Artificially induced Trypanosoma brucei brucei infection in Lagune and Borgou cattle in Benin.

Lagune (n = 10) and Borgou (n = 10) cattle of Benin were inoculated subcutaneously with Trypanosoma brucei brucei AnTat, 1.1E. Clinical signs, packed cell volume (PCV), parasitaemia, specific trypanolytic antibodies and haemolytic complement were monitored to evaluate the between-and-within breed variations. All the animals showed only transitory symptoms with clinical recovery within 20 days post infection. Infected animals showed a moderate drop in PCV after 5-10 days of infection. The drop in PCV at day 20 was 2.9 +/- 2.7% for Borgou and 1.2 +/- 1.8% for Lagune. Except two animals of Borgou breed, all animals developed detectable parasitaemia. Two peaks of parasitaemia, the first on day 5-6 and the second on day 9-10 post infection, were observed. Parasitaemia persisted for 25 days in two Borgou and one Lagune cattle. There were large individual variations in PCV and parasitaemia. AnTat 1.1 specific trypanolytic antibodies were detected from day 6-7 in all animals, except one Borgou and they persisted until the end of observation on day 30. A drop in serum haemolytic complement occurred corresponding to the first parasitaemic waves. After day 15, complement level was restored rapidly largely exceeding the initial values of day 0. The results indicate that all the artificially infected individuals belonging to the Borgou breed as well as to the better known Lagune breed are tolerant to Trypanosoma brucei brucei infection.

[Detection of blood antigens in Trypanosoma brucei brucei experimental infection in Boru, Lagoon cattle and Boro white zebus]. / Détection d'antigènes circulants au cours d'une infection expérimentale à Trypanosoma brucei brucei chez des bovins Borgou, Lagunaire et zébus Bororo blancs.

Borgu (n = 10), Lagoon (n = 10) and White Bororo zebu (n = 10) cattle were experimentally infected in Benin with a clone of Trypanosoma brucei brucei for evaluation of blood antigens using ELISA tests. None of the three non-inoculated control animals for each breed developed any infection. Borgu and Lagoon cattle developed a benign disease followed by spontaneous recovery, whereas White Bororo zebus developed a typical chronic disease, fatal within several months. Overall ELISA sensitivity to detect T. brucei antigens was 20.46%, clearly lower than that of the buffy coat method to detect parasites (40.24%). The sensitivity of ELISA tests differed greatly according to the type of animals and the dynamics of infection. It was highest in Borgu cattle. (44.44 %), which had high parasitaemias of short duration and lowest in White Bororo zebus (4.09%), which had low and intermittent parasitaemias. To increase the sensitivity of ELISA tests by decreasing the cut-off point of optical density (threshold of positivity) from 0.050 to 0.025 would highly compromise the test specificity. The false negatives at the beginning of the infection and false positives after spontaneous cure further compromise the validity of ELISA tests for diagnosis of active T. brucei infections.

[Serological evidence of the existence of a wild reservoir of Trypanosoma brucei gambiense in the Pendjari biosphere reservation in the Republic of Benin]. / Indications sérologiques de l'existence d'un réservoir sauvage du Trypanosoma brucei gambiense dans la réserve de la biosphère de la Pendjari en République du Bénin.

In the national park of Pendjari, situated in the North-West of Benin, 91 wild animals, belonging to seven species, were darted. Thick and thin blood smears were examined for trypanosomes and plasma for trypanolytic antibodies against 6 antigenic variants of Trypanosoma brucei gambiense. Parasites were found in 13.92% and trypanolytic antibodies in 20.88% of the samples. A total of 28.57% of animals were positive by at least one of the two test systems used. Morphologically Trypanosoma congolense, T. vivax and T. brucei were identified. Overall prevalence was 40% in Adenota kob (n: 50), 13.63% in Alcelaphus buselaphus (n: 22), 10% in Hippotragus equinus (n: 10), 33% in Kobus defassa (n: 3), 0% in Phacochoerus aethiopicus (n: 3) and in Syncerus caffer (n: 2). The only lion (Panthera leo) examined was serologically positive. The results indicate that the wild animals are reservoirs of animal trypanosomes and suggest that among them Adenota kob and Panthera leo are carriers of T. brucei gambiense, one of the etiological aspects of human trypanosomiasis.

Trypanosomiasis in different breeds of cattle from Benin.

Blood of different breeds of cattle, namely Lagune from the Atlantic province, Borgou and Borgou x Zebu from the Borgou province, and Somba and Zebu from the Atacora province of Benin, were examined for trypanosome infection. Thick and thin blood smears for trypanosomes, the card agglutination test (CATT), indirect immunofluorescent antibody test (IFAT) and trypanolytic test for antibodies to trypanosomes were used. Trypanosomes were detected in 19.3% (range 9.8-31.4%) of animals by examination of blood smears; antibodies to trypanosomes were found in 89.8% (range 88.4-100%) of samples by IFAT, 50.6% (range 34-87.5%) by CATT and 3.4% (range 1.1-7.1%) by trypanolytic test. Trypanosoma vivax and Trypanosoma congolense were the main species in Benin with a low number of Trypanosoma brucei. Zebu had lower infection rates than trypanotolerant breeds of Benin. The infection rates of various trypanotolerant breeds were not significantly different.

[Results of vaccination with the hepatitis B vaccine in patients and personnel at the Hemodialysis Center in Karlovac]. / Rezultati cijepljenja hepatitis B vakcinom bolesnika i osoblja Centra za dijalizu u Karlovcu.

Hepatitis B remains a significant risk to patients and staff members of hemodialysis unit. Prior to immunization, 38 hemodialysis patients and 24 staff members were screened for HBs antigen, HBc antibodies and HBs antibodies using ELISA method (Abbott). Of 18 (47%) patients, five were chronic carriers of HBsAg and 13 had anti-HBs and anti-HBc while anti-HBs and anti-HBc were found in four (17%) members of medical staff. A total of 20 (53%) susceptible patients (mean 51.2 years) and 19 (79%) susceptible staff members (mean 28.1 years) received hepatitis B vaccine (H-B-VAX, Merck, Sharp and Dohme). Between patients were four (20%) non-responders and seven (35%) low-responders while among medical staff were two (10.5%) non-responders and one (5.2%) low responder only. The geometric mean titer of anti-HBs was 724 IU/L in patients and 3407 IU/L in staff members. Non-responders (5 of 6) who were given a fourth vaccine dose also failed to mount an antibody response. In none of vaccinated patients antibody to human immunodeficiency virus (HIV-1) occurred in their sera three and six months after complete vaccination. Consideration should be given to a prevaccinal screening of presumptive vaccinees between patients and staff members of hemodialysis units because of high level of preexisting HBV infection among them. The data suggest a high non-responder and low-responder rate in vaccinated hemodialysis patients and serial surveillance for anti-HBs is warranted especially in persons aged over 40 years. Additional booster dose or some doses of HB vaccine should be given to low-responders and they should be retested thereafter. Non-responders still remain the unresolved problem.