Remarkably few attempts have been made to estimate contemporary effective population size (Ne) for parasitic species, despite the valuable perspectives it can offer on the tempo and pace of parasite evolution as well as coevolutionary dynamics of host–parasite interactions. In this study, we utilized multi-locus microsatellite data to derive single-sample and temporal estimates of contemporary Ne for a cestode parasite (Schistocephalus solidus) as well as three-spined stickleback hosts (Gasterosteus aculeatus) in lakes across Alaska. Consistent with prior studies, both approaches recovered small and highly variable estimates of parasite and host Ne. We also found that estimates of host Ne and parasite Ne were sensitive to assumptions about population genetic structure and connectivity. And, while prior work on the stickleback–cestode system indicates that physiographic factors external to stickleback hosts largely govern genetic variation in S. solidus, our findings indicate that stickleback host attributes and factors internal to the host – namely body length, genetic diversity and infection – shape contemporary Ne of cestode parasites.

History. Trypanosomes have been cultured from the blood of cattle in many parts of the world; in Germany, Denmark, Greece, Holland, France, Russia, Japan, the Philippines, Siberia, Algeria, Tunis, the United States and Brazil. But in only a few cases have the actual parasites been found in the circulating blood. From the scanty literature at my disposal, but especially from the Sleeping Sickness Bulletin, I find that the following observers have found and described the trypanosomes in the blood.

The development of Carmyerius exoporus Maplestone in the snail Anisus nata-lensis Krauss is described with the emphasis laid on the redial and cercarial productivity of the rediae of the first and subsequent generations.

The miracidium gives rise to one sporocyst. From 25 to 32 germinal cells present in the miracidium, only six to eleven develop into embryo balls in the sporocyst and, of these, only three to nine develop into rediae of the first generation.

The redia of the first generation gives birth to daughter rediae and cercariae. No alternation in the development of redial and cercarial embryos was noted in the rediae of C. exoporus and a small number of redial embryos was observed to develop alongside the more numerous cercarial embryos throughout the life of the first generation rediae.

The rediae of the second and subsequent generations also give birth to daughter rediae and cercariae.

The cercariae leave their parent redia when they are still immature and continue the development in the snail tissue.

Three new species of dactylogyrid monogeneans with three anchors are described: two of them, Eutrianchoratus magnum and E. minutus, from Ophiocephalus obscurus, and Heteronchocleidus ctenopomae from the anabantid Ctenopoma kingsleyae, all from south Ghana.

Analysis of the variation in the morphological patterns of the anchors and the bars in the known species of the Heteronchocleidinae suggests gradual specialization from an ancyrocephaliid type with two pairs of anchors to types with three anchors arranged in triangular symmetry.

Heteronchocleidinae occur on both ophiocephaliid and anabantiid fish in Southeast Asia as well as in West Africa.

Many protease genes have previously been shown to be involved in parasitism and in the development of Steinernema carpocapsae, including a gene predicted to encode an aspartic protease, Sc-ASP110, which was cloned and was analysed in this study. A cDNA encoding Sc-ASP110 was cloned based on an expressed sequence tag (EST) fragment from our EST library. The full-length cDNA of Sc-ASP110 consists of 1112 nucleotides with a catalytic aspartic domain (aa18–337). The putative 341 amino acid residues have a calculated molecular mass of 37·1 kDa and a theoretical pI of 4·7. BLASTp analysis of the Sc-ASP110 amino acid sequence showed 45–77% amino acid sequence identity to parasitic and non-parasitic nematode aspartic proteases. An expression analysis showed that the sc-asp110 gene was upregulated during the late parasitic stage, L4, and 24 h after induction of in vitro nematodes. A sequence comparison revealed that Sc-ASP110 was a member of an aspartic protease family; additionally, a phylogenetic analysis indicated that Sc-ASP110 was clustered with the closely related nematode Steinernema feltiae. In situ hybridization showed that sc-asp110 was expressed in the body walls of dorsal cells. The upregulated Sc-ASP110 expression revealed that this protease could play a role in the late parasitic process. In this study, we have cloned and analysed the gene transcript of Sc-ASP110 in S. carpocapsae.

