Both sex (biological) and gender (socio-cultural) are increasingly recognized as important factors in disease risks and outcomes, including parasitic infections and especially those of the genital tract. Many funding agencies now require these dimensions be incorporated into research proposals, though little guidance is given regarding how, leading to confusion among those who do not specialize in this area. In this commentary, I review instances of the use of the word ‘gender’ in the archives of Parasitology (174 articles) to assess how parasitologists are progressing in the incorporation of this dimension and identify what can be done to improve efforts. Use of the term has increased since 1990, reflecting an enthusiasm among parasitologists for including this dimension to their work. Examination of articles which use this term reveals that correct and thorough incorporation of the gender dimension has also increased, but that these articles only account for 8.0% of all articles using the term, demonstrating widespread persistent confusion around terminology regarding sex and gender and how to best account for gender in parasitological research. Parasitologists studying animals should only refer to sex and should incorporate sex into their research design and report whether there are differences in baseline or response between sexes. Parasitologists studying humans should incorporate sex, but then also consider whether any observed differences are due to biological factors like sex hormones and immunity or gendered social variables like behavioural norms and healthcare access. These considerations will further our understanding of host–parasite interactions and improve health outcomes.

High density should drive greater parasite exposure. However, evidence linking density with infection generally uses density proxies or measures of population size, rather than measures of individuals per space within a continuous population. We used a long-term study of wild sheep to link within-population spatiotemporal variation in host density with individual parasite counts. Although four parasites exhibited strong positive relationships with local density, these relationships were mostly restricted to juveniles and faded in adults. Furthermore, one ectoparasite showed strong negative relationships across all age classes. In contrast, population size – a measure of global density – had limited explanatory power, and its effects did not remove those of spatial density, but were distinct. These results indicate that local and global density can exhibit diverse and contrasting effects on infection within populations. Spatial measures of within-population local density may provide substantial additional insight to temporal metrics based on population size, and investigating them more widely could be revealing.

This study investigated the helminths of the mixed invasive population of Darevskia armeniaca and D. dahli, collected during two field trips in Denyshy, Zhytomyr region, Ukraine, in 2023. In total, 67 adult lizards (35 D. armeniaca and 32 D. dahli) were examined. Molecular and morphological approaches were used to identify the parasites. The analyses revealed six helminth species, including four nematodes (Toxocara cati, Strongyloides darevskyi, Oswaldocruzia sp., and Spirurida gen. sp.), one trematode (Pleurogenes claviger), and one cestode (Mesocestoides litteratus). Toxocara cati had the highest prevalence, found in cysts located primarily on the liver and in the body cavity of the hosts. The qualitative and quantitative comparative assessment of the helminth community suggests that, due to the introduction of these lizards, most helminth species from their native range have been lost. Additionally, most local helminth species have not yet adapted to parasitising these lizards as normal hosts of their life cycle.

Penguins include 18 species of seabirds distributed in the Southern Hemisphere. Climate change is a growing problem that affects penguins, especially those living in Antarctica, making them some of the most currently endangered species. Loss of habitat, commercial fishing and infectious diseases spread by anthropogenic activities in the Southern Ocean are threats facing penguins. In addition, environmental changes affect the distribution of free-living species that act as intermediate hosts for parasites (e.g. krill, fish) and consequently their transmission dynamics and distribution. The present work aims to provide an update on macro- and microparasites recorded in all penguin species in wildlife. Based on published records from penguins, we provide a list of 157 parasite taxa recorded in all penguin species. The list includes 54 helminths, 45 arthropods, 39 bacteria and 19 protozoa reported in 207 scientific publications. Most papers were focused on the genus Spheniscus. In the analysis, we identify the distribution of parasites among hosts to better predict the disease risk facing their populations worldwide. Some pathogenic effects of the parasites found are discussed.

