Based on the ability of bacterial associates of entomopathogenic nematodes to produce antibiotic compounds on artificial media, it has been commonly accepted that Xenorhabdus sp. and Photorhabdus sp. inhibit a wide range of invading microorganisms in insects infected with Steinernema spp. or Heterorhabditis spp. Therefore, the question of whether antibiotic compounds produced by the primary form of bacterial symbionts associated mutualistically with S. carpocapsae and H. bacteriophora explain why insect carcasses do not putrefy but provide nutritional requirements for insect parasitic rhabditoid nematodes to complete their life-cycle was examined. Laboratory bioassays of anti-bacterial activity on nutrient agar and during parasitism in larvae of Galleria mellonella have confirmed earlier observations that in vitro colonies of the primary form of X. nematophilus and P. luminescens produced agar-diffusible antibiotic compounds of a broad spectrum of anti-bacterial activity; their role in parasitism seems doubtful, however. This hypothesis is supported by a low antibiotic potency of a limited spectrum of anti-bacterial activity throughout the life-cycle of the parasites, principally in Galleria infected with S. carpocapsae. Since the lack of putrefaction cannot be explained simply by antibiotic inhibition of contaminating bacterial microflora, other competition mechanisms must be operating in parasitized insects. I postulated that a rapid and massive colonization of the insect body by nematophilic bacteria creates unfavourable conditions for the growth and multiplication of bacterial (proteolytic) contaminators making the insect carcass decay-resistant. In the case of H. bacteriophora, low antibiotic activity at an early stage of parasitism could support the colonization by P. luminescens of the host.

American tegumentary leishmaniasis is caused by different species of Leishmania. This protozoan employs several mechanisms to subvert the microbicidal activity of macrophages and, given the limited efficacy of current therapies, the development of alternative treatments is essential. Animal venoms are known to exhibit a variety of pharmacological activities, including antiparasitic effects. Crotoxin (CTX) is the main component of Crotalus durissus terrificus venom, and it has several biological effects. Nevertheless, there is no report of CTX activity during macrophage – Leishmania interactions. Thus, the main objective of this study was to evaluate whether CTX has a role in macrophage M1 polarization during Leishmania infection murine macrophages, Leishmania amazonensis promastigotes and L. amazonensis-infected macrophages were challenged with CTX. MTT [3-(4,5dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide] toxicity assays were performed on murine macrophages, and no damage was observed in these cells. Promastigotes, however, were affected by treatment with CTX (IC50 = 22·86 µg mL−1) as were intracellular amastigotes. Macrophages treated with CTX also demonstrated increased reactive oxygen species production. After they were infected with Leishmania, macrophages exhibited an increase in nitric oxide production that converged into an M1 activation profile, as suggested by their elevated production of the cytokines interleukin-6 and tumour necrosis factor-α and changes in their morphology. CTX was able to reverse the L. amazonensis-mediated inhibition of macrophage immune responses and is capable of polarizing macrophages to the M1 profile, which is associated with a better prognosis for cutaneous leishmaniasis treatment.

Visceral leishmaniasis (VL) is endemic in 70 countries and has been reported in 12 countries of Latin America, with over 90% of the cases reported in Brazil, where epidemics have occurred since 1980. The objective of this review is to describe the factors associated with the occurrence of VL epidemics in humans in urban areas. A systematic review was conducted according to the PRISMA-P guidelines. The databases PubMed (by Medline), Cochrane Library, Embase, Amed, LILACS and grey literature [Google Scholar and handsearch of the database of the Information System for Notifiable Diseases (SINAN) of Brazil's Unified Health System] were used. The protocol was registered under PROSPERO (CRD42019128998). Climatic, environmental factors and indicators of urban social structure were described as influencing the outbreaks in the North and Northeast regions. Gender and age characteristics were related to a greater chance of developing VL in the Central-West, Northeast and Southeast regions. Vector indicators showed a positive correlation with the incidence of VL in studies in the Northeast region. In the Southeast and Northeast regions, studies revealed the presence of dogs with positive correlation with VL. Knowledge gaps remain regarding the contribution to the increase in the risk factors described in ecological approaches, as no analysis was performed at the individual level, and it is still necessary to discuss the influence of other associated elements in epidemic episodes in the spread of VL.

