Detecting the presence of important parasites within a host and its environment is critical to understanding the dynamics that influence a pathogen's ability to persist, while accurate detection is also essential for the implementation of effective control strategies. Pseudoloma neurophilia is the most common pathogen reported in zebrafish (Danio rerio) research facilities. The only assays currently available for P. neurophilia are through lethal sampling, often requiring euthanasia of the entire population for accurate estimates of prevalence in small populations. We present a non-lethal screening method to detect P. neurophilia in tank water based on the detection of environmental DNA (eDNA) from this microsporidium, using a previously developed qPCR assay that was adapted to the digital PCR (dPCR) platform to complement current surveillance protocols. Using the generated dPCR data, a multi-state occupancy model was also implemented to predict the probability of detecting the microsporidium in tank water under different flow regimes and pathogen prevalence. The occupancy model revealed that samples collected in static conditions were more informative than samples collected from flow-through conditions, with a probability of detection at 80% and 47%, respectively. There was also a positive correlation between the frequency of detection in water and prevalence in fish based on qPCR.

This is the first study to empirically evaluate the mortality of Amblyomma mixtum larvae caused by native entomopathogenic fungi (EPF) from cattle farm soils and the impact of the physicochemical conditions of those soils on the ability of EPF to kill ticks. The efficacy of 25 EPF strains isolated from cattle farms soils in Veracruz, Mexico, against A. mixtum ticks was evaluated using a larval immersion test. Physicochemical analyses of the soils where the EPF were isolated were carried out, and the results were correlated with the obtained mortality. The MaV25 strain showed a mortality of 36.55% (P < 0.05), followed by MaV57 with 27.30%, MaV08 with 26.21%, and MaV31 with 24.32% (P < 0.05). Nitrogen and potassium are nutritional components of soils that seem to be associated with mortality caused by the evaluated fungal strains. This is the first study in Mexico where the effect of EPF against A. mixtum is evaluated and also is the first study in the world that uses native strains from livestock soils against larvae of this tick. It is necessary to determine the virulence characteristics of EPF on A. mixtum to improve knowledge of fungus–tick interactions (Metarhizium anisopliae–A. mixtum).

Between November 2018 and December 2021, 35 juvenile and adult Western Creek Chubsuckers, Erimyzon claviformis, were collected from 5 sites in western and southern Arkansas (Ouachita and Red River drainages), and their gills, gallbladders, fins, integument, other major organs, and musculature were examined for myxozoans. The fins of 12 (34%) individuals were infected with a novel species, Myxobolus stuartae n. sp. Qualitative and quantitative morphological data were obtained from formalin-fixed preserved myxospores. Molecular data from ethanol-preserved specimens consisted of a 2,028 base pair sequence of small subunit (SSU) ribosomal DNA (rDNA) from a specimen collected in Nevada County. Three other specimens from Polk County yielded partial SSU rDNA sequences that were identical to the first sequence. Phylogenetic analyses placed M. stuartae n. sp. as sister to Myxobolus bibullatus (Kudo, 1934), both clustering with other catostomid-infecting myxobolids. This is the first fin-infecting myxozoan reported from E. claviformis.

