In the course of a study of the bionomics of Hylemyia (Chortophila) brassicae Bouché, the Cabbage Root Fly, a small number of adults of this and a closely allied species were observed in the field to possess a somewhat unusual appearance. The capture and subsequent microscopical examination of these flies showed that they were parasitised by a micro-organism, which appears to be a fungus.

A few years ago it was believed that there was only one form of trematode responsible for the pathological conditions included in the term Bilharziosis, namely a worm, known as Schistosoma haematobium, which has had numerous other synonyms, but as I am dealing with the subject purely from a South African point of view, I need merely mention that given it by Dr John Harley, namely Distoma capense.

A large number of nematodes from Protemnodon rufogrisea, P. bicolor, P. dorsalis, and Macropus canguru, from southern Queensland, M. robustus from Western Australia, and Megaleia rufa (? locality) have been examined. The species described in this paper are: Pharyngostrongylus macropodis Yorke & Maplestone, P. kappa, sp.nov. (syn. P. macropodis in part), P. eta Johnston & Mawson, P. lambda, sp.nov., Rugopharynx epsilon (J. & M.), R. delta (J. & M.), R. zeta (J. & M.) (syn. R. longibursaris (Kung)), R. theta (J. & M.), Coronostrongylus coronatus J. & M.; a new genus is proposed, Oesophagonastes, with type O. kartana syn. Spirostrongylus kartana Mawson to include O. parma syn. Pharyngostrongylus parma J. & M., O. gallardi syn. P. gallardi J. & M., and O. leptos, sp.nov.

Most of the parasites were sent for examination by Dr M. J. Mackerras, then of the Queensland Institute of Medical Research. Those from Western Australia were from Dr T. Ealey of the Zoology Department, Monash University, Victoria, who was working on Macropus robustus in the north of that state. I am most grateful to both of these helpers.

Approximately 5000 birds (78 species) were trapped on Fair Isle and examined for fleas. Six species of flea were recorded: D. g. gallinulae (430 records), C. gallinae (205 records), C. borealis (126 records), C. garei (4 records), C. fringillae and C. vagabundus (1 record each).

The infestation rate among spring-passage migrants was 52·2% and among autumn-passage migrants only 2·7%. Spring migrants released and retrapped after ‘de-fleaing’ in the Fair Isle apparatus showed a 55% re-infestation rate. On spring migrants D. g. gallinulae was the dominant flea, but on autumn migrants C. gallinae was dominant. The most heavily infested group of birds were the Turdidae (61% spring, 3% autumn infestation rate) and Sylviidae (53% spring, 1% autumn infestation rate).

A number of double and triple infestations with 2 or 3 species of flea is recorded. Double infestations involving D. g. gallinulae and C. borealis occur more frequently than would be expected for purely chance associations. More male birds (90) than female birds (70) were infested.

The sex ratio of the fleas (on the bodies of birds) was: D. g. gallinulae 294 males, 325 females; C. gallinae 115 males, 214 females; C. borealis 77 males, 77 females. On the spring migrants there was an excess of male D. g. gallinulae and on the autumn migrants an excess of females.

On the resident birds there was definite evidence of host preference. The starling was the chief host of C. gallinae, the pipits of D. g. gallinulae and the wheatear of C. borealis. The re-infestation rate of ‘de-fleaed’ retraps showed a higher rate than original trappings in all cases, but the lack of D. g. gallinulae on retrapped starlings suggested some host selection on the part of the flea.

The proportions of the three principal species of flea found in (i) the nest of the wheatear, and (ii) on the body of the bird were strikingly different.

Male mice harboured more third-stage larvae of Amplicaecum robertsi than females; these larvae also grew longer than did those in female mice. Gonadectomy removed the differences, evident between the sexes, in both the numbers recovered and the growth of the third-stage larva, between male and female mice. The worms recovered from the gonadectomized hosts were smaller than those from the intact male and female host.

Pregnant female mice harboured more worms than either the male or the non-pregnant female mouse. These worms were also smaller than those from the male and non-pregnant females. There was no difference in the growth of the larvae from gonadectomized and pregnant hosts.

The treatment of spayed female mice with progesterone resulted in an increase in the size of worm population as compared with the numbers of worms recovered from intact female mice. The worms from the progesterone-treated spayed females were also longer than those from the spayed female hosts.

Treatment of normal female mice with progesterone resulted in an increased recovery of worms compared with the numbers of worms recovered from normal female animals. The worms were stunted but they were of a size comparable to those recovered from pregnant female mice.

