Use of folk tests to detect ciguateric fish: a scientific evaluation of their effectiveness in Raivavae Island (Australes, French Polynesia)

Abstract

Ciguatera fish poisoning is a seafood intoxication commonly afflicting island communities in the Pacific. These populations, which are strongly dependent on fish resources, have developed over centuries various strategies to decrease the risk of intoxication, including the use of folk tests to detect ciguateric fish. This study aims to evaluate the effectiveness of two folk tests commonly used in Raivavae Island (Australes, French Polynesia): the rigor mortis test (RMT) and the bleeding test (BT). A total of 107 fish were collected in Raivavae Lagoon, among which 80 were tested by five testers using the RMT versus 107 tested by four testers using BT. First, the performance between testers was compared. Second, the efficiency of these tests was compared with toxicity data obtained via the receptor binding assay (RBA) by assessing various parameter's values such as sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV). Comparisons of outcomes between folk tests and RBA analyses were considered: tests used separately or in a parallel versus the series approach by each tester. The overall efficiency of the RMT and BT tests was also evaluated when the judgments of all testers were “pooled”. The results demonstrate that efficiencies varied between testers with one showing the best scores in detecting toxic fish: 55% with RMT and 69.2% with BT. BT gave the best results in detecting toxic fish as compared with RMT, giving also better agreement between testers. If high NPV and Se values were to be privileged, the data also suggest that the best way to limit cases of intoxication would be to use RMT and BT tests in a parallel approach. The use of traditional knowledge and a good knowledge of risky versus healthy fishing areas may help reduce the risk of intoxication among communities where ciguatera fish poisoning is highly prevalent.

Keywords:

• ciguatera fish poisoning
• folk detection tests
• receptor binding assay
• Pacific Islands
• risk assessment

Acknowledgements

The authors wish particularly to thank the five testers – André Ani, Félix Terorotua, François Teapehu, Jimmy Jopeta and Tamaititahio – for their participation. Joel Teipoarii is gratefully acknowledged for his continuous availability and remarkable efficiency in the field; as well as the population of Raivavae; the municipal council; and the medical staff of the Rairua health centre for their contribution to this study. Many thanks to Rosine Oitokaia for interviewing the population regarding folk detection tests. This work was supported by funds from the Country of French Polynesia and the Lepercq Foundation.

Declaration of interest: The authors report no conflicts of interest and that the work was not supported by any pharmaceutical company. The authors alone are responsible for the content and writing of the paper.