Leptodactylus fuscus is a small-sized species widely distributed across South America. However, so far, no works have been addressed to analyze if biotic and abiotic factors may influence the parasite community in this species. Thus, the present work aims to describe the composition and structure of the parasite community and evaluate if biotic and environmental factors correlated to the distribution of the parasite community for this host. We collected 36 L. fuscus specimens from February 2018 to January 2019. The hosts were necropsied, and parasites were collected and identified. To test the effect of environmental variables (temperature, humidity, and precipitation) and morphological characters of the host (snout–vent length and body weight) on helminths of L. fuscus we used a multivariate distance matrix regression (MDMR). We found 10 helminth taxa: Aplectana sp., Aplectana membranosa, Cosmocercidae larvae, Mesocoelium sp., Mesocoelium aff. monas, Mesocoelium aff. sociale, Oswaldocruzia sp., Oxyascaris sp., Ortleppascaris sp. larvae, and Schrankiana formosula. In our study, the helminth community showed an aggregate pattern, and we did not observe a statistically significant correlation of body size and mass of the hosts regarding parasite abundance and richness. Thus, this study represents the first report of M. sociale, A. membranosa, and Ortleppascaris sp. larvae for L. fuscus and new locality reports. We conclude that there is no correlation between variables analyzed and the structure and composition of the parasite community of L. fuscus.

Parasitism is one of the most common consumer strategies and contributes a large portion to biological diversity. Trematodes in the family Diplostomidae are common in freshwater ecosystems worldwide, often residing in the eyes or brain of fish and then infecting fish-eating birds as adults. As a result, some species have broad geographic distributions due to the bird host's motility. In contrast to the cosmopolitan nature of diplostomids, only a single species, Tylodelphys darbyi, has been identified in New Zealand to date, and only from the South Island. Tylodelphys darbyi has a 3-host life cycle consisting of an unidentified snail, a freshwater fish (Gobiomorphus cotidianus), and the Australasian crested grebe (Podiceps cristatus australis). To date, T. darbyi has been found in 2 locations, Lake Hayes, in the eyes of G. cotidianus, and Lake Wanaka, adults recovered from grebes. Considering the near ubiquity of the fish host in New Zealand, it is likely the bird, listed as nationally vulnerable, is the limiting factor in the range of T. darbyi. Up to 10 G. cotidianus were sampled from 10 mountain lakes known to have populations of grebe in the Otago and Canterbury regions of New Zealand's South Island. The eyes of all fish were examined and any metacercariae present were set aside for genetic analysis. In addition to expanding the known range of T. darbyi to at least 4 water bodies across the South Island, 2 new taxa of diplostomid were identified. A lens-infecting metacercariae clustered with Diplostomum spathaceum, while the metacercariae from the humor clustered with Diplostomum baeri.

Seven new species of chewing lice in the genus Priceiella Gustafsson and Bush, 2017, are described and illustrated based on specimens collected in south China. They are Priceiella (Camurnirmus) tanydrepanus n. sp. from Garrulax castanotis castanotis (Ogilvie-Grant, 1899); Priceiella (Camurnirmus) nanlingensis n. sp. from Garrulax maesi maesi (Oustalet, 1890); Priceiella (Thescelovora) brutifrons n. sp. from Turdinus brevicaudatus stevensi (Kinnear, 1925); Priceiella (Thescelovora) chuae n. sp. from Pellorneum albiventre cinnamomeus (Rippon, 1900); Priceiella (Thescelovora) catanachei n. sp. from Stachyris strialata swinhoei Rothschild, 1903; Priceiella (Thescelovora) dehongensis n. sp. from Stachyris nigriceps yunnanensis La Touche, 1921; and Priceiella (Thescelovora) rotundiceps n. sp. from Pomatorhinus ruficollis styani Seebohm, 1884. Several of these new species constitute the second species of Priceiella known from the host, suggesting that local endemism may be high in this louse genus. We also provide new host records for Priceiella (Thescelovora) coleyae Gustafsson et al., 2018, and Priceiella (Thescelovora) austini Gustafsson et al., 2018, and correct the type host subspecies for the latter. Finally, we amend the subgenus descriptions of Camurnirmus Gustafsson and Bush, 2017, and Thescelovora Gustafsson and Bush, 2017. As a result of these changes, Priceiella najeri Gustafsson et al., 2018, is moved to subgenus Thescelovora. An updated checklist of the genus Priceiella is provided.

