(1) Simulium ornatum larvae were regularly collected from the River Lea (Hertfordshire) and from Tilling Bourne (Surrey) during 1967–9. Preliminary surveys revealed no parasitism in pupal and adult stages of S. ornatum but several parasites, some common, occurred in the Simulium larvae. These were studied by dissection, smears and histologically.(2) Microsporida were well represented by two genera - Thelohania and Plistophora. Infection rates never exceeded 9% of larvae. Spore measurements statistically evaluated from different larval infections justified recognition of five species of Thelohania (T. minuta sp.nov., T. bertrami sp.nov., T. canningi sp.nov., T. simulii sp.nov., and T. avacuolata sp.nov.), and two species of Plistophora (P. tillingbournei sp.nov. and P. leasei sp.nov.).(3) Intra-epithelial organisms of the larval gut wall, referred to provisionally as Microsporidan-like bodies, caused light infections.(4) With the exception of the slight Microsporidan-like infections, all species of Microsporida were found parasitizing the fat body of the larva, causing its disintegration. Delay in larval growth and pupation occurred, followed by death.(5) Seasonal cycles of abundance of infection were related to summer and overwintering populations of Simulium larvae.(6) Transmission of infection was attempted by exposing apparently uninfected wild-caught Simulium larvae to spores of Thelohania but no evidence of active infection being established in the exposed larvae was obtained.(7) Although the pathogenic Microsporida taken in this study must have exerted control on natural larval densities, too little is known of their biology, mode of transmission or methods of culture to envisage their development, for biological control of simuliids, at present.

The potential of antigenic differences for discriminating pathotypes of the potato cyst nematodes Globodera pallida and G. rostochiensis has been examined by the use of an antiserum raised to a homogenate of potato cyst nematode larvae. Species-specific antigens were detected among reference pathotypes but more variability was detected among field populations, and cluster analysis was used to interpret the precipitation are pattern produced by Laurell crossed-immunoelectrophoresis. A division into species was seen with this analysis but no definite pathotype groupings were detected. Cross-reaction with other cyst-nematode species was limited to general non-specific precipitation. The antigens were all proteinaceous, did not arise from micro-organisms within the cyst and were mainly hydrophilic with an acidic isoelectric point. Peptidase and acid phosphatase activity was detected in some precipitation arcs but this was not species specific.

1. The homonym Styphlodora compactum Dawes, 1941, has been renamed S. compressa.

2. Several suggestions have been made regarding the invalidity of proposed species of the genus Styphlodora. S. compactum Byrd, Parker & Reiber, 1940, should be regarded as a synonym of S. bascaniensis Goldberger, 1911, S. natricis as a synonym of S. magna Byrd & Denton, 1938, S. agkistrodontis as a synonym of S. floridanis Byrd, Parker & Reiber, 1940, S. lachesidis as a synonym of S. horridum (Leidy, 1850).

3. A suggestion has been made to relegate the proposed genus Paurophyllum Byrd, Parker & Reiber, 1940, to synonymity with the genus Styphlodora Looss, 1899. The proposed new species Paurophyllum simplexus and P. megametricus Byrd, Parker & Reiber, 1940, are identical and should be known as Styphlodora simplexa (Byrd, Parker & Reiber, 1940a) n.comb. S. aspina Byrd, Parker & Reiber, 1940, is a synonym of this species.

4. A revised key to the sixteen apparently valid species of the genus Styphlodora has been constructed. S. floridanis and S. simplexa have been found places in it provisionally, though it is suggested that further study of the trematode parasites of the kidney of Agkistrodon piscivorus might result in the merging of these species into a single species, namely, Styphlodora simplexa (Byrd, Parker & Reiber, 1940).

