The dinoflagellates Hematodinium spp. are important endoparasites of a wide range of decapod crustaceans from across the globe. High prevalences of infection have been reported particularly in decapods of commercial importance including crabs and some lobster species. While such infections usually result in their death, the dynamics of these differ widely depending on location, the genotype of Hematodinium and host. This review aims to explore the interaction between these parasites and their hosts with particular emphasis on the diversity of host range, methods of detection, impact on fisheries and how this parasite multiplies within hosts without causing any apparent cellular immune response. Emphasis is placed on evaluating the future directions required to solve key unanswered questions of this increasingly important parasite.

The Mediterranean and the Middle East represent unique biogeographical regions that significantly shaped the evolutionary history and particular diversity of their associated organisms. However, knowledge on the copepods parasitizing freshwater fishes in these regions is limited. This study aims to investigate the diversity and phylogeny of parasitic copepods in freshwater fishes across the Mediterranean and the Middle Eastern regions. A total of 169 freshwater fish species from the Mediterranean and Middle East were examined for metazoan parasites, yielding over 1000 parasitic copepods. A thorough morphological evaluation combined with molecular analyses of partial fragments of rDNA (18S and 28S) and mitochondrial cytochrome c oxidase subunit I (COI) led to the identification of 7 species of Ergasilidae and 3 species of Lernaeidae. These findings include the descriptions of 2 new species: Ergasilus italicus n. sp. parasitizing South European nase, Protochondrostoma genei (Bonaparte, 1839), in Italy and Pseudolamproglena zahrziensis n. sp. found in yellow barbel, Carasobarbus luteus (Heckel, 1843), in Iraq. New host and geographical records, along with molecular data are provided for 8 previously described species – Ergasilus barbi Rahemo, 1982, Ergasilus briani Markevich, 1933, Ergasilus lizae Krøyer, 1863, Ergasilus rostralis Ho, Jayarajan & Radhakrishnan 1992, Neoergasilus japonicus (Harada, 1930), Paraergasilus longidigitus Yin, 1954, Lamproglena pulchella von Nordmann, 1832 and Lernaea cyprinacea Linnaeus, 1758.

Clestobothrium Lühe, 1899 is a genus of cestodes belonging to the order Bothriocephalidea, which infects marine fish from the Gadiformes order. Herein, a novel species of Clestobothrium is described from the intestine of the European hake Merluccius merluccius (Linnaeus, 1758) in the Ionian Sea (Eastern Mediterranean Sea), through an integrative taxonomic approach that combines morphological and molecular data. The new species, named Clestobothrium brettiae n. sp., can be distinguished from all congeners by its unique ovary shape, and a combination of characters including the arrangement and number of testes. It shares similar morphological characters, with Clestobothrium crassiceps (Rudolphi, 1819) Lühe, 1899, which overlaps in host and geographic distribution. However, morphological differences between Clestobothrium brettiae n. sp. and C. crassiceps also include the arrangement of gladiate spinitriches, as well as a larger scolex, proglottids, testes and cirrus sac, and different ovary morphology. The establishment of Clestobothrium brettiae n. sp. as a novel taxon is supported by detailed morphological description and biometric statistics, in addition to molecular characterisation (based on partial small subunit ribosomal ribonucleic acid [rRNA], partial large subunit rRNA, and internal transcribed spacer region 2), genetic distance, and phylogenetic analyses.

The control of African animal trypanosomosis (AAT) relies on accurate diagnostic tools. Serological diagnosis using ELISA is well-suited for surveillance due to its high-throughput capacity, low cost, and adaptability to rapid formats. However, the WOAH-recommended antibody ELISA for AAT, based on trypanosome lysates purified from rodent blood, can lack specificity and presents standardization challenges as well as ethical concerns. Recombinant proteins offer a solution to standardization, often improving specificity, though potentially at the expense of sensitivity. Combining multiple recombinant proteins can enhance sensitivity while maintaining specificity. Therefore, this study developed chimeric proteins for serological diagnosis of AAT, composed of highly immunoreactive regions from multiple known antigens using genetic engineering. Following an inventory of immunodominant antigens, we selected candidates and, using bioinformatics, designed five chimeric constructs in silico: three species-specific and two pan-trypanosome. The coding sequences for these chimeras were synthesized, cloned into expression vectors, and expressed in Escherichia coli. Purification was achieved through a series of chromatographic steps, including Ni-NTA affinity chromatography, Q Sepharose ion-exchange chromatography, and Sephadex 200 size-exclusion chromatography. Preliminary assessment of their reactivity with sera from cattle experimentally infected with Trypanosoma vivax, T. congolense or T. brucei yielded promising results. Longitudinal analysis comparing their reactivity with trypanosome lysates revealed that those specific to T. congolense, and T. vivax, as well as one pan-trypanosome, can discriminate pre- and post-infection sera. These observations confirm the potential of our chimeric constructs. Future work will involve evaluating these chimeras against a broader panel of sera.

