Point mutations in mitochondrial topoisomerase enzymes of Trypanosoma congolense are not involved in isometamidium resistance.
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Animals↗
Biomedical subjects
D Geysen
Publications and source records attributed to D Geysen.
SSCP analysis of the P2 purine transporter TcoAT1 gene of Trypanosoma congolense leads to a simple PCR-RFLP test allowing the rapid identification of diminazene resistant stocks.
Analyses were made on a Trypanosoma congolense contig coding a putative P2-like nucleoside transporter (the contig was named in this study TcoAT1). The sequence includes a start and stop codon and presents a high similarity with the gene TbAT1 of T. brucei (Smallest Sum Probability 2.8e-136). To investigate a possible link between point mutations and diminazene aceturate (DA) resistance in mice, the TcoAT1 putative genes of 26 T. congolense strains, characterised for DA sensitivity in the single dose mouse test, were screened by means of the Single Strand Conformation Polymorphism technique (SSCP). Results showed that the SSCP profiles of 23 out of 26 (88.5%) T. congolense strains were confirmed by the sensitivity test in mice with the commonly accepted criterion for sensitivity to diminazene being a CD80 of 20mg/kg in the mouse test. The remaining T. congolense strains showed a resistant SSCP profile and relapsed in mice after treatment at doses lower than 20mg/kg indicating that the SSCP is more sensitive than the single dose mouse test for the detection of resistance to diminazene. However, none of the strains used in this study showed a sensitive SSCP profile while they were resistant in the single dose mouse test. The sequencing of the TcoAT1 gene of two sensitive, two intermediate and two resistant strains allowed the set up of a PCR-RFLP test for the discrimination between sensitive and resistant strains confirming the SSCP results for the 26 strains of this study.
Animals↗
Epidemiological studies on Theileriosis and the dynamics of Theileria parva infections in Rwanda.
An epidemiological analysis based on three country wide surveys was carried out to determine the prevalence of infections with Theileria spp. in Rwanda. In the 1998 dry season, a total of 264 blood samples were submitted to Theileria spp. characterisation using the 18S species-specific PCR-RFLP assay. The same samples together with 634 samples (317 samples/season) collected during the 2002 dry season and the 2003 wet season were further analysed using the p104 Theileria parva specific PCR. The results from the 18S characterisation showed the presence of four Theileria spp., namely T. parva, T. mutans, T. taurotragi and T. velifera in the field. Half of the animals had multiple Theileria spp. infections. T. parva was the most prevalent and a high correlation (94%) was found between the prevalence results using the 18S and the p104 PCR assays. The prevalence of T. parva infections was stable over time and over season but decreased significantly from the high land to the low land areas. This unexpected trend cannot be explained alone by ecology or the dynamics of the tick population in the different zones, many other components such as breed type, tick control practices and grazing system are likely to play a role. Another important finding was the fact that young animals are infected early in life in all regions except in the high land zone indicating the existence of a particular epidemiological situation in this part of the country.
Animals↗
An outbreak of East Coast Fever on the Comoros: a consequence of the import of immunised cattle from Tanzania?
In 2003 and 2004, a severe epidemic decimated the cattle population on Grand Comore, the largest island of the Union of Comoros. Fatalities started soon after the import of cattle from Tanzania. Theileria parva and its vector, Rhipicephalus appendiculatus, could be identified as the main culprits of the epidemic. Characterisation by multilocus genotyping revealed that the T. parva parasites isolated on the Comoros were identical to the components of the Muguga cocktail vaccine used in Tanzania to immunise cattle. Therefore, it is believed that East Coast Fever reached the Comoros while some of the imported livestock got infected in Tanzania by ticks of which the immature stadia fed on Muguga cocktail vaccinated animals. Since the Comorian government neither has the financial means nor the competent staff to pursue an adequate epidemiosurveillance, the danger exists that without external assistance and in a context of continuing globalisation more transboundary diseases will affect the Comorian livestock sector in the future.
Animals↗
Trypanosomosis prevalence in cattle on Mafia Island (Tanzania).
