The transmission of Theileria parva by nymphal and adult Rhipicephalus appendiculatus was compared by the assessment of salivary gland infections in tick batches fed on the same group of infected cattle at the same time. When larval and nymphal R. appendiculatus Muguga ticks were fed concurrently on cattle undergoing acute infection with T. parva Muguga, the resultant nymphae developed a slightly lower prevalence of infection than did the adult ticks. The abundance of infection was 5–20 times higher in the adult ticks than in the nymphae. When larval and nymphal R. appendiculatus Muguga and R. appendiculatus McIlwaine were fed to repletion on cattle infected with T. parva Boleni, a parasite causing subacute infection, resultant adult tick batches had a relatively high prevalence of infection, but infection was not detected in resultant nymphal batches. When cattle that were carriers of 2 stocks of T. parva, Marikebuni and Kiambu 5, were used as the source of infection, the infections developing in adult R. appendiculatus Muguga ticks were much higher than those developing in nymphae. The structure of salivary glands differed between nymphal ticks, adult males and adult females, and this is considered to be an important factor affecting the infection levels. The morphology of the type III acini, the target acini for sporogony, was similar, but the mean numbers of type III acini were different, with 87 in nymphae, 1346 in males and 1736 in females. This difference was correlated with the different infection levels produced in the various instars and sexes. While the process of sporogony in the different tick instars and sexes was similar, the rate of sporogony was fastest in feeding nymphae, taking on average 2–3 days, compared to 3–4 days in females and an irregular period in the males. These results are discussed in relation to the epidemiology of T. parva.

An ELISA was developed for serological detection of Echinococcus granulosus infection in dromedary camels. Antigen B (AgB) partially purified from hydatid cyst fluid of camels or sheep naturally infected with cystic echinococcosis (CE) due to E. granulosus, as well as a recombinant antigen B product (r-AgB) were used in an ELISA to screen panels of serum samples from slaughtered camels naturally infected with CE. Native hydatid cyst fluid antigen preparations were able to detect antibodies in sera from a significant proportion of camels with CE, as confirmed at post-mortem. Seroreactivity however, was variable. ELISA specificity for sera from naturally infected camels versus inspection-negative animals ranged from 90 to 99%. Native antigen B gave the highest sensitivity (97%) in ELISA for camel CE confirmed at slaughter. In contrast, r-AgB gave lower sensitivity for camel (84%) and sheep (28%) CE. The r-AgB-ELISA was, however, highly specific (90 and 95%) respectively for both camel and sheep natural CE infection. These results indicate that an ELISA based on serum antibody detection to AgB could be developed for immunodiagnosis of cystic echinococcosis in camels.

Cholinergic compounds inhibit FMRFamide-induced contractions in dispersed muscle fibres isolated from adult Schistosoma mansoni. Acetylcholine (ACh) was the most effective cholinergic agonist tested with an EC50 < 100 nM. Less effective were propionylcholine and arecoline with EC50 < 1 μM and butyrylcholine and carbachol with EC50 < 10μM. Choline, muscarine, pilocarpine, nicotine, DMPP (1,1-dimethylphenylpiperazine ) and levamisole were all ineffective. Amongst tested antagonists, d-tubocurarine (100μM), mecamylamine (1 mM), atropine (1 mM), scopolamine (1 mM) and quinuclidinyl benzilate (10 μM) were all ineffective. Bicuculline, picrotoxin and strychnine were also ineffective. However α-bungarotoxin, at 100 nM, was able to block the inhibitory ACh effect. From these data it appears that the cholinergic receptor on the schistosome muscle fibres may be of the nicotinic type, but that its pharmacology is different from that of nicotinic receptors of vertebrates as well as of nematodes or a variety of other invertebrates.

