Fasciola hepatica and Fasciola gigantica habitually co-exist as parasites of cattle (Bos taurus) and water buffalo (Bubalus bubalis), and despite variation in their morphometry, their species status is suspicious. Liver flukes isolated from cattle and water buffalo were initially sorted as F. gigantica or F. hepatica, and crude proteins were extracted and subjected to SDS-PAGE. Cattle had the preponderance of F. gigantica, while F. hepatica was the dominant species in water buffaloes. Co-existing cattle and bubaline fasciolids revealed similar protein profile suggestive of a close genetic relationship. The distinct heavy bands shared by co-existing bubaline F. hepatica and F. gigantica relative to those detected in cattle fasciolids suggests a host species-related influence. Between cattle and bubaline F. hepatica, six bands (220kDa, 150kDa, 115kDa, 67kDa, 34-37kDa, 30kDa) were bubaline-specific; between cattle and bubaline F. gigantica, four bands (212kDa, 150kDa, 70kDa, 30kDa) were bubaline-specific, while only three bands were shared (150kDa, 67-70kDa, 30kDa) by bubaline F. hepatica and F. gigantica. Current molecular findings represent the first in the country, where fascioliasia is prevalent. Confirmation of these results entails protein profiling of extracts of freshly-collected individual worms alongside extracts of infected and non-infected liver tissue samples, to mark out host-derived proteins. Its surveillance in susceptible host species in farms around the country, jointly with analysis of morphological and morphometric data of co-existing fasciolid species is highly recommended.

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Oligomannose-coated liposome (OML)-based vaccines have been reported to induce Th1-based immunity against entrapped antigens in immunized animals and to show protective effects against several protozoal diseases. In the present study, we produced a recombinant Babesia rodhaini ribosomal phosphoprotein P0 (rBrP0) that showed immunological cross reactivity with another rodent Babesia parasite, B. microti. We evaluated the efficacy of vaccination with OML-entrapped rBrP0 on B. rodhaini and B. microti infections in mice. Prior immunization with the OML-based rBrP0 vaccine, or with a Freund’s adjuvant-based rBrP0 vaccine, failed to demonstrate any protective effect against lethal infection with B. rodhaini, but the OML-based vaccine did induce protective immunity against B. microti infection, based on a reduction in peak parasitemia levels and prompt clearance of the parasite, compared with control mice. OML might be an effective adjuvant for future vaccines aimed at the control of severe domestic babesioses.

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Aflatoxins are known to alter the pathogenesis of many infectious diseases, but such effects have not been evaluated in trypanosome infections. The aim of the present work was to assess the effects of aflatoxin B1 on the pathogenesis of Trypanosoma brucei rhodesiense infection using a murine model. Mice fed on 0.50 mg/kg aflatoxin b. wt. were infected with T. b. rhodesiense and compared to trypanosome infected and uninfected aflatoxin-fed controls. The clinical and pathological changes were determined and the quantitative data statistically analysed using standard methods. The results showed that infected aflatoxin-fed mice had pronounced dyspnoea, significantly (P<0.05) reduced survival, extreme emaciation, pronounced macrocytic normochromic anaemia characterized by significantly (P<0.05) reduced red cell count, packed cell volume, haemoglobin levels and significantly (P<0.05) increased mean corpuscular volume compared to controls. Grossly, there were pronounced hydrothorax and ascites while histologically, haemorrhages, thrombosis, embolism, massive peri-vascular inflammatory cell infiltration were observed in the infected aflatoxin-fed mice. Severe anaemia, liver damage, nephritis and pancarditis were the major complicating factors which could have caused reduced host survival. It was concluded that aflatoxicosis aggravated the pathogenesis of T. b. rhodesiense infection in mice, and should therefore be taken into consideration during trypanosomosis control programs.

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Recently, Babesia bovis genome project identified a novel gene, which is homologous to the gene encoding sporozoite P36 antigen in Plasmodium parasites. In the present study, we isolated the P36 homologous gene from the genomic DNA of B. bovis and designated it as the BvP36 gene. The sequence of the BvP36 gene was identical to that reported previously. This gene was expressed in an Escherichia coli system to produce a recombinant protein (rBvP36). The rBvP36 protein was produced as a highly soluble form in E. coli and was detected by western blot analyses of sera collected from cattle experimentally infected with B. bovis and B. bigemina merozoites. In indirect immunofluorescence tests, sera collected from mice immunized with rBvP36 showed strong reactions to both B. bovis and B. bigemina merozoites. Our results indicate that the BvP36 antigen is expressed at least in the asexual merozoite stage of B. bovis and suggest that B. bigemina merozoite carries an antigen similar to BvP36.