During two consecutive surveys (February and August/Sept 2002), a total of 970 cattle from the cattle population of Mafia Island (United Republic of Tanzania) were blood-sampled. All blood samples were microscopically screened for the presence of trypanosomes and a portion of these were checked for antibodies with an Ab-ELISA and for the presence of trypanosomal DNA with PCR. Microscopic evidence of trypanosomes of the congolense group (sub-genus Nannomonas) was found in 0.8% of the animals (8/970) and in two cases the species identified was confirmed by PCR as Trypanosoma congolense savannah type. Non-pathogenic Trypanosoma theileri were detected in 3.2% (31/970) of the samples using the Dark Ground-Buffy Coat (DG-BC) technique. For survey 1 (S1), detection of antibodies (Ab-ELISA) against pathogenic trypanosomes indicated a seroprevalence of 14.2% (68/480). Of the samples, either DG positive or with a PCV lower then 25, examined by PCR, a total of 8.4% (5/59) (selected from 970 samples), were found positive for T. congolense. The low prevalence of pathogenic trypanosomes on Mafia Island is intriguing, especially in view of the omnipresence of the tsetse fly Glossina brevipalpis. Although the presence of detected trypanosomal antibodies does not necessarily indicate a current infection, the combination of serological/parasitological examinations and the results of the PCR do support this low prevalence of trypanosomosis in cattle. Despite the low prevalence, pathogenic trypanosomes are present on Mafia Island and possible reasons for this low infection rate, taking account of the relation between Glossina species present, transmission risk and trypanosomes found in cattle, are discussed also in view of a future appropriate intervention strategy.
Animals↗
A modified AFLP for Trypanosoma congolense isolate characterisation.
The amplified fragment length polymorphism (AFLP) technique is a reliable and powerful DNA fingerprint tool for genetic characterisation and analysis. In this paper, we described a modified AFLP with high resolution for Trypanosoma congolense using one enzyme and agarose or Elchrom gel electrophoresis. Eleven allopatric and fourteen sympatric isolates of T. congolense savannah were used to assess the resolution of the method and its ability to characterise T. congolense isolates. Two enzymes (Eco RI or Bgl II) and corresponding non-selective and selective primers were used to identify the most appropriate combination. Patterns generated by Bgl II enzyme and a single selective primer A, C, G or T produced clear profiles. Each of the four selective primers produced different profiles for all the 25 T. congolense isolates. Due to the reduction in the number of bands, profiles could be analysed using agarose or Elchrom gels. Although comparison of a great number of samples could benefit from software help, this technique did not require flurochrome detection methods. The results of the present study demonstrated that this modified AFLP makes the characterisation of T. congolense easier while maintaining high resolution.
Animals↗
Comparison of the virulence of Trypanosoma congolense strains isolated from cattle in a trypanosomiasis endemic area of eastern Zambia.
The virulence of 31 genetically different Trypanosoma congolense strains belonging to the Savannah subgroup and isolated from cattle at 11 sites in a trypanosomiasis endemic area of eastern Zambia was compared. Virulence testing, done in OF1 mice, revealed three virulence categories. Strains were considered extremely virulent when the median survival time ranged between 5 and 9 days. Moderately virulent strains had a median survival time between 10 and 30 days and low virulence, more than 30 days. For each strain, the prepatent period was determined and the PCV of the infected animals was measured at regular intervals. A total of six (19.4%) strains belonged to the extremely virulent category with a short prepatent period (mean 2.3+/-0.3 days), high parasitaemia, decline in PCV of 15.6+/-1.1% during the first 7 days p.i. and a short median survival time (mean 6 days). The remainder of the strains belonged to the moderate (13 strains) or low (12 strains) virulence categories with median survival times of 13 and 60 days, respectively. They had longer prepatent periods (means 3.2+/-1.6 days and 3.5+/-1.6 days for moderately virulent and strains with low virulence, respectively) and the decline in PCV was less steep (decline of 14.2+/-0.6 and 9.7+/-0.6% during the first 7 days of infection with moderately virulent strains and strains with low virulence, respectively). Extremely virulent strains were isolated from cattle at four sampling sites with 60% of the cattle from one sampling site harbouring such extremely virulent strains. Results from this study demonstrated substantial differences in the virulence of T. congolense strains of the Savannah subgroup, isolated in one geographic area from a single host species. On the assumption that information on virulence obtained from tests in mice can be extrapolated to cattle, the high proportion of strains with low to moderate virulence is thought to be attributed to the important role of susceptible cattle as reservoirs of trypanosomes in the study area and the ensuing selection against extremely virulent strains.
Animals↗
Effect of improving flue gas cleaning on characteristics and immobilisation of APC residues from MSW incineration.