One therapeutic oral dose (400 mg/kg) of 153C51 administered to infested mice caused pathological changes in the dorsal region of the tegument of male Schistosoma mansoni during the period 3–24 h after treatment. These changes occurred prior to the ‘hepatic shift’. At the ultrastructural level they consisted of a gradual accumulation in the tegument epidermis of numerous membranous inclusions with the characteristics of residual lysosomes and changes in the localization of acid phosphatase, a lysosomal enzyme. It seemed likely that these changes were due to inhibition or exhaustion of enzyme in the epidermis, followed by re-synthesis of enzyme in the cell bodies and its export to the epidermis. The elimination of hydrolytic activity from lysosomes in the epidermis would explain the accumulation of residual lysosomes. Drug- treated parasites retained their disguise of host red blood cell ghost antigens as shown by indirect fluorescent antibody-labelling and, therefore, it seemed unlikely that immunological factors could be important in producing the tegument pathology.

The benzodiazepine Ro 11-3128 (methyl-clonazepam) presents several similarities with praziquantel with regard to its anti-schistosomal mode of action, since both drugs cause spastic paralysis, calcium influx and tegumental disruption in the parasites. In order to know whether the two compounds share the same binding sites in the schistosomes, we performed in vivo and in vitro competition experiments. We took advantage of the fact that Ro 11-3128 is active against immature Schistosoma mansoni (whereas praziquantel is inactive), and praziquantel is active against S. japonicum (which is insensitive to Ro 11-3128). An excess of praziquantel did not inhibit the activity of Ro 11-3128 against immature S. mansoni and an excess of Ro 11-3128 did not inhibit the activity of praziquantel against S. japonicum, suggesting that the schistosome binding sites of the two drugs are different. On the other hand, cytochalasin D, an agent known to perturb – among other things – calcium channel function, was capable of inhibiting the schistosomicidal activity of both praziquantel and Ro 11-3128, thus adding another element of similarity between the two anti-schistosomal agents. A similar, albeit partial, inhibition of the schistosomicidal activity of the two drugs was exerted by some of the classical calcium channel blockers. Taken together, these results suggest that praziquantel and Ro 11-3128, although binding to different schistosome receptor sites, may use the same basic anti-schistosomal effector mechanisms.

The developmental stages of Braula coeca are described. The larva is an inquiline living in a tubular burrow which it makes by mining on the inner side of the capping of the honey cells in the comb of the hive bee. It is meta-pneustic and bears characteristic anterior and posterior girdles of sensoria.

The pupa is apparently unique among Cyclorrhapha in that it is enclosed within the unmodified cuticle of the 3rd instar larva, no puparium being formed. It is suggested that this feature is a degenerative change owing to the cessation of a particular phase of hormone activity.

The similarity of form and structure shown by the larvae of Braula and of the Chamaemyiidae (Ochthiphilidae) is indicative of a fundamentally close relationship. Their imagines on the other hand have undergone widely divergent evolution.

In a survey of animal trypanosomiasis in Musoma District, carried out in October and November 1970, 6344 G. swynnertoni were collected from six different localities of the Ikoma-Serengeti area and 623 G. pallidipes from Ikoma. These were dissected and examined for trypanosome infections.The mean infection rates of vivax-type in G. swynnertoni and G. pallidipes were 12.6% and 7.5%, respectively. The congolense group infection rates were 2.0% in G. swynnertoni and 1.8% in G. pallidipes. No salivary gland infection was encountered.The incidence of vivax- and congolense-type infections in general increased with age of both the tsetse species, suggesting that the latter can become infected with these trypanosome types at all ages. The infection rate among female tsetse was higher than among males in the six wing-fray categories. This was due to the slower rate of fraying of the wings with age of the former, so that at each wing-fray category the females were generally older than the males.Vivax-type greatly exceeded congolense-type infection rate in both G. swynnertoni and G. pallidipes. It is suggested that this probably reflects the known greater infectivity of the former group of trypanosomes to Glossina.It is concluded that in Ikoma, where game functions as the reservoir of animal trypanosomiasis and where infected tsetse are abundant, the domestic animals are exposed to a continuous trypanosome challenge.

