Biomedical subjects

J M Reifenberg

Publications and source records attributed to J M Reifenberg.

11 recordsLinked to original sources

PubMed2001

[Statistical Process Control applied to viral genome screening: experimental approach].

During the National Multicentric Study concerning the introduction of NAT for HCV and HIV-1 viruses in blood donation screening which was supervised by the Medical and Scientific departments of the French Blood Establishment (Etablissement français du sang--EFS), Transcription-Mediated transcription Amplification (TMA) technology (Chiron/Gen Probe) was experimented in the Molecular Biology Laboratory of Montpellier, EFS Pyrénées-Méditerranée. After a preliminary phase of qualification of the material and training of the technicians, routine screening of homologous blood and apheresis donations using this technology was applied for two months. In order to evaluate the different NAT systems, exhaustive daily operations and data were registered. Among these, the luminescence results expressed as RLU of the positive and negative calibrators and the associated internal controls were analysed using Control Charts, Statistical Process Control methods, which allow us to display rapidly process drift and to anticipate the appearance of incidents. This study demonstrated the interest of these quality control methods, mainly used for industrial purposes, to follow and to increase the quality of any transfusion process. it also showed the difficulties of the post-investigations of uncontrolled sources of variations of a process which was experimental. Such tools are in total accordance with the new version of the ISO 9000 norms which are particularly focused on the use of adapted indicators for processes control, and could be extended to other transfusion activities, such as blood collection and component preparation.

Blood Component Removal↗

PubMed2001

Trying to predict and explain the presence of African trypanosomes in tsetse flies.

Trypanosome infections identified by polymerase chain reaction on field-caught tsetse flies from various locations were analyzed with respect to factors intrinsic and extrinsic to the trypanosome-tsetse association. These factors were then simultaneously analyzed using artificial neural networks (ANNs) and the important factors were identified to predict and explain the presence of trypanosomes in tsetse. Among 4 trypanosome subgroups (Trypanosoma brucei s.l., T. congolense of the 'savannah' and of the 'riverine-forest' types, and T. simiae), the presence of the 2 types of T. congolense was predictable in more than 80% of cases, suggesting that the model incorporated some of the key variables. These 2 types of T. congolense were significantly associated in tsetse. Among all the examined factors, it was the presence of T. congolense savannah type that best explained the presence of T. congolense riverine forest type. One possible biological mechanism would be 'hitchhiking,' as previously suspected for other parasites. The model could be improved by adding other important variables to the trypanosome tsetse associations.

Africa, Western↗

PubMed1998

PCR analysis and spatial repartition of trypanosomes infecting tsetse flies in Sidéradougou area of Burkina Faso.

A parasitological and entomological survey was conducted in the Sideradougou area (south of Bobo Dioulasso, Burkina Faso) in order to identify transmission factors of African trypanosomosis. A total of 3600 tsetse flies (Glossina tachinoides, Glossina palpalis gambiensis) were captured along 120 km of linear gallery forest and half of them were dissected. PCR analysis was undertaken on parasitologically positive flies (161 G. tachinoides, 92 G. palpalis gambiensis) to characterize the different trypanosomes. All the results were integrated in a GIS (Geographical Information System). Spatial repartition of the characterized trypanosomes enabled to recognize different areas with specific patterns of infection. Relations with environmental factors are discussed.

Animals↗

PubMed1998

New epidemiological features on animal trypanosomiasis by molecular analysis in the pastoral zone of Sideradougou, Burkina Faso.

A multidisciplinary work was undertaken in the agropastoral zone of Sidéradougou, Burkina Faso to try to elucidate the key factors determining the presence of tsetse flies. In this study the PCR was used to characterize trypanosomes infecting the vector (Glossina tachinoides and Glossina palpalis gambiensis) and the host, i.e. cattle. A 2-year survey involved dissecting 2211 tsetse of the two Glossina species. A total of 298 parasitologically infected tsetse were analysed by PCR. Trypanosoma vivax was the most frequently identified trypanosome followed by the savannah type of T. congolense and, to a lesser extent, the riverine forest type of T. congolense, and by T brucei. No cases of T. simiae were found. From the 107 identified infections in cattle, the taxa were the same, but T. congolense savannah type was more frequent, whereas T. vivax and T. congolense riverine forest types were found less frequently. A correlation was found between midgut infection rates of tsetse, nonidentified infections and reptile bloodmeals. These rates were higher in G.p. gambiensis, and in the western part of the study area. T. vivax infections were related to cattle bloodmeals, and were more frequent in G. tachinoides and in the eastern study area. The PCR results combined with bloodmeal analysis helped us to establish the relationships between the vector and the host, to assess the trypanosome challenge in the two parts of the area, to elucidate the differences between the two types of T. congolense, and to suspect that most midgut infections were originating from reptilian trypanosomes.

Animals↗

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

Improvement of blood and fly gut processing for PCR diagnosis of trypanosomosis.

We have adapted a simple and efficient technique to detect trypanosomes in human blood, without DNA purification, and increased the sensitivity threshold to 1 parasite in 1 ml. We have then applied it for detection of parasites in midguts of tsetse flies, negative by microscopy. This technique has been developed for field conditions and could greatly facilitate epidemiological studies.

Animals↗

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↗

PubMed1995

[Improving the salivation technic in the tsetse fly for the detection of infective metatripanosomes: study of the effect of biologic and non-biologic factors in the probing behavior of the tsetse fly].

The probing and salivation behaviour on a warm slide of three tsetse fly species or subspecies (glossina morsitans morsitans, Glossina palpalis gambiensis, Glossina tachinoides) was examined with respect to various parameters (species, sex, age, starvation period, trypanosome infection, quality of support). Each fly was given the opportunity to probe the warm slide (38 degrees C) for 5 minutes (we mean by probing an attempt to touch the glass slide by the proboscis in a biting position). G.m morsitans is by far the most efficient at probing (70.50%) when compared with G. tachinoides (50.50%) and G. palpalis gambiensis (45.80%). Globally, males (61.30%) are more active than females (52%) and those of the morsitans group are more active than those of the palpalis group. Teneral flies probe more easily than non-teneral flies, with an increased advantage in G. m. morsitans. The starvation period increases the probing behaviour, but at 48 h. G. m. morsitans probed as much as G. palpalis gambiensis and G. tachinoides at 72 h. The males of G. m. morsitans and G. palpalis gambiensis are more precocious than females, but the inverse is observed in G. tachinoides. Infection by T. congolense (EATRO 325 strain) does not affect the probing behaviour of males of all 3 species but seems to lower that of females in the palpalis group. Addition of a drop of PSG or blood improves the probing behaviour of infected G. m. morsitans females (the only ones tested). The results are discussed in relation to biological data and knowledge of the receptor systems of tsetse flies.

Animals↗

PubMedDate not supplied

Review on the molecular tools for the understanding of the epidemiology of animal trypanosomosis in West Africa.

The epidemiology of animal trypanosomosis around Bobo-Dioulasso (Burkina Faso, West Africa) benefited a lot in the last years from the progress of molecular tools. The two most used molecular techniques were the polymerase chain reaction for the diagnosis of the disease in cattle and the characterization of the trypanosomes in the host and the vector on one hand, and the microsatellite DNA polymorphism in tsetse flies to study the intraspecific genetic variability of the vector on the other hand. The results obtained in the Sideradougou area during a recent two year survey with these techniques, associated with many other georeferenced informations concerning vector and cattle distribution, natural environment, landuse, ground occupation, livestock management, were combined in a Geographical Information System. This new approach of a complex pathogenic system led to a better evaluation of the risk of trypanosome transmission.

Africa, Western↗