Turtle blood flukes (“spirorchiids”) comprise a paraphyletic assemblage including the monophyletic Schistosomatidae Stiles and Hassall, 1898 as a crown group. We herein morphologically diagnose the natural groups of turtle blood flukes and propose family names for them. Spirorchiidae Stunkard, 1921 (Spirorchis MacCallum, 1919 [type]; Spirhapalum Ejsmont, 1927; Plasmiorchis Mehra, 1934; Monticellius Mehra, 1939; Vasotrema Stunkard, 1928; provisionally Uterotrema Platt and Pichelin, 1994) has a ventral sucker (lost in Spirorchis), an esophageal gland surrounding the entire esophagus, lateral esophageal diverticula (plicate organ and medial esophageal diverticulum present or absent), a glandular mass at the esophagus base, paired ceca surrounded by vitelline follicles for their entire length, a non-filamented, ovoid egg, and typically a Manter's organ. Baracktrematidae n. fam. (Baracktrema Roberts, Platt, and Bullard, 2016 [type]; Unicaecum Stunkard, 1925; Neospirorchis Price, 1934) has no ventral sucker, a single cecum or cyclocoel, a coiled or looped testis extending into the anterior body half, a convoluted post-cecal and post-gonadal uterus, a uterine pouch, no metraterm, no Manter's organ, and non-filamented eggs. Plattidae n. fam. (Platt Roberts and Bullard, 2018 [type]; Hapalorhynchus Stunkard, 1922; Coeuritrema Mehra, 1933; Enterohaematotrema Mehra, 1940; Cardiotrema Dwivedi, 1967; Ruavermis Dutton and Bullard, 2020) has the anatomical sequence of a ventral sucker, external seminal vesicle, cirrus sac, anterior testis, ovary, transverse vitelline duct, and posterior testis (except Enterohaematotrema) plus a pars prostatica, dorsal genital pore, globular excretory vesicle, and no Manter's organ. Carettacolidae Yamaguti, 1958 (Carettacola Manter and Larson, 1950 [type]) has a spinose oral sucker, a spinose and contractile ventral sucker (transverse cavity present), numerous testes distributing in a post-ovarian, inter-cecal column, and an ovary and transverse vitelline duct that are pre-testicular. Hapalotrematidae (Stunkard, 1921) Poche, 1926 (Hapalotrema Loos, 1899 [type]; Amphiorchis Price, 1934; Learedius Price, 1934; Cheloneotrema Simha and Chattopadhyaya, 1980; Neocaballerotrema Simha, 1977; Satyanarayanotrema Simha and Chattopadhyaya, 1980; Shobanotrema Simha and Chattopadhyaya, 1980) has the anatomical sequence of a ventral sucker, anterior testis(es), external seminal vesicle and cirrus sac, ovary, and posterior testis(es). Atamatamidae n. fam. (Atamatam Bullard and Roberts, 2019 [type]; Paratamatam Bullard and Roberts, 2019; Pitiutrema Dutton and Bullard, 2019) has an oral sucker with anteroventral spines, vasa efferentia connecting to a pre-ovarian external seminal vesicle, a cirrus sac directed postero-laterad and having an internal seminal vesicle and glandular luminal wall, and a dendritic ovary flanked by the external seminal vesicle and oviducal seminal receptacle. A 28S phylogenetic analysis failed to reject the monophyly of these families.

Most trematodes and some cestodes have obligate life history features that include an asexual developmental stage that can produce genetically-identical individuals (clonemates) followed by an adult stage with sexual reproduction. These life history features can influence the evolutionary mechanism of inbreeding in parasites, especially among self-compatible hermaphroditic endoparasites whose mating opportunities are restricted to within hosts. As clonemate mating in hermaphroditic species produces a genetic inbreeding signature identical to that of self-mating, it is important to understand how clonemates are transmitted through their life stages. A handful of prior studies compared clone richness (number of clones) across life cycle stages to infer transmission processes and to characterize clone abundance distributions (CADs) among hosts. Here we illustrate the use of the proportion of clonemate dyads (P_C) within hosts to describe the CADs. P_C has several advantages as an ecological metric in that it is unbiased by sample size, takes into account relative parasite burdens, and has a direct transmission interpretation, i.e., the probability of cotransmitting clonemates. Moreover, P_C is also an evolutionary metric as it can be used to estimate a potential clonemate mating rate. We demonstrate the use of P_C in comparing CADs within and across 2 trematode developmental stages in the lancet fluke Dicrocoelium dendriticum. Also, we show how genetic estimates of apparent selfing (true selfing plus clonemate mating) at larval and juvenile stages can be compared to P_C estimated at the adult stage to assess the contribution of clonemate mating to apparent selfing. The eco-evolutionary links presented are generalizable to assess sibling cotransmission as well. Thus, the framework presented herein will facilitate future field-based studies on the transmission and mating systems of parasitic flatworms.