The anthropogenic modification of natural landscapes, and the consequent changes in the environmental conditions and resources availability at multiple spatial scales can affect complex species interactions involving key-stone species such as bat–parasite interactions. In this study, we aimed to identify the drivers potentially influencing host–bat fly interactions at different spatial scales (at the host, vegetation stand and landscape level), in a tropical anthropogenic landscape. For this purpose, we mist-netted phyllostomid and moormopid bats and collected the bat flies (streblids) parasitizing them in 10 sites representing secondary and old growth forest. In general, the variation in fly communities largely mirrored the variation in bat communities as a result of the high level of specialization characterizing host–bat fly interaction networks. Nevertheless, we observed that: (1) bats roosting dynamics can shape bat–streblid interactions, modulating parasite prevalence and the intensity of infestation; (2) a degraded matrix could favor crowding and consequently the exchange of ectoparasites among bat species, lessening the level of specialization of the interaction networks and promoting novel interactions; and (3) bat–fly interaction can also be shaped by the dilution effect, as a decrease in bat diversity could be associated with a potential increase in the dissemination and prevalence of streblids.

The flagellated parasite Giardia duodenalis is known as one of the most common causes of protozoal diarrhoea in both humans and animals worldwide. The aim of the present work was to perform the first study of G. duodenalis in rodents in the Canary Islands (Spain) and analyse the level of genetic variation and the potential zoonotic role of the isolates. Stool samples were collected from 284 wild rodents and Giardia cysts were detected by light microscopy. The overall prevalence of giardiasis was 25·4% and ranged from 19·4% in El Hierro to 34% in Gran Canaria. Positive samples were further characterized by PCR and nucleotide sequencing of the triose phosphate isomerase (TPI), β-giardin (BG) and glutamate dehydrogenase (GDH) genes. Our study revealed assemblage G as the most frequent genotype and identified two rodent-infecting G. duodenalis haplotypes of this assemblage, HI and HII. Phylogenetic analysis supported the monophyly of haplotype HI, which we suggest to be considered as a novel G. duodenalis sub-assemblage GII, due to the high genetic distances among this sub-genotype and assemblage G. Furthermore, G. duodenalis assemblage B was detected in an inhabited area in La Palma, a fact that may pose a potential risk of G. duodenalis transmission from rodents to humans.

Toxoplasma gondii and Sarcocystis neurona are protozoan parasites with terrestrial definitive hosts, and both pathogens can cause fatal disease in a wide range of marine animals. Close monitoring of threatened southern sea otters (Enhydra lutris nereis) in California allowed for the diagnosis of dual transplacental transmission of T. gondii and S. neurona in a wild female otter that was chronically infected with both parasites. Congenital infection resulted in late-term abortion due to disseminated toxoplasmosis. Toxoplasma gondii and S. neurona DNA was amplified from placental tissue culture, as well as from fetal lung tissue. Molecular characterization of T. gondii revealed a Type X genotype in isolates derived from placenta and fetal brain, as well as in all tested fetal organs (brain, lung, spleen, liver and thymus). This report provides the first evidence for transplacental transmission of T. gondii in a chronically infected wild sea otter, and the first molecular and immunohistochemical confirmation of concurrent transplacental transmission of T. gondii and S. neurona in any species. Repeated fetal and/or neonatal losses in the sea otter dam also suggested that T. gondii has the potential to reduce fecundity in chronically infected marine mammals through parasite recrudescence and repeated fetal infection.

The literature contains many examples of changes induced by parasites in the behaviour and/or other phenotypic traits of insects. From an evolutionary perspective, the nature of these changes is usually difficult to assess. Parasite-induced changes in host behaviour can be adaptations of either host or parasite, or they can be mere pathological consequences of infection. Of the many criteria and experimental tests necessary to distinguish between adaptations and non-selected consequences, two are particularly important: the demonstration of fitness benefits for either host or parasite associated with the behavioural change, and the elucidation of the proximate mechanism responsible for the behavioural change. Another approach can serve to identify adaptive changes in behaviour: mapping specific behavioural alterations on a phylogeny of either hosts or parasites. The usefulness of this approach is illustrated with two examples, acanthocephalan- cockroach associations and insect-fungus associations. The adaptive nature of parasite-induced behavioural changes will always be difficult to evaluate because they are the product of two distinct but interacting genotypes. However, experimental and phylogenetic approaches can provide valuable insights into the evolutionary history of insect-parasite interactions.

