All the known species of Solenopotes Enderlein, 1904 are discussed with a complete synonymy, major references, diagnoses, host associations and distribution; they are S. binipilosus (Fahrenholz, 1916a); S. burmeisteri (Fahrenholz, 1919); S. capillatus Enderlein, 1904; S. capreoli Freund, 1935a; S. ferrisi (Fahrenholz, 1919); S. muntiacus Thompson, 1938; S. natalensis Ledger, 1970 and S. tarandi (Mjöberg, 1915). The species of Solenopotes are compared on the basis of major taxonomic characters. Solenopotes and Linognathus are compared and a key to the known species of Solenopotes is also presented. Taxonomic relationships among the cervid-infesting species are quantitatively studied. The status of Linognathus panamensis Ewing, 1927, previously assigned to Solenopotes, is discussed and the species is redescribed and illustrated.

A species of Eimeria from the Ceylon jungle fowl (Gallus lafayetti), at first thought to be a new species of Eimeria, has been identified as a strain of E. praecox. Oocysts of this jungle fowl strain were slightly larger than those of E. praecox, being 23·2 × 19·9 μm, but the endogenous stages were similar. The strain reproduced poorly in the domestic fowl but oocyst production was improved by treating the chickens with beta-methasone. A single infection of chickens with the strain of jungle fowl origin protected against challenge with the original culture and E. praecox, but did not cross-protect against E. acervulina. The name E. praecox var. ceylonensis is proposed for this strain of Eimeria.

The criteria used to identify new species of Eimeria are discussed.

Evidence has been adduced that the surface antigens of Trypanosoma brucei subgroup are a group of glycoproteins having D-galactose, D-mannose and D-glucosamine as monosaccharide components.

There was considerable variation in the number of antigen components, and their relative amounts, as revealed by isoelectric focusing on polyacrylamide gel. The relevance of these variations to the adaptation theory of antigenic variation in trypanosomes is discussed.

The activity of 12 anticoccidial drugs against an embryo-adapted strain of Eimeria tenella has been investigated. After seven and five serial passages respectively, in the presence of drug, resistance was developed to methyl benzoquate and buquinolate. A strain of E. tenella made resistant by exposure to drugs in chickens was resistant to the same drugs when evaluated in infections of chick embryos. This relatively simple technique would appear to offer advantages over existing methods for the study of drug resistance.

A comparative histochemical study is made on the distribution of succinate dehydrogenases, isocitrate dehydrogenases, malate dehydrogenases, glucose-6-phosphate dehydrogenases, α-glycerophosphate dehydrogenases, alcohol dehydrogenases, lactate dehydrogenases and glycogen phosphorylases in the tissues of sporocysts, rediae, cercariae and metacercariae parasitizing the gastropod mollusc Bithynia tentaculata. The results suggest that metabolic sequences resembling the conventional Embden–Meyerhoff pathway, the Pentose-Phosphate cycle and Krebs’ citric acid cycle may be operational in these larval digeneans. Heaviest enzyme activity is evident in the redial pharynx, the cercarial and metacercarial sucker and in the cercarial tail. Presumably the enzymes giving this heavy reaction form part of the energy producing mechanism for these active organs. Encysted metacercariae show a very heavy enzyme activity when compared with the sporocysts and developing cercariae of the same species. This is presumably associated with the breakdown of food storage materials, particularly glycogen, by these encysted stages.

Trout collected from the Hanningfield Trout Farm in Essex, England, were found to be infected with Diplostomum spathaceum. Yearling rainbow trout were blinded with heavy infections of eyefluke, whereas brown trout of the same age carried one-tenth the number of flukes and were clear eyed. Both species were reared under identical conditions, in parallel rearing channels which received water from a common source. Samples showed that young fish exhibited a similar differential in their infestations, and that rainbow trout did not appear to be age-resistant. Laboratory infections produced by exposure of fish to suspensions of cercariae and injection of cercariae into the body cavity reflected the field results, indicating that ecological factors were not involved. Recovery of cercariae from host tissues, and histological observations of similar numbers entering both hosts, indicated that cercariae were able to survive penetration. Excised eye preparations were equally susceptible to infection. Two cm fry of both species were shown to be highly susceptible. Migration in brown trout took 3 h longer than in rainbow trout of the same size, many cercariae being found in the heart during this time. Two mechanisms of insusceptibility were suggested: (1) a greater impenetrability of brown trout tissues; (2) a disorientation of migrating cercariae in brown trout.

The range of fish hosts parasitized by Diplostomum spathaceum was assessed. Natural and experimental levels of infection were compared between host species. The accumulation of eye flukes with age was established in one host – Rutilus rutilus. Development of metacarcariae in lenses of naturally infected Gasterosteus aculeatus throughout the year was compared with that of experimentally infected South African clawed toads, Xenopus laevis, maintained at various temperatures (5–30 °C). The importance of temperature changes to this part of the life-cycle of the parasite is discussed.

