Amputation experiments upon immature stages of Argas persicus (Oken 1818), Amblyomma hebraeum Koch 1844, and Hyalomma aegyptium (Linnaeus 1746) show that the mouthparts and legs of these ticks may be more or less regenerated when mutilated shortly after the ticks have abandoned the host in a fully engorged condition.

Ransom and Foster have published a preliminary account of experiments on the life history of Ascaris lumbricoides in the Journal of Agricultural Research of 19th November, 1917. They found that a repetition of my experiments on the feeding of rats and mice with ripe Ascaris eggs gave results agreeing very closely with those recorded by me in the British Medical Journal of July 1st, October 7th and December 2nd, 1916, and in Parasitology of February 1917.

Our knowledge of the systematics of the genus Sarcoptes is in an unsatisfactory state. About a score of species have been admitted, many of which have never been seen since they were described. Many of the descriptions date from between sixty and seventy years ago, a period when microscopes and microscopical technique were barely adequate to cope with so difficult a genus as Sarcoptes is. In order to provide a basis for further study of Sarcoptes, Warburton (1920) published a critical survey of our knowledge regarding these mites. His review of the literature has proved invaluable to myself, and is the foundation on which I have worked. In the foregoing paper (pp. 114–145) I published an only too lengthy description of the Sarcoptes of the horse, finding that a full description of one form was necessary as a basis for comparison. Since we do not know what anatomical points are of systematic importance, attention was given to all details of the external anatomy.

While collecting in the Shetland Islands during August 1923, I made examinations of many marine animals in the search for protozoan parasites. Among the species examined was Echinus esculentus, and I was interested to note the presence of a large number of ciliates in the intestine of three specimens. I can find no description of this ciliate, and am obliged to believe that it has never been recorded before. This is somewhat surprising, since many of these sea-urchins must be examined every year in zoological laboratories; it is difficult to understand how such conspicuous parasites have escaped observation for so long.

Tyrosinase provides an essential activity during egg production in diverse platyhelminths by mediating sclerotization of eggshells. In this study, we investigated the genomic and evolutionary features of tyrosinases in parasitic platyhelminths whose genomic information is available. A pair of paralogous tyrosinases was detected in most trematodes, whereas they were lost in cyclophyllidean cestodes. A pseudophyllidean cestode displaying egg biology similar to that of trematodes possessed an orthologous gene. Interestingly, one of the paralogous tyrosinases appeared to have been multiplied into three copies in Clonorchis sinensis and Opisthorchis viverrini. In addition, a fifth tyrosinase gene that was minimally transcribed through all developmental stages was further detected in these opisthorchiid genomes. Phylogenetic analyses demonstrated that the tyrosinase gene has undergone duplication at least three times in platyhelminths. The additional opisthorchiid gene arose from the first duplication. A paralogous copy generated from these gene duplications, except for the last one, seemed to be lost in the major neodermatans lineages. In C. sinensis, tyrosinase gene expressions were initiated following sexual maturation and the levels were significantly enhanced by the presence of O2 and bile. Taken together, our data suggest that tyrosinase has evolved lineage-specifically across platyhelminths related to its copy number and induction mechanism.

The rickettsial bacterium Ehrlichia ruminantium is the causative agent of heartwater, a serious tick-borne disease in ruminants. The genetic diversity of organisms in the field will have implications for cross-protective capacities of any vaccine developed, and for an effective vaccine design strategy proper genotyping and understanding of existing genetic diversity in the field is necessary. We searched for variable-number tandem-repeat (VNTR) loci for use in a multi-locus VNTR analysis (MLVA). Sequencing analysis of 30 potential VNTRs using a panel of 17 reference strains from geographically diverse origins identified 12 VNTRs with allelic profiles differing between strains. Application of MLVA to 38 E. ruminantium-infected Amblyomma variegatum collected from indigenous cattle in 6 different districts of Uganda identified 21 MLVA types. The discriminatory power of MLVA was greater than that of map1 PCR-restriction fragment length polymorphism analysis, with which only 6 genotypes were obtained. The high discriminatory power as well as cost- effective performance of MLVA provide the potential for this technique to be applied in the future with respect to optimizing vaccine trials by identifying local strain diversity, and also raise the possibility of exploring the association between E. ruminantium genotypes and phenotypes such as pathological outcome in the ruminant host.

Leishmania infantum immunoelectrophoretic antigen 24 (AG 24), a visceral leishmaniasis associated immunodominant antigen, has been characterized with a monospecific antiserum by combining SDS–PAGE, immunoblotting, metabolic labelling, radio-immunoprecipitation and in vitro poly A+ mRNA translation. AG 24 appeared to correspond to a multi-antigen family of 6–9 members ranging from 20 to 31 kDa and proteinic by nature with no post-translational modifications. A similar banding pattern was recognized by infection sera. AG 24 was not found exposed on the cell surface.

