Trichinosis is a parasitic disease caused by Trichinella spiralis that affects pigs, rodents, and some wild animals. Poor sanitation facilitates the spread of disease in swine, posing a risk to public health. In Mexico, pig farming ranks third in meat production and operates at 3 primary levels: industrial, semi-industrial, and backyard farming. In Mexico, backyard pig farming is a common practice primarily because it provides a source of meat at minimal or no cost. However, these pigs can act as reservoirs, sustaining the parasite's life cycle and potentially introducing it into domestic environments. Although human and pig infections with T. spiralis have been documented in Mexico, data on its prevalence and distribution remain inconsistent. For this reason, this study aimed to investigate the occurrence of antibodies against T. spiralis in backyard pigs from Veracruz, Mexico. Blood samples were collected from 472 backyard pigs and examined using an enzyme-linked immunosorbent assay. A detailed questionnaire (farm management, origin of animals, type of production, type of feed, presence of rodents, evidence of wildlife and domestic animals, exposure to pig carcasses and carcasses of other animals) was designed to gather information about potential exposures. The seroprevalence for T. spiralis was 1.6%; however, antibodies were only found in 4 localities and distributed in 4 municipalities. Proper pig management practices are crucial for controlling intestinal parasites in animals. This study advocates for public health education and promoting good pig farming practices.

In the present study, we examined nonnative returning Chinook salmon caught between 2018 and 2023 in the Valdivia River basin, Chile, for endohelminth parasites. Zoonotic endohelminths were identified by morphological and molecular methods, based on a multiplex PCR or PCR and sequencing targeting the cytochrome c oxidase gene of diphyllobothriids or Ascaridoidea mitochondrial DNA. A total of 5,350 larvae of helminths were detected in the salmon, with 3.6% corresponding to the cestodes Dibothriocephalus latus and Dibothriocephalus dendriticus, with freshwater life cycles, and 96% to “Scolex pleuronectis,” 0.2% to Hepatoxylon trichiuri, 0.1% to Nybelinia sp., and 0.1% to the nematode Phocanema cattani, all with a marine life cycle. All salmon had plerocercoids of Dibothriocephalus spp., with the highest percentage in the peritoneum and intestine. Only D. latus was identified in the muscles of 40% of salmon, with up to 7 larvae per host and a mean density of 0.1 larvae per 200 g. The present results indicate that most (63.6%) of the plerocercoids of Dibothriocephalus spp. can survive during the migration of Chinook salmon to the ocean and their return to freshwater. The sealworm P. cattani was found for the first time in Chinook salmon with a prevalence of 20% in the muscles. “Scolex pleuronectis” was abundant in the intestine and pyloric caeca, representing 96% of the identified endohelminths. One-third of the salmon had H. trichiuri in the body cavity, and Nybelinia sp. in the intestine wall. Plerocercoids of Dibothriocephalus spp. were mostly encapsulated and a few free in different organs. Histologically, the free larvae of Dibothriocephalus spp. were associated with an infiltrate of mononuclear and polymorphonuclear cells suggesting damage to their tegument. Larvae of Nybelinia sp. in the muscular layer of the intestine were surrounded by a thin capsule to which they were attached by the tegument; mononuclear and polymorphonuclear cells were observed outside the capsule and in some areas in contact with the larva. Plerocercoids of D. latus and Nybelinia sp. were associated with abundant mast cells in the intestinal wall. The presence of the zoonotic Dibothriocephalus spp. and P. cattani in returning salmon would increase their potential risk of transmission to the human population in the Valdivia River basin area. Similarly, salmon carcasses could facilitate the potential transmission of Dibothriocephalus spp. and P. cattani to wild and domestic mammals and wild birds.

