The life cycle and ecology of the horsehair worm Chordodes morgani (Nematomorpha) in Nebraska remain unknown. To identify its definitive host, we installed a series of pitfall traps along 3 first-order streams at 4 sites: Elk Creek, Upper Elk Creek, Maple Creek, and West Oak Creek, all located northwest of Lincoln, Nebraska. In addition, we opportunistically hand-collected insects at these sites, including wood cockroaches (Parcoblatta virginica), and maintained them in the lab until they passed adult worms. Two of these field-collected wood cockroaches each yielded 1 adult worm, which was identified as C. morgani by microscopy, showing that P. virginica serves as a definitive host. Experimental infections of captive-reared Parcoblatta americana supported this result. The wood cockroach was found at all 3 creeks, but C. morgani was not found at West Oak Creek, suggesting that the definitive host does not limit the distribution of C. morgani. Physical properties of the streams were measured to examine how these properties influenced the distribution of the worm. Flow rate and pH differed between the 3 sites where C. morgani was found and the West Oak Creek site, suggesting an important role for these abiotic factors in the distribution of this horsehair worm species.

Feline cytauxzoonosis is a disease caused by Cytauxzoon felis, a protozoan that infects the red blood cells and macrophages. It is responsible for an acute and often fatal disease in domestic cats. The purpose of this study was to investigate the occurrence of C. felis infections in healthy cats. Piroplasm forms were seen in the erythrocytes of 2 cats, and C. felis DNA was identified by polymerase chain reaction (PCR) in one of them. The results demonstrate that erythrocytic piroplasmids associated with tick-borne parasitic protozoa may be found circulating in the blood of healthy cats in Rio de Janeiro. These can be differentiated from the morphologically similar forms of species such as Babesia by analysis of DNA, thereby demonstrating the potential for further studies of feline populations in Brazil.

Canine babesiosis is a serious disease among tick-borne haemoprotozoan diseases that threaten dog health. To find out the prevalence of canine babesiosis and its main pathogenic species in Shaanxi Province, the study was centered on the infection of babesiosis in dogs in different regions of the Province. First, a total of 367 blood samples were collected in Shaanxi Province, and 53 Babesia nucleic-acid-positive samples were found by polymerase chain reaction (PCR) identification, with a positive rate of 14.44%, and Babesia gibsoni was found by sequencing analysis. Further analysis showed that the prevalence of canine babesiosis was significantly different in 5 regions. There was no significant difference in infection rates between age groups, with the lowest prevalence in young dogs (10.81%) and the highest in adult dogs (17.29%). The infection rate in male dogs was higher than in female dogs. The morbidity of canine Babesia spp. was significantly different between different seasons, with the highest infection rate in autumn (27.78%) and the lowest in winter (6.10%). In conclusion, the epidemicity of canine Babesia spp. in dogs was mainly affected by region and season, and B. gibsoni was the most common canine Babesia spp. within Shaanxi Province in our study. These results provide basic data for the prevention and control of canine babesiosis in this region.

Blastocystis is a common enteric protist that is linked to intestinal and extra-intestinal diseases. At least 24 subtypes (STs) have been described, with the main colonization of ST1–ST4 in humans. In our attempt to determine the distribution of Blastocystis STs in Olsztyn and surroundings in northeastern Poland, 319 stool samples from volunteers were subjected to copro-ELISA and PCR testing. Positive findings were identified in 77, 48, and 46 of the samples via copro-ELISA, PCR, and sequencing, respectively. Blastocystis colonization was not associated with gender or dwelling place but was statistically higher in people age 60–69 yr (32.6%). Five STs (ST1–ST4, ST7) were identified, in which ST3 (37%) was most prevalent, followed by ST2 (19.6%), ST1 (17.4%), ST4 (13%), and ST7 (8.7%). The current study revealed a similar rate of microorganism colonization in Polish volunteers compared to other developed countries, without significant differences in gender and dwelling place. Significant statistical differences were found in different age groups, where Blastocystis was highly detected in elderly people. In the current study, PCR was the most plausible method based on the sequencing results.

