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G Duvallet

Publications and source records attributed to G Duvallet.

At least 19 recordsLinked to original sources
PubMed2006

First survey of seasonal abundance and daily activity of Stomoxys spp. (Diptera: Muscidae) in Kamphaengsaen Campus, Nakornpathom province, Thailand.

The seasonal changes and the daily activity of Stomoxyine species (Diptera: Muscidae) were examined, using Vavoua traps, in a dairy and a beef cattle farm in Nakhonpathom province, Thailand during July 2004 to June 2005. Over this period, Stomoxys calcitrans was the most commonly trapped species, followed by S. sitiens and S. indica. For the later species, this is the first report of its presence in Thailand. A total of 80 % of flies were captured during the rainy season from May to October and 20 % during the dry season from November to April. No major difference of fly density was observed between the dairy and the beef cattle farm. The activity pattern of S. calcitrans was diurnal with a peak between 08:00 am to 10:00 am and another less marked one in the afternoon. The activity pattern of S. sitiens and S. indica was mainly crepuscular with 2 peaks, early in the morning (06:00 a.m.) and late in the afternoon (6:00 p.m.). Those species are important pests of livestock in Thailand, where they are known as a mechanical vector of trypanosomes. A better knowledge of their ecology is a prerequisite for more efficient control measures.

Animals↗
PubMed2004

[A new morphological character for the identification of Stomoxys calcitrans and S. niger (Diptera: Muscidae). Comparison of La Réunion island populations].

On La Reunion Island (France), two morphological closely related species of stable flies (Diptera: Muscidae), living in the same environment, Stomoxys calcitrans and S. niger, are involved in the transmission of blood parasites to the livestock. To facilitate a rapid identification of both species in the field conditions, we highlighted a diagnostic morphological character not yet described: the length of the maxillary palpus. The study of three populations of S. calcitrans and two populations of S. niger, collected at various elevations, showed that the maxillary palpi of S. niger were significantly longer than in S. calcitrans, independent of sex. This character, easily visible in the field with a simple magnifying glass, has been confirmed on individuals of both species from West Africa.

Animals↗
PubMed2000

Microsatellite DNA markers reveal genetic differentiation among populations of Glossina palpalis gambiensis collected in the agro-pastoral zone of Sideradougou, Burkina Faso.

Intraspecific genetic variability of Glossina palpalis gambiensis in the area of Sideradougou, Burkina Faso, was studied using polymorphic microsatellite DNA markers. This genetic study was combined with other epidemiological information on the same tsetse: bloodmeal identification, dissection of tsetse and molecular characterization of the trypanosomes detected. There was significant genetic differentiation among flies caught only a few kilometers apart, within the same riverine habitat. These distinct subpopulations were also differentially infected by trypanosomes. In part of the study area, a Factorial Correspondence Analysis undertaken on the genotypes allowed us to detect a Wahlund effect, suggesting the presence of tsetse originating from different source populations coming from two distinct drainage systems. The apparent structuring of populations of G. palpalis gambiensis is discussed relative to appropriate strategies to control African Trypanosomosis.

Animals↗
PubMed1999

Polymerase chain reaction characterization of trypanosomes in Glossina morsitans submorsitans and G. tachinoides collected on the game ranch of Nazinga, Burkina Faso.

The polymerase chain reaction was used to characterize the trypanosomes infecting Glossina morsitans submorsitans and G. tachinoides in the game ranch of Nazinga, Burkina Faso, situated near an agropastoral zone. Dissection of 435 tsetse flies, and PCR analysis of 166 infected flies were conducted to assess the epidemiological situation. Trypanosomes of the Nannomonas subgenus were the most abundant in the two tsetse species (80.4% and 73.7% of identified infections in G. m. submorsitans and G. tachinoides respectively). T. vivax and T. brucei infection rates were comparable between the two tsetse species. Mature infection pattern identified by PCR differed from overall infections, mainly because T. simiae infections did not mature, whereas T. vivax represented the predominant taxon. Parasitological and PCR results showed some discrepancies; possibly some typical Duttonella strains could not be recognized by the sets of primers used. The technologies used in this work helped to determine the high trypanosomosis risk in this area.

Animals↗
PubMed1998

Microsatellite markers for genetic population studies in Glossina palpalis gambiensis (Diptera: Glossinidae).

Little is known about intraspecific variability in tsetse flies and its consequences for vectorial capacity. Microsatellite markers have been developed for Glossina palpalis gambiensis. Three loci have been identified and showed size polymorphisms for insectarium samples. G. palpalis gambiensis from Burkina Faso were also subjected to PCR to investigate then genetic variability. Amplifications were observed in different species belonging to the palpalis group. These molecular markers will be useful to estimate gene flow within G. palpalis gambiensis populations and analysis could be extended to related species.