Toxoplasma gondii infects between 20 and 80% of the world population, with 80–90% of patients being asymptomatic. The risk of maternal transmission of the parasite to the fetus is relatively low (15–20%) during the first trimester of pregnancy, but high by the third trimester, (60%), and can result in hydrocephalus, microcephaly, and mental impairment. In this work, we investigate the prevalence of T. gondii infection in women who have had spontaneous abortions in Samarra city, Iraq, and evaluate their serum levels of key cytokines and auto-antibodies. The main objective is to measure correlation between toxoplasma status and cytokines, as well as with auto-antibodies, as biomarkers of autoimmune diseases. A sample of 153 women who got a spontaneous abortion in Samarra hospital or private lab in Samarra city between April 2021 and April 2022 was included in the study, 103 (67.3%) of which were found toxo-positive. General and clinical variables were collected using a questionnaire, and blood samples were taken from consenting women to measure the levels of Toxoplasma antibodies IgG, IgM, cytokines (IL4, IL6, IL10, IL17, TNF-α) and auto-antibodies (anticardiolipin, aCL; antiphospholipid, aPL; anti-beta-2 glycoprotein, anti-B2GPI; antinuclear Ab, ANA; anti-thyroperoxidase, ATPO; anti-glutamic acid decarboxylase, anti-GAD; and anti-sperm, ASA). Our results show that the 3 interleukins IL4, IL6, and IL10 as well as ASA, ATPO, and aCL were significantly higher in toxo-positive aborted women compared to toxo-negative ones, whereas IL17 and aCL were higher in toxo-seronegative aborted women.

Integrated morphological and molecular methods were used to reexamine, revise, and expand the gregarine species that are known members of the Blabericolidae infecting blaberid cockroaches of the subfamilies Blaberinae and Oxyhaloinae. Here, Protomagalhaensia serpicula n. sp. and Blabericola blaberae n. comb. are described from the Guyana spotted cockroach Blaptica dubia, and 3 new synonymies are recognized: Blabericola cubensis (=Blabericola princisi = Gregarina princisi) parasitizing Blaberus discoidalis and Blaberus boliviensis; Protomagalhaensia granulosae (=Protomagalhaensia vipera) parasitizing B. discoidalis and Eublaberus posticus; and Protomagalhaensia wolfi (=Protomagalhaensia richardsoni) parasitizing Nauphoeta cinerea and Henschoutedenia flexivitta. One new combination also is recognized, Blabericola cerastes n. comb. (=Protomagalhaensia cerastes) parasitizing Phoetalia pallida. This study revealed that gregarine species delimitation errors can be avoided by integrating morphological and molecular methods with multiple conspecifics as a reference framework. This approach is preferred for delimiting gregarine species. Blabericolidae and its component genera, Blabericola and Protomagalhaensia, are monophyletic groups with a likely Pangean origin whose members speciated as New World and Old World groups following the breakup of Gondwana. Patterns of speciation appear to be largely vicariant, but host switching through human introduction of pest host species may also have played a role in gregarine radiation. The gross alimentary anatomy of B. dubia is described, and the effects of gamont morphology and phylogeny on patterns of site specificity are discussed.

An updated checklist of adult thorny-headed worms (Acanthocephala) that parasitize wild North American amphibians and reptiles is presented: A total of 21 species grouped in 4 genera, 4 families, 2 orders, and 2 classes are registered; these infect a total of 19 species of reptiles and 17 species of amphibians in the region. An illustrated identification key for the families and genera listed is proposed.

Why parasites occur in certain hosts in certain locations has been a long-standing question among ecological and evolutionary parasitologists. Encounter and compatibility filters summarize the likelihood that a host and parasite will physically interact and establish an infection upon contact. Encounter and compatibility filters are not fixed and, among multiple locations, the abiotic environmental characteristics and biotic community composition that contribute to the filters often vary spatially and temporally. Abiotic variation may directly affect hosts or parasites—particularly parasites with 1 or more free-living stages—whereas the local biotic community may dilute or amplify parasite transmission. Unlike directly transmitted parasites, complex-life cycle parasites use multiple hosts, thus having life cycles that, we hypothesize, are highly susceptible to the effects of spatiotemporal environmental variation. We modeled infection probability relationships of endohelminths from post-metamorphic wood frogs (Rana [Lithobates] sylvatica) and northern leopard frogs (Rana pipiens) with wetland characteristics, landscape composition, and the anuran species within the local community. Parasites included complex-life cycle trematodes that use amphibians as definitive hosts (Haematoloechus spp., Glypthelmins quieta) or as intermediate hosts (Alaria sp., Neodiplostomum sp., echinostomatids, and Lechriorchis) and nematodes with direct or indirect life cycles (Cosmocercoides and Oswaldocruzia). Although our results demonstrate that distributions of parasites with complex and direct life cycles are correlated with some abiotic and biotic characteristics of the environment, there were few general trends. Each parasite's distribution had its own unique relationship with wetland, landscape, and amphibian-community variables, and there was overall low predictability for most species. One landscape feature—the number of wetlands within the vicinity of the site of amphibian capture—was commonly included in top models for leopard frogs and could be associated with how definitive hosts (e.g., amphibians, mammals, and birds) and intermediate hosts (e.g., snails and odonates) use the landscape. The amphibian community at any given site also commonly affected infection probabilities, such that the local presence of other species tended to reduce infection probabilities in sampled frogs, lending support to the dilution effect at the landscape level. Our research highlights the need to consider spatiotemporal sampling, environmental variation, and host-community variation when studying parasite prevalence in any given component community.

