The causative agent of urogenital schistosomiasis, Schistosoma haematobium, was thought to be the only schistosome species transmitted through Bulinus snails on Unguja and Pemba Island (Zanzibar, United Republic of Tanzania). For insights into the environmental risk of S. haematobium transmission on Pemba Island, malacological surveys collecting Bulinus globosus and B. nasutus, two closely related potential intermediate hosts of S. haematobium were conducted across the island in November 2016. Of 1317 B. globosus/B. nasutus collected, seven B. globosus, identified through sequencing a DNA region of the mitochondrial cytochrome oxidase subunit 1 (cox1), were observed with patent infections assumed to be S. haematobium. However, when the collected cercariae were identified through sequencing a region of the cox1 and the nuclear internal transcribed spacer (ITS1 + 2), schistosomes from five of these B. globosus collected from a single locality were in fact S. bovis. The identified presence of S. bovis raises concerns for animal health on Pemba, and complicates future transmission monitoring of S. haematobium. These results show the pertinence for not only sensitive, but also species-specific markers to be used when identifying cercariae during transmission monitoring, and also provide the first molecular confirmation for B. globosus transmitting S. bovis in East Africa.

Entamoeba histolytica is an enteric parasite that infects approximately 50 million people worldwide. Although E. histolytica is a zoonotic parasite that has the potential to infect nonhuman primates, such transmission is poorly understood. Consequently, this study examined whether E. histolytica is present among humans, chimpanzees and baboons living in the Greater Gombe Ecosystem (GGE), Tanzania. The primary aims were to determine patterns of E. histolytica infection in a system with human-nonhuman primate overlap and to test associations between infection status and potential risk factors of disease. Entamoeba spp. occurred in 60.3% of human, 65.6% of chimpanzee and 88.6% of baboon samples. Entamoeba histolytica occurred in 12.1% of human, 34.1% of chimpanzee and 10.9% of baboon samples. Human E. histolytica infection was associated with gastrointestinal symptoms. This was the first study to confirm the presence of E. histolytica in the GGE. The high sample prevalence of E. histolytica in three sympatric primates suggests that zoonotic transmission is possible and stresses the need for further phylogenetic studies. Interventions targeting better sanitation and hygiene practices for humans living in the GGE can help prevent E. histolytica infection in humans, while also protecting the endangered chimpanzees and other primates in this region.

Carbon dioxide (CO2) is an important sensory cue for many animals, including both parasitic and free-living nematodes. Many nematodes show context-dependent, experience-dependent and/or life-stage-dependent behavioural responses to CO2, suggesting that CO2 plays crucial roles throughout the nematode life cycle in multiple ethological contexts. Nematodes also show a wide range of physiological responses to CO2. Here, we review the diverse responses of parasitic and free-living nematodes to CO2. We also discuss the molecular, cellular and neural circuit mechanisms that mediate CO2 detection in nematodes, and that drive context-dependent and experience-dependent responses of nematodes to CO2.

With increasing resistance to anti-parasitic drugs, it has become more important to detect and recognize phenotypes of resistant isolates. Molecular methods of detecting resistant isolates are limited at present. Here, we introduce a microfluidic bioassay to measure phenotype using parameters of nematode locomotion. We illustrate the technique on larvae of an animal parasite Oesophagostomum dentatum. Parameters of sinusoidal motion such as propagation velocity, wavelength, wave amplitude, and oscillation frequency depended on the levamisole-sensitivity of the isolate of parasitic nematode. The levamisole-sensitive isolate (SENS) had a mean wave amplitude of 135 μm, which was larger than 123 μm of the levamisole-resistant isolate (LEVR). SENS had a mean wavelength of 373 μm, which was less than 393 μm of LEVR. The mean propagation velocity of SENS, 149 μm s−1, was similar to LEVR, 143 μm s−1. The propagation velocity of the isolates was inhibited by levamisole in a concentration-dependent manner above 0·5 μm. The EC50 for SENS was 3 μm and the EC50 for LEVR was 10 μm. This microfluidic technology advances present-day nematode migration assays and provides a better quantification and increased drug sensitivity. It is anticipated that the bioassay will facilitate study of resistance to other anthelmintic drugs that affect locomotion.

