Contracaecum larvae: morphological and morphometric retrospective analysis, biogeography and zoonotic risk in the amazon

Abstract

In Brazil there are several records of parasitic nematodes of fish with zoonotic potential, especially those belonging to the family Anisakidae. This study considers the morphology, morphometry and prevalence of Contracaecum in Astronotus ocellatus , fish consumed in the Amazon and sold as ornamental and it also performs a retrospective analysis of the diversity of fish with larvae of Contracaecum, in studies carried out in Brazil over a period of 90 years. 40 specimens of A. ocellatus were necropsied, and the nematodes were collected and fixed in 93 parts 70% ethyl alcohol, 5 parts formaldehyde, and 2 parts glacial acetic acid (AFA) for morphological analysis under light microscopy and scanning electron microscopy. Of the 40 fish collected during this work, 27 were parasitized by Contracaecum larvae with a total intensity of 150 larvae. Retrospective analysis of intermediate host diversity for Contracaecum larvae resulted in 16 orders, 49 families, 96 genera, 140 species and a hybrid morphotype. In the retrospective study, half of the fish were from freshwater, with the order Perciformes being the most representative, with 16 families, 30 genera and 37 species. In Brazil, the occurrence of larvae of Contracaecum in fish was reported in 15 of the 26 states, with Rio de Janeiro presenting the most information regarding fish harboring Contracaecum larvae.

CONDITION FACTOR AND ECOLOGY OF ENDOHELMINTHS IN <i>Metynnis lippincottianus</i> FROM THE CURIAí­Å¡ RIVER, IN EASTERN AMAZON (BRAZIL)

“…Both nematode species present low host specificity, but P. (S.) inopinatus uses fish species as definitive hosts, while larvae of Contracaecum sp. use fish species as intermediate or paratenic hosts, and piscivorous birds are definitive hosts (Gonçalves et al, 2014;Pinheiro et al, 2019). Therefore, the presence of Contracaecum sp.…”

“…Larvae of Contracaecum sp. belong to family Anisakidae, which has zoonotic potential to humans (Pinheiro et al, 2019), when there is ingestion of raw or under-cooked fish infected with this nematode.…”

Helminth parasites in two populations of Astronotus ocellatus (Cichliformes: Cichlidae) from the eastern Amazon, Northern Brazil

“…The fish that act as intermediate hosts acquire this parasite by predation on smaller fish, which in turn become infected by ingesting copepods, gastropods, mollusks, coelenterates or ctenophores that contain infective forms, or when they directly acquire the larvae of Contracaecum sp. in their free life stage (OLIVEIRA et al, 2017;PINHEIRO et al, 2019). Metacercariae of Posthodiplostomum sp.…”

“…Mann-Whitney test as hosts due to their lack of parasitic host specificity, including A. ocellatus(BITTENCOURT et al, 2014;OLIVEIRA et al, 2017;TAVARES-DIAS & NEVES, 2017). Contracaecum sp., a parasite with zoonotic potential for humans(PINHEIRO et al, 2019), was present in A. ocellatus from the Tapajós River in higher prevalence and low abundance, while Posthodiplostomum sp. had a low prevalence and abundance.…”

Community structure of metazoan parasites in Hemibrycon surinamensis (Characidae) from the Matapi River in the State of Amapá, Brazil

“…Contracaecum sp. are nematodes that at the adult phase preferentially infect piscivorous birds and fish, which may act as intermediate or paratenic hosts when they acquire these parasites by predation of other smaller fish or by predation of infected microcrustaceans (Vicente et al 1995, Madi and Silva 2005, Torres et al 2000, Pinheiro et al 2019.…”