Dinámica de la bio-acumulación de las ciguatoxinas en una cadena alimentaria / Dynamics of the bioaccumulation of ciguatoxins in a food chain

Introducción: frecuentemente en las regiones insulares de países tropicales se reportan casos de intoxicación por ciguatera, los cuales se asocian al consumo de ciertos tipos de peces que se alimentan de algas tóxicas. Debido a que la aparición de la intoxicación es impredecible, y que los peces portadores de la ciguatoxinas presentan sabor y olor como los peces no contaminados, existen grandes dificultades en la prevención de esta enfermedad, ocacionando serios problemas socio-económicos en las comunidades que habitan estas regiones. Objetivo: con el propósito de entender la bio-acumulación de las ciguatoxinas en la cadena alimentaria marina, se propone un sistema no lineal de ecuaciones diferenciales que puede ser utilizado como herramienta en la determinación de tiempos de veda en el consumo de peces y mitigar los riesgos de intoxicación. Métodos: se analiza la estabilidad de la solución de equilibrio del sistema que tienen sentido ecológico y se presentan y discuten simulaciones numéricas para diferentes escenarios de brotes de las ciguatoxinas. Resultados: los resultados indican que la evolución del sistema de transporte y bio-acumulación de toxina depende de la dinámica del sistema poblacional. Conclusiones: El modelo puede convertirse en una orientación para los ecólogos que investigan en actividades de campo relacionadas con la enfermedad, ya que sugiere algunas medidas importantes que son necesarias para calibrar el modelo y hacer de él una herramienta valiosa en la toma de decisiones por las autoridades encargadas del tema de salud pública en zonas costeras caribeñas donde la enfermedad sea endémica.

Introduction: Island regions in tropical countries often report cases of ciguatera fish poisoning associated with consumption of certain types of fish feeding on toxic algae. The emergence of intoxication is unpredictable, and fish carrying ciguatoxins taste and smell just like uncontaminated fish. Therefore, it is very difficult to prevent this disease, which causes serious socio-economic problems in the communities inhabiting these regions. Objective: with the purpose of understanding the bioaccumulation of ciguatoxins in the marine food chain, a proposal is made of a non-linear system of differential equations which may be used as a tool to lay down closed seasons in fish consumption and thus mitigate poisoning risks. Methods: an analysis is conducted of the stability of the equilibrium solution of the system which makes ecological sense, and a presentation and discussion are provided of numerical simulations for various scenarios of ciguatoxin outbreaks. Results: results show that evolution of the toxin transport and bioaccumulation system depends on the dynamics of the population system. Conclusions: the model may be used as a guideline for ecologists carrying out field research into the disease, since important measures are suggested which are required to calibrate the model and turn it into a valuable tool for the taking of decisions by public health authorities in Caribbean coastal areas where the disease is endemic.

Ciguatera Fish Poisoning on Kakeroma Island, Kagoshima Prefecture, Japan

In this paper we report two incidents of ciguatera fish poisoning (CFP) that occurred in 2008 on Kakeroma Island in Kagoshima Prefecture, Japan. A family consisting of father (42 y.o.), mother (39 y.o.), daughter (11 y.o.) and son (6 y.o.), as well as a friend of the family (male, 78 y.o.) consumed sliced flesh (sashimi) and developed typical symptoms of CPF 4-5 h later: diarrhea, vomiting, and paresthesia of the extremities. Additionally, the two male adults (42 and 78 y.o.) developed mild hypotention (84/48 and 94/40 mmHg, respectively) and bradycardia (36 and 50 bpm, respectively) and were rushed to the ER of the nearest hospital, located on an adjacent island. The implicated fish were caught together off the west coast of the island and were identified as <i>Variola louti</i> and <i>Lutjanus monostigma</i> based on analysis of 16S rRNA gene coded on mtDNA. Remnants of the implicated fish and other fish caught on the same occasion were examined by the official mouse bioassay method (MBA), which defines the minimum amount of CFP toxin needed to kill a male mouse of ddY strain of 20 g body weight within 24 h as one mouse unit (MU). A significantly high toxicity was detected in the <i>V. louti</i> (0.2 MU/g) eaten by the family and the <i>L. monostigma</i> (0.8 MU/g) eaten by the elderly man. Other specimens of <i>Lethrinus nebulosus</i>, <i>Variola albimarginata</i>, <i>Lutjanus gibbus</i> (2 specimens), <i>Aphareus rutilans</i>, and <i>Sphyraena forsteri</i> (2 specimens) were found to be nontoxic (< 0.025 MU/g).<br> The medical records regarding island inhabitants (ca. 1,500) kept at Kakeroma Tokushukai Clinic, the only medical facility on the Island, and also at Setouchi Tokushukai Hospital, a nearest hospital on an adjacent island (Amami) revealed 6 CFP outbreaks involving 13 cases between 2005 and 2008. The estimated frequency of CFP was 10.0 incidents/10,000 persons/year and the morbidity rate was 21.7 cases/10,000 persons/year. The symptoms and signs observed in the patients and the implicated fish species, <i>L. monostigma</i> and<i> V. louti</i>, were typical of CFP in this region.