Meteterakis striatura Oshmarin & Demshin, 1972 is redescribed from the posterior intestine of tropical tortoise Geoemyda spengleri (Gmelin, 1789) (Testudines: Geoemydidae) from China. Some characteristic features of the male reproductive system not reported previously are now reported for the present species. These include the presence of two blind diverticula near the mid-region of the seminal vesicle and a small cuticular structure near the opening of the cloaca – which we propose to name the ‘scutum.’ The morphological function and diagnostic value of these characters as well as presence of gubernaculum or ‘gubernacular mass’ in examined representatives of the genus, including paratype specimens of M. amamiensis Hasegawa, 1990 and M. ishikawanae Hasegawa, 1987 is discussed. Illustrative material is supplemented with scanning electron microscope and light microscope images of adult males and females. The molecular characterization of the species is inferred from 18S and 28S rDNA. The taxonomic composition of the genus Meteterakis is discussed and the full list of species with taxonomic remarks is updated.

The nutria was introduced to Europe from South America and kept for the fur industry. This semiaquatic rodent became a well-established species in the Czech Republic; however, it still poses a significant threat to the native fauna, not only as a natural competitor but also as a vector of non-indigenous parasites. Our research aimed to investigate the diversity of endoparasitic helminths in nutria, with a particular focus on assessing the risk posed by helminth species with zoonotic potential. A total of 46 nutria cadavers were collected at 8 locations in the Morava River basin and examined using standard parasitological post-mortem procedures. Additionally, coprological and molecular methods were used to identify the parasites. The presence of 6 helminth species was revealed. The highest prevalence was observed for Strongyloides myopotami (78.3%) and Trichuris myocastoris (37.0%), both of which are host-specific nematodes of nutria. Only 2 trematode taxa were recorded (Echinostoma sp. and a representative of the family Psilostomidae). The presence of alveolar hydatid cysts of Echinococcus multilocularis in the livers of 5 nutria specimens was also recorded. Herein, we provide novel molecular data for each parasite species collected, which is valuable for future phylogenetic analyses. Our findings also demonstrate that nutria in the Czech Republic serve as a carrier of helminths with zoonotic potential, particularly E. multilocularis and S. myopotami. Although the nutria is a relatively new species in local fauna, its synanthropic behaviour raises concerns about potential threats to human health, underscoring the importance of exercising caution when handling these animals.

Most studies concerning parasitic infections in European bison have been performed on free-ranging animals: comparatively little is known about the abomasal nematodes of captive wisents, which are widely used in reintroduction programmes. The aim of the study was to determine the infection level and species composition of abomasal nematodes in captive European bison in enclosures (including zoos) and breeding centres compared to free-ranging individuals. It also includes a morphological analysis of the parasites based on figures and measurement data. Altogether, 11 species of nematodes were detected, with both captive and free-ranging animals demonstrating similar species compositions. Among those, 2 species of blood-sucking nematodes were detected, including Ashworthius sidemi and Haemonchus contortus. Interestingly, A. sidemi was found in almost all free-roaming animals, but only in 1 captive European bison. In addition, H. contortus was predominant in captive animals. The morphological identification was confirmed molecularly for 5 nematode species: A. sidemi, H. contortus, Ostertagia kolchida, O. ostertagi and Spiculopteragia boehmi. The identification was performed using small subunit ribosomal rDNA. The study provides the first available set of specular lengths of the gastric nematodes of European bison, and the first molecular data of O. kolchida and S. boehmi derived from the same host species. Our findings may simplify the morphometrical and molecular identification of Trichostrongylidae species infecting European bison, and can be useful in developing new management strategies for populations of this near-threatened species in Europe.

The functioning and richness of marine systems (and biological interactions such as parasitism) are continuously influenced by a changing environment. Using hierarchical modelling of species communities (HMSC), the presence and abundance of multiple parasite species of the black-spotted croaker, Protonibea diacanthus (Sciaenidae), was modelled against environmental measures reflecting seasonal change. Protonibea diacanthus were collected in three seasons across 2019–2021 from four locations within the waters of the Northern Territory, Australia. The length of P. diacanthus proved to have a strong positive effect on the abundance of parasite taxa and overall parasitic assemblage of the sciaenid host. This finding introduces potential implications for parasitism in the future as fish body size responds to fishing pressure and climate changes. Of the various environmental factors measured during the tropical seasons of northern Australia, water temperature and salinity changes were shown as potential causal factors for the variance in parasite presence and abundance, with changes most influential on external parasitic organisms. As environmental factors like ocean temperature and salinity directly affect parasite–host relationships, this study suggests that parasite assemblages and the ecological functions that they perform are likely to change considerably over the coming decades in response to climate change and its proceeding effects.