We collected specimens of Axine trickyvagina Brule and Bullard n. sp. (Monogenoidea: Axinidae) from the gill lamellae of Atlantic flyingfish, Cheilopogon melanurus (Valenciennes) (Exocoetidae) in the north-central Gulf of America. Specimens of the new species were heat-killed and formalin-fixed for morphology, and others were preserved in 95% EtOH for DNA extraction and sequencing of the 28S gene and ITS1 region. The new species differs from all congeners by the combination of having a long haptor (∼40–50% of the total body length), a male copulatory organ with 10–15 spines, and a genital atrium having bilateral spinous patches each with 18–25 spines. Our study of specimens of the new species, type and voucher specimens representing 8 congeners, and all published accounts of all congeners revealed that the terminal female genitalia of Axine spp. comprises 2 ducts (a multi-chambered vagina that lacks a sclerite plus an accessory duct with a sclerotized nozzle comprising its opening) that open into a common female genital atrium. Descriptions of Axine spp. published from 1794 through 2023 failed to recognize the vaginal duct and accessory duct as distinct components and unanimously misinterpreted the accessory duct's sclerotized nozzle as a “vaginal spine.” The phylogenetic analysis inferred from 28S rDNA sequences placed our sequence in a clade of other Mazocraeidea spp. and sister to a nonugen sequence ascribed to Axine japonica Price, 1946 (GenBank LC799038). We recovered Axinidae as sister to Heteromicrocotylidae, Heteraxinidae, and Microcotylidae. The present study is the first published description of an axinid from a flyingfish in the western Atlantic Ocean.

We herein describe 2 new species of Henneguya Thélohan, 1892 (Bivalvulida: Myxobolidae), Henneguya auburnensis Ksepka and Bullard n. sp. and Henneguya chesapeakensis Ksepka, Walsh, and Bullard n. sp., infecting the inter-lamellar epithelium of cultured blue catfish (Ictalurus furcatus [Valenciennes, 1840] [Siluriformes: Ictaluridae]) from Saugahatchee Creek (Tallapoosa River; Auburn, Alabama) and the inter-lamellar epithelium of invasive blue catfish captured in Chesapeake Bay tributaries, respectively. Henneguya auburnensis resembles Henneguya mississippiensis Rosser, Griffin, Quiniou, Khoo, Greenway, Wise, and Pote, 2015, and Henneguya sutherlandi Griffin, Pote, Wise, Greenway, Mauel, and Camus, 2008, which both infect channel catfish (Ictalurus punctatus [Rafinesque, 1818] [Siluriformes: Ictaluridae]) in Mississippi, but differs from these species by having more polar tubule coils (10–12 vs. 8–9 and 6, respectively). Henneguya chesapeakensis resembles Henneguya longicauda Minchew, 1977, which infects channel catfish in Mississippi, but differs from this species by having shorter polar capsules (6.0–7.0 vs. 7.0–9.0). A phylogenetic analysis of the small subunit (SSU) rDNA recovered ictalurid-infecting Henneguya spp. as monophyletic, with H. auburnensis sister to a clade of Henneguya spp. that, except for H. chesapeakensis, infect the gill or adipose fin of channel catfish. Henneguya chesapeakensis was recovered sister to Henneguya ictaluri Pote, Hanson, and Shivaji, 2000. Histological sections of infected gill filaments revealed that the plasmodia of both new species developed within the inter-lamellar epithelium. The new species comprise the second and third species of Henneguya reported from blue catfish.

