Metacercariae of Posthodiplostomum Dubois, 1936 (Diplostomidae) infecting freshwater fish worldwide: infection patterns, host-parasite interactions, distribution range, and disease control.

This study aimed to investigate the infection patterns, host-parasite interactions, distribution ranges, and control diseases by Posthodiplostomum metacercariae in freshwater fish on a global scale. We analyzed parasitological data from 203 freshwater fish species across 17 orders and 44 families, predominantly representing the Leuciscidae and Cichlidae families. The analysis identified a total of 10 Posthodiplostomum metacercariae species, although several studies did not identify the parasites to the species level. In host fish, prevalence, intensity and abundance levels of Posthodiplostomum metacercariae ranging from low to high. The metacercariae typically infected the body surface, musculature, mesentery or abdominal cavity, and internal organs of fish hosts, causing pathological effects that ranged from tissue damages to mortality, particularly in fry and juveniles. Regarding geographical distribution, metacercariae of Posthodiplostomum minimum occur across North America, whereas Posthodiplostomum vancleavei, Posthodiplostomum ptychocheilus and Posthodiplostomum centrarchi range from Canada to the United States. Posthodiplostomum cuticola, P. centrarchi and Posthodiplostomum brevicaudatum are distributed from Europa to Asia, while Posthodiplostomum scardini is restricted to Europe. In the Neotropics, metacercariae of Posthodiplostomum nanum occurs across South America, while Posthodiplostomum macrocotyle spans both South and Central America. Finally, this study highlights key research gaps particularly regarding parasite identification, prevention and treatments strategies.