In the course of investigations conducted in Cambridge upon dogs infected with Piroplasma canis, a number of animals have been incidentally examined for intestinal parasites. In an unbroken series of 24 dogs, which died (March—September 1907) from piroplasmosis, the animals were autopsied immediately after death and the intestine examined by slitting it open along its whole length. We briefly record the results of these examinations, for the reason that similar reports do not appear to have hitherto been published in this country. All of the dogs harboured worms. Only three species of worms were encountered: Ascaris mystax, Dipylidium caninum and Taenia serrata.

While investigating the nutrition of parasitic helminthes it became possible to estimate the amounts of several members of the vitamin B complex in the parasites. Information on this point was required in order to obtain some idea of the composition of a satisfactory in vitro diet.

The haemogregarine which is the subject of the present communication was obtained in material collected by me during two voyages made in a trawler in July 1910, round the Shetlands and the north coast of Scotland. It was found in large adult specimens of catfish (Anarrhichas lupus), taken by otter trawl from a depth of 50 to 80 fathoms, in the vicinity of Fair Isle and Foula, and on Whitenhead Bank about nine miles to the N.N.E. of Cape Wrath. Catfish taken near Rhona and Sulisker in the Atlantic showed no infection, but the number of fish examined was so small that one could not assume the infection to be absent in this locality.

Studies of the kinetics of adenosine transport were carried out on the P1 and P2 transporters of drug-sensitive Trypanosoma evansi and its cloned derivative, resistant to the melaminophenyl arsenical Mel CY. Characterization of adenosine uptake was made by estimation of the maximum concentration taken up at time infinity (Amax). Amax on the P2 transporter of sensitive T. evansi was greater than Amax on the P1 transporter. Amax of the P2 transporter was significantly decreased in drug-resistant trypanosomes. The effect of adenosine concentration and inhibitors, on the rate of adenosine uptake, was described by Michaelis-Menten equations. In sensitive T. evansi, the maximum velocity of adenosine uptake (Vmax) of the P2 transporter was 2-fold greater than Vmax of the P1 transporter. The Vmax of the P2 transporter in resistant parasites was reduced 9-fold. The binding constants Km and Ki on the P2 transporter of resistant T. evansi, showed that resistance was associated with an increased affinity for adenosine, and a decreased affinity for adenine and Berenil. We suggest that resistance to melaminophenyl arsenicals in T. evansi, occurs via 2 mechanisms: (1) a reduction in the number of expressed P2 transporter molecules resulting in decreased uptake of melaminophenyl arsenicals; (2) a change in the binding properties of the P2 transporter.

Among Helminth material collected in the Sudan by the late Dr A. J. Chalmers, I have found some eight or nine mounted specimens of a Cestode, from the intestine of Gyps rüppelli, which has not, so far as I am aware, yet been described, and which apparently belongs to a new genus.

Methionine adenosyltransferase (MAT) is an important enzyme for metabolic processes, to the extent that its product, S-adenosylmethionine (AdoMet), plays a key role in trans-methylation, trans-sulphuration and polyamine synthesis. Previous studies have shown that a MAT-overexpressing strain of Leishmania donovani controls AdoMet production, keeping the intracellular AdoMet concentration at levels that are compatible with cell survival. This unexpected result, together with the fact that MAT activity and abundance changed with time in culture, suggests that different regulatory mechanisms acting beyond the post-transcriptional level are controlling this protein. In order to gain an insight into these mechanisms, several experiments were carried out to explain the MAT abundance during promastigote cell growth. Determination of MAT turnover in cycloheximide (CHX)-treated cultures resulted in a surprising 5-fold increase in MAT turnover compared to CHX-untreated cultures. This increase agrees with a stabilization of the MAT protein, whose integrity was maintained during culture. The presence of proteasome inhibitors, namely MG-132, MG-115, epoxomycin and lactacystin in the culture medium prevented MAT degradation in both MAT-overexpressing and ‘mock-transfected’ leishmanial strains. The role of the ubiquitin (Ub) pathway in MAT down-regulation was supported using immunoprecipitation experiments. Immunoprecipitated MAT cross-reacted with anti-Ub antibodies, which provides evidence of a proteasome-mediated down-regulation of the leishmanial MAT abundance.