Immunoglobulin synthesis in response to experimental infection of cattle with Theileria parva (Muguga) was studied by Sephadex G 200 chromatography. Serum samples were collected for 88 days following inoculation. Indirect fluorescent antibody (IFA), complement fixation (CF), indirect haemagglutination (IHA) and immunodiffusion (ID) tests were used to detect activity against T. parva piroplasm antigen. There was a small and transient IgM response in the IFA test, thereafter all IFA activity was 7S Ig. A sequential production of IgM and 7S Ig CF antibodies was demonstrated. In all sera tested only IgM activity was demonstrated by the IHA test. These results are compared with those from similar studies with T. parva and other protozoan diseases, especially in the differential immunoglobulin response shown by the contrasting results from the three serological tests.

Golden hamsters were given plerocercoids of Diphyllobothrium dendriticum either singly or in groups of 2, 4, 8 or 15. There was a higher rate of recovery of worms from hamsters given many (8 and 15) than from those given few (1, 2 or 4) plerocercoids. The difference in rate of recovery of worms was present from 2 h after administration of plerocercoids and persisted up to day 20 when experiments were ended. Denser tapeworm populations had the smallest individuals and some of them contained worms with primary strobilae at the start of egg production. The size of the tapeworm population did not influence the prepatent time. Also, with the common gull there was a higher rate of recovery of worms when plerocercoids were given in groups. These results are discussed in relation to aspects of the life-cycle of D. dendriticum where the natural final host is most probably normally infected by a larger number of plerocercoids at the same time.

Lambs were infected at daily intervals from 3 weeks of age with increasing doses of infective larvae of Trichostrongylus colubriformis, according to an exponential infection schedule designed to simulate the pattern of infection experienced by grazing lambs during the spring and early summer in Britain. The faecal egg counts and the worm burdens in the lambs followed a similar exponential trend for 12 weeks after initial infection.

The T. colubriformis burdens in these lambs appeared to be cumulative during the first 12 weeks, after which the animals developed a resistance to further reinfection, which was very strong by 16 weeks after initial infection. However, even lambs which were refractory to new infection continued to harbour large numbers of adult worms, which caused clinical disease in most of the lambs.

There was no evidence to suggest that either a turnover of the worm burden, inhibition of larval development or the sudden loss of established parasites played any major role in the regulation of the burdens of T. colubriformis in these young lambs.

The removal of the established burden 16 weeks after initial infection in one lamb appeared to result in a partial loss of resistance to a challenge infection given 10 days later.

Cattle were inoculated with purified Theileria parva piroplasm and/or schizont antigen. Two similar inoculations were given 10 days apart. Serum samples were regularly collected and the indirect haemagglutination (IHA), indirect immunofluorescence (IFA), complement-fixation (CF) and immunodiffusion (ID) tests were used to detect T. parva antibodies. Selected sera were separated by Sephadex G 200 and fractions examined for specific immunoglobulin activity.

With the IHA test specific antibody first appeared 4 days post inoculation (dpi) and reached high titres by 8 dpi. With the IFA and CF tests specific antibody also appeared 4 dpi and reached high titres by 8–14 and 10–14 dpi respectively. Specific ID activity was detected as early as 6 dpi and persisted for the length of the experiment.

On fractionation of the sera both the IHA and CF tests indicated a sequential production of T. parva IgM and 7S Ig. However, in cattle inoculated with schizont antigen only, a significant 7S Ig component was not detected by the IHA test until 16 dpi, but was demonstrated by the CF test 7 dpi. The IFA test, however, detected anti T. parva activity almost exclusively in the 7S Ig fractions. All cattle were challenged 35–42 dpi with infective T. parva stabilate and all cattle proved fully susceptible. The lack of protection by high titres of specific T. parva immunoglobulin is discussed, together with the data on the differential immunoglobulin response, in relation to previous results.

Experiments are described which show that in a recently isolated field strain of the cattle nematode, Ostertagia ostertagi, the primary stimulus to the induction of inhibited development at the early fourth larval stage (EL4) in the host is chilling of the infective larvae (L3). Thus exposure of L3 to a temperature of 4 °C for 8 weeks prior to their oral administration to calves resulted in a mean of 66% of the established worm burden becoming inhibited at the EL4 stage. This provides an explanation for the seasonal occurrence in Britain of inhibited EL4 stages of O. ostertagi in cattle during the cold climate of late autumn and winter.