The flue gas cleaning system of a MSW incinerator with a capacity of 350 kt/year was changed to improve the HCl elimination efficiency. Instead of the semi-wet operating spray reactor and subsequent baghouse, a two-step wet flue gas cleaning was added behind the baghouse. Elemental composition, X-ray powder diffraction patterns and TGA measurements showed that the resulting APC residue was totally different from the former residue. As a consequence, leaching characteristics of both residues also differed and another treatment was required prior to disposal. For the former residue, mainly leaching of Pb (>100 mg/l), necessitated treatment prior to landfilling. The lower alkalinity of the new residue resulted in a leachate pH of 9.7 and a Pb concentration of 0.8 mg/l. The leachate pH of the former residue was 12.4. The leaching of Pb and Zn increased above 100 mg/l when immobilising the new residue with cement. Better results were obtained when immobilising with micro silica. The high CaCl2 x 2H2O content of the new residue brought along clogging of the bag filter system. Adding 1.4% of CaO (or 1.9% of Ca(OH)2) to the residue already improved these inconveniences but again significantly changed the leaching behaviour of the residue.
Calcium Carbonate↗
A survey for Mycobacterium avium subspecies paratuberculosis in the Royal Zoological Society of Antwerp.
Paratuberculosis is a chronic intestinal disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (Map). Very little is known about the status of paratuberculosis in European zoos. In this study, the presence of Map in the animal collection of the Royal Zoological Society of Antwerp (RZSA) was investigated. Faecal and post mortem samples from 48 ruminants were used to set up cultures. DNA from faeces, tissue and positive cultures were tested by IS900 polymerase chain reaction (PCR). Additionally, 448 serum samples were tested with an ELISA kit. All culture samples were negative whereas PCR gave three positives on biopsy samples and one positive on faecal samples. With the ELISA, 21 sera could be classified as positive. There is evidence that Map is present in the RZSA but no high level faecal shedders could be detected. Further investigations are required in other European Zoos in order to complete the picture of Map infections.
Animals↗
Management of incinerator residues in Flanders (Belgium) and in neighbouring countries. A comparison.
This paper covers the Flemish legislative tools concerning the management of bottom ash, fly ash and APC residue from municipal waste incinerators, with respect to their contamination with heavy metals. The situation in Flanders is compared to the one in the Walloon region, The Netherlands, Germany and France. Waste management in the countries considered differs on the level of available management options, of leaching tests and of limit values. To make an indicative comparison of leaching tests and limit values in the different countries, leaching tests were carried out on bottom ash and fly ash, and the results are compared to the relevant limit values for recycling and landfilling of the different countries. The comparison of legislations as well as the leaching results show that discrepancies in waste management between the different regions and countries exist. Recently, European limit values for landfilling became available. European legislation on recycling, however, has not been developed and urgently needs to be considered and drafted as the market for recycling can be expanding rapidly.
Belgium↗
Identification of a genetic marker for isometamidium chloride resistance in Trypanosoma congolense.
Isometamidium chloride has remained a very important prophylactic and therapeutic drug against trypanosomosis in cattle since its introduction into the market in the 1950s with, unfortunately, a concomitant development of resistance in trypanosomosis endemic areas. Amplified Fragment Length Polymorphism (AFLP) was used to compare two isogenic clones of Trypanosoma congolense. The parent clone, sensitive to isometamidium, has a CD50 (the curative dose that gives complete cure in 50% of the animals) in the mouse of 0.018 mg/kg and its derivative exposed to increasing doses of isometamidium, has a CD50 that is 94-fold higher. Sixty-four combinations of eight Eco RI and eight Mse I primers were used in comparative AFLP analysis to detect subtle genetic differences between the two clones. Thirty-five polymorphic fragments of DNA that were observed only in the resistant clone were purified and then sequenced. The nucleotide sequences were used in searching the GeneDB T. congolense database to find surrounding sequences upstream of an open reading frame and downstream to a stop codon. The sequences of the open reading frames were subsequently compared to the sequences in the genomic databases. A predicted gene coding for an 854 amino acids protein was thus identified. The protein contains a putative ATP binding site, Walker B and LSGG motifs and eight predicted trans-membrane domains. The gene in the resistant strain of T. congolense has a triplet insertion coding for an extra lysine. Using polymerase chain reaction-restriction fragment length polymorphism, the insertion was sought in the genomes of 35 T. congolense strains isolated from different geographic origins and whose response to isometamidium chloride had been determined through single dose mouse tests. The presence of the insertion, specifying an extra codon was found to always be present in the genomes of T. congolense clones that were resistant to isometamidium chloride.
ATP-Binding Cassette Transporters↗
Epidemiological study of the prevalence of Babesia divergens in a veterinary practice in the mid-east of France.