Animals↗
PubMed1997

Identification of trypanosomes isolated by KIVI from wild mammals in Côte d'Ivoire: diagnostic, taxonomic and epidemiological considerations.

In Côte d'Ivoire, a comparative study was carried out on 122 wild mammals by parasitological and serological examination and by in vitro isolation of trypanosomes from fresh blood (KIVI). Thirteen isolated stocks were studied by isoenzymes and compared with Trypanosoma congolense and T. brucei bouaflé group reference stocks. Of the 122 animals, only 22 were positive on blood smears while 88 were KIVI positive and 92 were CATT/T. b. gambiense positive. For six stocks identified by isoenzymes as T. congolense, the agreement between ELISA and CATT was good (75%). As compared with CATT, antigen detection ELISA was not satisfactory for T. brucei (20%). Out of 18, 16 stocks represented a separate zymodeme (seven T. congolense and nine T. brucei) and a high genetic heterogeneity was observed. For T. congolense, savanna, kilifi and forest groups were represented by one zymodeme each. The four remaining zymodemes while put into this T. congolense group, were strongly independent of each other. Morphology indicated that those new zymodemes correspond to T. congolense. In the other hand, five new zymodemes fit into T. brucei classification.

Animals↗
PubMed1997

Microsatellite markers for genetic population studies in Glossina palpalis (Diptera: Glossinidae).

Little is known about tsetse intraspecific variability and its consequences on vectorial capacity. Since isoenzyme analyses revealed little polymorphism, microsatellite markers have been developed for Glossina palpalis gambiensis species. Three loci have been identified and showed size polymorphisms for insectarium samples. Moreover, amplifications were observed in different species belonging to palpalis group. These molecular markers will be useful to estimate gene flow within G. p. gambiensis populations and analyses could be extended to related species.

Africa, Western↗
PubMed1997

Molecular characterization of trypanosome isolates from naturally infected domestic animals in Burkina, Faso.

A total of 33 trypanosome cryostabilates isolated from domestic animals (bovine and dogs) were analysed using the polymerase chain reaction (PCR). The PCR was undertaken on diluted and treated buffy coat solutions according to an easy protocol of purification, using primers specific to Trypanosoma (Nannomonas) congolense of Savannah, Riverine-Forest, Kilifi and Tsavo types, T. (N) simiae, T. (Trypanozoon) brucei and T. (Duttonella) vivax. The results showed a lack of PCR sensitivity when target solutions were simply diluted, probably a reflection of the inaccuracy of the dilution procedure at very low trypanosome numbers. Nine mixed infections were found in purified samples whereas only three were detected in diluted crude solutions. T. congolense Savannah-type was present in all stabilates. Double infections involving this type with the Riverine-Forest type, T. vivax or T. brucei, were found. One stabilate was found to be infected with the three trypanosome types, namely T. congolense Savannah and Riverine-Forest genotypes and T. vivax. No infection attributable to T. congolense Kilifi and Tsavo types or T. simiae was detected in these stabilates. This work confirmed the abundance of mixed infections in the field, which could not have been detected by the classical parasitological methods. Amongst the T. congolense infections, the Savannah genotype was found to be predominant over the Riverine-Forest type; that could be a consequence of differences in genotype virulence in cattle. The detection of T. congolense Riverine-Forest type in vertebrate hosts living in wet areas could be confirmation of the suspected affinity of relationships between this taxa and the riverine forest tsetse fly species.

Animals↗
PubMed1997

Comparison of the susceptibility of different Glossina species to simple and mixed infections with Trypanosoma (Nannomonas) congolense savannah and riverine forest types.

Teneral Glossina morsitans mositans, G.m.submorsitans, G.palpalis gambiensis and G.tachinoides were allowed to feed on rabbits infected with Trypanosoma congolense savannah type or on mice infected with T.congolense riverine-forest type. The four tsetse species and subspecies were also infected simultaneously in vitro on the blood of mice infected with the two clones of T.congolense via a silicone membrane. The infected tsetse were maintained on rabbits and from the day 25 after the infective feed, the surviving tsetse were dissected in order to determine the infection rates. Results showed higher mature infection rates in morsitans-group tsetse flies than in palpalis-group tsetse flies when infected with the savannah type of T.congolense. In contrast, infection rates with the riverine-forest type of T.congolense were lower, and fewer flies showed full development cycle. The intrinsec vectorial capacity of G.m.submorsitans for the two T.congolense types was the highest, whereas the intrinsic vectorial capacity of G.p.gambiensis for the Savannah type and G.m.morsitans for the riverine-forest type were the lowest. Among all tsetse which were infected simultaneously with the two types of T.congolense, the polymerase chain reaction detected only five flies which had both trypanosome taxa in the midgut and the proboscis. All the other infections were attributable to the savannah type. The differences in the gut of different Glossina species and subspecies allowing these two sub-groups of T.congolense to survive better and undergo the complete developmental cycle more readily in some species than other are discussed.

