Illustration of fish in the Balearic Sea with glowing parasitic worms inside.

Are You Eating Worms? Anisakis & Other Parasites Found in Balearic Sea Fish

Samir D’Costa in Health & Wellness August 2025 • 3 min read.

"New research reveals the prevalence of Anisakis and Hysterothylacium larvae in popular fish species from the Balearic Sea, raising concerns about food safety and potential health risks."

Anisakis and related parasites are common in many fish and aquatic creatures. They can live as intermediate, paratenic, or definitive hosts. Humans can accidentally ingest these nematodes by eating raw, undercooked, or improperly processed seafood. This can lead to anisakiasis, a fish-borne zoonosis that causes abdominal pain, digestive issues like nausea and vomiting, and allergic reactions.

A new study investigated the presence of anisakids and raphidascarids in commercial fish from the Balearic Sea, a region in the Western Mediterranean. Researchers examined several popular fish species to determine the prevalence and intensity of parasitic larvae.

The study looked at 335 fish, including black anglerfish, white anglerfish, European hake, red mullet, and striped mullet. They used enzymatic digestion to isolate and identify nematode larvae. Molecular analyses, including PCR and sequencing, were used to identify the species of the parasites.

What Fish Are Most Likely to Be Infected?

Illustration of fish in the Balearic Sea with glowing parasitic worms inside.

The research team isolated a total of 948 nematode larvae, with an overall prevalence of 52.53%. The highest prevalence was found in striped mullet (Mullus surmuletus).

Using molecular analyses, 46 larvae were identified. The species detected were:

Anisakis pegreffii (80.43%)
Anisakis physeteris (8.69%)
Hysterothylacium fabri (6.52%)
Anisakis simplex (4.35%)

The study also found that total nematode prevalence was positively correlated with several factors:

What Does This Mean for Consumers?

This study highlights the importance of proper food handling and preparation techniques to minimize the risk of parasite ingestion. Cooking fish thoroughly or freezing it at appropriate temperatures can kill these nematodes and prevent anisakiasis.

Consumers should be aware of the potential risks associated with eating raw or undercooked fish and take necessary precautions. This is especially important for individuals with compromised immune systems or those who are prone to allergic reactions.

The findings emphasize the need for continued monitoring and research to better understand the prevalence and distribution of these parasites in seafood. This information is crucial for developing effective strategies to protect public health and ensure the safety of the food supply.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1007/s00436-018-6110-5, Alternate LINK

Title: Occurrence Of Anisakis And Hysterothylacium Larvae In Commercial Fish From Balearic Sea (Western Mediterranean Sea)

Subject: Infectious Diseases

Journal: Parasitology Research

Publisher: Springer Science and Business Media LLC

Authors: Elena Barcala, Andrea Ramilo, Nieves Ortega, Gabriela Picó, Elvira Abollo, Santiago Pascual, Pilar Muñoz

Published: 2018-10-16

Everything You Need To Know

Which fish types were examined for parasites in the Balearic Sea study?

The study focused on the presence of nematode larvae in commercial fish from the Balearic Sea. Researchers examined species like black anglerfish, white anglerfish, European hake, red mullet, and striped mullet to determine the prevalence of parasites. This information is essential for assessing the risk associated with consuming these particular types of fish from that region.

What specific types of parasitic larvae were found in the Balearic Sea fish samples, and which was most common?

The most common species of parasitic larvae identified in the study were Anisakis pegreffii, followed by Anisakis physeteris, Hysterothylacium fabri, and Anisakis simplex. These parasites can cause anisakiasis in humans if ingested alive, leading to various gastrointestinal and allergic symptoms. The high prevalence of Anisakis pegreffii highlights its significance as a food safety concern in the region.

What is anisakiasis, and how can you prevent it after learning about Anisakis?

Anisakiasis is a fish-borne zoonosis caused by ingesting live Anisakis larvae. Symptoms can include abdominal pain, nausea, vomiting, and allergic reactions. Proper cooking or freezing of fish can effectively kill these parasites, preventing the disease. While the study identified several species, understanding how each contributes to the severity and type of symptoms experienced by humans would require further research.

What does the discovery of Anisakis and Hysterothylacium larvae in fish mean for consumers?

The presence of Anisakis and Hysterothylacium larvae means consumers need to be vigilant about how fish is prepared. Thorough cooking to high temperatures or freezing at temperatures that kill the parasites are effective preventative measures. Eating raw or undercooked fish poses a risk, especially if the fish comes from regions with a high prevalence of these parasites. Consumers should inquire about the sourcing and handling practices when eating fish at restaurants.

What are the broader implications of finding Anisakis in fish, and what further research could build on these findings?

The study reveals a significant prevalence of parasitic nematodes in fish from the Balearic Sea and this poses a risk to human health. Factors like the fish species and ecological conditions play a crucial role. While this study focused on the Balearic Sea, similar investigations in other regions can give a more comprehensive understanding of global parasitic prevalence in fish populations. Understanding these patterns are essential for developing effective food safety strategies worldwide.