It has been shown that Atropa belladonna acts as a symptomless carrier of Hyosoyamus Virus I. Some symptoms caused by this virus on other solanaceous plants are described.

A naturally occurring virus complex in Hyoscyamus niger was found to consist of Solanum Virus I (potato virus X) and Brassica Virus I. During the course of the investigation it was found that potato virus X forms local lesions on the cotyledons of ridge cucumber without systemic infection and that Brassica Virus I behaves similarly on the inoculated leaves of Nicotiana sylvestris.

Biochemical studies on the non-specific phosphomonoesterases have demonstrated the presence of acid phosphomonoesterase with maximum activity at pH 4·0 in Gastrodiscus aegyptiacus (enzyme I) and at pH 4·5 in the case of Fasdolopsis buski (enzyme II). The Km for ρ-nitrophenyl phosphate hydrolysis was 0·66 mM for enzyme I and 1·1 mM for enzyme II. Different concentrations of fluoride, arsenate, tartrate, tartaric acid, cysteine and copper brought about inhibition of both enzymes and magnesium, iodoaeetate, iodoacetamide and EDTA had no influence on either enzyme activity. Cobalt activated both enzymes while zinc inhibited enzyme I and strongly stimulated enzyme II.

The reproductive duct of the male blood fluke Schistosoma mansoni is relatively short and undulating, extending from the most posterior testis to the beginning of the gynecophoric canal. The reproductive duct may be divided into 3 main regions which differ in ultrastructure; the vas efferens/deferens, the seminal vesicle and the cirrus tube. The epithelium of the vas efferens/deferens consists of a single layer of elongate cells with abundant convoluted lamellae on their apical surfaces. The wall of the seminal vesicle and the cirrus tube are tegumentary in nature. The basic similarities in structure of the surface tegument, the seminal vesicle and the cirrus tube suggest a common embryological origin. The presence of complex lamellae on the luminal surface suggests that the vas efferens and deferens have secretory and possibly nutritive functions apart from temporarily storing developing germ cells. The primary function of the seminal vesicle appears to be that of sperm storage; while the cirrus tube with its complex infolded wall is extensible for insemination. The presence of abundant concentrically distributed sensory papillae around the male genital pore may assist in the pairing of males and females.

The reproduction and survival of the ectoparasitic digenean Transversotrema patialense on the fish host Brachydanio rerio are shown to be temperature-dependent. Survival is reduced by any deviation from an optimum temperature of approximately 23°C. With increasing temperature the rate of egg production per surviving fluke rises progressively faster to a higher peak up to 29°C but falls to zero by 35°C. The span of egg production varies closely with the life-span of the parasite at each temperature. The optimum temperature for the total number of eggs produced by each cohort of parasites is also 23°C. This number is a function of both adult parasite survival and the rate of egg output.

The occurrence of 3 mites (Acari: Astigmata) is reported, from the Central African hedgehog Erinaceus albiventris Wagner, in the Nairobi area of Kenya. Notoedres oudemansi Fain (Sarcoptidae) showed sporadic incidence, affected males particularly and caused high mortality. A description of the male mite is given. Caparinia erinacei Fain (Psoroptidae) was found on 72% of animals on capture but showed very low pathogenicity. Rodentopus sciuri Fain (Hypoderidae) was found in the hair follicles of 46% of 43 animals examined; adverse effects were slight.

An in vitro anthelmintic primary screen in which the effects of compounds on the aggregation response of newly moulted adult worms of Trichostrongylus colubriformis was monitored is described. Representatives of all the major classes of the anti-trichostrongyle anthelmintics all inhibited worm aggregation completely when present in the culture medium either at or at less than micromolar concentrations. The screen proved highly selective for these broad-spectrum agents, much higher concentrations of the narrower spectrum anthelmintics, active only against blood-sucking nematodes, trematodes and/or cestodes, having little or no effect on this response. This in vitro assay, based solely on the occurrence or absence of worm aggregation following the final moult in culture, proved very easy to interpret rapidly and accurately. It can be recommended therefore for the primary mass screening of synthetic compounds or natural products for intrinsic activity against the trichostrongylid helminths of ruminants.