The available chemotherapeutics for the cure of visceral leishmaniasis (VL) are linked with many detrimental effects. Moreover, VL is associated with the suppression of protective Th1 immune response of the host and induction of disease exaggerating Th2 immune response. Therefore, there is an urgent requirement of therapeutics which can augment the immune status of the host to cure this disease. In the current investigation, the antileishmanial potential of lupeol was monitored in vitro and in vivo in inbred BALB/c mice against Leishmania donovani. Lupeol showed potent antipromastigote activity via arresting parasites at sub G0/G1 phase in vitro. Lupeol significantly decreased the splenic parasite burden by inducing strong delayed-type hypersensitivity responses in contrary to untreated infected animals. The therapeutic efficacy of lupeol was observed to be similar to the reference drug, AmB. Treatment of infected animals with lupeol depicted enhanced levels of T cells and Th1 cytokines in contrast to only infected controls. Further lupeol treatment upregulated the levels of nuclear factor κ B and nitric oxide synthase genes and elevated the production of reactive oxygen species and nitric oxide. Unlike AmB, lupeol-treated infected animals did not show any toxicity. These findings are promising and indicate that lupeol can serve as a prototype drug for the cure of VL.

Factors affecting survival of parasites introduced to new geographical regions include changes in environmental temperature. Protopolystoma xenopodis is a monogenean introduced with the amphibian Xenopus laevis from South Africa to Wales (probably in the 1960s) where low water temperatures impose major constraints on life-cycle processes. Effects were quantified by maintenance of eggs from infections in Wales under controlled conditions at 10, 12, 15, 18, 20 and 25°C. The threshold for egg viability/ development was 15°C. Mean times to hatching were 22 days at 25°C, 32 days at 20°C, extending to 66 days at 15°C. Field temperature records provided calibration of transmission schedules. Although egg production continues year-round, all eggs produced during >8 months/ year die without hatching. Output contributing significantly to transmission is restricted to 10 weeks (May–mid-July). Host infection, beginning after a time lag of 8 weeks for egg development, is also restricted to 10 weeks (July–September). Habitat temperatures (mean 15·5°C in summer 2008) allow only a narrow margin for life-cycle progress: even small temperature increases, predicted with ‘global warming’, enhance infection. This system provides empirical data on the metrics of transmission permitting long-term persistence of isolated parasite populations in limiting environments.

The size of the infecting inoculum may influence the severity of malaria, but evidence is scarce. Malaria therapy records provide a unique source of information on induced malaria in people. The therapy was given to large numbers of neurosyphilis patients and the malaria was left untreated as long as possible. Data from patients treated at the Horton Hospital, Epsom 1923–60 with a single strain of vivax malaria were analysed to assess the influence of inoculum size on severity of disease. Malaria was induced by mosquito bite, blood inoculation or direct sporozoite inoculation. The different measures of inoculum size were inversely correlated with pre-patent period, as expected. Overall, information was available on a total of 563 non-immune patients who were not treated during the first 5 days of patent parasitaemia. No strong or consistent relationships were found between measures of inoculum size and any of the measures of severity used: neither parasitaemia levels, nor peak fevers, nor number of paroxysms of fever. In the largest data set, longer pre-patent periods were associated with tertian fever, spontaneous recovery and less use of modifying treatment. Difficulties in interpreting the results are discussed, particularly with respect to misclassification of both exposure and outcome variables. While an inoculum size-severity relationship cannot be ruled out, a strong relationship is very unlikely.

