Distribución temporal de nematodos anisakidos del calamar gigante Dosidicus gigas (d ́Orbigny, 1835) en el Pacífico ecuatoriano

Abstract

Anisakidosis in humans is caused by the infection of anisakid nematodes acquired by the consumption of raw or undercooked marine products. It is an emerging disease and of growing concern that affects public health in developed countries; however, in the countries of Latin America and particularly in Ecuador, there is very little information about the species of anisakids, as well as the infection parameters of these nematodes both in the intermediate hosts and in the human population. Therefore, the objective of this investigation was to determine the temporal distribution of anisakid nematodes in giant squid Dosidicus gigas, an intermediate hosts for anisakid species in the Ecuadorian Pacific. A total of 224 specimens of D. gigas were collected between September 2016 and July 2017, and reviewed internally and externally by conventional parasitological techniques in the CSA laboratory from the Escuela de Acuicultura y Pesquería, Universidad Técnica de Manabí. The nematodes obtained were preserved in 70% ethanol, cleared with glycerin and lactic acid, and identified with the help of taxonomic keys. The infection parameters, prevalence and mean abundance for each species of nematode, were determined by month of sampling and by climatic season. Additionally, parasitized tissue fragments were fixed in 10% neutral formalin and processed by the paraffin inclusion technique to evaluate histological damages. Two morphotypes belonging to the genera Porrocaecum and Anisakis were identified. Porrocaecum sp. showed the highest infection parameters during the study. The prevalence did not vary between climatic seasons for any of the two species nor for the total of anisakids. The prevalence of Anisakis sp. did not vary between months, but the total prevalence of anisakids and Porrocaecum sp. varied significantly between a few months. The month of September represents a peak in the mean intensity of Anisakis sp. Anisakid larvae cause local reactions in infected tissues. The mantle, an edible part of the squid, showed the highest prevalence and intensity of infection, which constitutes a risk to public health.