The transmission from one host to another constitutes a challenging obstacle for parasites and is a key determinant of their fitness. Due to their complex life histories involving several different hosts, the free-living dispersal stages (cercariae) of digenean trematodes show a huge diversity in morphology and behaviour. On a finer scale, we still have an extremely limited understanding of the inter- and intraspecific variation in transmission strategies of many trematode species. Here, we present a novel method to study the movement patterns of cercariae of four New Zealand trematode species (Coitocaecum parvum, Maritrema poulini, Apatemon sp. and Aporocotylid sp. I.) via automated video tracking. This approach allows to quantify parameters otherwise not measurable and clearly illustrates the individual strategies of parasites to search for their respective target hosts. Cercariae that seek out an evasive fish target hosts showed higher swimming speeds (acceleration and velocity) and travelled further distances, compared with species searching for high-density crustacean hosts. Automated video tracking provides a powerful tool for such detailed analyses of parasites’ host-searching strategies and can enhance our understanding of complex host–parasite interactions, ranging from parasite community structure to the transmission of potential disease agents.

Splenectomy, either alone or in conjunction with hormonal bursectomy, did not appreciably affect E. tenella infections as measured by oocyst output.

Operated birds became resistant to re-infection as readily as the controls and it seems unlikely that the spleen in chickens plays an essential role in the host's defence against the Eimeria.

Thanks are due to my colleague, Mr P. L. Long, for his advice and interest throughout the work. Mrs J. Simpson gave valuable technical assistance.

Nippostrongylus brasiliensis larvae are particularly susceptible to immunological attack during the pre-lung stage of primary and secondary infections in mice. Whilst most of the common laboratory strains of mice are permissive hosts for the parasite, in this study we report for the first time, the strong resistance of naïve FVB/N mice to N. brasiliensis. Damage to larvae is evident within the first 24 h of infection and this may be critical to later larval development and reproductive success. Inflammatory responses in the skin, and larval escape from this tissue were comparable in susceptible CBA/Ca and resistant FVB/N mice, with most larvae exiting within 4 h of a primary infection. Lung larval burdens were also similar between strains, but larvae recovered from FVB/N mice were smaller and less motile. In FVB/N mice, larval colonization of the gut was impaired and worms produced very few eggs. However FVB/N mice did not show enhanced resistance to Heligmosomoides bakeri (also known as Heligmosomoides polygyrus), a nematode largely restricted to the gut. Damage done in the pre-lung or lung stages of infection with N. brasiliensis is likely to contribute to ongoing developmental and functional abnormalities, which are profoundly evident in the gut phase of infection.

Data presented in this work represents the first record of parasites from the Alpine and Pyrenean Lagopus muta subspecies, providing valuable information to consider for conservation management. From 1987 to 2018, 207 Rock ptarmigans were collected in the framework of a long-term sanitary monitoring in France. Eight parasites were found in the Alpine Rock ptarmigan, and one in the Pyrenean subspecies. Only two parasites occurred with high prevalence in the Alpine Rock ptarmigan: Capillaria caudinflata (38.9%) and Eimeria sp. (34.7%). Prevalence of the other parasites (Ascaridia compar, Cestodes, Amphimerus sp. and Trichostrongylus tenuis) was lower than 20%. Dispharynx nasuta was found with a prevalence of 52.9% in the Pyrenean Rock ptarmigan. Overall, we found a spatially aggregated distribution of parasites in the northern French Alps, probably due to both favourable climatic conditions for parasite cycle and high host density. Statistical analyses indicated a positive effect of altitude and latitude on C. caudinflata occurrence whereas risk factors for Eimeria sp. were the distance from urban areas and land cover. In addition, the majority of the infested birds came from areas close to ski-pistes, where human disturbance increases the susceptibility to diseases, causing stress to wildlife.

The β-diversity of fleas parasitic on small mammals in 45 regions of the Palearctic was partitioned into species [species contributions to β-diversity (SCBD)] and site ( = assemblage) contributions [local contributions to β-diversity (LCBD)]. We asked what are the factors affecting SCBD and LCBD and tested whether (a) variation in ecological, morphological, life history and geographic traits of fleas can predict SCBD and (b) variation in flea and host community metrics, off-host environmental factors, host species composition of flea assemblages can predict LCBD. We used spatial variables to describe geographic distribution of flea assemblages with various LCBD values. SCBD significantly increased with an increase in abundance and a decrease in phylogenetic host specificity of a flea as well as with size and latitude of its geographic range, but was not associated with any morphological/life history trait. LCBD of flea assemblages did not depend on either flea or host species richness or environmental predictors, but was significantly affected by compositional uniqueness ( = LCBD) of regional host assemblages and variables describing their species composition. In addition, variation in LCBD was also explained by broad-to-moderate-scale spatial variables. We conclude that SCBD of fleas could be predicted via their ecological and geographic traits, whereas LCBD of their assemblages could be predicted via host composition.

