Occurrence of Ascocotyle (Phagicola) longa Ransom, 1920 (Digenea: Heterophyidae) in Mugil incilis from Cartagena Bay, Colombia.

Fishborne metacercariae have not been reported in Colombia. During an 8-month period, 250 mullet/lisa (Mugil incilis) were examined for trematode metacercariae in the liver. Average prevalence and intensity were 93.4+/-2.5% and 8476+/-1238 cysts per gram of liver, respectively. Monthly prevalence of the trematode, identified as Ascocotyle (Phagicola) longa Ransom (1920), was always high (>79%) and there was no difference between sampling periods (P>0.05). Trematode intensity in lisa had a significant negative effect on host size (R=-0.325, P<0.001), condition factor (R=-0.352, P<0.001), and liver-somatic index (R=-0.372, P<0.001); in contrast, a positive relationship was found with gill-somatic index (R=0.446, P<0.001). Histopathological analysis indicated the presence of abundant cysts together with inflammatory reactions involving macrophage aggregates and necrosis. These results suggest that trematodes infecting the liver of M. incilis affect the growth and well-being of these fish, and their consumption could represent a major risk for human infection.