If the L3 stages were exposed to chilling for a prolonged period (> 19 weeks), prior to infection of calves, then the prevalence of inhibited EL4 stages amongst the worms established declined. After 33 weeks chilling the worm population consisted almost entirely of adults and only 2% inhibited EL4 stages. This suggested that a selective mortality of inhibition prone L3 was taking place and explained why under natural grazing conditions inhibition prone L3 were not available on the pasture in spring.

The duration of inhibition at the EL4 stage in calves infected with chilled L3 was consistently between 16 and 18 weeks and maturation of the majority of the inhibited larvae occurred spontaneously after such a period and irrespective of season. This period is equivalent to the duration of a normal winter in Britain when conditions unsuitable for the free living development of O. ostertagi larvae prevail.

The induction of inhibition by the environmental stimulus of chilling, the fixed period for the duration of inhibition within the host and the spontaneous maturation of the inhibited larvae are characteristic of a true diapause.

Adult Haemonchus contortus obtained from freshly killed sheep were incubated in a medium similar to Tyrode's saline containing known amounts of D-[U-14C]glucose. The worms appeared to remain in a healthy condition throughout the incubations which lasted for up to 6 h. All the radioactivity was recovered either within the worms or in the incubation vessel in the form of CO2, excretory products and unmetabolized glucose. An oxygen electrode in the incubation liquid showed that, because of their rapid oxygen consumption, the worms were under anaerobic conditions during all or nearly all of the incubation period, despite the presence of oxygen in the gas phase of the vessel. In terms both of quantity and radioactivity the main excretory products in solution were propan-1-ol, propionate and acetate. Smaller amounts of ethanol, lactate and succinate were excreted. Much radioactivity was associated with the expired CO2. At the end of the incubations glucose other than the initial radioactive glucose was detected indicating that the absorption of glucose by H. contortus is complex and needs further investigation. The present experiments suggest that the rate of absorption depends on the worm's need for nutrients. The results are compared with those found for other parasitic nematodes, particularly Ascaris lumbricoides, Heterakis gallinae and Trichuris vulpis. The importance of CO2 fixation in the utilization of energy from glucose by H. contortus is discussed.

The ultrastructural changes in the encysted phase of Trichinella larvae, during and after treatment of the rat with mebendazole, were studied.

The earliest modifications in the infected area concerned the immediate larval environment (matrix). These degenerative changes in the matrix were seen before any alteration could be observed in the larvae.

Subsequently, oedematous swelling, intracellular vacuolization and loss of glycogen were noted in the larval cells.

Together with the progressive involution of the larvae and their matrix, inflammatory and immunocompetent cells invade the infected area and penetrate the altered capsule. Calcification of the larvae and massive infiltration of mononuclear phagocytes with subsequent elimination of the calcified remnants were the prominent features in the first weeks after treatment. The infected areas were completely cleared from larval and matrix residues 50 days after the end of treatment and a nearly normalized tissue was seen from day 111 after treatment.

Three groups of lambs, aged 3, 5 and 6 months respectively, were infected daily with 5000 infective larvae of Trichostrongylus colubriformis for periods of 15–20 weeks. Some of the lambs also received a single challenge infection at the end of week 16. The course of the infections was monitored by means of faecal egg counts, measurement of live-weight gains and regular post mortem worm counts.

There was an initial rapid increase in egg counts soon after patency, which was followed by an exponential fall in the counts in most lambs. This fall seemed to precede the expulsion of worms by a few weeks and was associated with reduced fecundity in the female worms. Furthermore, although the trend of the egg counts of some lambs suggested that a self-cure reaction had taken place, in a number of these lambs the low faecal egg counts did not reflect the size of their worm burden.

Heavy worm burdens were usually associated with clinical symptoms of trichostrongylosis, including anorexia, diarrhoea and loss of weight. As the lambs developed resistance to reinfection and expelled their worm burden a rapid clinical recovery occurred, except in a few lambs which appeared to have suffered irreversible damage from the earlier heavy worm burden.

The worm burden in most lambs appeared to be cumulative during the first 4–8 weeks before they developed a strong resistance to reinfection. There was considerable loss of the adult worm burden by 8–15 weeks after initial infection and some evidence of stunting in the remaining parasites.

The immunological control of T. colubriformis infections in these lambs was achieved by means of the development of resistance to reinfection, inhibition of the ovulation of the female worms, stunting of adult worms and expulsion of adult worms by resistant lambs. These may be separate immune phenomena requiring different thresholds of parasitic material in individual animals, depending on their age, the rate and duration of infection and their innate ability to develop resistance to the parasite.

Approximately 90% of Hymenolepis citelli cysticercoids given to 6-week-old male CFLP mice by stomach tube became established. Equally high recovery rates were obtained from administering 1, 3 and 6 cysticercoids.

In 1-worm infections worms increase in weight until about day 25–28 post infection. After a few days at maximum weight (mean weights of worms 24–42 mg) there is a small, 10–25%, decrease in weight, after which there is little change in weight up to day 90 (as long as studied).