An emended diagnosis of Thaumatocotyle (Monogenoidea: Monocotylidae) and a list of its species are provided. Merizocotyle urolophi , Merizocotyle macrostrobus , Merizocotyle papillae , and Merizocotyle rhadinopeos are transferred to Thaumatocotyle as new combinations. Thaumatocotyle pseudodasybatis is redescribed and is currently restricted to Thaumatocotyle-like helminths parasitizing the olfactory organs of the white-spotted eagle ray Aetobatus narinari (Euphrasen, 1790) (Myliobatiformes: Aetobatidae) in the western Atlantic Ocean. Two new species are described that infect the olfactory organs of pelagic eagle rays: Thaumatocotyle adelpha n. sp. from the ocellated eagle ray Aetobatus ocellatus (Kuhl, 1823) in the central and western Pacific Ocean and Thaumatocotyle casigneta n. sp. from the Pacific eagle ray Aetobatus laticeps Gill, 1865 from the eastern Pacific Ocean off the western coast of Mexico. Based on comparative morphology, T. pseudodasybatis, T. adelpha, and T. casigneta appear to form a subgroup of species that developed secondarily within the genus.

Allintoshius is the only genus of the family Ornithostrongylidae (Travassos, 1937) Durette-Desset and Chabaud, 1981 that parasitizes bats. Currently, there are 10 valid species in the genus, of which 3 were described from Brazil. This study describes a new species of Allintoshius and records the first occurrence of a nematode of this genus parasitizing Artibeus lituratus (Olfers). Allintoshius gomesae n. sp. is characterized by having anterior region coiled, cephalic vesicle with cuticular dilation striated transversely, and claviform esophagus. Synlophe in females consists of 16 cuticular ridges at the mid-body. Males have large caudal bursa, and conic and small spicules, and the gubernaculum is absent. Females have uterus didelphic, amphidelphic, tail tip tapered, and ovijector divided into 2 divergent branches, subequal in length. The new species differs from its congeners especially by the shape of the tail tip, vulvar opening, and size of spicules. Allintoshius gomesae is the fourth species of Allintoshius from Brazil and the first report in Ar. lituratus, increasing the number of species recognized of the genus.

This study aimed to investigate whether the infection intensity of Theileria orientalis Ikeda type organisms within Haemaphysalis longicornis larvae and nymph stages fluctuated over 6 mo after feeding as larvae on infected calves in the field. Naïve larvae, hatched from eggs, were fed on infected calves for 5 days while contained within cotton socks glued over the calves' ears. Larvae were first sampled immediately post-feeding and then sampled every 3 wk for 23 wk in total, after molting to nymphs. All larvae and nymphs were tested for T. orientalis Ikeda organisms using quantitative PCR. The qPCR results showed that the infection intensity of Haemaphysalis longicornis larvae and nymphs was not constant over the sampling period, and after initially dropping after molting to nymphs, it then rose with fasting to a maximum at 17 and 23 wk post-feeding. The significant rise in T. orientalis Ikeda organisms observed at 23 wk postfeeding may explain why more severe clinical cases of bovine theileriosis in New Zealand are seen in the spring when nymphs are the predominant instar questing.

Parasitic lineages have acquired suites of new traits compared to their nearest free-living relatives. When and why did these traits arise? We can envision lineages evolving through multiple stable intermediate steps such as a series of increasingly exploitative species interactions. This view allows us to use non-parasitic species that approximate those intermediate steps to uncover the timing and original function of parasitic traits, knowledge critical to understanding the evolution of parasitism. The dauer hypothesis proposes that free-living nematode lineages evolved into parasites through two intermediate steps, phoresy and necromeny. Here we delve into the proposed steps of the dauer hypothesis by collecting and organizing data from genetic, behavioral, and ecological studies in a range of nematode species. We argue that hypotheses on the evolution of parasites will be strengthened by complementing comparative genomic studies with ecological studies on non-parasites that approximate intermediate steps.