In the blood of a Cercocebus albigena and of a C. galeritus agilis monkey, the infection with Plasmodium gonderi was found to follow its well-known chronic course; P. georgesi seemed to occur as a relapsing type of malaria parasite; P. petersi was found for only a few days and at a low level in C. albigena (end of an attack?). As shown by using polarized light, the pigment granules appeared mostly as fine dots in P. georgesi, short rods in P. gonderi and long needles in P. petersi. The three species can be distinguished by the morphological appearance of the nucleus of the young trophozoites, and also by the measurement of its surface area (Sa): small round nucleus (Sa= 0·81 ± 0·06 μm2) in P. gonderi, large 2-coloured nucleus (Sa= 1·43 ± 0·21 μm2) in P. petersi, and long crescent-shaped nucleus (Sa= 2·18±0·25 μm2) in P. georgesi. The first colour illustrations of the blood-stages of P. georgesi are presented. The dynamics of single and mixed blood infections in primate malaria parasites are discussed, with a proposal to classify them into 3 types.

The duognathous haemadipsid leeches of the genus Chtonobdella show a trans-oceanic distribution throughout the Indo-Pacific region. Although passive long-distance dispersal (LDD) of Chtonobdella leeches by birds has been suggested, little is known about the host–parasite relationships between avian hosts and Chtonobdella leeches. In the current study, we investigated Chtonobdella leech infestations of the eyes and other mucus membranes of migratory procellariiform seabirds, Pterodroma hypoleuca and Oceanodroma tristrami, captured at six locations in the Bonin Islands, Honshu and Okinawa Island, Japan. Analyses of the partial sequences of 18S rRNA, 28S rRNA, and mitochondrial cytochrome c oxidase subunit I (COI) and morphological examination of the specimens demonstrated that the Chtonobdella leeches belonged to Chtonobdella palmyrae, which is indigenous to Palmyra Atoll in the Northern Line Islands. A dominant COI sequence type was observed in samples from all six sites; therefore, C. palmyrae almost surely dispersed approximately 1000 km by infesting the eyes and mucus membranes of procellariiform seabirds. The host–parasite relationships between procellariiform seabirds and C. palmyrae provide explicit evidence of the LDD of duognathous haemadipsid leeches. The taxonomic status of Haemadipsa zeylanica ivosimae from the Volcano Islands is also briefly discussed.

Complete specimens of this nematode are difficult to obtain, owing to the manner in which the worms bury themselves in the tissues of the urinogenital system of the Cetacea in which they are found. Mr A. G. Bennett, to whom the writer has previously been indebted on more than one occasion for Crassicauda material, has recently sent home further interesting specimens from South Georgia, accompanied by notes and a sketch which throw some light upon the burrowing habits of the worm. A special effort was made to obtain complete specimens by dissection.

Here, we describe a new microsporidium Percutemincola moriokae gen. nov., sp. nov., which was discovered in the intestinal and hypodermal cells of a wild strain of the nematode Oscheius tipulae that inhabits in the soil of Morioka, Iwate Prefecture, Japan. The spores of Pe. moriokae had an average size of 1.0 × 3.8 µm and 1.3 × 3.2 µm in the intestine and hypodermis, respectively, and electron microscopy revealed that they exhibited distinguishing features with morphological diversity in the hypodermis. Isolated spores were able to infect a reference strain of O. tipulae (CEW1) through horizontal transmission but not the nematode Caenorhabditis elegans. Upon infection, the spores were first observed in the hypodermis and then in the intestine the following day, suggesting a unique infectious route among nematode-infective microsporidia. Molecular phylogenetic analysis grouped this new species with the recently identified nematode-infective parasites Enteropsectra and Pancytospora forming a monophyletic sister clade to Orthosomella in clade IV, which also includes human pathogens such as Enterocytozoon and Vittaforma. We believe that this newly discovered species and its host could have application as a new model in microsporidia–nematode association studies.

The male, female and fourth-stage larva (female) of Hammerschmidtiella diesingi are described. Characters are given by which this species can be identified from the female fourth-stage larva.

A constriction and ring of clear cells separate the intestine of the male and of the female fourth-stage larva into two parts, and descriptions of the structure and mode of action of this ‘sphincter’ are given.

This work was carried out during the tenure of a Research Studentship awarded by the Department of Scientific and Industrial Research.