The respiratory chain of the procyclic stage of Trypanosoma brucei contains the standard complexes I through IV, as well as several alternative enzymes contributing to electron flow. In this work, we studied the function of an alternative NADH : ubiquinone oxidoreductase (NDH2). Depletion of target mRNA was achieved using RNA interference (RNAi). In the non-induced and RNAi-induced cell growth, membrane potential change, alteration in production of reactive oxygen species, overall respiration, enzymatic activities of complexes I, III and/or IV and distribution of NADH : ubiquinone oxidoreductase activities in glycerol gradient fractions were measured. Finally, respiration using different substrates was tested on digitonin-permeabilized cells. The induced RNAi cell line exhibited slower growth, decreased mitochondrial membrane potential and lower sensitivity of respiration to inhibitors. Mitochondrial glycerol-3-phosphate dehydrogenase was the only enzymatic activity that has significantly changed in the interfered cells. This elevation as well as a decrease of respiration using NADH was confirmed on digitonin-permeabilized cells. The data presented here together with previously published findings on complex I led us to propose that NDH2 is the major NADH : ubiquinone oxidoreductase responsible for cytosolic and not for mitochondrial NAD+ regeneration in the mitochondrion of procyclic T. brucei.

The calcium-dependent protein kinases (CDPKs) are unique enzymes found only in plants, green algae, ciliates and apicomplexan parasites. In this study, a novel CDPK gene of Eimeria tenella, designed EtCDPK3, was cloned using rapid amplification of cDNA ends (RACE) based on the expressed sequence tag (EST). The entire cDNA of EtCDPK3 contained 1637 nucleotides encoding 433 amino acids and the deduced EtCDPK3 protein had canonical characteristic domains identified in other CDPKs, including a well-conserved amino-terminal kinase domain and a carboxy-terminal calmodulin-like structure with 4 EF-hand motifs for calcium binding. The expression profiles of the EtCDPK3 gene in different development stages were investigated by real-time quantitative PCR. Messenger RNA levels from the EtCDPK3 gene were higher in sporozoites than in other stages (unsporulated oocysts, sporulated oocysts and merozoites). Western blot analysis showed that rabbit antiserum against recombinant EtCDPK3 could recognize a native 49 kDa protein band of parasite. Indirect immunofluorescent antibody labelling revealed dispersed localization of EtCDPK3 during the first schizogony and intense specific staining. EtCDPK3 was located at the apical end of the sporozoites after early infection of DF-1 cells and the protein was highly expressed. Inhibition of EtCDPK3 function using specific antibodies reduced the ability of E. tenella to invade host cells. These results suggested that EtCDPK3 may be involved in invasion and survival of the parasite intracellular stages of E. tenella. Because this kinase family is absent from hosts, it represents a valid target that could be exploited for chemotherapy against Eimeria spp.

Acetylcholinesterase (AChE) has been purified from the excretory/secretory (ES) products of Trichostrongylus colubriformis (using edrophonium chloride linked to epoxy-activated Sepharose) with yields of 40–50%. Purity was confirmed by polyacrylamide gel electrophoresis (using silver [protein] and Karnovsky [activity] stains) and measurement of specific AChE activity. Further analysis of the purified fractions by gel filtration and sucrose density gradient techniques revealed the existence of 2 forms of hydrophilic AChE (Mr 189 and 80 kDa). From the data we deduce these to be the globular monomer and dimer, G1 and G2 forms of AChE. Inhibition studies using BW284C51, iso-OMPA and excess substrate, along with substrate specificity studies, show both forms to be true acetylcholinesterases. We are currently assessing the protective immunogenicity of purified AChE in sheep.

For normal development of the parasites, Eimeria acervulina and E. tenella in the chicken, dietary thiamine, riboflavin, biotin, nicotinic acid and folic acid are required. E. acervulina required thiamine for second schizogony and sporulation; riboflavin for first schizogony and possibly gametogony, biotin for the development of the sporozoites/trophozoites and for gametogony, and nicotinic acid for schizogony and gametogony. E. tenella required thiamine and riboflavin for gametogony; biotin for first schizogony; and nicotinic acid for second schizogony.

The human hookworm Necator americanus appears to have evolved a number of complementary strategies to overcome the host's haemostatic processes. These include the inhibition of blood coagulation, platelet aggregation and mediator release, and the secretion of fibrinogenolytic enzymes. These strategies presumably allow the parasite to establish the chronic infections so often documented in human populations.

In the present paper seven species of cymothoid isopods parasitic on the marine fishes of the Kerala coast are described. A preliminary diagnosis of three of them was published earlier (Pillai, 1954). Full descriptions of all the species are given below. The larval stages described were in all cases taken from the brood pouch. The present work forms part of a thesis for which the author was awarded the Ph.D. Degree by the Kerala University.