The present study aims to evaluate the antiparasitic activity of active components from Costus speciosus against Ichthyophthirius multifiliis. Bioassay-guided fractionation was employed to identify active compounds from C. speciosus yielding 2 bioactive compounds: Gracillin and Zingibernsis newsaponin. In-vitro assays revealed that Gracillin and Zingibernsis newsaponin could be 100% effective against I. multifiliis at concentrations of 0·8 and 4·5 mg L−1, with median effective concentration (EC50) values of 0·53 and 3·2 mg L−1, respectively. All protomonts and encysted tomonts were killed when the concentrations of Gracillin and Zingibernsis newsaponin were 1·0 and 5·0 mg L−1. In-vivo experiments demonstrated that fish treated with Gracillin and Zingibernsis newsaponin at concentrations of 1·0 and 5·0 mg L−1 carried significantly fewer parasites than the control (P<0·05). Mortality of fish did not occur in the treatment group (Zingibernsis newsaponin at 5·0 mg L−1) during the trial, although 100% of untreated fish died. Acute toxicities (LD50) of Gracillin and Zingibernsis newsaponin for grass carp were 1·64 and 20·7 mg L−1, respectively. These results provided evidence that the 2 compounds can be selected as lead compounds for the development of new drugs against I. multifiliis.

Arid zones of northern Venezuela are represented by isolated areas, important from an ornithological and ecological perspective due to the occurrence of restricted-range species of birds. We analysed the prevalence and molecular diversity of haemosporidian parasites of wild birds in this region by screening 527 individuals (11 families and 20 species) for parasite mitochondrial DNA. The overall prevalence of parasites was 41%, representing 17 mitochondrial lineages: 7 of Plasmodium and 10 of Haemoproteus. Two parasite lineages occurred in both the eastern and western regions infecting a single host species, Mimus gilvus. These lineages are also present throughout northern and central Venezuela in a variety of arid and mesic habitats. Some lineages found in this study in northern Venezuela have also been observed in different localities in the Americas, including the West Indies. In spite of the widespread distributions of some of the parasite lineages found in northern Venezuela, several, including some that are relatively common (e.g. Ven05 and Ven06), have not been reported from elsewhere. Additional studies are needed to characterize the host and geographical distribution of avian malaria parasite lineages, which will provide a better understanding of the influence of landscape, vector abundance and diversity, and host identity on haemosporidian parasite diversity and prevalence.

A study has been carried out to determine whether the action of triclabendazole (TCBZ) against the liver fluke, Fasciola hepatica is altered by inhibition of the cytochrome P450 (CYP 450)-mediated drug metabolism pathway. The Oberon TCBZ-resistant and Cullompton TCBZ-susceptible fluke isolates were used for these experiments, the basic design of which is given in the paper by Devine et al. (2010a). Piperonyl butoxide (PB) was the CYP P450 inhibitor used. Morphological changes resulting from drug treatment and following metabolic inhibition were assessed by means of transmission electron microscopy. After treatment with either TCBZ or TCBZ.SO on their own, there was greater disruption to the TCBZ-susceptible than TCBZ–resistant isolate. However, co-incubation with PB+TCBZ, but more particularly PB+TCBZ.SO, led to greater changes to the TCBZ-resistant isolate than with each drug on its own, with blebbing of the apical plasma membrane, severe swelling of the basal infolds and their associated mucopolysaccharide masses in the syncytium and flooding in the internal tissues. Golgi complexes were greatly reduced or absent in the tegumental cells and the synthesis and production of secretory bodies were badly disrupted. The mitochondria were swollen throughout the tegumental system and the somatic muscle blocks were disrupted. With the TCBZ-susceptible Cullompton isolate, there was a limited increase in drug action following co-incubation with PB. The results provide evidence that the condition of a TCBZ-resistant fluke can be altered by inhibition of drug metabolism. Moreover, they support the concept that altered drug metabolism contributes to the mechanism of resistance to TCBZ.

Each transmission event in complex, multi-host life cycles create obstacles selecting for adaptations by trematodes. One such adaptation is life cycle abbreviation through progenesis, in which the trematode precociously matures and reproduces within the second intermediate host. Progenesis eliminates the need for the definitive host and increases the chance of life cycle completion. However, progenetic individuals face egg-dispersal challenges associated with reproducing within metacercarial cysts in the tissues or body cavity of the second intermediate host. Most progenetic species await host death for their eggs to be released into the environment. The present study investigated temporal variation of progenesis in Stegodexamene anguillae in one of its second intermediate fish hosts and the effect of the fish's reproductive cycle on progenesis. The study involved monthly sampling over 13 months at one locality. A greater proportion of individuals became progenetic in the gonads of female fish hosts. Additionally, progenesis of worms in the gonads was correlated with seasonal daylight and temperature changes, major factors controlling fish reproduction. Host spawning events are likely to be an avenue of egg dispersal for this progenetic species, with the adoption of progenesis being conditional on whether or not the parasite can benefit from fish spawning.