Animals↗
PubMed1996

[Evaluation of vectorial capacity of Glossina tachinoides (Diptera, Glossinidae) infected by Trypanosoma (Nannomonas) congolense: epidemiological implications].

A total of 182 Glossina tachinoides were infected with Trypanosoma congolense savannah type. Infection rates were determined according to microscopical examination of dissected flies and PCR on proboscis. Different techniques of trypanosomes detection in the saliva of live tsetse flies were compared. Results show a high percentage of immature infection rates. PCR amplification of trypanosomes in tsetse flies proboscis confirm parasitological observations. The salivation technique showed fluctuations of the number of trypanosomes deposited with saliva. Variability between individual flies was observed in the mean number of parasites ejected, the rate of positive salivates detected by PCR and the rate of infected mice. PCR technique was as efficient as parasitological technique to detect trypanosomes in the salivates. The infectivity on mice was the less efficient method. These results improve our knowledge on G. tachinoides vectorial competence in the laboratory, and precise the role of this tsetse species in the epidemiology of this disease.

Africa South of the Sahara↗
PubMed1996

Trypanosome characterization by polymerase chain reaction in Glossina palpalis gambiensis and G.tachinoides from Burkina Faso.

Following the discovery of four cases of African human trypanosomiasis, an entomological survey was conducted along the Mouhoun river in southwest Burkina Faso to collect Glossina palpalis gambiensis and G.tachinoides. Among 226 flies dissected, 4.87% (eleven individuals) were infected in midgut or proboscis, but never in the salivary glands. Polymerase chain reaction analysis was undertaken, and was able to characterize all the proboscis infections, and half of the midgut infections. Only Trypanosoma simiae and T. vivax were found in the organs of infected flies, in single or mixed-species infections. Ten more flies, negative with parasitological examination, were tested with Trypanozoon primers and remained negative. The epidemiological significance of the absence of T.brucei group infections in wild tsetse populations and the presence of T.simiae in G.p.gambiensis are discussed.

Animals↗
PubMed1996

[Use of Trypanosoma antigen detection ELISA during an epidemiological follow-up in the Sideradougou, Burkina Faso].

Plasmas taken during a parasitological survey on bovine trypanosomosis were tested a posteriori with an antigen detection ELISA test. The objective was to evaluate the value of this test for epidemiological monitoring. The results were compared to those obtained using the usual parasitological technique (buffy coat examination). Of the 297 zebu cattle heads studied, 216 came from four villages in the pastoral zone of Sideradougou. A large eradication programme had led to the disappearance of tsetse in the area. Blood samples were taken during the rainy saison (September 1986), at the beginning (January 1987) and at the end (May 1987) of the dry season. The parasitological diagnosis was carried out in the field and plasmas were stored at -20 degrees C. The serological test was performed in August 1993. The incidence rates of bovine trypanosomosis obtained with antigen detection ELISA were low in the center of the zone. These rates decreased proportionally to the distance between the blood sampling area and the limit of the infested area. The results of the parasitological diagnosis were similar except for a village located on the border of the treated zone. The use of antigen detection ELISA confirmed the low incidence of trypanosomosis in the center of the area of Sideradougou following the eradication campaign. It also enables to obtain finer parasitological results pointing out the trypanosome persistence in peripheric zones, more exposed to reinfestations.

Animals↗
PubMed1995

[Absence of interaction between Trypanosoma theileri infections with the diagnosis of animal trypanosomiasis by detection of circulating antigens].

This work presents data gathered at the CIRDES (Centre international de Recherche-Développement sur l'Elevage en Zone subhumide) during epidemiological monitoring. The prevalence levels of Trypanosoma vivax, Trypanosoma congolense and Trypansoma brucei obtained using antigen-detection ELISA were compared in non-infected animals and in animals infected with Trypanosoma theileri. The aim was to investigate whether there were any serological cross-reactions between T. theileri and the pathogenic trypanosomes. The results show that there was no interaction by Trypanosoma theileri with the diagnosis of the pathogenic trypanosomes using antigen-detection ELISA.

Animals↗
PubMed1995

Evaluation of an antigen detection-ELISA test for the diagnosis of trypanosomiasis in naturally infected cattle.