The tissue stages and the erythrocytic stages of a malarial parasite infecting a flying squirrel of Darjeeling (Petaurista magnificus) are described. It is shown that this parasite cannot be accommodated in the existing genera of the malarial parasites of mammals (Plasmodium, Hepatocystis and Nycteria). A new genus, Rayella, is proposed to receive this parasite, which is named Rayella rayi (synonym: Plasmodium sp., Ray, 1949; Hepatocystis rayi, Tokura & Wu, 1961). The tissue stages of the parasite are represented by the groups of small schizonts in the form of cystic bodies, which occur in association with the smaller blood-vessels of the liver.

The author is grateful to Professor P. C. C. Garnham of the London School of Hygiene and Tropical Medicine, London, for his interest and valuable advice. The author wishes to record his special thanks to Professor H. N. Ray who kindly placed the relevant literature and his slides and drawings at the disposal of the author. Professor Ray's unpublished drawings of the erythrocytic stages of the malarial parasite of the flying squirrel (Petaurista inornatus) are reproduced here with his special permission.

In March 1947 I collected a number of digenetic trematodes from the gullets of Cantherines setosus (Waite) and Cantherines güntheri Macleay. Three individuals of each species were examined and two of each were found to contain four or five trematodes. The fishes are known locally as ‘Leather-jackets’, and were taken from the shallow coastal waters of southern Tasmania. The parasites appear to be Lintonium vibex (Linton, 1899) Stunkard & Nigrelli, 1930.

The following marine Ichthyobdellid leeches have been taken at Plymouth:

I.Calliobdella lophii van Beneden and Hesse, on a large Lophius piscatorius; 1 capture, 4 specimens (vide Leigh-Sharpe, 1913 and 1914).

II. Pontobdella muricata (Linn.) on various species of Raia; rare at times; moderate-sized specimens common on skates and rays in the spring and summer of 1932.

Gastrointestinal nematodes represent important sources of economic losses in farmed ruminants, and the increasing frequency of anthelmintic resistance requires an increased ability to explore alternative strategies. Theoretical approaches at the crossroads of immunology and epidemiology are valuable tools in that context. In the case of Teladorsagia circumcincta in sheep, the immunological mechanisms important for resistance are increasingly well-characterized. However, despite the existence of a wide range of theoretical models, there is no framework integrating the characteristic features of this immune response into a tractable phenomenological model. Here, we propose to bridge that gap by developing a flexible modelling framework that allows for variability in nematode larval intake which can be used to track the variations in worm burdens. We parameterize this model using data from trickle infection of sheep and show that using simple immunological assumptions, our model can capture the dynamics of both adult worm burdens and nematode fecal egg counts. In addition, our analysis reveals interesting dose-dependent effects on the immune response. Finally, we discuss potential developments of this model and highlight how an improved cross-talk between empiricists and theoreticians would facilitate important advances in the study of infectious diseases.

Cutaneous Leishmaniasis (CL) is considered a neglected tropical disease which in Pakistan can now be considered as a growing public health problem. The exact figures on the magnitude of the disease are lacking both at the national and regional level and only a few health centres are available for diagnosis of CL. The present study was designed to identify the epidemiology of CL infection from August 2018 to December 2019 and to assess clinical aspects of CL in Baluchistan Province of Pakistan. A total of 4072 clinically suspected CL cases were analysed statistically. The highest number of CL cases were reported in May, followed by April, January and then July, February and June and the lowest number of cases were observed in March and November. The highest prevalence rate was found in males where 38% of reported cases were aged 0–9 years. The majority (24.4%) of lesions were found on the hands followed by the face in which cheeks, ears and nose were the effected organs. About 50% of the participants have single lesion while 14% of the participants had two and nearly 3% of the participants have six lesions. The atypical clinical presentations were observed in Baluchistan and common unusual presentations were lupus erythematosus. The study findings suggest that more epidemiological studies and health education campaigns are needed for the population awareness regarding CL in Baluchistan. It is recommended that risk factors should be evaluated to establish control and management strategies to prevent disease at the individual and community level.

Dujardin (1845) was the first to give a satisfactory account of the small Strongylid worms inhabiting the intestinal tract of field-mice and voles. His descriptions of the various species were careful and for the most part accurate, they were, unfortunately, not accompanied by figures, and incomplete in that the characters of the bursal rays of the males were not given, an omission which has led to considerable confusion, since the modern classification of the Trichostrongylidae is based largely on the structure of the male bursa.