Avian haemosporidians are a diverse group of apicomplexan parasites that are globally distributed and infect almost all avian orders. Haemosporidian surveys of raptors (birds of prey) are underrepresented compared to those of songbirds, perhaps because of the greater difficulty in capturing and handling raptors. In this study, we captured raptors over a 7-yr period from northeastern North Dakota and northwestern Minnesota. Using standard molecular methods, we successfully screened 595 individuals representing 5 species of hawks (Accipitriformes), 3 species of falcons (Falconiformes), and 7 species of owls (Strigiformes). The overall infection prevalence averaged 41.5%, ranging from 31.6% in falcons (n = 38) to 85.7% in owls (n = 14). Thirty-one (12.6%) of the 247 infected raptors were infected concurrently with 2 or more haemosporidian genera. Leucocytozoon was the most common parasite genus identified. A total of 27 haemosporidian lineages were identified composed of 8 Leucocytozoon, 6 Parahaemoproteus, and 13 Plasmodium lineages. Twelve lineages (44%) were novel lineages identified for the first time. Raptor host order showed a significant phylogenetic signal within the tree topology of haemosporidian lineages from North American raptors. A significant effect of host order was also identified in the phylogenetic reconstructions of Haemoproteus, Leucocytozoon, and Parahaemoproteus lineages, with large clades restricted to mostly Accipitriformes and Strigiformes. Similar host specificity was not evident within the Plasmodium phylogeny, with most lineages infecting multiple raptor host orders and some lineages not restricted to raptors. Our results demonstrate that raptors support a unique and diverse community of haemosporidian parasites, many of which are distinct to raptor species. Studying haemosporidians within raptors expands our knowledge of host–parasite evolutionary relationships, species diversity, and cryptic speciation within this ubiquitous group of parasites.

This study focuses on the taxonomy and systematics of Kroyeria, a genus of ectoparasitic copepods found on the gills of sharks. Members of the genus Kroyeria exhibit species-specific appendage ornamentation, including denticles, membranes, and setules, in addition to the setae and spines typical of most copepods. The taxonomy and systematics of Kroyeria have been hampered by the lack of observation of these fine morphological details. This study is a systematic revision of the genus in which 11 species of Kroyeria are redescribed, 6 species are synonymized, and 5 new species are described: Kroyeria branchiocetes n. sp. from Carcharhinus amblyrhynchos from the Red Sea, Kroyeria cresseyi n. sp. from Triakis semifasciata from off California, Kroyeria decepta n. sp. from Carcharhinus obscurus from the Pacific Ocean off Mexico, Kroyeria procerobscena n. sp. from Carcharhinus leucas from off Madagascar, and Kroyeria rhophemophaga n. sp. from Galeorhinus galeus from off California. With this work, Kroyeria now comprises 20 valid species. The 16 species of Kroyeria that were examined in this study were scored for 44 morphological characters, which were used for a phylogenetic analysis of the genus.

While surveying the parasites of the leopard frog Lithobates spectabilis in the Barranca de Metztitlán Biosphere Reserve, Hidalgo, Mexico, we found several specimens of an undescribed species of Halipegus (Trematoda: Derogenidae: Halipeginae) in the buccal cavity of this species of frog. The objective of this study was to describe the new species using an integrative approach, incorporating morphological data, multivariate analyses (principal and discriminant components), and phylogenetic analyses based on partial sequences of the conserved ribosomal regions (28S rDNA) of DNA and the mitochondrial subunit of the cytochrome c oxidase I gene (COI mtDNA). The methods of maximum likelihood, Bayesian inference, and maximum parsimony were used to determine the relationships of the new species to other hemiurids. Halipegus metztitlanensis n. sp. differs from its congeners mainly by the combination of the following characters: the distance from the ventral sucker to the right anterior testis, the distance from the ventral sucker to the left posterior testis, the length and width of the ovary, the width of the left testis, the distance between the oral sucker and the ventral sucker, and the length of the egg filament. The new species was recovered as a distinct group separate from other hemiuroideans based on the 28S rDNA and COI mtDNA phylogenetic analyses. This is the first report of a hemiurid trematode infecting the endemic leopard frog in Hidalgo, México and the second species described from the country.