There has been a growing interest in characterizing the parasite faunas of species populations as they expand their geographical ranges as a result of climate change. Expanded-range populations often exhibit lower parasite diversity than historical-range populations, and reduced parasitism may, in part, be attributable to expanded-range populations escaping their native range parasites. The present study compares the helminth faunas of green treefrogs (Hyla cinerea) from 4 historical and 4 expanded-range populations to determine whether these latter populations have undergone parasite escape. Results of this study found relatively high degrees of similarity in species composition among helminth assemblages within historical or within range-expansion locations, with marked differences in the composition of helminth faunas between historical and expanded-range populations of these frogs. Because green treefrogs from expanded-range locations exhibited significant decreases in helminth species diversity compared with those from historical sites, they appear to be escaping levels of parasitism typically experienced by these frogs in their native range. Most notably, there was a decrease in the abundance of helminths with direct life cycles and the absence of trematode assemblages with indirect life cycles among expanded-range populations of H. cinerea. The low prevalence of trematode assemblages among historical populations of green treefrogs could limit these parasites' ability to be introduced and propagated in expanded-range locations. However, the lack of trematode assemblages among populations of H. cinerea in its expanded range may also be due to the absence or limited availability of other aquatic hosts that are required to complete the life cycles of these parasites. The reduction in helminth diversity among expanded-range populations of green treefrogs lends some credence to the notion that individuals at the front of a range expansion often invest less energy in reproduction and in doing so allocate more energy to dispersal and other life-history traits, including resistance to parasites. There may, however, be other explanations for differences in parasite species diversity between historical and expanded-range populations of H. cinerea. Because many of the helminths reported from this study are host generalists of amphibians whose recruitment and transmission among intermediate and paratenic hosts are known to be constrained by water and/or soil moisture conditions, we cannot ignore the role of both local amphibian diversity and local abiotic factors in influencing helminth diversity between the 2 population types of green treefrogs. These latter factors would decrease the role of parasite escape or energy trade-offs in driving helminth diversity among populations of H. cinerea and instead would suggest that local conditions play a more prominent role in structuring their helminth communities.

Rictularia jiyeoni n. sp. from the small intestine of the striped field mouse, Apodemus agrarius, in Korea, is described and illustrated. Specimens were studied using light and scanning electron microscopies. This rictulariid nematode is closest to the Rictularia species that have a reduced number of combs and spines. However, the new species can be differentiated from the other species of Rictularia by having 36–58 perioral denticles, a buccal capsule with a single esophageal tooth, and 37–44 pairs of combs and spines of which 32–37 are prevulvar and 5–11 are postvulvar.

Myxosporean species in the genus Cystodiscus are parasites of amphibians and have been reported from several continents. Typically used for the identification of myxozoans, the spores produced by these species are similar to one another, possessing 2 polar capsules and being ovoid. The number of transverse depressions on the spore can be useful for delineating species, but these can sometimes be difficult to distinguish. In North America, Cystodiscus serotinus and Cystodiscus melleni have been described, and for C. serotinus in particular, numerous reports and a wide range of hosts have been associated with this species. Given the challenges of identifying some of these species, we questioned whether all encounters of Cystodiscus species can be attributed to these 2 described species, or if there may be additional undescribed species or cryptic species. Over 7 yr, 383 amphibians representing 13 species of toads, frogs, and salamanders were collected from sites in Oklahoma and Arkansas. Cystodiscus infections were found in 56 individuals (14.6%). Tissues from these infected individuals were preserved in alcohol for genetic analysis. The small subunit (SSU) and large subunit (LSU) ribosomal RNA genes were partially sequenced and analyzed phylogenetically. Nine distinct SSU sequence types and 7 distinct LSU sequence types were identified. Phylogenetically, sequence types were attributable to C. serotinus, C. melleni, Cystodiscus axonis, and an undescribed species. For the previously described species, there were multiple SSU sequence types: 4 for C. serotinus and 2 for both C. melleni and C. axonis. Phylogenetic patterns were similar for the LSU sequence analysis using a shorter sequence than the SSU, and we propose that the LSU is useful for initial barcoding of Cystodiscus species in any future surveys. In our qualitative assessment of sequence types compared to geography and host species, SSU types C1 and C2 (C. axonis) were only found in Union County, Arkansas, and McCurtain County, Oklahoma, respectively. Also, salamanders were only infected with SSU types B or D (C. melleni), and type B was only found in salamanders. Our finding of C. axonis in North America is notable because this species was described in Australia and is associated with host pathology. Our work reveals that there are cryptic species of Cystodiscus in the United States, one of which may be a pathogen, highlighting the importance of genetic analysis for future surveys of these species.

The Asian fish tapeworm (Schyzocotyle acheilognathi syn. Bothriocephalus acheilognathi) (AFT) is an invasive parasite that can infect many species of fish, although most hosts are primarily members of Cyprinidae. Pathogenicity has most often been reported in aquaculture settings in fry and fingerling stages of carp (Cyprinus spp.). More recently, it has been shown to cause growth retardation in the endangered bonytail chub (Gila elegans) and found to be widespread in populations of endangered humpback chub (Gila cypha) in the Colorado River, Grand Canyon, Arizona. AFT spreads most often through the transport of infected fish, particularly baitfish. Despite its harmful potential, there is no efficient or accurate ante mortem test to detect AFT in water or fish samples before transport. Herein, we report on the development of a sensitive and specific loop-mediated isothermal amplification (LAMP) assay to detect the parasite in under 30 min from laboratory prepared samples. Six LAMP primers were designed to amplify a variable region of the 18S ribosomal RNA gene in AFT with the detection and quantification of DNA on a real-time fluorometer. The limit of detection was 1 × 10¹ copies/µl of DNA extracted from as few as 2 AFT eggs. Future application of our assay would be a low-cost test to rapidly and accurately detect AFT DNA from environmental samples on-site so that preventive actions can be taken to halt the spread of the AFT through the movement of infected fish.