The three species of gregarines described in the present paper—Monocystis cambrensis sp.nov., M. lanceata sp.nov. and M. elongata (Phillips & Mackinnon, 1946), Loubatières, 1949—are all parasites of British earthworms. The observations upon which these descriptions are based form part of a larger survey of the monocystid fauna of several British earthworms. The methods used are fully described in a previous paper (Rees, 196).

The miracidium of Sanguinicola inermis contains a stylet and rodlet complex located within the single apical gland, which lies between a pair of lateral glands. The miracidial stylet consists of an arrangement of hollow tubes, composed of microtubules, connected at their base to large secretory granules and opening anteriorly through the apical papilla. A single rodlet lies adjacent to the stylet base and at least 8 rodlets are arranged at the apical tip of the stylet. The surface plasma membrane of the apical papilla is drawn into knob-like projections and 2 ciliated sensory endings are associated with the papilla. The ultrastructure of the apical gland, especially the stylet and rodlet complex, is related to the requirement for sanguinicolid miracidia to penetrate the double barrier of fish and snail hosts.

The relative fecundity of populations of Eimeria tenella was estimated by means of mixed infection using electrophoretic variation of glucose-phosphate isomerases (GPIs) as a genetic marker. A decoquinate-resistant strain with GPI-9 isozyme (DR-NIAH), a decoquinate-sensitive one with GPI-1 (DS-Iwate), and three decoquinate-resistant lines (No. 3, 4, and 5) derived from cross-fertilization between DR-NIAH and DS-Iwate, were used. The GPI phenotypes of the No. 3 and No. 4 lines are GPI-9, and that of No. 5 is GPI-1. Mixed infection experiments were performed between DR-NIAH and DS-Iwate, No. 3 and No. 5, and No. 4 and No. 5. DR-NIAH was predominant over DS-Iwate in the mixed infection, whereas, in single infections, the total oocyst output of DR-NIAH was similar to or less than that of DS-Iwate. Among three lines, No. 4 was predominant over No. 5, and No. 5 was predominant over No. 3 in the mixed infection. Relative fecundity between No. 3 and No. 5 and their patterns of oocyst output in single infections were similar to those in the mixed infection. In contrast, No. 5 produced more oocysts than No. 4 in single infections, suggesting that the oocyst production in the mixed infection may be influenced by the mutual interference or competition between the populations of E. tenella in the chicken caeca.

Formation of the tegument and alimentary tract in developing Fellodistomum fellis cercariae has been examined by electron microscopy. Morphogenesis of the tegument is a two-stage event: (1) ectodermal cells at the germ ball periphery coalesce beneath a closely apposed and transitory primitive epithelium of sporocyst origin, forming a syncytial boundary of nucleated tegument. The primitive epithelium is then lost and the nuclei in the surface layer of the early tegument degenerate; (2) cells in the mesenchyme of the cercarial embryo differentiate as secretory cells and connect with the anucleate layer to form the true tegument. The foregut develops as an apical invagination of early nucleated tegument, with the primordial digestive cells differentiating behind the oesophagus. When fully formed, the surface anucleate layer of oesophagus tegument extends posteriorly over the apposed surfaces of the developing digestive cells, thus isolating them from each other and from the gut lumen. An apical cavity develops in each of the digestive cells and later communicates with the gut lumen through a pore in the overlying caecal tegument. Lamellated extensions of digestive cell cytoplasm project into the cavity, and development of GER and a Golgi apparatus in the cell mark the onset of digestive secretion.

Warburton (1920) has recently published a survey of our present knowledge of the mites of the genus Sarcoptes; from his survey it is clear that in spite of all the work that has been done upon these mites, much of it by most pains-taking anatomists, we are still without an accurate knowledge of the anatomy of any one species of Sarcoptes. This is, in part at any rate, due to the fact that some of the best work was done, by Robin and others, between 1860 and 1865, at a time when microscopes and technique were by no means as highly developed as they now are.