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Apicidin, a histone deacetylase inhibitor, has a broad spectrum of anti-protozoal activities against apicomplexan parasites. In the present study, we evaluated the inhibitory effect of apicidin on the asexual growth of bovine Babesia parasites (B. bovis and B. bigemina) in vitro, as well as on the in vivo growth of B. microti in mice. The growth of B. bovis and B. bigemina was significantly inhibited in the presence of 3 ng/ml apicidin. Complete inhibition of B. bovis and B. bigemina growth was achieved on the fourth and third days, respectively, after treatment with 729 ng/ml apicidin. These parasites failed to grow again even when drug-free medium was substituted. The 50% inhibitory concentrations of apicidin against B. bovis and B. bigemina were determined as 7.1 and 20.7 ng/ml, respectively, in in vitro cultures with serum-containing M199 medium. Severe morphological signs of damage, such as pyknotic and degenerative changes, were observed in the treated parasites. Apicidin 2 mg/kg caused significant inhibition of B. microti growth and altered the parasitemia dynamics in mice, compared with untreated control mice. Apicidin could be an effective chemotherapeutic agent for the treatment of bovine and human babesioses.

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Clinical and pathological characterisation of blood stream (BSF) and cerebrospinal fluid (CSF) forms of Trypanosoma brucei rhodesiense trypanosome isolated from a sleeping sickness patient were investigated in rabbits. The study aimed at investigating whether there is any significant difference in clinical and pathological presentation in rabbits infected by the two forms of trypanosomes. Each form of parasite was inoculated into five rabbits at 10⁴ trypanosomes/ml while five rabbits were used as un-infected controls. Parasitaemia development, body temperature, packed cell volume (PCV), body weight, food and water intake, heartbeat and respiration were monitored daily for 30 days post infection when the experiment was terminated. Pathological changes were evaluated following euthanasia. All the infected rabbits became parasitaemic 6 days post infection (dpi) and the parasitaemia levels were significantly higher (p=0.01) for the BSF than the CSF infected rabbits. No significant difference was observed in heartbeat, respiration, food and water intake as well as PCV. However, CSF infected rabbits had a significantly (p=0.01) higher body temperature and weights than BSF infected rabbits. There was no major difference in the clinical manifestation of the disease caused by the two forms of parasite. However, temporary paralysis was observed around the left side of the neck in one rabbit infected with CSF trypanosomes whereas mucoid stool with the presence of amoeba cysts were observed in the rabbits infected with the BSF trypanosomes. The spleen weights of CSF infected rabbits was heavier (3.59 ± 1.13 grams) than the BSF infected rabbits (2.92± 0.78 grams). The proportions of monocytes were significantly higher (p<0.05) in the CSF infected rabbits while neutrophils proportions were significantly higher (p<0.05) in the BSF infected rabbits. The rest of the haematological changes were not significantly different. Results from this study demonstrate that BSF trypanosomes appeared relatively more virulent than the CSF trypanosomes. It would be important to carry out similar studies using a higher number of both BSF and CSF trypanosomes isolated from the same patient and different patients to authenticate this observation.

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A fragment of a novel gene, designated as the BboP67 gene, of Babesia bovis, which had been recently reported as a homolog of the gene encoding a sporozoite-specific P67 antigen of Theileria parva, was isolated from the genomic DNA of B. bovis and expressed as a recombinant (rBboP67) in E. coli. The antigenicity of rBboP67 was evaluated using 102 and 68 field serum samples collected from cattle in Ghana and Mongolia, respectively. All of the B. bovis- and B. bigemina-infected sera, which had been identified by the species-specific antigens, rRAP-1/CTs, for B. bovis and B. bigemina in the standard ELISA, positively reacted with the rBboP67 in ELISA. While B. bovis-infected field serum samples recognized the rBboP67 in Western blot analysis, sera collected from the experimentally infected cattle with B. bovis merozoites failed to react to it. IFAT analysis conducted with polyclonal antisera collected from the immunized mice with rBboP67 did not show any positive reaction to the B. bovis merozoites. These results indicate that the p67 homolog is not expressed in merozoite stage but is likely expressed in sporozoites; they also suggest that the antigen might be relatively conserved among different isolates of B. bovis and, at least, several epitopes of the antigens might be shared between B. bovis and B. bigemina sporozoites.

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