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 trispanning orphan receptor (TOR) has been described in Schistosoma haematobium and S. mansoni. Here we report the complete molecular organization of the S. mansoni TOR gene, also known as SmCRIT (complement C2 receptor inhibitor trispanning). The SmTOR gene consists of 4 exons and 3 introns as shown by cloning the single exons from S. mansoni genomic DNA and the corresponding cDNA from the larval stage (cercaria) and the adult worm. The SmTOR ORF consists of 1260 bp and is longer than previously reported, with a fourth trans-membrane domain (proposed new name: Tetraspanning Orphan Receptor) and with, however, an unchanged C2-binding domain on the extracellular domain 1 (ed1). This domain differs in S. japonicum. A protein at the approximate expected molecular weight (55 kDa) was detected in adult worm extracts with polyclonal and monoclonal antibodies, and was found to be expressed on the tegumental surface of cercariae.

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.

In this study, a microsporidian pathogen of the date moth (Apomyelois (Ectomyelois) ceratoniae, Zeller, 1839) also known as the carob moth, is described based on light microscopy, ultrastructural characteristics and comparative molecular analysis. The pathogen infects the gut and hemolymph of A. ceratoniae. All development stages are in direct contact with the host cell cytoplasm. Fresh spores with nuclei arranged in a diplokaryon are oval and measured 3.29 ± 0.23 μm (4.18–3.03 μm, n = 200) in length and 1.91 ± 0.23 μm (2.98–1.66 μm, n = 200) in width. Spores stained with Giemsa's stain measured 3.11 ± 0.31 μm (3.72–2.41 μm, n = 150) in length and 1.76 ± 0.23 μm (2.16–1.25 μm, n = 150) in width. Spores have an isofilar polar filament with 10-12 coils. An 1110 bp long alignment of the current microsporidium showed an SSU rRNA gene difference of only 0.0009, corresponding to >99.91% sequence similarity with Nosema fumiferanae, while RPB1 gene sequences were 98.03% similar within an alignment of 969 bp. All morphological, ultrastructural and molecular features indicate that the microsporidian pathogen of A. ceratoniae is the new isolate of the N. fumiferanae and is named here as Nosema fumiferanae TY61.

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.

Haemoproteus species (Haemoproteidae) are widespread blood parasites and are transmitted by Culicoides biting midges and Hippoboscidae louse flies. Although these pathogens may cause morbidity or mortality, the vectors and patterns of transmission remain unknown for the great majority of avian haemoproteids. Haemoproteus nucleocondensus has been frequently reported in Europe in great reed warblers Acrocephalus arundinaceus after their arrival from African wintering grounds, but this infection has not been found in juveniles at the breeding sites. The factors that prevent its transmission remain unclear. This study was designed to test whether the sporogony of H. nucleocondensus (lineage hGRW8) can be completed in Culicoides impunctatus, one of the most abundant European biting midge species. Wild-caught females were infected with H. nucleocondensus from great reed warblers. Microscopic examination and PCR-based methods were used to detect sporogonic stages and to confirm species identity. This study showed that H. nucleocondensus completes sporogony in C. impunctatus, suggesting that there are no obstacles to its transmission from the point of view of vector availability and average temperature in Northern Europe. We discuss other ecological factors which should be considered to explain why the transmission of H. nucleocondensus and some other Southern origin haemosporidians are interrupted in North Europe.

The variability within schistosome populations was explored using mixed populations of cercariae from multimiracidial snail infections and individual clones of Schistosoma mansoni cercariae obtained from monomiracidial snail infections. We investigated the heterogeneity between different clones of S. mansoni with respect to infectivity and metabolism. One difference between clones of cercariae was found in the recovery of adult worms from Balb/C mice. Recovery of adult worms was greater after infections with a mixed population than with a clonal population. To investigate some biochemical features of individuals in clones or mixed populations, the uptake of [35S]methionine into individual parasites and their membrane proteins was measured. Isoelectric focusing of a soluble membrane fraction: the frozen–thawed supernatant extracted from individual clones, showed the presence of proteins of isoelectric point between 7.2 and 8.2 in all clones. These proteins were less labelled with [35S]methionine in the clones than in the mixed population. It was concluded that basic proteins are synthesized by all clones and in the mixed population but at different rates. Differences in the rate of incorporation of [35S]methionine into the surface membranes of schistosomula and adult worms derived from individual clones are reported. In addition, a direct correlation between the percentage of recovery of adult worms from mice infected with individual clones of S. mansoni and the rate of incorporation of [35S]methionine into schistosomula of these particular clones was observed. It is suggested that the high rate of metabolism shown by an individual clone may account for the enhanced survival of the cercariae derived from that clone during penetration of the skin and migration through the vertebrate host. In order to examine individuals in a population of schistosomula, from a clone or mixed population, the lysosome-specific fluorescent probe LysoTracker DND-99 was used to label the parasites and quantitative fluorescent measurements were made on individual parasites. There were significant differences between clones and a mixed population. Furthermore, the variation between individuals from a mixed population was greater than from that in any clone, just as was found in the infectivity studies. Freshly transformed schistosomula of individual clones labelled with the LysoTracker DND-99 showed less variations in the quantitative uptake of the dye within a single clone when compared to the mixed population. We conclude that for any biochemical and biological parameter, a population of cercariae consists of individuals showing a wide range of values, with a much greater range in a mixed population. This variability is likely to have great relevance for infectivity of the final host and the efficacy of drugs and the immune system.