 incidence/1973–1983 incidence), controlling for missing values.
2) Environmental disturbance.
We tested whether ciguatera incidence correlated with the incidence of cyclones or bleaching using independent-sample t-test. We also tested whether ciguatera incidence correlated with coral reef condition using spearman rank correlation. We used natural log transformed total incidence (per 100,000 people) within PICTs from 1998–2008 as our measure of incidence for all environmental disturbance analyses, controlling for missing ciguatera values.
3) Social consequences of ciguatera.
We tested whether the per capita incidence of ciguatera was associated with diet change, secondary medical problems, reactive management, proactive management, and perceived management benefit from additional support across the PICTs surveyed using independent-sample t-test, controlling for missing ciguatera values. A number of respondents did not complete this section of the questionnaire. Therefore, to ensure that non responses were not due to low or high ciguatera incidence, we also compared incidence rates between PICTs that responded and PICTs that did not, using independent-sample t-test.
Nearly all PICTs responded (17 or 85%), with half fully completing the ciguatera questionnaires. Whilst we contacted the health authorities for the ciguatera data (which were returned by the health authorities in all cases), other questions were left incomplete as they were not directly about the ciguatera health issue or were sent to the other government authorities to be fully completed.
Temporal incidence of ciguatera
The reported cases for the recent 11 year period showed high levels of inter-year variability within and between PICTs. In Fiji, Kiribati and French Polynesia, more cases occurred at the start of the period. Annual reported cases peaked around the middle of the period at Cook Islands, Marshall Islands, Tokelau, Mariana's, and Hawaii. Reported cases in Vanuatu peaked towards the later part of the 11 year period and since 2005, Fiji experienced an increase in the number of ciguatera cases. Finally, Palau, Hawaii, Guam, Samoa, Wallis and Futuna, and Nauru all had relatively consistent incidence rates of under 5/100,000 (Table 1). Additional data relating to ciguatera incidence within PICT archipelagos are presented in Table 2.
Table 1. Ciguatera cases and mean annual incidence rates/100,000 by participating PICT: 1998–2008.doi:10.1371/journal.pntd.0001416.t001
Table 2. Ciguatera cases and incidence rates/100,000 for selected islands of the participating PICTs: 1998–2008.doi:10.1371/journal.pntd.0001416.t002
Within the 35 year period (1973–2008), including the study by Lewis  and this study, there was a clear overall increase in CPF incidence; however, the results show inter-PICT incidence variability between the two time periods (Figure 1). Cook Islands, Vanuatu, Fiji, Tokelau, Marshall Islands, Niue, Tonga, and Palau all have increased ciguatera incidence (Table 3). Others have shown a decrease in ciguatera incidence in comparison to the other PICTs (such as Tuvalu and New Caledonia). From 1973–1983, only four nations demonstrated a ciguatera incidence over 300/100,000; now seven nations have an incidence over this value. Fiji now outranks French Polynesia as the nation with the highest number of ciguatera cases. Previously only four nations had over 2,000 ciguatera cases; recently six nations reported ciguatera cases over this value. Fiji, French Polynesia, Vanuatu, Kiribati, Cook Islands, and Tokelau all demonstrated an increase in the number of ciguatera cases; New Caledonia, Tuvalu and Guam showed a decrease in the number of cases.
Figure 1. Annual incidence of ciguatera in the Pacific.
Mean annual incidence (per 100,000 people) of ciguatera across Pacific Island Countries and Territories (PICT) from 1973–2008 are reported. Hawaii, North Marianas, Marshall Islands and Palau were omitted because comparable data was not available for both time periods.doi:10.1371/journal.pntd.0001416.g001
Table 3. PICT rankings by ciguatera incidence/100,000: 