It is suggested that the increase in the size of worm populations and the stunting of the worms recovered from pregnant female mice is associated with the effects of progesterone in relation to the hormone balance associated with the ovary at the time of pregnancy.

This trematode was obtained from cockles brought up with mussels to the Conway Mussel Cleansing Station and also from cockles collected from several other localities on the Menai Straits. It was present in every cockle examined, a total of several thousand in all. It occurred as a brown mass of varying size situated immediately beneath the hinge and occupying a small wedge-shaped cavity which occurs there. It could be obtained by cutting away the hinge with a knife when the brown mass was exposed. The latter breaks up very easily on teasing and consists of numerous more or less oval thick-walled sporocysts loosely embedded in the tissue of the cockle. These sporocysts are colourless or slightly straw-coloured and immobile. They contain a varying number of cercariae and a considerable amount of granular brown material. The fully developed cercaria (Fig. 1) is transparent except for the excretory sacs, which are full of very highly refractive granules and appear dark. The maximum diameter of these granules has been put forward by Rothschild (1935) as a valuable diagnostic character; in this species it is 5μ. The cercariae are moderately active and survive some time in sea water after removal from the sporocyst. This trematode was found throughout the year.

Mitotic metaphase chromosomes of the tsetse fly Glossina palpalis R.-D. have been investigated.

The chromosomes studied were in circumoesophageal nervous tissue from young pupae, stained with aceto-orcein and spread by squashing.

The diploid number of chromosomes was shown to be 6, consisting of 2 long pairs and 1 short pair at metaphase.

This finding is discussed briefly in relation to previous descriptions of the chromosomes of G. tachinoides West. and G. morsitans morsitans West. and to accepted systematic divisions of the genus Glossina into subgeneric groups.

I wish to thank Mr H. Dickson for assistance with photography. I thank Mr D. A. T. Baldry for advice and suggestions concerning the manuscript. Mr T. M. Leach has also made suggestions concerning the manuscript, and as Director of the Nigerian Institute for Trypanosomiasis Research, has given his permission to publish this paper.

Several ortho-naphthoquinones (o-NQs) have trypanocidal activity against Trypanosoma cruzi, the aetiological agent of Chagas disease. Previously, we demonstrated that the aldo-keto reductase from this parasite (TcAKR) reduces o-NQs, such as β-lapachone (β-Lap) and 9,10-phenanthrenequinone (9,10-PQ), with concomitant reactive oxygen species (ROS) production. Recent characterization of TcAKR activity and expression in two T. cruzi strains, CL Brener and Nicaragua, showed that TcAKR expression is 2.2-fold higher in CL Brener than in Nicaragua. Here, we studied the trypanocidal effect and induction of several death phenotypes by β-Lap and 9,10-PQ in epimastigotes of these two strains. The CL Brener strain was more resistant to both o-NQs than Nicaragua, indicating that greater TcAKR activity is unlikely to be a major influence on o-NQ toxicity. Evaluation of changes in ROS production, mitochondrial membrane potential, phosphatidylserine exposure and monodansylcadaverine labelling evidenced that β-Lap and 9,10-PQ induce different death phenotypes depending on the combination of drug and T. cruzi strain analysed. To study whether TcAKR participates in o-NQ activation in intact parasites, β-Lap and 9,10-PQ trypanocidal effect was next evaluated in TcAKR-overexpressing parasites. Only β-Lap was more effective and induced greater ROS production in TcAKR-overexpressing epimastigotes than in controls, suggesting that TcAKR may participate in β-Lap activation.

Absorption of glucose in vitro by enteric stages of Trichinella spiralis was examined in worms isolated at different times following infection. Glucose absorption by 6-h-old worms was similar to that seen during moulting (24 h post-infection (p.i.)). As embryogenesis began (48 h p.i.) glucose absorption in vitro by the parasite rose dramatically to a peak in 72-h-old worms. Absorption of glucose in vitro remained high in 96-h-old worms but as larviposition began (120 h p.i.) glucose uptake by T. spiralis dropped significantly. Glucose absorption by worms isolated from the host during the primary immune response was unaffected. Glucose absorption in vitro remained at similar levels in worms isolated between 120 and 312 h p.i. The percentage of absorbed label incorporated into parasite tissues was greatest in 48- and 312-h-old worms. Glucose uptake in vitro by pre-adult and adult worms changed with time and these changes accompanied specific events in the biology of the parasite.

Since the appearance of the papers by Hadwen and myself dealing with the subject of “Tick Paralysis”, I have had my attention drawn to two interesting papers. The reference to the first paper, by Borthwick (1905), was found whilst compiling Part II of the Bibliography of the Ixodoidea, and secondly, I am indebted to the author, Dr I. U. Temple, of Pendleton, Oregon, for sending me a copy of his valuable contribution. The latter appeared in a journal which will scarcely be accessible to European readers, and I therefore have no hesitation in reprinting the greater part of it below.