To assess the epidemiology of Babesia divergens in a veterinary practice based in the mid-east of France ("Monts du Lyonnais"), blood was collected from 254 cattle belonging to 24 herds. To assess the dynamics of the carrier state, six carriers were identified, treated with flumethrin and sampled once every 3 weeks during 6 months. Two different DNA extraction methods were compared. Each sample was tested for the presence of parasites using a PCR-RFLP test based on the 18S rRNA gene. The sensitivity of the test was equivalent to a parasitaemia as low as 10(-5)% (in "Filter Paper" samples) and 10(-6)% in 1 ml blood (extracted using "Matrix"). With the latter method, the rate of detection diminishes in the low parasitaemia range but could probably be improved. This test proved to be very useful in the detection of B. divergens carriers. Serology using IFAT showed 7% of the cattle seropositive, which is suggestive of a disease situation with a low clinical risk level. Analysis of the PCR results suggests a 20% prevalence rate of carriers in the cattle population. The use of the mean parasitaemia is proposed to serve as a babesiosis clinical risk indicator. This approach could also be used in other babesia infections provided the lowest detectable parasitaemia level (threshold level) could be resolved for each parasite species.
Animals↗
Comparison of immobilisation of air pollution control residues with cement and with silica.
Cement as agent for immobilising Pb from air pollution control residues is compared with the use of different silica-containing materials. The DIN 38414-S4 leaching test was used to control Pb leachability and to compare obtained Pb leachate concentrations with the landfill limit of 2 mg/l for Pb. Firstly, one scrubber residues was treated with cement and micro-silica. With cement, the Pb leachability could be reduced with a factor ranging from 3 to 50 depending on the type and amount of cement used and depending on the curing time. The landfill limit of 2 mg/l was, however, never attained. From all tested silica-containing additives, aerosil could reduce the initial Pb leaching (101.3mg/l) to below the detection limit at a dosage of 0.13 g aerosil/g residue. Second best and an economically preferable silica-containing additive was micro-silica: a reduction from 101.3 to 0.7 mg/l was observed at a dosage of 0.4 g micro-silica/g residue. The formation of Ca-silicates was found to be responsible for the decreased Pb leachability. To generalise the findings, the Pb leachability of five cement-treated and five micro-silica-treated air pollution control residues were compared. For three scrubber residues, 2-20 times lower Pb leachate concentrations were measured for micro-silica-treated samples (cured for 5 weeks) than cement-treated samples. For a fly ash and a boiler ash the difference was, respectively, 48 and 17 times. pH-dependent leaching tests showed that at pH=2.5, Pb leaching is 250 times lower for the micro-silica-treated residue than for the cement-treated residue and almost seven times lower at pH 12.4.
Air Pollutants↗
The transmission of mixed Trypanosoma brucei brucei/T. congolense infections by tsetse (Glossina morsitans morsitans).
Laboratory experiments and field observations clearly show that tsetse flies can be carriers of mixed trypanosome infections. Question remains how easy it is for the tsetse fly to acquire such a mixed infection during the first bloodmeal. This is of particular importance in the epidemiology of Trypanosoma brucei s.l., often a cryptic infection and difficult to transmit to non-teneral tsetse flies. To determine the transmission rate of T. brucei as part of a mixed infection, teneral Glossina morsitans morsitans were fed once on cattle with a mixed (Trypanosoma brucei brucei/Trypanosoma congolense) or single (T. brucei) infection. Of the 140 flies fed on animals with a mixed infection and examined 30 days later, 4 had a metacylic T. brucei infection, 29 a T. congolense infection and 13 a mixed T. brucei/T. congolense infection. There was no significant difference between the transmission rate of T. brucei as a single or as part of a mixed infection. The high proportion of mixed T.b. brucei/T. congolense infections was explained best by a model implying that if a fly is refractory to T. congolense, it is also refractory to T.b. brucei and vice versa. Hence, results suggest that the transmission of T.b. brucei is affected mainly by the vectorial capacity of flies and not by concurrent trypanosome infections in the host.
Animals↗
Immobilization of lead and zinc in scrubber residues from MSW combustion using soluble phosphates.