For parasites in natural systems, the most common pattern of spatial distribution is aggregation among hosts. The main causes of such aggregation are variable exposure of hosts to parasites and heterogeneity in host susceptibility. The objective of this study was to determine if there are differences in the aggregation pattern of two species of ectoparasitic flies between the Pantanal and Cerrado regions of Brazil on the bat Artibeus planirostris. We collected the ectoparasites from bats captured between 2002 and 2017 with mist nets in 21 sites in the Pantanal and 15 sites in the surrounding plateaus. The results showed that the aggregation of ectoparasitic flies in Pantanal was more pronounced than in Cerrado. The discrepancy aggregation index (D) of the bat fly Megistopoda aranea was 0.877 in Pantanal and 0.724 in Cerrado. The D values of Aspidoptera phyllostomatis was even higher, with 0.916 and 0.848 in the Pantanal and Cerrado, respectively. Differences in the shelters used may be the main factor shaping variation in aggregation, since the Pantanal does not have rock formations, with only foliage, crowns and hollow tree trunks. These differences likely affect host exposure to the parasites, leading to an increase in parasite aggregation.

A Babesia divergens merozoite antigen was purified by affinity chromatography using a monoclonal antibody. Silver staining of SDS-PAGE gels revealed 2 bands of Mr 50–60 kDa and Mr 24–29. It is proposed that the Mr 24–29 kDa band represents the native protein and that it is complexed, perhaps as a dimer or perhaps to host protein to give the Mr 50–60 kDa band. Peptide analysis of the antigen followed by Western blotting with the monoclonal antibody revealed only an Mr 20–24 kDa band. After affinity purification the antigen was precipitated with acetone and inoculated subcutaneously, together with complete Freund's adjuvant, into gerbils. Two inoculations were given 3 weeks apart, after which the immunized animals and a group of control animals were challenged with 5 × parasitized red cells from a virulent microaerophilus stationary phase (MASP) culture of an homologous strain of B. divergens. Parasitaemias rose rapidly in control animals and all were dead by the fifth day. Two of the vaccinated animals survived the challenge. Parasitaemias in the remaining two rose slowly but both animals succumbed on the seventh day. Western blotting of merozoites and of the purified antigen, using sera from the surviving animals showed strong reactivity with the Mr 24–29 kDa band.

Protein deficiency impairs local and systemic immune responses to Heligmosomoides bakeri infection but little is known about their individual and interactive impacts on tissue architecture of maternal lymphoid (thymus, spleen) and visceral (small intestine, kidney, liver, pancreas) organs during the demanding period of lactation. Using a 2×2 factorial design, pregnant CD1 mice were fed a 24% protein sufficient (PS) or a 6% protein deficient (PD) isoenergetic diet beginning on day 14 of pregnancy and were infected with 100 H. bakeri larvae four times or exposed to four sham infections. On day 20 of lactation, maternal organs were examined histologically and serum analytes were assayed as indicators of organ function. The absence of villus atrophy in response to infection was associated with increased crypt depth and infiltration of mast cells and eosinophils but only in lactating dams fed adequate protein. Infection-induced lobular liver inflammation was reduced in PD dams, however, abnormalities in the kidney caused by protein deficiency were absent in infected dams. Bilirubin and creatinine were highest in PD infected mice. Infection-induced splenomegaly was not due to an increase in the lymphoid compartment of the spleen. During lactation, infection and protein deficiency have interactive effects on extra-intestinal pathologies.

Environmental toxicants are pervasive in nature, but sub-lethal effects on non-target organisms and their parasites are often overlooked. Particularly, studies on terrestrial hosts and their parasites exposed to agricultural toxicants are lacking. Here, we studied the effect of sequence and timing of sub-lethal exposures of the pyrethroid insecticide alpha-cypermethrin on parasite establishment using the tapeworm Hymenolepis diminuta and its intermediate insect host Tenebrio molitor as a model system. We exposed T. molitor to alpha-cypermethrin (LD20) before and after experimental H. diminuta infection and measured the establishment success of larval tapeworms. Also, we conducted in vitro studies quantifying the direct effect of the insecticide on parasite viability. Our results showed that there was no direct lethal effect of alpha-cypermethrin on H. diminuta cysticercoids at relevant concentrations (LD10 to LD90 of the intermediate host). However, we observed a significantly increased establishment of H. diminuta in beetles exposed to alpha-cypermethrin (LD20) after parasite infection. In contrast, parasite establishment was significantly lower in beetles exposed to the insecticide before parasite infection. Thus, our results indicate that environmental toxicants potentially impact host-parasite interactions in terrestrial systems, but that the outcome is context-dependent by enhancing or reducing parasite establishment depending on timing and sequence of exposure.