Despite significant advances in therapies against Trypanosoma evansi, its effective elimination from the central nervous system (CNS) remains a difficult task. The incapacity of trypanocidal drugs to cross the blood–brain barrier (BBB) after systemic administrations makes the brain the main refuge area for T. evansi. Nanotechnology is showing great potential to improve drug efficacy, such as nerolidol-loaded nanospheres (N-NS). Thus, the aim of this study was to investigate whether the treatment with N-NS was able to cross the BBB and to eliminate T. evansi from the CNS. High-performance liquid chromatography revealed that N-NS can cross the BBB of T. evansi-infected mice, while free nerolidol (F-N) neither the trypanocidal drug diminazene aceturate (D.A.) were not detected in the brain tissue. Polymerase chain reaction revealed that 100% of the animals treated with N-NS were negatives for T. evansi in the brain tissue, while all infected animals treated with F-N or D.A. were positives. Thus, we concluded that nanotechnology improves the therapeutic efficacy of nerolidol, and enables the transport of its active principle through the BBB. In summary, N-NS treatment can eliminate the parasite from the CNS, and possesses potential to treat infected animals.

A drug-resistant strain of T. vivax was transmitted through a series of four duikers (S. grimmia) and a gazelle (G. rufifrons) by G. palpalis and G. tachinoides. The cyclical transmission of the strain in cattle, started in earlier work, was continued for control purposes. Infections with the drug-resistant strain in the antelope were of the same type as those produced by field strains of T. vivax in the same host species, and infection rates in tsetse flies fed at early stages of infection on the antelope were similar to those found in flies fed on cattle infected with the drug-resistant strain. The strain retained resistance to diminazene aceturate at a dose rate of 7-0 mg/kg and quinapyramine sulphate at 5'0 mg/kg in the absence of the drugs for 7 months in tsetse flies and antelope, and for a total period of 29 months in tsetse flies and cattle.

We wish to thank Dr A. A. Amodu, Director of the Nigerian Institute for Trypanosomiasis Research, for permission to publish this paper.

Rotylenchulus reniformis, Anguina agrostis and Meloidogyne javanica respond differently to gradients of chemical attractants. In chemotaxis assays performed on agarose plates, R. reniformis L2 larvae oriented their movement to several common inorganic salts, cyclic AMP and AMP, as well as to germinated host plant seeds. M. javanica L2 larvae were attracted to germinated seeds, but not to the salts tested, and A. agrostis dauer larvae were not strongly attracted to any of 12 different tested agents, including host root or shoot tips. Attraction of R. reniformis to salts was measured by comparing different pairwise combinations of ions at equivalent concentrations. The indicated order of attractiveness was: Cl− > Na+ > C2H3O2− > Mg2+, NH4+, SO42−. The least attractive salts, (NH4)2 SO4 and MgSO4, were weakly attractive at an orientation threshold of 1 mm, whereas the most attractive salt, MgCl2, was strongly attractive at a threshold of 0·2 mM Cl−. 3′, 5′ cyclic AMP was strongly attractive at a threshold of 0·05 mM, whereas 5′-AMP was a weak attractant. Some of these responses may affect the distribution of R. reniformis in its natural environment.

1. Permanent and temporary pastures were examined using a modification of Taylor's method.

2. The goodness of fit of Neyman's Contagious Distribution Type A when applied to larvae on pastures is discussed.

3. Examination of permanent pastures over a period of 3 years showed that the difference in time of maximum infestation was greater between fields in the same year than between years for the same field.

4. Counts made on pastures where disease had occurred showed reasonably close agreement with Taylor's estimate.

5. No larvae were detected on fields after ploughing and reseeding.

6. The number of larvae per lb. of herbage on reseeded pastures was low, but the growth of grass masked the fact that the total population was relatively high at the end of the season.

F1, Quackenbush (Q) × Wild (W) Mus musculus were assayed and selected for their level of immunity to secondary infections with 100 Nematospiroides dubius using faecal parasite egg counts. A significant positive linear correlation was found between the number of parasite eggs voided in the faeces and the number of N. dubius recovered after secondary infections in mice. Selection for immunity was not influenced by the conformation of the mice. High (H) and low (L) responder colonies together with a randomly (Rd) bred colony of mice were established over 5 generations. Adaptive immunity was more efficacious in protecting female than male mice and appeared to be controlled by a few dominant genes; the heritability (h2) of the trait was estimated at 0·56 for the parental stock and 0·55 for the F5 Rd colony and the realized heritability was 0·49. Higher anti-N. dubius antibody titres were detected in H than L mice. H mice harboured fewer and less fecund parasites than Rd colony mice; L mice had more worms with greater fecundities than Rd mice. The levels of primary infection in H and L mice related to the levels developed after secondary infection from F4. This suggested at least partial linkage of genes controlling innate with genes controlling adaptive immunity against N. dubius.