Schrankiana are gastrointestinal parasites of anurans, distributed throughout Central and South America. Schrankiana formosula and Schrankiana inconspicata are some of the most commonly reported species parasitising anurans from Brazil, and the morphological differences between them are unclear. In the present study, we redescribed S. formosula based on a re-examination of type series and newly collected material from the frog Leptodactylus pentadactylus in the state of Amapá, Brazil. Additionally, we re-examined the type series of S. inconspicata, and propose it as a junior synonym of S. formosula. We provide detailed morphological and morphometric data with intraspecific variation analyses and new molecular data for S. formosula. In the present phylogeny, S. formosula formed a well-supported clade with Raillietnema sp. and Labeonema synodontisi. Based on molecular phylogenetic analyses and some morphological similarities, our findings support the hypothesis that Schrankiana is a member of the family Cosmocercidae, not Atractidae. Additionally, we provide the first ultrastructural descriptions of S. formosula, and establish the species' phylogenetic position from the Cosmocercidae.

Avian schistosomes are snail-borne trematode parasites (Trichobilharzia spp.) that can cause a nasty skin rash in humans when their cercariae mistake us for their normal bird hosts. We sought to investigate drivers of the spatial distribution of Trichobilharzia cercaria abundance throughout Northern Michigan lakes. For 38 sites on 16 lakes, we assessed several dozen potential environmental predictors that we hypothesized might have direct or indirect effects on overall cercaria abundance, based on known relationships between abiotic and biotic factors in wetland ecosystems. We included variables quantifying local densities of intermediate hosts, temperature, periphyton growth rates, human land use and hydrology. We also measured daily abundance of schistosome cercariae in the water over a 5-week period, supported by community scientists who collected and preserved filtered water samples for qPCR. The strongest predictor of cercaria abundance was Lymnaea host snail density. Lymnaea density was higher in deeper lakes and at sites with more deciduous tree cover, consistent with their association with cool temperature habitats. Contrary to past studies of human schistosomes, we also found a significant negative relationship between cercaria abundance and submerged aquatic vegetation, possibly due to vegetation blocking cercaria movement from offshore snail beds. If future work shows that these effects are indeed causal, then these results suggest possible new approaches to managing swimmer's itch risk in northern MI lakes, such as modifying tree cover and shallow-water vegetation at local sites.

The epidemiological picture of Taenia saginata infections in Kenya is fragmented with limited available data. Although Sarcocystis species are significant meat-borne parasites, few studies have explored their occurrence in Kenya. This study aimed to estimate the occurrence of bovine cysticercosis and screen for the presence of Sarcocystis spp. A meat inspection-based survey was conducted in ten abattoirs in Narok County, Kenya, and inspection for T. saginata cysticerci was limited to the Triceps brachii muscle. The apparent occurrence of the parasite was 5.4% (95% CI, 3.8, 7.6, n=573). Molecular confirmation of T. saginata was done via nested polymerase chain reaction targeting the mitochondrial 12S ribosomal RNA gene and restricted fragment length polymorphism. Sarcocystis species were identified using a multiplex polymerase chain reaction method targeting the 18S ribosomal RNA gene sequences and the mitochondrial cytochrome c oxidase subunit I gene. Of the 31 cystic lesions tested, 26/31 (83.9%) were confirmed to be T. saginata. Sarcocystis cruzi and S. hominis were detected in 8/31 (25.8%) and 1/31 (3.2%) of the cystic lesions, respectively. Co-infections of S. cruzi and T. saginata were found in 6/31 lesions (19.4%). The confirmation of bovine cysticercosis and S. hominis is suggestive of the presence of risky culinary and sanitation practices that facilitate transmission. This is the first report and molecular confirmation of Sarcocystis spp. in cattle in the country. The presence of both zoonotic S. hominis and pathogenic S. cruzi highlights an underexplored concern of veterinary and human health significance, warranting further epidemiological investigation.

