Prevalence, Morphological and Molecular Identification of Anisakis sp. (Nematoda: Anisakidae) in Squid from Timor Island, East Nusa Tenggara, Indonesia

Abstrak

Graphical Abstract Highlight Research 1. Anisakis larvae were detected in 32% of Loligo sp. squid collected from East Nusa Tenggara, Indonesia. 2. Anisakis larvae were recovered from the mantle of the abdominal cavity of Loligo sp. squid 3. First molecular identification of Anisakis typica in Loligo sp. squid from Indonesia 4. The presence of A. typica in Loligo sp. indicates a potential risk of allergic reactions associated with squid consumption. Abstract Anisakis larvae in marketed squid warrant species-level investigation because morphological identification alone cannot reliably distinguish closely related taxa, while evidence from Timor Island, Indonesia, remains limited. This study assessed larval prevalence and examined selected larvae morphologically and molecularly in Loligo sp. squid collected from five fish auction sites across Timor Island, East Nusa Tenggara. Between June and October 2024, 500 squid (100 per site) were visually examined, with ten larvae per site selected for morphometry. Molecular analysis involved five pooled samples, each comprising two larvae from one site, using mitochondrial cox2 amplification, sequencing, and Bayesian phylogenetic inference. Anisakis larvae occurred in 160 squid (32%; 95% confidence interval, 28.1–36.2%), with site-specific prevalence ranging from 20% to 42%. Overall, 172 larvae were recovered, with one to three larvae per infected squid. Recovered larvae exhibited Type I morphology, including a long ventriculus and distinct mucron. All five pooled-sample sequences showed 100% identity to selected Anisakis typica references and clustered within the A. typica clade. These findings document larval occurrence in squid marketed on Timor Island and provide molecular evidence of A. typica in the analyzed pools, without establishing species identity for every recovered larva. Because visual inspection may overlook larvae embedded in tissue, prevalence estimates may be conservative. The findings do not quantify human infection risk, which cannot be inferred from parasite detection in marketed squid. Broader individual-larva sequencing and improved detection methods, alongside surveys of marine fish and copepods, are needed to clarify parasite occurrence, transmission, and seafood-safety implications in the region.

Kata kunci

• Anisakis typica
• Loligo squid
• Public health
• Zoonotic parasites