1. Oxynema crassispiculum (Sonsino, 1889) has been redescribed and shown to possess two spicules.

2. The genus Numidica Barreto, 1919 has been shown to be synonymous with the genus Oxynema von Linstow, 1899.

3. The genus Oxynema has been redefined and a synonymic list is given of the species that it now contains.

4. Oxynema typicum Kreis, 1940 is considered to be a species incertae sedis.

5. Baylisnumidica petrodromi (Baylis, 1934) has been redescribed and shown to belong to the genus Parasubulura Berghe & Vuylsteke, 1938.

6. The family Parasubuluridae is reduced to subfamily rank, and placed in the family Subuluridae.

Many different drug-resistant lines of rodent malaria are available as screening models. It is obligatory to screen new compounds for antimalarial activity against a series of resistant lines in order to identify a compound with potential for the treatment of multi-drug resistant (MDR) malaria infections. Instead of using a battery of resistant lines, a single MDR Plasmodium yoelii nigeriensis strain that shows a wide spectrum of drug resistance to high doses of chloroquine, mepacrine, amodiaquine, mefloquine, quinine, quinidine, halofantrine as well as tetracyclines, fluoroquinolines and erythromycin, was used to assess the blood schizontocidal efficacy of a new macrolide azithromycin and other antibiotics. The present study shows that only azithromycin has the potential to control an MDR P. y. nigeriensis infection in Swiss mice, provided the treatment with a dose of 50–100 mg/kg/day by oral route is continued for a period of 7 days. Tetracycline, oxytetracycline, doxycyline, erythromycin, ciprofloxacin and norfloxacin, although active in vitro, failed to protect the mice. Tetracycline, ciprofloxacin and norfloxacin combinations with chloroquine did not control the infection. Additionally, the antimalarial efficacy of azithromycin can be potentiated with the addition of arteether, which is an ethyl ether derivative of artemisinin. A total (100%) curative effect has been obtained with a shorter regimen of 4 days only.

The nematode worms discovered by Mr Shipley in the swim-bladder of Trout belong to the species Cystidicola farionis, first described by Fischer, and considered by him to represent a new and distinct type in nematode structure for which he proposed the generic name Cystidicola. Later writers refused to accept the new genus and included it in various other groups (see Synonymy, p. 190). In accordance with an old nomenclatural practice the proposed generic name was adopted as the specific name in place of that originally given, thus Cystidicola farionis became, for Rudolphi, Spiroptera cystidicola. From a detailed examination of the various characters of C. farionis I have come to the conclusion that Fischer was correct in creating a new genus for the new forms, and I therefore propose the reinstatement of the abandoned name Cystidicola. It is also in accordance with modern nomenclatural ruling that the original specific name farionis should be adopted in place of cystidicola.

Non-random assemblages have been described as a common pattern of flea co-occurrence across mainland host species. However, to date, patterns of flea co-occurrence on islands are unknown. The present work investigates, on one hand, whether the decrease in the number of species on islands affects the pattern of flea co-occurrence, and on the other hand, how the cost of higher flea burdens affects host body mass. The study was carried out in the Canary Islands (Spain) using null models to analyse flea co-occurrence on Rattus rattus and Mus musculus. Results supported aggregation of flea species in Mus but not in Rattus, probably due to the relationship between abundance and both prevalence and intensity of infection of the main flea species parasitizing Mus. In addition, heavy individuals of both rodent species showed the highest flea burdens as well as higher species richness, probably due to the continued accumulation of fleas throughout life and/or immunological resistance mechanisms. Whatever the mechanisms involved, it is clear that co-occurrence and high parasite intensities do not imply a detrimental biological cost for the rodents of the Canary Islands.