For Isospora (Protozoa: Eimeriidae) parasites of passerine birds, diurnal periodicity of oocyst output is a well-described phenomenon. From the temporal zone to the tropics, oocyst production is correlated with the light-dark cycle, peaking in the afternoon hours. However, nothing is known about the existence of diurnal periodicity of these parasites in the birds of High Arctic environments, under permanent light during summer. We sampled free-ranging Snow Bunting (Aves: Passeriformes), on Svalbard in summer and tested oocysts output of Isospora plectrophenaxia. Here we show that under the permanent light conditions of Arctic summer in the wild, Isospora plectrophenaxia, a parasite of the Snow Bunting, still keeps the 24-h rhythm of oocyst output with the peak in the post-meridiem hours, despite the absence of diurnal periodicity in host's activity. Our findings prove the ability of avian Isospora to invoke alternative cues for synchronizing the circadian rhythms. Possible cues and adaptive significance of diurnal periodicity of parasite output in High Arctic are discussed. The maintenance of synchronization and timing of the parasite life-cycle stages is under positive selection pressure even in permanent daylight in the Arctic.

1. The development of resistance to proguanil and pyrimethamine was studied in a clone of Plasmodium gallinaceum (strain A) derived from a single erythrocytic parasite and maintained by a standard method of serial inoculations in young chicks.

2. The rate of the development of resistance to 0·05 mg./20 g. doses of proguanil was compared in strains maintained by inocula of 5 × 107, 108 and 109 parasites. Some evidence was obtained that the rate of the development of resistance to the drug was related to the numbers of parasites in the inocula.

3. No correlation was observed between the rate of the development of resistance to pyrimethamine and the size of the population of parasites exposed to its action in strains treated with 0·001 g./20 g. doses of the drug and maintained by inocula of 5 × 107 parasites or 109 parasites; but a greater variability was observed in the rate in the strains maintained by the small inocula than in the strains maintained by the large inocula. Resistance appeared to develop sporadically.

4. Some evidence was obtained that strains treated with a high dose of pyrimethamine (0·05 mg./20 g.) might become more sensitive to the drug as a result of treatment. In three experiments the infections were eradicated by the second or third course of treatment with the drug. However, strains which withstood this dose, developed resistance as rapidly, or more rapidly than those treated with 0·001 mg./20 g. doses. There was therefore no evidence from these experiments with pyrimethamine that resistance to the drug could be produced more readily with small than with large doses of the drug.

5. Except for slight variations, resistance to proguanil developed concurrently with resistance to pyrimethamine in strains treated with that drug.

6. In many of the strains, whether treated with proguanil or with pyrimethamine, resistance appeared to develop quite suddenly, but in others it developed more gradually. The pattern of the development of resistance in strains treated with either of these drugs could be explained by the selection of spontaneously occurring mutants, though some of the data suggested that the mutants differed in degree of resistance to the drug.

7. The rate of development of resistance to pyrimethamine was studied in strains derived from primary inocula composed of known numbers of pyrimethamine resistant parasites and 5 × 107 parasites of the untreated strain A. The addition of at least 106 resistant parasites to the inoculum was required to produce an increase in parasitaemia during the subsequent course of treatment with the drug, but the addition of 102 resistant parasites or, in some experiments, fewer than 102 resistant parasites to the primary inoculum was sufficient to produce a heavy parasitaemia during the second serial course of treatment if the strain was maintained by the standard method (p. 496). When these results are compared with the pattern of the development of resistance to pyrimethamine in the strains treated with that drug, it can be concluded that only in one strain was there any evidence that resistant parasites were present in the primary inoculum when it consisted only of parasites of the untreated parent strain. The rate of development of resistance in many of the strains treated with either proguanil or pyrimethamine suggested a mutation rate of a low frequency.