1. Observations on E. histolytica from the human intestine have been made and compared with amoebae living in culture media and in the ulcers of the large intestines of cats, which have died of amoebic dysentery.

2. The effects of the substances chlorine, tyrosin, and skatol on culture amoebae have been investigated; it has been found that the two first substances stimulate vegetative reproduction, but that skatol induces cyst formation.

3. The changes that the nucleus undergoes preparatory to division and the behaviour of the karyosome during division are fully described. It is shown that the nuclei originally described as characteristic of E. histolytica and E. tetragena are phases of nuclear change in the life history of the same animal.

4. Cyst formation and the nuclear divisions in the cysts are described, together with a short discussion as to the view taken that the chromatoid bodies are not comparable with the chromidia of other Rhizopoda.

5. Reasons are adduced for the suggestion that during the further development of the cysts quadrinucleate amoebae emerge, which divide to form four small amoebulae.

6. Degeneration in E. histolylica is described and the view of Darling, that budding phenomena are degenerative ones, is confirmed.

A tegumental vesicle preparation from adult male Schistosoma mansoni was developed that allows the resolution of single ion-channel currents. Adult male schistosomes were exposed to a low pH (3·75) medium for a period of approximately 30 min at 37°C. During this period smooth vesicles formed from the tegument. Fluorescence microscopy following staining of the tegument with the dye, 5-N-[octadecanoyl]aminofluorescein (AF-18), transmission electron microscopy and scanning electron microscopy revealed that the vesicles were produced from the outer tegumental membrane. The fluorescence studies showed the presence of the double bilayer structure of the outer membrane in >41% of the vesicles. These studies suggested that the preparation is suitable for single-channel recording with the patch-clamp technique. Cell-attached and isolated inside-out patch recordings of ion-channel activity were obtained with giga-ohm resistance seals. Different types of ion-channel were recorded from tegumental vesicles from male schistosomes, illustrating the potential of the technique. The channels observed included: a non-selective cation channel (360 pS); a K+ channel (with a conductance of 115 pS in high bath-K conditions); and a Cl− selective channel (20 pS). The currents of these ion-channels may cross the double bilayer of the outer tegumental membrane.

The range of hosts used by a parasite is influenced by macro-evolutionary processes (host switching, host–parasite co-evolution), as well as ‘encounter filters’ and ‘compatibility filters’ at the micro-evolutionary level driven by host/parasite ecology and physiology. Host specialization is hypothesized to result in trade-offs with aspects of parasite life history (e.g. reproductive output), but these have not been well studied. We used previously published data to create models examining general relationships among host specificity and important aspects of life history and reproduction for nematodes parasitizing animals. Our results indicate no general trade-off between host specificity and the average pre-patent period (time to first reproduction), female size, egg size, or fecundity of these nematodes. However, female size was positively related to egg size, fecundity, and pre-patent period. Host compatibility may thus not be the primary determinant of specificity in these parasitic nematodes if there are few apparent trade-offs with reproduction, but rather, the encounter opportunities for new host species at the micro-evolutionary level, and other processes at the macro-evolutionary level (i.e. phylogeny). Because host specificity is recognized as a key factor determining the spread of parasitic diseases understanding factors limiting host use are essential to predict future changes in parasite range and occurrence.

Large inocula of dividing form-enriched Trypanosoma musculi parasites, harvested from the peritoneal cavity of infected CBA mice, were given intravenously to mice at various times during the infection. Mice infected for 10 or 15 days (including T cell-deprived, infected mice) eliminated dividing parasites from the blood within a few min, whereas those at earlier stages (1 or 5 days) were less efficient. The initial control of T. musculi parasitaemia thus appears to be due to a trypanocidal mechanism rather than reproduction-inhibiting factor (ablastin).

Snell normal and dwarf mice were infected with Spirometra erinacei plerocercoids collected in Japan, to investigate the relationship between the growth-promoting effects of plerocercoids and the growth hormone releasing factor and the somatostatin – growth hormone – somatomedin axis in the host. Infection with plerocercoids caused increases in body weight and weights of muscle, liver, spleen and heart in the normal male mice, and increases in the head–body length, body weight and weights of muscle, liver, spleen, kidney and heart in the normal female mice, but did not increase the weight of the fat pad. Infection with plerocercoids caused increases in body weights and weights of muscle, liver and spleen in the male dwarf mice, and increases in the head–body length, body weight and weights of muscle, liver, spleen and kidney in the female dwarf mice. These observations suggest that plerocercoids promote the growth of dwarf mice as well as normal mice. As the dwarfism of Snell mice is due to a defective anterior pituitary gland, it seems that plerocercoids do not stimulate secretion of growth hormone from the pituitary. Accordingly, it seems to be more probable that the larvae secrete a growth hormone-like substance.