The species boundary between the paramyxid parasitic protists Marteilia refringens sensu stricto and Marteilia pararefringens has been disputed, and their classification as separate species has been a topic of debate for the past 2 decades. Originally described as separate species, they were later synonymized based on limited evidence and referred to as 2 types of M. refringens (O-type and M-type). In 2018, longer rRNA gene sequences from a small number of samples supported their reclassification as distinct species. However, limited sample sizes and incomplete array coverage left questions regarding the robustness of this separation. We present full transcribed ribosomal RNA (rRNA) gene arrays from a broad set of Marteilia samples collected across their known host and geographic ranges. Phylogenetic and species delimitation analysis of these sequences robustly distinguished M. refringens sensu stricto from M. pararefringens. We identified sites across the entire rRNA array with consistent sequence differences between species and carried out phylogenetic analyses on the most variable regions of the rRNA array (ITS1 and ETS), which also distinguished between the 2 species. We also provide new evidence for distinct host preference profiles for M. refringens sensu stricto and M. pararefringens. The results support the recognition of M. refringens sensu stricto and M. pararefringens as separate species and identify robust markers for their detection, allowing a better understanding of their respective ecologies, host preference, pathogenicity and life cycle. The study also lays a foundation for future genomic comparisons to explore evolutionary divergence and diagnostic marker development beyond the rRNA array.

Lund’s fly, Cordylobia rodhaini (Calliphoridae), is an African blowfly considered to be an uncommon cause of furuncular myiasis. Far less is known about C. rodhaini than about the more frequently reported tumbu fly, Cordylobia anthropophaga. From 2011 to 2020, fly larvae were collected and analysed from 11 independent infestations of wild non-human primates and 10 independent infestations of humans (including 1 from this author) in Kibale National Park, Uganda. All 21 larvae were identified morphologically and genetically as C. rodhaini. Larvae from non-human primates were on average 4·5 times larger than larvae from humans. Non-human primates had empty furuncles, indicating recent egress of mature third instar larvae and completion of the larval stage of the lifecycle; however, eastern chimpanzees (Pan troglodytes schweinfurthii) were photographed removing larvae from furuncles of grooming partners. A total of 4 closely related mitochondrial haplotypes were identified, 2 of which were shared by larvae from humans and non-human primates. Genetic variation within C. rodhaini from this single location was comparable to that within other calliphorid species. Non-human primates may play a larger role in the maintenance of C. rodhaini than previously known, and in certain forested locations C. rodhaini may be the predominant cause of furuncular myiasis. The sylvatic lifecycle of C. rodhaini may explain its differentiation from Cordylobia anthropophaga, which has a peridomestic lifecycle. In general, these findings shed new light on how myiasis-causing flies can adapt to different ecological settings and be regionally rare but locally abundant.

Recent zoonotic disease emergences emphasize the importance of studying wildlife parasite communities. As wild hosts frequently harbour diverse parasite species, understanding the drivers of multiple infection patterns in free-ranging hosts is critical for elucidating the ecological and epidemiological dynamics of parasite communities. In this study, we analysed co-infection patterns in European roe deer (Capreolus capreolus) inhabiting a fragmented rural landscape in southwestern France. Using data from 130 samples of GPS-tracked deer, we examined the influence of proximity to livestock, host activity levels, age, sex and between-parasite interactions on the presence of 11 parasitic taxa. Hierarchical modelling of species communities (HMSC) revealed that proximity to livestock significantly increased the likelihood of infection with orofecally transmitted parasites (Toxoplasma gondii, gastrointestinal parasites). Sex and age were other key predictors, with males and juveniles exhibiting a higher frequency of parasite presence, likely influenced by hormonal and immune system differences. Activity levels showed distinct age-related effects, with higher activity levels being positively associated with increased parasite prevalence in yearlings, but not in adults. In contrast, parasite association patterns within individual hosts were weak, suggesting minimal interactions between parasite species. Our findings highlight the interplay between exposure and susceptibility in shaping co-infection patterns and underscore the value of hierarchical modelling approaches in multi-parasite systems.