Stable isotope analyses of carbon and nitrogen (δ¹³C and δ¹⁵N) are useful for elucidating consumer relationships of free-living organisms, as carbon isotopes indicate dietary carbon sources and incremental increases in nitrogen isotopic enrichment are correlated with increases in trophic position. However, host–parasite relationships are more difficult to interpret using isotopes, as data from different host–parasite systems rarely show any consistent pattern. This inconsistency of pattern reflects the complexity of host–parasite relationships, but also the scarcity of data from a diverse assemblage of host–parasite systems. We present stable isotope data from a host–parasite system including 2 ecologically contrasting helminths, an acanthocephalan (Filisoma filiformis) and a digenetic trematode (Enenterum sp.), which co-occur in the intestine of the same marine fish (Kyphosus bigibbus), the diet of which consists almost exclusively of macroalgae. We obtained δ¹³C and δ¹⁵N data from K. bigibbus muscle, stomach contents, and pooled infrapopulations of Enenterum sp. and F. filiformis. Consistent with other isotope studies including acanthocephalans, F. filiformis was depleted in δ¹³C and δ¹⁵N relative to K. bigibbus. Although Enenterum sp. exhibited values for δ¹³C similar to those for F. filiformis, they were enriched in δ¹⁵N relative to the acanthocephalan, with a signature similar to that of K. bigibbus. These findings are discussed within a host–ecosystem context, highlighting the importance of considering species-specific biology when interpreting host–parasite relationships using stable isotopes. Our study adds to the growing body of literature indicating that absorptive feeders, such as acanthocephalans, are typically depleted in δ¹³C and δ¹⁵N relative to their hosts, whereas trematodes, with a greater diversity of feeding opportunities, exhibit a wide variety of isotopic signatures across life stage and different host–parasite systems.

Within-host distributions of parasites can have relevance to parasite competition, parasite mating, transmission, and host health. We examined the within-host distribution of the adult trematode Alloglossidium renale infecting the paired antennal glands of grass shrimp. There are 4 possible parasite distributions for infections of paired organs: random, uniform, biased aggregation to 1 particular organ (e.g., left vs. right), or inconsistently biased (aggregated, but does not favor 1 side). Previous work has shown that morphological asymmetries in hosts can lead to biased infections of paired organs. Apparent symmetry between the antennal glands of grass shrimp leads to the prediction that there would be no bias for 1 particular organ. However, an alternative prediction stems from the fact that A. renale is hermaphroditic: aggregation between glands would increase outcrossing opportunities and thus, avoid inbreeding via self-mating. Existing methods to test for an overall pattern did not apply to the A. renale system because of low-intensity infections as well as many 0 values for abundance per unit of the antennal gland. Hence, we used Monte Carlo simulations to determine if the observed overall patterns differed from those expected by randomly allocating parasites into groups of 2. We found that in 3 of 4 data sets, A. renale infections did not deviate from random distributions. The fourth data set had a more uniform pattern than expected by chance. As there was no aggregation between glands and the proportion of worms in single gland infections did not differ from that expected by chance alone, we found no evidence of inbreeding avoidance as might be manifested via a within-host distribution. Given the large proportion of worms in single infections, we predict as a major evolutionary outcome that populations of A. renale will be largely inbred.

The role of invertebrates in some acanthocephalan life cycles is unclear because juvenile acanthocephalans are difficult to identify to species using morphology. Most reports suggest acanthocephalans from turtle definitive hosts use ostracods as intermediate hosts and snails as paratenic hosts. However, laboratory studies of the life cycle suggest that ostracods and snails are both required hosts in the life cycle. To elucidate the role of ostracods and snails in acanthocephalan life cycles better, we collected 558 freshwater snails of 2 species, including Planorbella cf. Planorbella trivolvis and Physa acuta, from 23 wetlands in Oklahoma, U.S.A., and examined them for acanthocephalan infections. Additionally, we examined 37,208 ostracods of 4 species, Physocypria sp. (morphotype 1), Cypridopsis sp., Stenocypris sp., and Physocypria sp. (morphotype 2) for juvenile acanthocephalans from 2 wetlands in Oklahoma. Juvenile acanthocephalans were morphologically characterized, and the complete internal transcribed spacer (ITS) region of nuclear rDNA was sequenced from acanthocephalans infecting 11 ostracod and 13 snail hosts. We also sampled 10 red-eared slider turtles, Trachemys scripta elegans, and 1 common map turtle, Graptemys geographica, collected from Oklahoma, Arkansas, and Texas and recovered 1,854 adult acanthocephalans of 4 species. The ITS of 17 adult acanthocephalans of 4 species from turtle hosts were sequenced and compared to juvenile acanthocephalan sequences from ostracod and snail hosts from this study and GenBank to determine conspecificity. Of the 23 locations sampled for snails, 7 (30%) were positive for juvenile acanthocephalans in the genus Neoechinorhynchus. The overall prevalence and mean intensity of acanthocephalans in Planorbella cf. P. trivolvis and P. acuta were 20% and 2 (1–6) and 2% and 1 (1), respectively. In contrast, only 1 of 4 species of ostracods, Physocypria sp. (morphotype 1), was infected with larval/juvenile Neoechinorhynchus spp. with an overall prevalence of 0.1% and a mean intensity of 1 (1–2). Although 4 species of acanthocephalans infected turtle definitive hosts, including Neoechinorhynchus chrysemydis, Neoechinorhynchus emydis, Neoechinorhynchus emyditoides, and Neoechinorhynchus pseudemydis, all the ITS sequences from cystacanths infecting snail hosts were conspecific with N. emydis. In contrast, the ITS sequences from larval/juvenile acanthocephalans from ostracods were conspecific with 2 species of acanthocephalans from turtles (N. emydis and N. pseudemydis) and 1 species of acanthocephalan from fish (Neoechinorhynchus cylindratus). These results indicate that N. emydis infects freshwater snails, whereas other species of Neoechinorhynchus appear not to infect snail hosts. We document new ostracod and snail hosts for Neoechinorhynchus species, including the first report of an ostracod host for N. pseudemydis, and we provide novel molecular barcodes that can be used to determine larva, juvenile, and adult conspecificity of Neoechinorhynchus species.

