Genetic characterization of Trypanosoma brucei gambiense and clinical evolution of human African trypanosomiasis in Côte d'Ivoire.

Human African trypanosomiasis is a parasitic infection caused by protozoa belonging to Trypanosoma brucei subspecies. The clinical evolution of this disease is complex and might be because of the parasite itself, as genetic diversity has been observed in T. brucei ssp. We investigated the relationship between the genetic diversity of trypanosomes and the diversity of clinical patterns in Côte d'Ivoire. We studied clinical sleeping sickness cases, and genetically analysed the trypanosomes isolated from these patients. An important genetic monomorphism among stocks isolated in Côte d'Ivoire was observed by using various markers: isoenzymes electrophoresis, random amplified polymorphism DNA and PCR of microsatellite sequences. At the same time, the diversity of clinical patterns and evolutions was confirmed by clinical analysis. The existence of an individual susceptibility to disease (human trypanotolerance) should be taken into account even if our genetic conclusions might be distorted because the isolation success rates were particularly poor. In fact, we observed that the isolation success rate varied significantly depending both on the focus of origin (P=0.0002) and on the ethnic group (P=0.0317) of the patient. Further investigations are required in order to study a possible selective impact of the use of the kit for in vitro isolation of trypanosomes as an isolation technique.

Use of polymerase chain reaction in human African trypanosomiasis stage determination and follow-up.

Stage determination of human African trypanosomiasis is based on the detection of parasites and measurements of biological changes in the cerebrospinal fluid (CSF) (concentration of white blood cells > 5 cells per mm3 and increased total protein levels). The patient is treated accordingly. Demonstration of the absence or presence of trypanosomes by the double centrifugation technique is still the only test available to clinicians for assessing treatment success. In this study, however, we evaluate the polymerase chain reaction (PCR) as a tool for assessing the disease stage of trypanosomiasis and for determining whether treatment has been successful. All 15 study patients considered to be in the advanced stage of the disease were PCR positive; however, trypanosomes were demonstrated by double centrifugation in only 11 patients. Of the five remaining patients, who were considered to be in the early stage, PCR and double centrifugation were negative. Following treatment, 13 of the 15 second-stage patients were found to be negative for the disease in at least two samples by PCR and double centrifugation. Two others were still positive by PCR immediately and one month after the treatment. Trypanosome DNA detection using PCR suggested that the two positive patients were not cured but that their possible relapse could not be identified by a search for parasites using the double centrifugation technique. Further evaluation of the PCR method is required, in particular to determine whether PCR assays could be used in studies on patients who fail to respond to melarsoprol, as observed in several foci.

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.

[Evaluation of vectorial capacity of Glossina tachinoides (Diptera, Glossinidae) infected by Trypanosoma (Nannomonas) congolense: epidemiological implications]. / Evaluation de la capacité vectorielle de Glossina tachinoides (Diptera, Glossinidae) vis-à-vis de Trypanosoma (Nannomonas) congolense: implications épidémiologiques.

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.

[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]. / Amélioration de la technique de salivation des glossines pour la détection des métatrypanosomes infectants: étude de quelques facteurs biologiques et non biologiques sur le comportement de sondage des glossines.

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.

Trypanosomiases; maladies d'avenir : leurs perspectives et leurs inconnues

En Afrique intertropicale; malgre pres d'un siecle de lutte; la maladie du sommeil sevit encore et toujours sous forme endemique ou epidemique dans la plupart des anciens foyers historiques. Des progres certains ont ainsi ete enregistres dans la connaissance epidemiologique et les methodes de lutte mais il existe encore de redoutables inconnues notamment le cadre des interrelations hotes/vecteurs/parasites; inconnues qui pourraient sans doute entrer en compte dans l'explication d l'irritante permanence de cette endemie. C'est ainsi que les auteurs se sont interroges sur les questions essentielles qui remontent du terrain et dont les reponses paraissent intimement liees aux possibilites de controle de cette affection

Red blood cells' auto-agglutination as an indicator test in human trypanosomiasis.

Spontaneous red blood cells' auto-agglutination was assessed as an indicator for the diagnosis of human African trypanosomiasis. This test is easily carried out by health workers with minimum qualification. It presents a high sensitivity (0.91) and a high predictive value of a negative result (0.99). Although a positive result gives a low indication of infection, the health care workers should refer the patient to a screening centre.

The epidemiological importance of the animal reservoir of Trypanosoma brucei gambiense in the Congo. 2. Characterization of the Trypanosoma brucei complex.

Biological and biochemical characterization of 36 human and 5 animal congolese stocks of Trypanosoma brucei were performed. One human and all the animal stocks showed a quick adaptation to rodent host whereas the other 35 human stocks were characterized by a low virulence degree (Group 1 of T. gambiense). The virulent stocks showed hybridization patterns specific to the gambiense subspecies. Our results confirm the absence of the T. b. brucei subspecies in the Congo and the low prevalence of domestic animals infected with T. b. gambiense (0.5%). Two cycles of human trypanosomiasis may thus occur in Central Africa: a predominant man-to-man cycle with group 1 trypanosomes and a minor cycle involving an animal reservoir.

