Seasonality of nematode larvae in Iguanodectes spilurus (Characidae) an ornamental fish from northeastern Para, Brazil

Abstract

The current study presents a parasitological survey of larval nematodes from freshwater ornamental fish Iguanodectes spilurus caught in the watercourse of the Caete River, in the northeast region of the State of Para, Brazil. A total of 176 specimens, 1.36±0.75 g weight and 5.53±0.98 cm total length, were analyzed. Nematode larvae were identified as Capillaria sp., Procamallanus sp. and Anisakidae, with prevalence of 70.45% and infection intensity ranging from 1.81 to 4.70 larvae. The highest prevalence 57.38% occurred in the liver, but no seasonality was observed, indicating high infection throughout the year. Seasonality was observed in fish parasitized in the stomach, intestine and caecum, with prevalence and mean intensity of 17.61% and 2.32 parasites, 12.5% and 1.81 parasites, 10.79% and 2.21 parasites, respectively. The highest degree of infection was observed in the rainy season, probably due to increased availability of intermediate hosts or food. KEYWORDS: Characidae, Parasitology, Seasonality, River. Sazonalidade de larvas de nematóide em Iguanodectes spilurus (Characidae) um peixe ornamental no nordeste do Pará, Brasil RESUMOO presente estudo apresenta um levantamento parasitológico de larvas de nematóides de Iguanodectes spilurus capturados no fluxo do Rio Caeté, nordeste do Pará, Brasil. Um total de 176 espécimes com médias de 1,36 ± 0,75 g de peso e 5,53 ± 0,98 cm de comprimento total foram analisados. Foram identificados em 124 peixes os nematóides Capillaria sp., Procamallanus sp. e da família Anisakidae, apresentaram uma prevalência de 70,45% e intensidade de infecção de 1,81 a 4,70 larvas. A maior prevalência foi de 57,38% no fígado, mas não foi observada sazonalidade, indicando alta potência de infecção ao longo do ano. A sazonalidade foi observada em peixes parasitados no intestino, estômago e ceco com prevalência e intensidade média de 17,61% e 2,32 parasitas, 12,5% e 1,81 parasitas, 10,79% e 2,21 parasitas, respectivamente. A maior infecção foi encontrada na estação chuvosa, provavelmente devido ao aumento da disponibilidade de hospedeiros intermediários ou de alimentos.

Liver of the fish Gymnotus inaequilabiatus and nematode larvae infection: Histochemical features and expression of proliferative cell nuclear antigen

“…Several accounts have been published on encapsulated third stage larvae of various species of nematodes in the organs of freshwater fish (Dezfuli et al., ; Dezfuli, Manera, Lorenzoni, et al., ; Dezfuli, Manera, et al., ; Emde et al., ; Fujimoto et al., ). It is well established that fish react to extraintestinal helminths by producing granulomas or connectival encapsulation, where granulomas are chronic inflammatory focal lesions that appear as nodules in tissues/organs of the host (Adams, ; Dezfuli, Fernandes, et al., ; Dezfuli, Manera, et al., ; Ferguson, ).…”

“…Liver of G. inaequilabiatus is generally the most heavily infected organ with third‐larval stage Brevimulticaecum sp. Several accounts have been published on larval stages of nematodes encountered in freshwater fish (Dezfuli, Manera, & Giari, ; Dezfuli, Manera, Lorenzoni, et al., ; Dezfuli, Fernandes, et al., ; Emde et al., ; Fujimoto, dos Anjos, Ramos, & Martins, ) and in fish which inhabit a marine environment (Abollo, Gestal, & Pascual, ; Horbowy, Podolska, & Nadolna‐Altyn, ; Mehrdana et al., ). Liver has been the focus of many studies as it is a nutrient‐rich site and metabolizes numerous drugs and other compounds.…”