Knowledge about parasitic diseases of wildlife will help us to understand the dynamics of parasites and their effects on host populations. The capybara (Hydrochoerus hydrochaeris) is the largest living rodent in the world, and its distribution is associated with the presence of tropical and subtropical wetlands in South America. The Los Padres Lake Integral Reserve (LPLIR) is an important conservation zone in the pampean region of Argentina. One of the emblematic species found within the reserve is the capybara. The objective of this study was to determine the gastrointestinal parasites present in wild capybaras of the LPLIR and to compare different coprological methodologies. Free-ranging capybara fresh feces from 57 individuals were randomly collected from the area of LPLIR in the summer of 2022. Three different techniques were applied: spontaneous sedimentation technique (SS), INTA modified McMaster technique (MM), and Mini-FLOTAC (MF) technique. Fifty-six samples from all samples analysed (56/57, 98%) were found to be positive for gastrointestinal parasites. Two species of Strongylida, Protozoophaga obesa, Echinocoleus hydrochaeris, one unidentified nematode, one unidentified spirurid, and at least two morphotypes of Eimeria spp. oocysts were recorded. There were found significant differences in the proportion of positive samples and in richness by technique, but no significant differences were found in parasite counting. In conclusion, the choice of methodology depends on the specific objectives of the study. This is the first parasitological study of capybaras from the LPLIR and represents an exploration of parasite communities present in these wild rodents at their southernmost distribution.

Metastrongyle lungworms could be particularly detrimental for diving animals such as marine mammals; however, little is known of the drivers of pathogenic host–parasite relationships in this group. This systematic review analysed the diversity of metastrongyles in marine mammals and the host and parasite traits associated with virulence. There have been at least 40 species of metastrongyles described in 66 species of marine mammals. After penalization for study biases, Halocercus hyperoodoni, Otostrongylus circumlitus, Parafilaroides gymnurus, Halocercus brasiliensis and Stenurus minor were the metastrongyles with the widest host range. Most studies (80.12%, n = 133/166) reported that metastrongyles caused bronchopneumonia, while in the cardiovascular system metastrongyles caused vasculitis in nearly half of the studies (45.45%, n = 5/11) that assessed these tissues. Metastrongyles were associated with otitis in 23.08% (n = 6/26) of the studies. Metastrongyle infection was considered a potential contributory to mortality in 44.78% (n = 90/201) of the studies while 10.45% (n = 21/201) of these studies considered metastrongyles the main cause of death. Metastrongyle species with a wider host range were more likely to induce pathogenic effects. Metastrongyles can cause significant tissue damage and mortality in marine mammals although virulent host–parasite relationships are dominated by a few metastrongyle species with wider host ranges.

In many countries, urban areas are commonly contaminated with canine feces that spread parasites, a situation related to the natural and social environment. Dogs having free access to public areas therefore constitutes a health risk. Because in Patagonia there are no records of city comparisons that consider the number of free-roaming dogs and the local environmental and socioeconomic characteristics, in this study we analyse and compare canine parasitoses in two cities of Rio Negro province, Argentina. Canine feces were collected from public areas of El Bolsón and Cipolletti cities and examined using enrichment methods, Kinyoun stain and immunoassay (Copro-Elisa). The total percentage of positive feces in El Bolsón was 68.95% and 16 parasite taxa being identified, whereas in Cipolletti the total positive feces was 41.1%, with 11 taxa. Both cities presented more helminth species than protozoans. The variables that explained the occurrence of all parasites were rainfall and socioeconomic stratum with the highest values being found in low-income areas.

Soil moisture is conditioned by rainfall. This study highlights the presence of the zoonotic Echinococcus sp. in dogs in urban areas of the Rio Negro province. The occurrence of this parasite in Cipolletti is unexpected, given that this city is not considered an endemic zone for this disease, which is not included in local monitoring and control plans.