The sensitivity and the specificity of the antigen detection ELISA proposed by Nantulya and Lindqvist (1989) for the diagnosis of African Animal Trypanosomiasis have been assessed in naturally-occurring infections. 1633 cattle were sampled in trypanosomiasis endemic area and examined for trypanosomes by darkground/phase contrast buffy-coat method described by Murray et al. (1977) and for circulating antigen by ELISA. Fifty sera from Markoye, a tsetse free area in north of Burkina Faso, and 49 sera from Germany were also tested. In trypanosomiasis infested area, BCT detected 144 (8.8%) positive animals while Ag-ELISA revealed 65.8% of positive. Out of the 144 BCT-parasite-positive, Ag-ELISA enable to detect 75% of positive. The predominant trypanosomes identified by BCT was Trypanosoma vivax followed by T. congolense while Ag-ELISA indicated T. congolense followed by T. brucei. Ag-ELISA detected 76.5% out of the 51 T. congolense-BCT-positive and only 17% of all T. vivax BCT-positive. Cattle carring mixed infection involving two or three trypanosomes, particularly those with T. brucei and T. congolense are the most frequent. In tsetse free area, Ag-ELISA detected one positive cattle carring T. brucei and T. congolense and showed an apparent specificity of 98%. No serum from Germany was detected positive. This study suggests the joint use of Ag-ELISA and BCT for the diagnosis of trypanosomiasis particularly in epidemiological study in endemic area.

Animals↗
PubMed1994

[Prevalence of Trypanosoma infections in different species of wild animals in the Comoé national park on the Ivory Coast: preliminary results of the comparison of 3 diagnostic methods].

Compared with the numerous studies of trypanosomosis in domestic animals, few such studies have been carried out on wild animals in West Africa. Preliminary results on the comparison of three detection methods (thin smears, detection of trypanosome antigens by ELISA-Test and Kit for in vitro isolation of trypanosomes, KIVI) in wild animals of Comoe Game Reserve in Côte d'Ivoire confirm the actual presence of trypanosomes; however, no accurate identification of those parasites has been possible, but work is in progress to clarify the taxonomical status of stocks isolated by KIVI.

Animals↗
PubMed1993

Antibody responses to a 33 kDa cysteine protease of Trypanosoma congolense: relationship to 'trypanotolerance' in cattle.

A cysteine protease of Trypanosoma congolense (congopain) elicited IgG1 antibodies in those cattle which exhibited a degree of resistance to disease during experimental infections (Authié et al. 1992, 1993). The aim of the present study was to investigate further the association between anti-congopain antibodies and resistance to trypanosomiasis, and to provide a lead into the mechanisms responsible for the differential responses to congopain in cattle. Isotype characteristics and kinetics of the antibody response to congopain were studied in three N'Dama (trypanoresistant) and three Boran (susceptible) cattle during primary infection with T. congolense ILNat 3.1. In both groups an IgM response to congopain was elicited, thus demonstrating that congopain is antigenic in both types of cattle. Most of the IgM appeared to be incorporated into immune complexes. IgG was detected as free antibody; IgG1 but not IgG2 was detected. All three N'Dama, but none of the three Boran cattle, mounted a significant IgG response to congopain. Sera from 70 primary-infected cattle belonging to five breeds of differing susceptibility were tested for their reactivity to congopain. High levels of IgG to congopain were observed in the two trypanotolerant breeds, whereas the three susceptible breeds had lower levels of these antibodies. Crosses between N'Dama and Boran cattle, which exhibit an intermediate susceptibility, had intermediate levels of antibodies. Thus, the results from experimental infections confirmed our initial observations. However, under natural tsetse challenge, repeated infections and trypanocidal treatments in Zebu cattle stimulated as high anti-congopain antibody levels as in non-treated trypanotolerant taurine cattle.

Analysis of Variance↗
PubMed1993

[Comparison of experimental trypanosomiasis in various breeds of small ruminants in Burkina Faso].

Twenty-four dwarf Djallonké sheep and goats, and 16 Sahelian Fulani sheep and goats, were inoculated with strains of Trypanosoma vivax and Trypanosoma congolense to compare their degree of susceptibility to trypanosomosis. One animal from each breed was used as a control. Anaemia was observed in all inoculated animals. In the group of animals inoculated with T. vivax, 1 Djallonké goat out of 6, 3 Sahelian goats out of 4 and 2 Fulani sheep out of 4 died within the experimental period of 16 weeks. One single Sahelian Fulani sheep out of 4 died among animals inoculated with T. congolense. During a period of 8 weeks, no significant difference was observed between Djallonké and Fulani Sahelian in the decrease of body weight and leucocyte count. Results in this study show a better resistance of Djallonké sheep and goats to infection by T. vivax, whereas there was no significant difference between all sheep and goats inoculated with T. congolense.

Animals↗