Several studies have confirmed that epidermal Langerhans' cells (LC) play a central role in the induction of skin-related immunological events. In order to assess the role of LC in Chagas' disease, guinea-pigs were infected intradermally with Trypanosoma cruzi, sacrificed at different time-points, and their tissues were processed for routine histology, electron microscopy and immunohistochemistry. Parasitaemia was observed earliest at day 6 p.i. with 2 peaks at days 9 and 28, and disappeared on day 56 p.i. Parasite-specific serum IgG and IgM were first detected on day 12 p.i. The level of IgG gradually increased by day 84 p.i. All the infected guinea-pigs showed significant alterations in the distribution and morphology of epidermal LC during parasitaemia. The number of LC had significantly decreased in the epidermis by day 3 p.i., only returning to normal levels by day 56 p.i., although the number of LC in the underlying dermis increased concomitantly. Parasites were carried to the regional lymph node, where clustering of parasite-laden dendritic cells (DC) with lymphocytes was seen by electron microscopy. This evidence suggests that LC might be involved in antigen presentation in Chagas' disease.

Activation of prophenol oxidase of Fasciola gigantica has been demonstrated using biochemical and electrophoretic techniques. Based on the difference in the electrophoretic pattern of the proenzyme and activated enzyme, a probable mechanism of activation of the prophenol oxidase is suggested. A role for Mehlis' gland in the activation process is suggested. The significance of the results is discussed in the light of related studies in insects.

Flagellates belonging to four genera, Trichomonas, Giardia, Chilomastix, and Retortamonas, have been found in the caecum and colic loops of the muskrat, Fiber (= Ondatra) zibethica.

A Retortamonas is described from the caecum of two laboratory guinea-pigs.

High levels of molecular diversity were identified in mitochondrial cytochrome c oxidase (cox1) gene sequences of Schistosoma turkestanicum from Hungary. These cox1 sequences were all specific to Hungary which contrasted with the low levels of diversity seen in the nuclear internal transcribed spacer region (ITS) sequences, the majority of which were shared between China and Iran isolates. Measures of within and between host molecular variation within S. turkestanicum showed there to be substantial differences in molecular diversity, with cox1 being significantly more diverse than the ITS. Measures of haplotype frequencies revealed that each host contained its own subpopulation of genetically unique parasites with significant levels of differentiation. Pairwise mismatch analysis of cox1 sequences indicated S. turkestanicum populations to have a bimodal pairwise difference distribution and to be stable unlike the ITS sequences, which appeared to have undergone a recent population expansion event. Positive selection was also detected in the cox1 sequences, and biochemical modelling of the resulting protein illustrated significant mutational events causing an alteration to the isoelectric point of the cox1 protein, potentially altering metabolism. The evolutionary signature from the cox1 indicates local adaptation and long establishment of S. turkestanicum in Hungary with continual introgression of nuclear genes from Asian isolates. These processes have led to the occurrence of mito-nuclear discordance in a schistosome population

BALB/c mice of both sexes were infected with a non-virulent strain of Plasmodium chabaudi chabaudi and any pathologies occurring in the urogenital tract and its accessory glands were investigated. Organs and tracts were removed from infected and control mice at 15, 40 and 100 days post-injection, weighed and processed for macroscopical and histological analyses. The relative weights of preputial, clitoral glands and testes were modified in infected mice during the 40 days following infection. The preputial glands show a marked hypotrophy at 15 days post-infection. The bladders of half of the infected female mice and a few infected male mice displayed a conspicuous haemoglobinuria and frequent interstitial cystitis that worsened throughout the experiment. Also, several chronic inflammatory reactions were detected in the prostates, preputial and clitoral glands up to 100 days post-infection. A probable cause of such a divergence in the characteristics of the infection and in the nature of the pathologies identified in infected male and female mice is the interaction between the infection and the immune and endocrine systems of the host. The cause of the pathologies and their consequences on the host condition are discussed.