Three strains of male and female mice, CFLP, BALB/c and CBA/ca, were infected i.p. with the tetrathyridia of Mesocestoides corti and examined in groups of 5 at 0, 7, 14, 21, 28 and 42 days post-infection. At post-mortem the numbers of parasites both loose in the peritoneal cavity and in the liver tissue were counted, the livers weighed fresh and sections of liver stained to examine the inflammatory response, encapsulation of the tetrathyridia and for eosinophils, neutrophils, mast cells and plasma cells. BALB/c mice had significantly more parasites loose in the peritoneal cavity than CFLP and CBA/ca mice. Infected livers of all three strains were significantly heavier than control livers; the heaviest livers were those of the CFLP followed by the CBA/ca mice which also showed the greatest rate of weight increase. The tetrathyridia from the peritoneal cavities of the CBA/ca and CFLP mice were covered with a ‘mucilage-like’ substance. Tetrathyridia within the host capsules of the CBA/ca mice contained host cells. There was no strain difference with regard to numbers of tetrathyridia in the liver but male mice harboured significantly more parasites than females. Differences in the numbers of cell types within the liver were detected between the strains but no one strain showed any consistent pattern. There was an overall increase in total white blood counts as well as an increase in the number of eosinophils, monocytes, neutrophils and lymphocytes during the course of the infection.

Although much work has already been published on the bucco-pharyngeal mechanism of a blow-fly larva, a close examination reveals the presence of parts hitherto overlooked or but imperfectly recorded. In this account current nomenclature is retained as far as possible; but where the evidence warrants it new terms are employed based on homology, or on the function of the regions concerned, in an endeavour to arrive at a more useful basis for future reference.

The intra-erythrocytic development of a parasite of the frugivorous bat, Roussettus leachi, has been, observed. The name Plasmodium roussetti has been suggested temporarily. The rosettes are typical of the genus Plasmodium. The parasites can be transmitted congenitally and gametocytes have been found in foetal blood.

This work has been made possible by grants from the Fonds National de la Recherche Scientifique and from the Institut pour la Recherche Scientifique en Afrique Centrale.

Plastic ear tags impregnated with acaricides (synthetic pyrethroids; fenvalerate, 10% (w/w); fenpropathrin, 10% (w/w); fiuvalinate, 10% (w/w); and permethrin, 8% (w/w)) were evaluated for the control of Rhipicephalus appendiculatus infesting cattle in the laboratory and field in Kenya. These controlled release devices gave excellent control of R. appendiculatus for over 20 weeks on cattle in the laboratory where they were housed mostly indoors. Fluvalinate-impregnated tags gave consistently the most rapid control of ticks, but all of the tags normally prevented feeding of the ticks on the ears of cattle. Under field conditions in the Trans-Mara Division of Kenya, excellent control of R. appendiculatus naturally infested cattle was obtained by fluvalinate-impregnated tags followed by fenpropathrin. Less impressive control was obtained by fenvalerate- and permethrin-impregnated tags, but this control was more effective than immersion of cattle in toxaphene. In contrast to the laboratory experiments, the effect of the tags on R. appendiculatus infestation waned by 58 days after application. The potential of synthetic pyrethroid-impregnated tags for the control of ticks infesting cattle in Africa was demonstrated, but a more prolonged release of the active ingredients at an effective level in the field and, in some cases, a more robust tag design will have to be achieved before tick control with impregnated tags becomes a practical proposition.

To dissociate the influence of host age from length of exposure on acquisition of filarial infection, we examined the development of microfilaraemia and anti-filarial IgG4 in all ages of a naive population that became suddenly exposed to Brugia malayi as a result of transmigration. Responses in 247 transmigrants, who had settled for periods of several months up to 6 years in their new homesteads, were compared with those of 133 life-long residents. As shown in earlier studies, anti-filarial IgG4 increased with age in the indigenous population, whose age is equivalent to length of exposure. However, by examining transmigrants, it became clear that development of specific IgG4 was influenced by age, since levels of this antibody were consistently higher in transmigrant adults than in transmigrant children, despite an equal length of exposure to filarial infection. Examining microfilaraemia, it was confirmed that infection establishes more rapidly in adults than in children.