ciguatera. Such problems increase financial and social burdens on PICTs. Addressing the underlying causes of ciguatera outbreaks will reduce this burden, enabling PICT authorities to redistribute their limited resources to other priorities. Management action and prevention do not correlate with ciguatera incidence highlighting the lack of a unified and systematic approach for addressing ciguatera in the region. A clear desire for assistance exists within the PICTs that have high ciguatera incidence, suggesting that PICTs would be highly receptive to an external body aiding in enabling unified and systematic action. In addition to exploring new and better apporaches to detection and treatment, research is needed into the causes of ciguatera outbreaks, including environmental and anthropogenic parameters, to explain the hypotheses raised by this study.
Limitations of study
It is possible that the unusual collaboration of the majority of the PICTs in this project might have contributed to the observed increased reporting of ciguatera (as well as other unidentified infrastructure changes), and thus a possible reporting bias for the more recent 1998–2008 data when compared with the 1973–83. However, these data represent a decade of reporting during a period of competing public health interests and lack of surveillance resources for ciguatera in the PICTs. As with all ciguatera studies where the case definition does not include active confirmation of ciguatoxin in the fish consumed, there is the possibility of the misclassification of reported cases; however, this situation has not changed from the 1970s .
It is also beyond the scope of this study to speculate on the causes of the high spatial and temporal variability of ciguatera . This study, instead, aimed to demonstrate that ciguatera is still of major and possibly growing concern in the region. Addressing ciguatera will require significant investment in research and continuing education campaigns. If the suspected disturbances (including coral bleaching, cyclones, shipwrecks, and port facilities) are major causes of ciguatera outbreaks, then it is likely that the general temporal pattern