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D Mehlitz

Publications and source records attributed to D Mehlitz.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Animal reservoir hosts of Trypanosoma brucei gambiense in Zaire: trypanosome infections in two foci in Bas-Zaire].

The prevalence of Trypanosoma spp. infections in domestic animals was estimated in a forest (Boma) and a savanna (Kimpese) sleeping focus in Bas-Zaire. The miniature anion-exchange centrifugation technique was used to determine the infection rates with T. congolense, T. vivax and T. brucei spp. in 505 animals. T. congolense predominated in both foci with the highest prevalence in pigs (76.2%), followed by sheep (31.3%), dogs (30.6%) and goats (7.4%). T. vivax was seen only on two occasions. In the forest zone, T. brucei spp. infections were frequent (pigs 16.5%, sheep 6.2%, dogs 3.4%, goats 1.1%) in contrast to the savanna area where only one T. brucei spp. infection was diagnosed. Twenty five primary isolations of T. brucei were done using different isolation and stabilization approaches. Isolates and stocks await behavioural, biochemical and molecular biological identification to discriminate T. b. brucei and T. b. gambiense of domestic animal origin.

Animals↗
PubMed1987

Enzyme polymorphism and the identity of Trypanosoma brucei gambiense.

Thirty-two isolates from man in known areas of Gambian trypanosomiasis, in the Sudan, Kenya, Zaire, Nigeria, Ivory Coast, Burkina Faso, Liberia and Senegal, were examined by isoenzyme electrophoresis of 11 enzymes. Comparisons were also made with our previously published results on 23 other stocks of similar origins, which had been examined in the same manner. All those stocks of low initial virulence to laboratory rodents, which thus conform to the accepted view of the behaviour of Trypanosoma brucei gambiense can be identified by characteristic combinations of enzyme patterns, especially certain aminotransferase markers. A limited study of superoxide dismutase polymorphism suggested a further marker of value. The isolates of high initial virulence to rodents, which are thus behaviourally akin to T. b. rhodesiense, did not share these characteristics. We conclude that there exists a homogeneous group of trypanosomes of wide dispersion throughout tropical Africa, characterized by certain isoenzyme combinations and low initial virulence to rodents, which corresponds to the classical concept of T. b. gambiense. The features of limited antigenic repertoire, high resistance to normal human serum and restriction fragment length polymorphisms of the genes for certain variant surface glycoproteins also appear to be characteristic of this group.

Africa↗
PubMed1987

Geographical distribution of Glossina palpalis gambiensis and G.p.palpalis in Liberia.

The two subspecies of Glossina palpalis (Robineau-Desvoidy) occurring in Liberia could be reliably separated morphometrically by measuring the width of the terminal dilatations of the male inferior claspers. Subspecies differentiation of female flies was less conclusive. Identification of flies from fifty-four sites revealed that most of Liberia lies in the belt of Glossina palpalis palpalis. However, pure and substantial populations of G.p.gambiensis Vanderplank occur north of 8 degrees 20'N in the north-west of Liberia.

Animals↗
PubMed1986

The use of DNA hybridization and numerical taxonomy in determining relationships between Trypanosoma brucei stocks and subspecies.

The nuclear DNAs of 71 trypanosome stocks from different African countries, representative of the three Trypanosoma brucei subspecies, and one T. evansi stock, have been analysed by the combined use of restriction endonuclease digestion, gel electrophoresis and molecular hybridization with both trypanosome surface-antigen-specific and undefined genomic DNA probes. In contrast with T. brucei brucei and T. brucei rhodesiense stocks, all the T. b. gambiense stocks are characterized by a conserved, specific DNA band pattern, regardless of the probe. This allows T. b. gambiense to be non-ambiguously identified. On the contrary, T.b. brucei and T. b. rhodesiense, which could not be discriminated by the same criteria, both yield highly variable DNA band patterns. Our data confirm that domestic animals like pig, dog and sheep constitute a potential reservoir for T.b. gambiense. Using a numerical analysis of the DNA hybridization patterns we have measured the degree of similarity between the 72 trypanosome stocks. This investigation shows that all T.b. gambiense stocks are included in the same homogeneous population, while the stocks from the two other subspecies seem to be distributed in several heterogeneous groups, some of these showing correlation with the geographical origin of the trypanosomes. It is concluded that (i) T.b. gambiense stands out as a real subspecies that has undergone a distinct evolution relative to the 'non-gambiense' group, (ii) the alleged T.b. rhodesiense subspecies does not fit with any of the groups evidenced by our cladistic analysis and hence does not appear as a distinct subspecies and (iii) 'non-gambiense' trypanosomes are probably evolving much more rapidly than T.b. gambiense. Different aspects of trypanosome relationships and evolution are discussed.