One-worm infections survived without loss until day 30, after which a slow loss occurred, but only in two experiments, both with older mice, did loss exceed 50% by day 80. In 3-worm infections worms were rejected between days 17 and 30, but loss varied from 50 to 80% during this period in replicate experiments. With 6-worm infections rejection occurred over a shorter period (days 17–22), was more uniform between experiments and was more complete, over 75% of worms being lost. In both 3- and 6-worm infections a residual population, usually of only a single worm, persisted in 20–50% of the mice until the end of the experiments (day 63–78).

Cortisone prevented loss of worms from both 3- and 6-worm infections; worms continued to grow until day 25 ± 2 (as in 1-worm infections), by which time they were considerably larger than (the surviving) worms in mice not receiving cortisone. The biomass (worm burden per mouse) remained constant from day 25 to 55 in mice receiving cortisone.

The results are discussed with particular reference to: H. diminuta and the evidence that mice do mount an immunological response against tapeworms in the intestine; the existence of an antigenic threshold in mice; the apparent existence of a similar rejection pattern in a natural population of H. citelli in Peromyscus maniculatus, and hence the importance of immunity as a factor preventing gradual increase in number of tapeworms in the intestine during the life of a host.

Normal mouse erythrocytes and erythrocytes containing Plasmodium berghei were incubated for 1 h in a medium containing either adenosine, guanosine, cytidine or thymidine labelled with 14C or 3H. The purine nucleosides, adenosine and guanosine, but not the pyrimidine nucleosides, cytidine and thymidine, were incorporated into the nucleic acid of the parasite–host cell complex. The concentration achieved by all four nucleosides in both normal and parasitized cells was at least as high as that in the suspending medium, showing that not only purines but also pyrimidines enter the parasitized erythrocyte.

An anthelmintic test was carried out in lambs against fourth-stage larvae of Haemonchus contortus to determine whether a natural loss of worms from either untreated control animals or from animals treated with anthelmintic affected the estimated activity of the anthelmintic.

Thirty-two lambs were each infected with 1500 larvae of H. contortus on 4 consecutive days and divided into 4 groups of 8 animals. Two groups of lambs were treated with anthelmintic on day 7, the first group being slaughtered on day 9 and the second on day 29. An untreated control group was slaughtered 7 days after infection and a second control group was killed 29 days after infection.

The numbers of worms recovered indicated that in the untreated control lambs there was an estimated daily loss of about 7% of the parasite population between the first day of infection and day 29, and in the lambs given anthelmintic an estimated daily loss of about 2% of the worm population was indicated between days 9 and 29. If the rate of worm loss is not the same in the untreated control hosts and in the treated animals, the estimate of anthelmintic efficacy will vary according to the time of autopsy. To minimize the possibility of an incorrect result occurring in an anthelmintic trial due to a natural loss of worms, it is recommended that the untreated control and the treated lambs are slaughtered on the same day, and that the autopsy is carried out as soon as possible after anthelmintic therapy.

Two species of Eimeria isolated from jungle fowl of Malaysia were examined in infections of chickens. Eimeria diminuta reproduced well in the embryo CAM and caused severe infection of the lower small intestine and caeca of chickens, but did not develop in the duodenum. It reproduced well in chickens and severely affected their body weight gain. The endogenous stages and oocysts were similar to E. acervulina var. mivati and cross-protection tests with this parasite and E. acervulina confirmed the close relationship between them. It is suggested that the parasite should be referred to as E. acervulina var. diminuta.

The oocysts of another species examined (E. indentata) were similar to E. maxima: the parasite reproduced well in chickens, was pathogenic and showed marked cross-protection against two strains of E. maxima isolated in Britain. The name E. maxima var. indentata is suggested for this parasite.

When low immunizing doses of two strains of E. maxima isolated and maintained in Britain were given, they did not completely cross-protect against re-infection with the heterologous strain.

In CFLP male tapeworm-free mice, from 2 to 7 weeks old at infection, at least 80% of single Hymenolepis diminuta establish and grow but then are rejected; day of rejection defined as the first day when ≦ 50% of the worms were recovered. Young mice, 2 to 4 weeks old, usually reject their worms during days 16–20 while older mice, 5 to 7 weeks old, reject them during days 12–14. Biomass (total dry weight of all worms recovered on a given day from a group of mice) varied markedly with host age and was consistently greatest in 4-week-old mice. The position of the worm in the intestine did not vary with host age. The quality of mice (categorized by the Medical Research Council Laboratory Animals Centre) did not appear to affect the course of a primary, single H. diminuta infection although, undoubtedly, the mice had varied immunological histories. Variations in time of rejection and biomass of worms recovered are accounted for by both immunological and physiological mechanisms.