During the cyst formation of Trichinella spiralis, the infected muscle cell undergoes basophilic change and apoptosis, which results in nurse cell formation. This study revealed expression kinetics of some apoptosis genes such as p53 and its closely related genes (tumor suppressor genes p53, p53; mouse double minute 2, MDM2; cyclin-dependent kinase inhibitor p21, p21waf). RT-PCR (reverse transcription polymerase chain reaction) results showed that these genes were temporarily expressed in the infected muscles during the cyst formation period, but not in normal muscles (or very low if any), which suggested the involvement of these apoptosis genes in the nurse cell formation. Cysts and neighbouring muscle cells were separately collected and RT-PCR was performed, which suggested that p53 was expressed in the cysts. An immunocytochemical study showed that p53 was expressed in the nucleoplasm of basophilic cell in the cyst and Trichinella larvae, which suggested involvement of these apoptosis genes in the nurse cell formation. The same p53 expression kinetic study was performed on p53 knockout mice. The knockout mice did not express p53 genes, but expressed the other apoptosis genes in the same kinetics with only minor exceptions, suggesting that the expressions of these genes during the cyst formation were more or less p53-independent. There were no differences in the number and morphology of the cysts between the knockout mice and wild type mice. Thus apoptosis seen during the Trichinella cyst formation can be operated in the presence or absence of p53.

Acute toxoplasmosis was induced in mice, and interferon (IFN) production in serum and by spleen cells was evaluated during the infection period. Interferon was characterized by acid-treatment and anti-IFN-α/β neutralization. In order to verify the correlation between the unusual aspects of the IFN production and the induction of immunosuppression, splenocyte mitogen responsiveness was investigated concomitantly to IFN synthesis. The activity of Toxoplasma-induced serum IFN-α/β increased gradually throughout all post-infection days, but IFN-γ was not detected in the systemic circulation at any time during the infection. It was also observed that IFN-α/β production and the capacity to produce IFN-γ by spleen cells were closely and inversely correlated. As the infection progressed, more IFN-α/β was produced, and the ability of spleen cells to produce IFN-γ decreased. The observation that Toxoplasma-infected mice were concomitantly immunosuppressed (as documented by mitogen unresponsiveness and defective IFN-γ production) in direct correlation to IFN-α/β production, suggests that such IFN-α/β production is an important factor associated with acute toxoplasmosis-induced immunosuppression.

Borrelia crocidurae infection rates in different organs of adult Ornithodoros (Pavlovskyella) erraticus and O. (Ornithodoros) savignyi were studied at intervals during a 60-day period following an infective meal. The spirochaetes persisted in tick guts for 1 month, were first observed in other organs 1–7 days post-feeding, and persisted for 20–60 days in different organs. The ovaries, Gene's organ, testes and male accessory glands of only O. erraticus were infected. The infection rates in adult and immature O. erraticus and O. savignyi post-feeding on infected hamsters were 26·7–60·0% and 26·7–80·0%, respectively. Spirochaete trans-stadial transfer from originally infected larval O. erraticus to first-instar nymphs (N1) was 33·3%; to subsequent N2–N5 it was 40·0–60·0%. Infection rates in the resulting adults were 26·7% (males) and 46·7% (females). In O. savignyi, trans-stadial transfer from originally infected N1 to N2 was 26·7% and to subsequent N3–N7 13·3–33·3%; of the resulting males and females, 20·0% were infected. Transovarial transmission from female O. erraticus infected as adults occurred after the second gonotrophic cycle to 33·3–53·3% of the F1 larvae, and to 26·7 and 46·7% of the F1 males and females, respectively. All infected F1 females transmitted the spirochaetes to 26·7–73·3% of the F2 larval progeny after the first gonotrophic cycle. Transovarial transmission was not observed in O. savignyi.

A cross-sectional study of bancroftian filariasis was conducted in 2 adjacent communities, Mvumoni and Kilore in Muhaka, Kwale District. Wuchereria bancrofti infection, clinical manifestations and anti-filarial IgG responsiveness were determined before the long rains, a time coinciding with a low transmission season. The prevalence of microfilaraemia increased gradually with age and was significantly higher in Kilore (24%) than in Mvumoni (6·3%, P<0·001). Similarly, the prevalence of antigenaemia increased with age and also was significantly higher in Kilore, 48·9% than in Mvumoni, 20·5% (P<0·001). Hydrocele, funiculitis, lymphangitis and lymphadenitis were also significantly more common in Kilore than in Mvumoni. In comparing the 2 communities, levels of IgG4 responsiveness in antigen-positive persons were higher in Kilore than Mvumoni (P=0·034), but this was related to higher antigen loads in persons in Kilore than in Mvumoni. In antigen-negative persons, anti-filarial antibodies of 3 IgG isotypes were significantly higher in Kilore than Mvumoni (P<0·001, for IgG1, IgG2, IgG4). These results emphasize the highly focal nature of bancroftian filariasis in this setting and demonstrate that anti-filarial antibody levels are related to transmission intensity.