Africa↗
PubMed1985

West African dogs as a model for research on trypanotolerance.

Autochthonous dogs from Liberia/West Africa were reared trypanosome-free and brought to West Berlin/germany. Together with Beagle dogs they were infected cyclically by tsetseflies with Trypanosoma congolense. While the European dogs died soon of the trypanosomal infection, the African dogs developed milder parasitaemias and remained clinically unaffected. The authors' opinion is, that this dog model could make a contribution to research on trypanotolerance.

Africa, Western↗
PubMed1984

Evaluation of immunoassays for diagnosis and management of sleeping sickness in Liberia.

Nineteen parasitologically confirmed Liberian sleeping sickness patients were observed for up to 40 months. Efficacy of suramin therapy was indicated by decrease of serum and CSF immunoglobulins as well as by decreasing IgG and IgM serum antibody levels as determined by ELISA and fluorescence antibody tests. The tendency of serum antibody concentrations to increase again during the second and third years after treatment could be explained in one patient only who experienced relapse or reinfection, confirmed by demonstration of blood trypanosomes. Known endemic and nonendemic areas in Liberia could not be discriminated by the prevalence of Trypanosoma IgG antibodies. Furthermore, IgM antibody was present in 18% of a random sample of sera from non-endemic ares. The possibility of trypanosomes other than T.b. gambiense to stimulate antibody production in man is discussed.

Animals↗
PubMed1984

Identity of Trypanozoon stocks isolated from man and a domestic dog in Liberia.

The isoenzyme patterns (electrophoresis on thin-layer starch gel) and the human serum resistance (blood incubation infectivity test) of a Trypanozoon stock from a dog and 14 stocks from man in Liberia were examined. The complete conformity of criteria for man-infectivity of the dog stock with 5 human stocks and the very close similarity to the 9 remaining stocks from the same epidemiological locality indicates the dog as a reservoir host of gambiense sleeping sickness.

Alanine Transaminase↗
PubMed1984

Histopathological findings in mini-pigs infected with different strains of Trypanosoma brucei.

Two pigs infected with Trypanosoma brucei gambiense developed low parasitemia which became undetectable after 6 months; on autopsy 13 months after infection they showed no histopathological alterations. --Five of six pigs infected with a Trypanosoma brucei brucei strain from the Ivory Coast developed low parasitemia (up to about antilog 6.5 per ml of blood) which became progressively lower but was detectable up to one year after infection. On autopsy they showed interstitial myocarditis and meningo-encephalitis; during the course of the infection, the first became milder, the second more intense; no trypanosomes were seen in the tissues. One of these pigs developed a parasitemia of up to antilog 8 and died 172 days after infection from bacterial pneumonia, histologically it had severe myocarditis with many trypanosomes in the tissue and mild meningo-encephalitis. --Three pigs infected with a Trypanosoma brucei brucei strain from the Serengeti died 47, 68, 130 days after infection. The first dying pig had a high terminal parasitemia, in the others, the parasitemia was low until the end, being only detectable by the hematocrit centrifugation technique or by mouse passage. At autopsy, all showed massive myocarditis and interstitial nephritis with masses of extravascular trypanosomes, moderate meningo-encephalitis with very few trypanosomes, and widespread colonization of other organs and tissues by trypanosomes, still without marked cellular infiltrations.

Animals↗
PubMed1982

Epidemiological studies on the animal reservoir of Gambiense sleeping sickness. Part III. Characterization of trypanozoon stocks by isoenzymes and sensitivity to human serum.

Polymorphism in 12 enzymes, as shown by electrophoresis on thin-layer starch-gel, was examined in 88 stocks of trypanosomes of the subgenus Trypanozoon isolated from man and animals in the Ivory Coast and Upper Volta. Three of the enzyme profiles seen in trypanosomes from man in the Ivory Coast were exactly the same as in trypanosomes from local domestic pigs and from various game animals and a bovine in the Upper volta, thus confirming previous evidence that human trypanosomiasis is a zoonosis in West Africa. Altogether 9 zymodemes were found in man; one was exactly the same as another from the Congo while a further one was identical to a Ugandan zymodeme. Thirty-one zymodemes were found only in animals, and 6 were exactly the same as others from elsewhere in Africa, including the eastern part. All zymodemes resembled each other by possessing common electrophoretic patterns in 5 enzymes. In most zymodemes, the variants of two other enzymes were characteristically West African, although an East African influence was apparent, together with further evidence of hybridization. Many zymodemes differed from others only to a minor extent in a few isoenzyme bands. A group of closely related minor zymodemes constituted another trypanosome population ineffective to man in West Africa which had a variable sensitivity to normal human serum; enzymatically it was clearly separated from the major zymodeme previously described in West Africa, which was consistently resistant to normal human serum and had been previously associated with chronic gambiense sleeping sickness.