Freshwater fishes in the southwestern United States live in some of the most highly modified habitats in the country. As a result, the relatively small number of native fish species has been impacted in many ways, including the introduction of nonnative fishes and their parasites. Both Gila orcutti and Pimephales promelas have been introduced to the Santa Clara Drainage, the former is native to adjacent drainages in southern California, while the latter was introduced from the eastern United States. Two hundred and fourteen G. orcutti (arroyo chub) and 18 P. promelas (fathead minnow) were collected and necropsied in June through September 2017 and May through September 2018. Eight macroparasite taxa were collected from these fishes, including 6 native and 2 nonnative parasites. Four taxa of parasites were shared between G. orcutti and P. promelas: Schyzocotyle acheilognathi (Asian fish tapeworm), diplostomid metacercariae, larval acuariid cysts, and Lernaea cyprinacea (anchor worm). This study also reports the first host-association records of G. orcutti with Gyrodactylus sp., S. acheilognathi, diplostomid metacercariae, Rhabdochona sp., Contracaecum sp., and larval acuariid cysts in the Santa Clara River. Additionally, it provides the first host-association records of P. promelas with larval acuariid cysts in the Santa Clara River. This study identifies new host–parasite associations that may be useful for future conservation efforts.

An updated checklist of tongue worms (Pentastomida) which parasitize wild North American amphibians and reptiles is presented: a total of 14 species grouped in 6 genera, 4 families, and 2 orders are registered; these infect a total of 58 species of reptiles and 3 amphibians in the region. An illustrated identification key for the taxa listed is proposed. Kiricephalus coarctatus (Diesing, 1860) (Porocephalidae) is recorded for the first time in the snakes Arizona elegans Kennicott, 1859 (Colubridae); Micrurus tener Baird and Girard, 1853 (Elapidae); and Bothrops asper (Garman, 1884) (Viperidae); the exotic Raillietiella taegueselfi Riley, McAllister, and Freed, 1988 (Raillietiellidae) is recorded in the exotic lizard Hemidactylus frenatus Duméril and Bibron, 1836 (Gekkonidae) for the first time, and in Hemidactylus turcicus (Linnaeus, 1758) (Gekkonidae) for the first time in Mexico, this is also the first time it is recorded in a species of lizard native of the Americas, Sceloporus cyanogenys Cope, 1885 (Phrynosomatidae), this latter record represents a parasite spillover event; finally, Porocephalus stilesi Sambon, 1910 (Porocephalidae) is formally recorded for the first time in Mexico in the snake Bothrops asper.

Cats (Felis catus) have the potential to spread and infect humans and other animals with a variety of endoparasites. This study was conducted to investigate the prevalence of parasites in community, outdoor, and strictly indoor domestic cats in Rockland County, New York. Between November 2020 and June 2021, fecal samples were collected from 3 populations (community = 65, outdoor domestic = 28, strictly indoor domestic = 35). A minimum of 2 g of feces were collected per sample and examined with centrifugal fecal floatation tests with 33% zinc sulfate solution and microscopy. Overall, community cats had a significantly higher prevalence of parasites compared to outdoor and strictly indoor cats (chi-square test, X² = 24.943, df = 2, P = 3.835 × 10^–6). The most prevalent endoparasite in all 3 populations was Toxocara cati. There was a significant difference between the 3 populations and parasite richness (chi-square test, X² = 25.452, df = 4, P = 4.081 × 10^–5). Polyparasitism was frequently observed in the community population, followed by the outdoor population. This study demonstrates that because community cats spend their entire lives outdoors, they are more at risk of being exposed to parasites and contribute to the contamination of the environment with these parasites.

A survey was conducted in the lowland areas of Binh Dinh and Phu Yen provinces in south central Vietnam to study the diversity of digenean cercariae within freshwater snails. These regions are known as highly endemic areas for the transmission of liver flukes, Fasciola spp. and Opisthorchis viverrini. In total, 13 snail species were found, and 3 of these were dominant, comprising 51.9% of all collected snails, i.e., Bithynia funiculata, Melanoides tuberculata, and Radix auriculata. Cercariae were found in 5 snail species, and among these, Indoplanorbis exustus had the highest overall prevalence of infection (38.5%). No cercarial infections were found in viviparid and ampullariid snails. Morphological identification resulted in 10 cercariae types that were illustrated and measured. Among them, xiphidiocercariae and echinostomata were the most common, causing 70.55% of all cercariae infections. Bithynia species had the most diverse digenean fauna. Molecular data revealed the presence of cercariae of 13 digenean species, including O. viverrini. The 18S rDNA sequences of echinostomata and xiphidiocercariae type 3, which were shed from different snail hosts, were similar to 2 and 3 digenean species, respectively. In conclusion, our findings highlight the diversity of digenean fauna in Binh Dinh and Phu Yen provinces.