In comparative studies, the advantage of increased sample sizes might be outweighed by detrimental effects on sample homogeneity and comparability when small numbers of hosts from a different demographic of the same species are included in samples. A mixed sample of sunfishes (Lepomis spp.) was subdivided in different ways and examined using cumulative performance curves to determine whether the exclusion of larger hosts from a single-species sample and/or the inclusion of hosts of the same size demographic from closely related host species would produce more homogeneous samples. The exclusion of larger hosts from the single-species samples tended to reduce the aggregation of the infrapopulation samples, and mixed-species samples of smaller fishes tended to have lower degrees of aggregation for a given sample size relative to the single-species sample. Cumulative performance curves for diversity and richness, in concert with nonmetric multidimensional scaling of the infracommunities, demonstrated sunfish size to be a more reliable determinant of infracommunity similarity than sunfish species in this particular sample. The results demonstrate that cumulative aggregation curves can be an effective tool for delineating homogeneous and comparable subsamples and that, under some circumstances, it is possible to offset the smaller sample sizes that result from the exclusion of older/larger hosts by the addition of congeneric or confamilial hosts within the same size/age classes as the stratified sample.

Cryptosporidium spp. have been identified in a wide range of hosts, such as humans and domestic and wild animals, while less information about the prevalence of Cryptosporidium spp. in pet hamsters is documented. A total of 351 dwarf winter white Russian hamsters' fecal specimens were collected from 6 pet markets from the cities of Luzhou and Ziyang in Sichuan province in the southwestern part of China. The prevalence of Cryptosporidium spp. determined with nested-PCR amplification of the partial small-subunit (SSU) rRNA gene was 39.32% (138/351). The highest prevalence of Cryptosporidium spp. was in pet market 5 (79.49%, 62/78), followed by pet market 6 (38.64%, 17/44). The lowest prevalence of Cryptosporidium spp. was observed in pet market 3 (14.89%, 7/47). Statistically significant differences in the prevalence of Cryptosporidium spp. were observed among different pet markets (χ² = 76.386, df = 5, P < 0.05), and a further post hoc test revealed that only pet market 5 was significantly different from other pet markets. Molecular analysis showed that 4 different Cryptosporidium species or genotypes were identified: Cryptosporidium parvum (n = 127), Cryptosporidium chipmunk genotype III (n = 6), Cryptosporidium andersoni (n = 4), and Cryptosporidium wrairi (n = 1). The identification of Cryptosporidium spp. was further tested with the 60-kDa glycoprotein (GP60) gene, and the positive rate was 29.7% (41/138). This is the first molecular report on Cryptosporidium spp. infection in dwarf winter white Russian hamsters in China. With C. parvum and C. andersoni being identified in both humans and pet hamsters, these findings suggest that pet hamsters may be potential reservoirs of zoonotic Cryptosporidium species and subtypes.