A sensitive and specific nitrocellulose (NC) membrane-based dot–ELISA, utilizing a panel of monoclonal antibodies (mAbs), was developed for differentiation between in vitro-derived procyclic forms of Trypanosoma brucei, T. congolense and T. simiae, and epimastigotes of T. vivax. Trypanosomes in suspension were applied onto NC membrane in dots and probed with unlabelled trypanosome species-specific mAbs. Bound mAb was revealed by enzyme labelled anti-mouse IgG and precipitable chromogenic substrate. The assay detected the aforementioned trypanosome species in both single and artificially mixed preparations. Ten T. brucei, 4 T. vivax, 7 T. congolense and 3 T. simiae procyclic stocks and clones from different geographical areas were tested and identified using the specific mAbs in the dot–ELISA which had a specificity of 100%. Some of the T. brucei, T. congolense and Nannomonas-specific mAbs could detect as few as 10 trypanosomes/dot, whilst 1 T. vivax mAb was able to detect a minimum of 100 trypanosomes/dot in monospecies preparations. A concentration of 1 × 104 trypanosomes/μ/dot was eventually determined as ideal for testing in the dot–ELISA. Antigen dots stored at 4 °C under desiccated conditions did not show any loss in activity for up to 90 days. However, when stored under similar conditions at room temperature (17–26 °C), the T. congolense-specific antigen remained unaffected up to 60 days, and then showed decreased activity when tested on day 90.

In recent papers I have given, in relatively compact form, lists of the genera and species of metastrongylid lungworms; these publications are in turn summarized in a paper which follows (Dougherty, 1948). However, the trichostrongylid lungworms, constituting the subfamily Skrjabingylinae Skriabin, 1933, have not been completely treated, although in a recent work (Dougherty, 1945), in which certain lungworms were formally transferred from the Metastrongylidae to the Trichostrongylidae, the Skrjabingylin genera were listed without critical appraisal, and in the same paper the genus Crenosoma Molin, 1861, was reviewed in detail; subsequently the genus Dictyocaulus Railliet & Henry, 1907, has also been reviewed (by Dougherty, 1946).

Codon usage has been analysed in individual gene sequences, derived from a variety of parasitic protozoa in the class Sporozoa of the phylum Apicomplexa using metric multidimensional scaling. The two groups of codon usage patterns detected reflect the two main subgroups of organisms studied (the coccidia and the piroplasms), and it is the pattern usage of synonymous codons that has the largest influence on overall codon usage in the individual genes, rather than being the pattern of amino acid composition of the gene product. The magnitude of the codon usage bias in the sequences was determined using three commonly used indices – NC', GC3s and B. In general, although relatively low levels of codon usage bias were detected in these gene sequences, codon usage bias does explain at least some of the codon usage patterns observed. Codon usage bias was observed to be dependent on the overall base composition of the genes analysed, which in turn was reflected in the types of codons that were either over-or under-represented in the nucleotide sequences. keeping with observations on prokaryotic organisms, it is speculated that the codon usage patterns detected in these parasitic protozoa are the result of directional mutation pressure on the base composition of the genomic DNA.

An aurantiactinomyxon type is described from the marine naidid Tubificoides pseudogaster (Dahl, 1960), collected from the lower estuary of a Northern Portuguese River. This type constitutes the first of its collective group to be reported from Portugal, and only the fourth described from a marine oligochaete worldwide. Extensive morphological comparisons of new aurantiactinomyxon isolates to all known types without available molecular data are proposed to be unnecessary, given the artificiality of the usage of morphological criteria for actinosporean differentiation and the apparent strict host specificity of the group. Recognition of naidid oligochaetes as the hosts of choice for marine types of aurantiactinomyxon and other collective groups, suggests that the family Naididae played a preponderant role in the myxosporean colonization of estuarine communities. Molecular analyses of the type in study further infer its involvement in the life cycle of Paramyxidium giardi (Cépède, 1906) Freeman and Kristmundsson, 2018, a species that infects the kidney of European eel Anguilla anguilla (Linnaeus, 1758) and that has been reported globally, including from Portuguese waters. The low intraspecific difference registered in relation to Icelandic isolates of P. giardi (0.6%) is hypothesized to result from the emergence of genotypically different subspecies due to geographic isolation.

Bacterial symbiosis and/or parasitism is widespread in hydrothermal bivalves, and is typically developed in gills, with a lower incidence in mantle and digestive glands, while it has never been described in byssus. Using ultrastructural examination, we provide evidence for the existence of a potentially new group of filamentous prokaryotic organism in Bathymodiolus azoricus byssus, with putative parasitic influence. Additionally, a cystic, undefined organism was found with an unclear physiological role within the spongy net of the byssus plaque. Our results indicate that in spite of its antibacterial protective sheath, byssus gives access to prokaryotic organisms becoming prone to failure through damaged collagen fibres.