Prosogonotrema iraqiense n. sp. (Sclerodistomidae: Prosogonotrematinae) is described in the flathead grey mullet, Mugil cephalus Linnaeus (Mugiliformes: Mugilidae), collected from the Arabian Gulf off Iraq during June and October 2019. Currently there are 11 species of Prosogonotrema Vigueras, 1940 commonly accepted: Prosogonotrema arabica Yadav, 1980; Prosogonotrema bilabiatum Vigueras, 1940 (type species); Prosogonotrema caesionis Gu and Shen, 1979; Prosogonotrema diacanthi Bilqees and Durrani, 1980; Prosogonotrema karachiense Bilqees and Durrani, 1980; Prosogonotrema pavasi Lokhande, 1990; Prosogonotrema piscicola (Srivastava, 1949) Gibson, 2002 (Syn. Bhaleraoia piscicola Srivastava, 1949); Prosogonotrema plataxum Gu and Shen, 1979; Prosogonotrema posterouterina Yadav, 1980; and Prosogonotrema symmetricum Oshmarin, 1965 originally described from marine fishes, and Prosogonotrema nickoli Bilqees and Khan, 1992 described from a freshwater cyprinid. Six additional species that have been considered synonyms of P. bilabiatum are also considered. Prosogonotrema diacanthi is considered a junior synonym of P. piscicola and Prosogonotrema carangi Hussain and Rao, 1980 nec Velasquez, 1961 is determined to be a species distinct from P. bilabiatum and is reassigned herein as Prosogonotrema aluteri nomen novum per the ICZN. Prosogonotrema iraqiense differs from all currently recognized species in the genus by having the width of the ventral sucker approach or exceed the width of the body and from all except P. pavasi (body length/width ratio 1:1.4–1:1.5) by having a distinctive narrower, more elongate body profile with a larger body length/width ratio (1:5.8–1:6.1 vs. 1: 2.0–1:4.1). A key to the 18 species we recognize in Prosogonotrema is included.

Didelphonema longispiculata (Hill, 1939), a gastric nematode parasite of the black-eared opossum, Didelphis marsupialis Linnaeus, 1758, collected from 2 municipalities of Mato Grosso state, Brazil, in the ecotone region of the Amazon and Cerrado biomes was analyzed with integrative taxonomy using light and scanning electron microscopy (SEM) for morphological studies and sequencing of the 18S small subunit ribosomal RNA for phylogenetic inference through maximum likelihood and Bayesian phylogenetic inference. Here details of the helminth surface, oral aperture with octagonal border, pseudo- and inter-labia, amphids, external cephalic papillae, 2 dorsal and ventral internal plates distally indented, and stoma with strongly chitinized wall are presented. Caudal male papillae, spicules, female vulva, anus, and caudal tip were detailed using SEM. Morphological characteristics and phylogenetic data corroborated the taxonomic placement of the genus Didelphonema within the subfamily Ascaropsinae.

Encyclometra japonica Yoshida and Ozaki, 1929 is a fluke that parasitizes the digestive tract of snakes. When the species was first reported, it was originally characterized on the basis of morphologic features, namely, the characteristics of the 2 testes located obliquely in the anterior–posterior direction, and the position of the ventral sucker one-fourth to one-third from the anterior extremity. Thereafter, more specimens with other morphologic variations were reported, and a new morphologic feature for species discrimination was proposed. However, the proposal is uncertain, and the criteria for morphologic discrimination between E. japonica and other Encyclometra species remain debatable. Thus, morphologically discriminable characteristics on the basis of a sufficient number of specimens are required, and molecular methods for species identification that allow for a more objective assessment need to be established. Therefore, in the present study, nucleotide sequences of 18S, 28S ribosomal deoxyribonucleic acid and cytochrome c oxidase subunit I (COI) of E. japonica were determined along with detailed morphologic observations for the first time. Key characteristics were observed in all specimens, whereas some morphologic variations were observed in the symmetry of the cecum. The COI sequences, which are known to be variable genetic regions, were identical among all specimens; therefore, all of them were considered the same species. This result clarifies the high morphologic variation in E. japonica. The 18S and 28S sequences were 99.78% and 99.11–99.19% similar to those of Encylometra colubrimurorum. The high degree of homology between these genes indicates that E. japonica and E. colubrimurorum are closely related but independent species. The present data will be used for the identification of E. japonica and to evaluate the relationships within the genus Encyclometra.