Many important and interesting hypotheses about cultural evolution are evaluated using cross-cultural correlations: if knowing one particular feature of a culture (e.g. environmental conditions such as temperature, humidity or parasite load) allows you to predict other features (e.g. language features, religious beliefs, cuisine), it is often interpreted as indicating a causal link between the two (e.g. hotter climates carry greater disease risk, which encourages belief in supernatural forces and favours the use of antimicrobial ingredients in food preparation; dry climates make the production of distinct tones more difficult). However, testing such hypotheses from cross-cultural comparisons requires us to take proximity of cultures into account: nearby cultures share many aspects of their environment and are more likely to be similar in many culturally inherited traits. This can generate indirect associations between environment and culture which could be misinterpreted as signals of a direct causal link. Evaluating examples of cross-cultural correlations from the literature, we show that significant correlations interpreted as causal relationships can often be explained as a result of similarity between neighbouring cultures. We discuss some strategies for sorting the explanatory wheat from the co-varying chaff, distinguishing incidental correlations from causal relationships.

Eight species (four new) of Urocleidoides are reported from Characiformes and Gymnotiformes fishes of the coastal drainages of the Eastern Amazon. Urocleidoides vanini n. sp. is characterized by having a male copulatory organ (MCO) with three and a half counterclockwise rings, absence of vaginal sclerite, and a V-shaped ventral bar. Urocleidoides atilaiamarinoi n. sp. has MCO with two and a half counterclockwise rings, dumbbell-shaped accessory piece, similar anchors, open V-shaped ventral bar, and open U-shaped dorsal bar. Urocleidoides macrosoma n. sp. exhibits an elongate and robust body, MCO comprising one counterclockwise ring, similar anchors with wavy point, and dumbbell-shaped ventral and dorsal bars. Urocleidoides nataliapasternakae n. sp. has MCO comprising two and a half counterclockwise rings, vaginal canal convoluted, point of the dorsal anchor with ornamentation as sclerotized shredded filaments, elongate dumbbell-shaped ventral bar, and U-shaped dorsal bar. Urocleidoides naris and Urocleidoides brasiliensis from H. malabaricus (Characiformes) and the incertae sedis species, Urocleidoides gymnotus and Urocleidoides carapus, from Sternopygus macrurus (Gymnotiformes) are reported, and their molecular sequences are presented in this study. Phylogenetic analyses based on molecular data (28S rDNA and COI mtDNA) reveal that species of Urocleidoides lacking vaginal sclerite are closely related to species that possess vaginal sclerite, suggesting that the absence of vaginal sclerite in Urocleidoides may be the result of a secondary loss. The relationships between species of Urocleidoides and other Neotropical dactylogyrids are also addressed.

Parasites and parasitologists have always lived together in good and bad luck in a sort of forced marriage. In recent times bad luck certainly prevailed, because of increasing man-made emergencies such as wars, chemical disasters, but also because of natural disasters, amplified by climate change, that condition more and more parasite–host equilibrium. The symposium at the National Congress of the Italian Society for Parasitology, was a first occasion for Italian parasitologists to reason about ‘disaster parasitology’ and researchers’ responsibilities. Extreme weather events and their impacts on parasites’ epidemiology are illustrated, comparing disasters that recently occurred in Italy with literature data. In particular, the Sardinian Island was hit subsequently by fires and floods exacerbating the effects on ecosystems and parasite–host-relationships. Examples of Cryptosporidium outbreaks in man and Fasciola hepatica infections in various hosts after heavy rains are reviewed and effects of droughts on pasture borne parasites, such as gastro-intestinal nematodes of ruminants are discussed. Heavy rains may also cause dissemination of toxic substances released accidentally from chemical plants as happened e.g. in Milan province (IT) after the dioxin hazard. The overlapping effects of strictly man-made disasters with climate change dependent extreme weather events is further challenging the understanding of what are the consequences of disasters on ecosystems and parasite epidemiology.

GIS applications combined with AI programs may help to face the complex challenges, allowing the collection and analysis of spatial/temporal data at whatever level desired. Examples illustrated in the article suggest their employment also in a more systematic, prevention-oriented manner.