University Researchers Discover a New Parasite in the Common Sardine
Although there is no evidence of a risk to human health, scientists emphasize the importance of monitoring this subject infections, given its potential future implications
02 | 07 | 2026
A team of researchers from the University of Navarra has identified, for the first time, the presence of a microsporidian of the genus Glugea infecting the common sardine (Sardina pilchardus), one of the most commercially and nutritionally important fish species in the Atlantic.
The finding, published in the journal *Life*, describes a new association detected in sardines from an Atlantic fishery. Although there is no evidence that Glugea species cause disease in humans, “the results highlight the need to monitor this subject infections from an integrated perspective that takes into account both the health of marine ecosystems and food quality,” explains Enrique Baquero, one of the study’s authors along with Rafael Jordana and Gabriel Reina.
Scientists observed whitish cysts measuring between 5 and 20 mm in the visceral cavity of the fish; these cysts contained millions of spores of a microorganism belonging group , intracellular parasites capable of infecting a wide variety of animals. To characterize the organism, the team combined techniques such as optical microscopy, histology, electron microscopy, and molecular analysis.
The results show that the parasite shares some characteristics with other species of the genus Glugea, but exhibits unique morphological and ultrastructural features that allow it to be distinguished. work This work expands our knowledge the parasites that affect a species of great ecological and commercial importance, work notesEnrique Baquero, aresearcher the BIOMA Institute for Biodiversity and the Environment at the University of Navarra.
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The study also addresses the potential implications from a One Health perspective, approach that recognizes that the health of people, animals, and the environment are closely interconnected and interdependent.
Various species of the genus Glugea have historically been linked to health problems in populations of other fish species, and even to the decline of commercial fisheries. Researchers emphasize that the emergence of infections in species caught in the open sea warrants special monitoring, as controlling them is much more complex than in aquaculture systems.
“The findings highlight the need for further research into these microorganisms, with a focus on public health and the protection of the most vulnerable populations,” notes Gabriel Reina, a specialistwith the Microbiology Service at the Clínica Universidad de Navarra.
This finding new avenues of work for understanding the parasite’s geographic distribution, its prevalence in sardine populations, and its potential impact. Furthermore, the authors believe that phenomena such as ocean warming and the increasing incidence of diseases in aquatic organisms make it increasingly important to strengthen surveillance of this subject parasites.
reference letter
Baquero, E., Reina, G., & Jordana, R. (2026). A New Host–Parasite Association: A Glugea sp. (Microsporidia) Infecting the Commercial Fish Sardina pilchardus from an Atlantic Fishery. Life, 16(5), 733. https://doi.org/10.3390/life16050733