Toxoplasma gondii is an apicomplexan parasite that affects both humans and livestock. Transmitted to humans through ingestion, it is the second-leading cause of foodborne illness-related death. Currently, there exists no approved vaccine for humans or most livestock against the parasite. DNA vaccines, a type of subunit vaccine which uses segments of the pathogen's DNA to generate immunity, have shown varying degrees of experimental efficacy against infection caused by the parasite. This review compiles DNA vaccine efforts against Toxoplasma gondii, segmenting the analysis by parasite antigen, as well as a review of concomitant adjuvant usage. No single antigenic group was consistently more effective within in vivo trials relative to others.

To avoid confusions related to the resurrection of Adenocephalus Nybelin, 1931 (Cestoda: Diphyllobothriidea), the type material of the Pacific broad tapeworm, Adenocephalus pacificus Nybelin, 1931, which also infects humans, is morphologically characterized. Transverse protuberances on the ventral side of proglottids anterior to gonopores, which are a diagnostic feature of the genus, are illustrated for the first time. The present study supports the importance of a study of type material even in the ‘molecular era’ of taxonomy, where the value of morphology is often underestimated. It also points out the need for specimen deposition in publicly accessible collections.

A total of 1,218 helminths ascribed to 11 taxa (6 at species, 3 at generic, 1 at family, and 1 at order level) in 101 specimens of Halichoeres radiatus (Pisces: Labridae) were caught in the Veracruz Coral Reef System National Park, southern Gulf of Mexico. These helminths include 4 trematode species (3 adults and 1 metacercaria), a cestode species (larvae), 5 nematode species (2 adults and 3 larvae), and an acanthocephalan species (juvenile). Nine correspond to new host records, 2 of them are new geographic records, and 6 species were recorded with 1 helminth per infected host. The larvae of Scaphanocephalus expansus (Creplin, 1842) Jägerskiöld, 1903, and larvae of the order Tetraphyllidea were the parasites with the highest prevalence and mean intensity. Species richness (S = 11) and the Shannon-Wiener diversity index (H′ = 1.1) were lower than those recorded for host-parasite communities in the locality. The fact that 10 of the total of 11 parasitic species were found in fish intestines suggests that infection is a result of host feeding habits.

The yellow-billed cuckoo, Coccyzus americanus, is a threatened passerine bird native to North America that migrates to overwinter in South America. Although migratory birds have drawn broad attention, given their assumed role in the long-distance dispersal of parasites, studies on the helminth fauna of this cuculid are scarce. In the present study, nematodes found in the gastrointestinal tract of a specimen of C. americanus found in Belo Horizonte, State of Minas Gerais, southeastern Brazil, were characterized morphologically. Five species of gastrointestinal nematodes belonging to 4 families were identified: Synhimantus (Dispharynx) nasuta (Rudolphi, 1819) and Synhimantus (Dispharynx) resticula Canavan, 1929 (Acuariidae), Microtetrameres sp. (Tetrameridae), and Cyrnea piayae Sandground, 1929 (Habronematidae) and Subulura halli Barreto, 1918 (Subuluridae). Except for Microtetrameres sp., all other nematodes are reported in this host for the first time. Although it is difficult to accurately determine the geographical origin of infections, it is important to note that Sy. (D.) resticula and Su. halli are reported for the first time in Brazil. Additionally, the absence of the former species infecting hosts where the widespread and generalist Sy. (D.) nasuta was found may indicate that Sy. (D.) resticula have either been overlooked in previous studies or that this nematode is rare indeed. Finally, the geographical distribution of Su. halli is greatly expanded and now includes the Americas. Aspects related to the dispersion of these parasites, both in migrating and native hosts, are briefly discussed.

Counting oocysts in feces or litter is 1 method to monitor infection levels with Eimeria spp. in chickens after experimental infection or in commercial flocks. Counts of oocysts shed in the feces are thought to follow a typical pattern, with clear peaks representing infection cycles while oocyst counts in litter are representative for at least 2 wk before they begin to deteriorate. The objective of the study was to compare oocyst counts in fresh feces and litter of broilers kept in floor pens with fresh pine shavings as litter material for 42 days. The birds were spray-vaccinated against coccidia in the hatchery. Every 2 to 3 days, 7 pens were sampled by collecting fresh feces and litter from at least 3 locations per pen. Oocysts were counted using a McMaster chamber (Vetslides, Park City, Utah). There were significant differences between pens in oocyst counts in feces as well as in litter, and there were no obvious shedding patterns. Overall, the geometric mean of oocyst counts on day 8 and later was 1,300 oocysts per gram (opg) in feces and 2,700 opg in litter. The variability was lower in litter samples, and the number of pens required to find significant differences between groups in a hypothetical experiment was unrealistically high on most days. Investigating individual fecal samples showed large differences within the pens in addition to the differences between the pens.