[Clinical review of endocrine disorders observed in adults with trypanosomiasis]. / Revue clinique des troubles endocriniens observés chez l'adulte trypanosome.

Clinical manifestations associated with endocrinological disorders were investigated in 21 Congolese patients suffering from Gambian trypanosomiasis. 90.5% of them showed cytological abnormality in the cerebrospinal fluid. Signs and symptoms of endocrinology dysfunction occur during the course of the parasitic disease. Gonadal deficiency is the most frequent and probably the most specific disorder. Reversibility of the endocrine dysfunction after treatment is likely but needs further investigations.

[House effect and family contamination in sleeping sickness: interpretative trial of the phenomenon. Study of 3 Congolese foci]. / "Effet de case" et "contamination familiale" dans la maladie du sommeil: essai d'interprétation du phénomène. Exemple de trois foyers congolais.

A review is given of the different hypotheses concerning the concentration of trypanosomiasis cases at the house or family level: 1. Mechanical transmission by haematophagous insects. 2. Interrupted feeding of a tsetse fly with cyclic infection on different people. 3. Family biological factor. These hypotheses are used as a introduction to an epidemiological field study in three congolese foci. Whereas their distribution among village districts is random, patients are significantly aggregated at the house and/or family level. This distribution may be partly explained by the behaviour of members of the family and community cells, associated with amplifying factors, the most probable being interrupted feeding of a tsetse fly with cyclic infection. In some foci other possibilities can be considered, such as mechanical transmission by Aedes or hereditary population factors. This spatial and/or familial concentration of cases is an important epidemiological property of sleeping sickness, the practical implication of which is the exhaustive survey of the human environment of cases.

[Contribution of serologic technics to the analysis of the cerebrospinal fluid in Congolese patients with sleeping sickness]. / Apport des techniques sérologiques dans l'analyse du liquide céphalo-rachidien de patients congolais atteints de la maladie du sommeil.

Three serological tests: the Card Agglutination Test (Testryp CATT), the Indirect Immunofluorescence Antibody Test (IFAT) and the Cellognost Indirect Haemagglutination technique (CIHA) were used to analyse the cerebrospinal fluid (CSF) of 41 patients infected with Trypanosoma gambiense and 30 uninfected persons. The authors reported the following data: --IFAT and especially CIHA were more efficient than CATT to demonstrate the presence of specific antibodies in the CSF; --the intensity of the cell and protein alterations paralleled the IFAT fluorescence intensity and the CIHA dilution titers; --this study indicated that the immunological analysis applied to CSF may prove to be a useful procedure to diagnosis the early onset of the attack on the nervous system and the evolution of the disease measured by the intensity of the reactions.

Serodiagnosis of sleeping sickness in the Republic of the Congo: comparison of indirect immunofluorescent antibody test and card agglutination test.

The card agglutination test for trypanosomiasis (CATT) was evaluated and compared to the classical immunofluorescent antibody test (IFAT) in the immunological diagnosis of Gambian trypanosomiasis. Tests were performed on serum and whole blood. Cross-reactions were found in the CATT with sera from patients suffering from parasitic infections other than sleeping sickness, but could be largely overcome by selecting 1/10 as the specific threshold dilution. At 1/40 dilution no false positive result was observed in the IFAT. At the specific threshold dilution, the sensitivity of IFAT was 94.7%, compared with 91.6% for the CATT. On whole blood, a more convenient sample in the field, IFAT specificity (100%) was greater than that of the CATT (94.3%), as was its sensitivity (92% compared with 82.5%). In view of its simplicity and rapidity of execution, the CATT is an efficient serological test to detect new foci. When greater sensitivity is required, IFAT should be preferred to CATT.

[Cost of the individual treatment of Trypanosoma brucei gambiense trypanosomiasis in a focus of infection in Niari (Congo)]. / Le coût du traitement individuel de la trypanosomiase à T.b. gambiense dans le foyer du Niari (Congo).

A survey carried out on 101 patients has shown that the treatment of human sleeping sickness, theoretically free, is relatively costly. The average total cost amount to 58,000 F C.F.A., ranging from free treatment up to much as 110,000 F C.F.A. This high cost in part explains the cases where treatment is refused, something which has frequently been observed in the Congo. It would therefore be desirable for patients, who are significant epidemiological reservoirs of T. b. gambiense, to receive economic aid.

[Morphologic comparison of Congo and Cameroon species of Glossina caliginea Austen, 1911]. / Comparaison morphologique des spécimens congolais et camerounais de Glossina caliginea Austen, 1911.

G. caliginea have been discovered in the south-western part of the People's Republic of Congo, along the littoral of the Atlantic Ocean. Congolese specimens were compared with specimens from Cameroon and the geographical distribution is rewieved.