The immobilization of MSWI-scrubber residues with soluble PO4(3-) was studied and compared to the immobilization using cement. The DIN 38414-S4 leaching protocol and pH dependent leaching were used to evaluate the leaching of Pb and Zn. Four different scrubber residues from MSW combustion (Pb concentration: 2.8-4.8 mg/g; Zn concentration: 3.0-12.3 mg/g) were mixed with water and cement or Na2HPO4 as source of soluble PO4(3-) at dosages of at least 0, 0.1, 0.2, 0.3 and 0.4 g per g residue. With cement as well as with PO4(3-) a reduction in Pb and Zn leaching was observed. With 0.4 g cement per g residue, the Pb leaching was reduced by a factor ranging from 70 to 100, but still exceeded the Pb landfill limit of 2 mg/l. With PO4(3-) the Pb leaching was reduced with a factor of 100-300 to below 2 mg/l. The Zn landfill limit (10 mg/l) was only exceeded by one untreated residue. Adding 0.2 g cement or 0.1 g PO4(3-) per g of that residue was enough to reduce leaching below 10 mg/l. However, when 0.6 g Na2HPO4 per g residue was added to a lime based scrubber residue, an increase in Zn leaching up to 12.5 mg/l was observed due to an increase in pH of up to 13.0. When using NaH2PO4 and H3PO4 no such increase in Zn leaching was observed. pH dependent leaching performed on one of the four residues showed that in the pH range of 2.5-6, Pb leaching was 100-50 times lower with Na2HPO4 treatment than with cement. In the pH range from 7-11, almost equal results were obtained for cement treated and Na2HPO4 treated residue. Above a pH of 12, Pb leaching was three times lower for the PO(4)(3-)-treated residue than for the cement treated residue. With soluble PO4(3-), Pb leaching below 2 mg/l could be attained at a dosage of 0.27 g PO4(3-)/g residue. With cement, Pb leaching was never below 2 mg/l.
Belgium↗
Taeniosis-cysticercosis in man and animals in the Sierra of Northern Ecuador.
Taenia solium is endemic in the Andean region of Ecuador. The recent rediscovery of Taenia saginata in humans urges to reconsider some assumptions in relation to the epidemiology of the taeniosis/cysticercosis complex in this country.Therefore, data were compiled on the infection of both tapeworms in man and animals in Pichincha and Imbabura provinces in the Andean region, north of Quito. On post mortem inspection 3 out of 806 (0.37%) carcasses had T. saginata metacestodes, however, 35 sera out of 869 (4.03%) showed circulating antigen in a monoclonal antibody-based sandwich ELISA (Ag-ELISA). Porcine cysticercosis was detected in 15 out of 2896 (0.52%) carcasses and 93 out of 1032 serum samples (9.01%) were positive in Ag-ELISA. In humans, 4.99% (215 out of 4306) cases of antigen positives were found, whereas coprological examination of 1935 stools resulted in 30 positive cases (1.55%). The limited number of adult tapeworms (29) that were collected does not allow firm conclusions on the proportion of each species, but in total 21 specimen were identified as T. saginata and 8 as T. solium. These data have been discussed in view of the epidemiology of human cysticercosis.
Animals↗
PCR-RFLP using Ssu-rDNA amplification: applicability for the diagnosis of mixed infections with different trypanosome species in cattle.
The use of a single restriction fragment length polymorphism (RFLP)-PCR assay which is able to characterise all important bovine trypanosome species was evaluated for the detection of mixed infections with Trypanosoma brucei brucei, Trypanosoma theileri, Trypanosoma congolense and Trypanosoma vivax. Results showed that mixed infections are detectable at a minimum ratio of 2%/98% of standardised DNA solutions with a concentration of 10 ng ml(-1). All mixed infections gave clear profiles that could be easily differentiated except with T. theileri and T. congolense where the T. theileri band was concealed by the T. congolense profile.
Animals↗
PCR-RFLP using Ssu-rDNA amplification as an easy method for species-specific diagnosis of Trypanosoma species in cattle.
A single polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay was used to characterise all important bovine trypanosome species. This is the first report of a sensitive pan-trypanosome PCR assay amplifying all species including T. vivax to a comparable extent using a single primer pair. A semi-nested PCR approach resulted in the detection of one T. congolense trypanosome genome/40 microl of blood, applied as buffy coat on filter paper. Restriction enzyme analysis using Msp1 and Eco571 gave a clear distinction between T. congolense, T. brucei, T. vivax and T. theileri. Several subgroups within the T. congolense group could be distinguished but no differences between the species belonging to the subgenus Trypanozoon or between T. simiae and T. theileri could be found. The use of MboII restriction enzyme allowed differentiation between T. simiae and T. theileri. The potential of the essay to be used as a suitable diagnostic tool is discussed.
Animals↗