Miracidia and in vitro-derived primary sporocysts of the avian schistosome Trichobilharzia ocellata were studied for the expression and the characteristics of glycoconjugate moieties comprising the surface coat. Using a panel of 9 peroxidase labelled lectins, several different lectin binding sites were demonstrated on the larvae. Fixed miracidia have binding sites for 7 of the lectins; wheat-germ agglutinin binds to both the ciliated plates and the tegumental ridges between them; the other 6 lectins bind to the plates only. Three of the miracidia-binding lectins, wheat-germ agglutinin, concanavalin A and peanut agglutinin, also bind to fixed sporocysts. Since the miracidial ridges are devoid of binding sites for concanavalin A and peanut agglutinin, whereas the sporocyst tegument binds these lectins, it appears that these sites become exposed during or shortly after transformation. In saturation experiments, low concentrations of peanut agglutinin and concanavalin A are bound more avidly by sporocysts than by miracidia, indicating a higher binding affinity of the former. The two larval forms do not differ in affinity for wheat-germ agglutinin but they have different binding capacities; when offered in high concentrations, more of this lectin is bound by sporocysts than by miracidia. Lectin binding was competitively inhibited by adding the appropriate free saccharides. Live larvae showed the same lectin binding pattern as did fixed specimens. Proteinase treatment reduced lectin binding to living and, to a lesser extent, to fixed larvae, suggesting that binding sites are constituents of proteoglycoconjugates. After SDS–PAGE of extracts from miracidia and sporocysts and subsequent Western blotting, some of the lectins failed to bind glycoproteins, others reacted with an array of bands. The patterns differed among the lectins and each lectin gave different patterns for miracidia and sporocysts. The results obtained with these two lectin-binding techniques support the conclusion that stage-specific proteoglycoconjugates occur at the surface of T. ocellata larvae.

A Collection of ticks from British Somaliland recently sent to the British Museum (Natural History) contained specimens of a species of Ornithodoros unlike any in the national collection and (from the appearance of the integument) related to the North African species O. foleyi Parrot (from Algeria) and O. delanoëi Roubaud & Colas-Belcour (from Morocco). The late Prof. G. H. F. Nuttall presented to the Museum a specimen of O. foleyi, and the writer is indebted to Prof. E. Roubaud for comparing one of the present specimens with the type of O. delanoëi. Prof. Roubaud writes to say that, having examined the Somaliland specimen, he and M. Colas-Belcour are of the opinion that it belongs to the species O. delanoëi: and that the various details of structural difference do not warrant a specific distinction, but indicate that the present specimens may belong to a different biological or geographical race. The large size of these Somaliland ticks, the discovery of their larvae and their presence in a locality so widely separated from that of the type, are considered important enough to be placed on record, and the specimens are regarded as representing a subspecies of O. delanoëi

Levamisole (Lms) is an anthelminthic drug with immunomodulatory activity. Chagas disease (CD) is caused by Trypanosoma cruzi and there is very low access to the drugs available, benznidazole (Bz) and nifurtimox, both far from ideal. In a drug-repurposing strategy to test potential activity as antiparasitic and immunomodulatory agent for CD, Lms was assayed on acute T. cruzi murine infection, alone and in co-administration with Bz. During protocol standardization, 100 and 10 mpk of Bz given for five consecutive days resulted in parasitaemia suppression and 100% animal survival only with the highest dose. Flow cytometry showed that both optimal (100 mpk) and suboptimal (10 mpk) doses of Bz equally decreased the plasma levels of cytokines commonly elevated in this acute infection model. Lms alone (10–0.5 mpk) did not decrease parasitaemia nor mortality rates. Co-administration was investigated using the suboptimal dose of Bz and different doses of Lms. While Bz 10 mpk did not alter parasitaemia, the combo partially reduced it but only slightly promoted animal survival. This effect could be related to Th1-response modulation since interleukin-6 and interferon-γ were higher after treatment with the combo.