Jameson (1926) has described from the caeca of cattle a ciliate belonging to the family Isotrichidae to which he has given the name Buxtonella sulcata. The most prominent character of this ciliate is a dorsal ridge running in a wide sweeping curve from one end of the body to the other with a groove running down the middle. Other characters of importance are a peculiar indentation near the mouth and the not uncommon occurrence of the macronucleus in two separate rounded portions. Roundish oval cysts of this ciliate, 80 to 100 microns in length by 60 to 80 microns in width, were also found by him.

The impact of Toxocara canis infection of Balb/c mice mothers on the future immune response of their offspring towards reinfection with the same parasite was studied. Two groups of offspring, the first originating from the mothers infected with a single dose of 1000 Toxocara canis eggs and the second from non-infected mothers, were both challenged with 500 T. canis eggs per animal at 6 weeks of age. The proportions of spleen CD4+ and CD8+ T lymphocytes, the level of serum cytokines IFN-γ and IL-5, eosinophilia in peripheral blood, the production of specific antibodies and the number of migrating larvae were monitored. In both groups of offspring, the challenge infection resulted in an increase in CD4+ T-cell subtype in comparison with the non-infected healthy control, although after an initial decline a subsequent increase in CD8+ was observed. The immunoregulation index (CD4+/CD8+) was lower in the group of mice originating from infected mothers throughout the whole experiment compared to the offspring of non-infected mothers as well as in healthy control mice of the same age. In the offspring of infected mothers mainly, a reduced production of IFN-γ and of IL-5, suppressed eosinophilia and a higher level of protective antibodies was detected, compared to the control second group, in which the INF-γ concentration significantly increased after day 42 p.i. In the first group of offspring before challenge, 12·7±2·5 larvae in the brains and 32±2·1 larvae in the muscles transmitted from the infected mothers were detected. There was a significant reduction in larval recovery from brain on days 42 and 49 p.i. (56·7 and 56·8%, respectively), while from muscles in the same time there was a reduction of 46·7 and 39%, respectively, compared to the offspring of non-infected mothers. These results indicate a significant protective memory of immune mechanisms against T. canis induced in offspring of Toxocara-infected mother mice.

Two nematodes, a male and a female, were found in the stomach of a haddock, Gadus aeglefinus Linn.; they were lying close together and protruding from the wall of the stomach into its cavity. They were sent to Mr Stephen Prudhoe of the British Museum (N.H.), who identified them as probably Ascarophis morrhuae van Beneden. The worms were the only two nematodes found in this fish, and on account of their proximity, and the fact that they both belong to the genus Ascarophis, it is assumed that they are a pair. As the male of this species has not apparently been described so far, an account of the single specimen is given below.

The causal chain of parasite–host–environment interactions, the so-called ‘dual parasite environment’, makes studying parasites more complicated than other wild organisms. A sample of 65 282 fleas taken from 336 different locations were analysed for changes in the distribution, diversity and compensation of flea communities found on small mammals along an elevational diversity gradient ranging from the Pannonian Plain to the base of the Carpathian summits. The fleas were divided into four groups, which were derived from changes in abundance and occurrence determined from cluster analysis. They are (1) flea species whose range seems unrelated to any change in elevation; (2) species that avoid high altitudes; (3) a group that can be subdivided into two types: (i) host-specific fleas and (ii) mountains species and (4) species opting for high altitudes on the gradient or preferring lower to middle elevations below 1000 m. Our study showed a unimodal pattern of flea diversity along the elevational gradient. It indicated that seasonality significantly conditions changes in biodiversity and patterns of spatial change along the elevational gradient, with specific flea species influenced by their host, while the impact of environmental conditions is more pronounced in opportunistic flea species.

Antigens of three lines of the rodent malaria parasite Plasmodium yoelii have been studied using crossed immunoelectrophoresis. P. y. yoelii line A1 is a mild line which is restricted to reticulocytes. P. y. yoelii line YM and P. y. nigeriensis line D1 are virulent infections which multiply in both immature and mature erythrocytes. One antigen, designated Py-1, was found to differ in its electrophoretic mobility between the lines, being fast (F) in lines A1 and YM and slow (S) in line D1. Antigen Py-1 also varied in quantity among the three lines; greater amounts were detected in parasites inhabiting mature erythrocytes than in those in reticulocytes. These characters were stable during blood and mosquito passage.