rienced 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: 1973–1983 vs 1998–2008.doi:10.1371/journal.pntd.0001416.t003
Statistical analysis of temporal change in ciguatera incidence showed varied results. There was no statistically significant difference between 1973–1983 mean incidence and 1998–2008 mean incidence across PICTs (p = 0.949), comparing all PICTs (except the State of Hawaii which was not presented by Lewis ) using paired t-test (Table 4). However, there was a highly significant difference in mean incidence, between the two time periods when comparing mean incidence across years (p = 0.002), using independent-sample t-test. Linear regression analysis of annual mean incidence from 1973 to 2008 was also statistically significant (p = 0.005) despite high inter-year variability. The rate ratio (1998–2008 mean annual incidence/1973–1983 mean annual incidence) was 1.60; therefore, there was a 60% increase in the mean annual incidence from the earlier period to the more recent period. Hawaii, North Marianas, Marshall Islands, and Palau were omitted for the independent sample t-test, regression analysis and the rate ratio due to data limitations (Table 1).
Table 4. Change in the incidence of ciguatera: 1973–1983 vs 1998–2008.doi:10.1371/journal.pntd.0001416.t004
Of the 18 PICTs in this study, 11 reported on all (i.e. coral bleaching, cyclone incidence and perceived reef condition), whilst New Caledonia reported only on coral bleaching (Table 5). All three environmental disturbance types were positively related to ciguatera incidence. However, there was no statistically significant correlation between mean annual ciguatera incidence and occurrence of bleaching (p = 0.20), cyclone incidence (p = 0.17) or perceived coral reef condition (p = 0.57).
Table 5. Cyclones, coral bleaching and reef conditions reported by participating PICT: 1998–2008.doi:10.1371/journal.pntd.0001416.t005
Social consequences of ciguatera
Responses to questions relating to the social consequences of ciguatera demonstrated that the incidence of ciguatera might be having a negative impact on PICT