Aggravation of pathogenesis mediated by ochratoxin A in mice infected with Trypanosoma brucei rhodesiense.

Mice fed 1.5 mg ochratoxin A (OTA) per kg body weight and infected with Trypanosoma brucei rhodesiense were compared with trypanosome-infected placebo-fed and uninfected OTA-fed controls. Uninfected OTA-fed mice showed fever, lethargy, facial and eyelid oedemas, mild hepatitis and nephritis, and high survival. Infected placebo-fed controls had mean pre-patent period (PPP) of 3.26 days, lethargy, dyspnoea, fever, facial and scrotal oedema, survival of 33-65 days, reduced red cell counts (RCC: 10.96-6.87x106 cells/microl of blood), packed cell volume (PCV: 43.19-26.36%), haemoglobin levels (Hb: 13.37-7.92 g/dL) and mean corpuscular volume (MCV) of 37.96-41.31 fL, hepatosplenomegaly, generalized oedemas, heart congestion, hepatitis and nephritis. Compared to infected placebo-fed controls, infected OTA-fed mice had significantly (P<0.05) shorter mean PPP (2.58 days), reduced survival (6-47 days), more pronounced fever and dyspnoea. The latter had significantly (P<0.05) reduced RCC (10.74-4.56x106 cells/microl of blood), PCV (43.90-20.78%), Hb (13.06-5.74 g/dL), increased MCV (39.10-43.97 fL), severe generalized oedemas, haemorrhages, congestion, hepatic haemosiderosis, hepatitis, nephritis, endocarditis, pericarditis and exclusively, splenic macrophage and giant cell hyperplasia, expanded red pulp and splenic erythrophagocytosis. It was concluded that OTA aggravated the pathogenesis of T. b. rhodesiense infection in mice, and should therefore be taken into consideration during trypanosomosis control programmes.

Knowledge, attitudes and practices regarding rabies and its control among dog owners in Kigali city, Rwanda.

BACKGROUND: Rabies is a zoonotic viral disease that can occur in all warm-blooded animals, including humans. Vaccinating dogs can protect people from contracting rabies. Rabies is a public health threat in Rwanda, but the country does not have information on the epidemiology of rabies. The present study aimed to understand the knowledge, attitudes and practices (KAP) of rabies and its control among dog owners in Kigali city of Rwanda. METHODS: We conducted a cross-sectional survey using a structured questionnaire among 137 dog owners selected from nine administrative study sites. A two-stage random sampling procedure was used to select the participants. Frequency distributions analysis and a series of chi-square tests of associations as well as binary logistic regressions were performed to determine the important factors associated with the response variables. RESULTS: The results showed that 99.5% of respondents knew at least a host susceptible to rabies. Only 22.4% and 21.3% knew that dogs and people can develop rabies, respectively. Nearly 73.6% knew that human rabies can be transmitted through dog-bites and 99% could identify at least a clinical sign of canine rabies. Overall, 81.8% knew that regular vaccination of dogs helps to prevent dog-transmitted human rabies and 43.1% and 26.3% were aware that rabies in humans and in dogs are fatal once clinical symptoms have shown, respectively. Only 69% would observe a dog for 10 days after it bites a man or an animal. Approximately 20.4% were familiar with appropriate cleaning of dog-bites wounds, and 20.6% knew that puppies could receive rabies vaccination before they are three months old. Of those who owned vaccinated dogs, 78% were happy about the cost (US $ ≤ 34) of rabies vaccination. Of all the respondents, 58% had their dogs vaccinated at home by veterinarians while 86% indicated their veterinarians kept rabies vaccines on ice in a cool box. Overall, 53% of the dog owners had sufficient knowledge of rabies, whilst 66% and 17% adopted adequate practices and positive attitudes towards rabies, respectively. Multivariable logistic regression analyses indicated that none of the respondents' sex, educational level, and the length of dog ownership were statistically associated with their knowledge, attitudes and practices of rabies. CONCLUSIONS: This study showed that majority of the dog owners had sufficient knowledge and adopted appropriate practices of rabies. However there exist some knowledge gaps among the dog owners particularly on treatment, transmission and control methods. Therefore, rabies awareness campaign is required to upgrade rabies knowledge of the dog owners on rabies prevention and control in Rwanda.

Application of immunoaffinity chromatography and enzyme immunoassay in rapid detection of aflatoxin B1 in chicken liver tissues.

Existing physicochemical analytical methods for the determination of aflatoxins in animal tissues are expensive, cumbersome, and hazardous. To offer an alternative to these methods, a novel and highly sensitive immunochemical method for the rapid detection of aflatoxin B1 (AFB1) in chicken liver tissues is described in this study. Liver tissues were homogenized with cold methanol-acetone (50:50), followed by AFB1 extraction with methanol-acetone-PBS (25:25:50). The tissue extracts were, with or without further purification by immunoaffinity chromatography (IAC), applied to a highly sensitive direct ELISA for determination of AFB1. The detection limits for this assay were 15 +/- 0.77 pg/mL when standards and samples were dissolved in methanol-PBS (10:90) and 17 +/- 2.0 pg/mL when methanol-acetone-PBS (5:5:90) solution was used. The average recoveries of AFB1 were 54.3 to 65.5% in artificially contaminated tissue samples at 1 to 5 ng/g. In samples spiked with AFB1 at 1 ng/g, the method had diagnostic sensitivity and specificity of 100% for samples processed with IAC and 91.7 and 100%, respectively, for samples without IAC purification. The test was successfully applied to the detection of AFB1 in liver tissues from chickens that were experimentally dosed with AFB1. It is hoped that this test will be applicable in rapid detection of aflatoxins in poultry meats and in diagnosis of aflatoxicosis in chicken.

Production of ultrasensitive antibodies against aflatoxin B1.

AIMS: To produce specific antibodies against the haptenic fungal toxin aflatoxin B1 (AFB1) and apply these antibodies in immunochemical assays for aflatoxins. METHODS AND RESULTS: Rabbits were immunized using an AFB1-bovine serum albumin conjugate and serum titres determined by double-antibody enzyme immunoassay. High titres of antibodies with very high affinity for AFB1 were obtained 15 and 4 weeks after the initial immunization and the first booster immunization respectively. The antibodies were employed in enzyme immunoassay (EIA) and immunoaffinity chromatography (IAC) methods for aflatoxins. With a detection limit of 15.8 pg ml(-1) for AFB1, the EIA employing these antibodies is the most sensitive test for AFB1 described so far. In IAC columns, these antibodies provided high binding capacity for all major aflatoxins, including AFB1, AFB2, AFG1 and AFG2. CONCLUSION: The antibodies described here are useful for the analysis of trace levels of aflatoxins. SIGNIFICANCE AND IMPACT OF THE STUDY: Polyclonal antibody-based EIA and IAC methods for aflatoxin analysis offer a suitable alternative to the more expensive monoclonal antibody-based methods.