Africa, Western↗
PubMed1981

On the persistence of human serum resistance and isoenzyme patterns of Trypanozoon in experimentally infected pigs.

'Mini-pigs' were infected with salivarian Trypanozoon clones to examine the persistence and stability of the human serum resistance [Blood Incubation Infectivity Test (BIIT)] and isoenzyme characteristics during infection in a new host. A stock regarded as Trypanosoma brucei, derived from a domestic pig in the Ivory Coast, retained its BIIT negative (serum sensitive), alanine aminotransferase (ALAT) and peptidase 2 (PEP 2) characteristics throughout 343 days of infection in pigs. Similarly there was no change in the BIIT positive (serum resistant) and different ALAT and PEP characteristics of a human isolate from the same area, and regarded as T. b. gambiense, during 154 days before the infection became undetectable. In mixed infections of the two clones in pigs, trypanosomes which were not treated with human serum and inoculated into Mastomys natalensis invariably displayed the 'T. b. brucei' characteristics. However, simultaneous inoculations of trypanosomes treated with human serum into M. natalensis always displayed the characteristics of the T. b. gambiense. Thus, in mixed infections, in which 'T. b. brucei' predominated, the minority 'T. b. gambiense' population was recoverable after treatment with human serum by subinoculation into Mastomys.

Animals↗
PubMed1981

Epidemiological studies on the animal reservoir of gambiense sleeping sickness. Part I. Review of literature and description of the study areas.

A review of literature of the previous and recent evidence of potential animal reservoir hosts of gambiense sleeping sickness is given. A highly endemic sleeping sickness area in the Ivory Coast is described together with an area of recent low endemicity in southwestern Upper Volta. These areas were surveyed as part of a study on the significance of any potential animal reservoir of the disease. The results are described in detail in subsequent papers.

Animals↗
PubMed1981

Epidemiological studies on the animal reservoir of gambiense sleeping sickness. Part II. Parasitological and immunodiagnostic examination of the human population.

The prevalence of the disease was determined in the population (n = 3402) of a highly endemic sleeping sickness area in the Ivory Coast and an area of recent low endemicity in southwestern Upper Volta by using parasitological techniques supplemented by the determination of trypanosome specific antibodies and serum macroglobulins (IgM). 62 cases of trypanosomiasis were diagnosed parasitologically in the sleeping sickness focus in the Ivory Coast. 30 Trypanozoon stocks were established for their behavioural and biochemical characterization. The percentage of specific antibody carriers. 26% and 10% obtained with the enzyme-linked immunosorbent assay (ELISA) in both areas, respectively, was compared to that obtained for raised IgM levels. False negative diagnosis resulted in 24% with the ELISA, 12% with the indirect immunofluorescent test (IFT) and 19% with the radial immunodiffusion (RID). Considering IFT and IgM levels together, the proportion of false negative results fell to 8%. Possible reasons for low sensitivities, especially of the ELISA are discussed.

Adolescent↗
PubMed1981

On the immobilization of hartebeest and kob in Upper Volta.

24 hartebeests (Alcelaphus buselaphus major), one waterbuck (Kobus defassa) and 16 kobs (Kobus kob) were immobilized during field work in Upper Volta. The use of the newly developed piperidine derivative R 33799 at weight treated dosage levels can be strongly recommended for the immobilisation of hartebeest. In this species the drug produces a sufficient deep analgesia within a reasonable short period for all handling purposes. It is safe, has a wide therapeutic index, can be used in syringes of not more than 1 ml capacity and is quickly reversed by the antidote (nalorphine hydrobromide). No fatalities occurred. The limited number of kobs immobilized did not allow final conclusions to be drawn on the compatibility of the drug for this game species unless the central nervous side effects as described can be explained better and overcome. Further investigation should be undertaken to study the reaction of kob to lower dosages of R 33799 and other combinations of this analgesic with other neuroleptics. Nalorphine hydrobromide proved to be a useful antidote in hartebeest, but less effective in kob.

Animals↗
PubMed1979

The natural occurrence of Trypanozoon in domestic chicken in the Ivory Coast.

From a natural infected chicken (Gallus gallus var. domesticus) in the Ivory Coast trypanosomes were isolated using Mastomys natalensis as recipient animal. Trypanosomes were diagnosed as belonging to the subgenus Trypanozoon from its morphology and its infectivity for rodents. The stabilated stock was able to infect a laboratory chicken. The stock proved to be human plasma subresistant and showed electrophoretic patterns of three enzymes (ALAT III, ME I, PEP III) so far only seen in pig and dog originated Trypanozoon stocks from the same region surveyed. The discovery for the first time of chicken harbouring Trypanozoon has to be considered in epizootiology and epidemiology of trypanosomiases.

Animals↗