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J P Dedet

Publications and source records attributed to J P Dedet.

At least 19 recordsLinked to original sources
PubMed2003

Human cutaneous leishmaniasis due to Leishmania infantum in the Sidi Bourouis focus (Northern Tunisia): epidemiological study and isoenzymatic characterization of the parasites.

The authors report an increase of the number of case of cutaneous leishmaniasis in the Sidi Bourouis region community of Siliana Governorate (Tunisia), with 38 cases diagnosed in 6 months (1st November 2000-30th April 2001), contrary to its usual sporadic character. The isoenzymatic identification of 15 isolated strains emphasizes the role of the Leishmania infantum zymodeme MON-1 as an important factor in the genesis of the sporadic cutaneous leishmaniasis of Northern Tunisia. In fact it was isolated in 6 cases while L. infantum MON-24, the usual agent was isolated in 9 cases.

Aged↗
PubMed2002

A previously unclassified trypanosomatid responsible for human cutaneous lesions in Martinique (French West Indies) is the most divergent member of the genus Leishmania ss.

Two cases of skin lesions similar to those caused by Leishmania parasites have been reported from Martinique. Parasites isolated from these lesions were unlike Leishmania reference strains by isoenzyme analysis and electron microscopy and were assumed to be monoxenous trypanosomatids which normally only infect invertebrates. Both strains have now been retyped by isoenzyme analysis and found to be identical to each other and distantly related to all other Leishmania species. The sequence of the 18S ribosomal RNA gene and partial sequences of the DNA polymerase alpha and RNA polymerase II largest subunit genes were obtained. These sequences indicated that the Martinique parasites clustered with L. enriettii and were basal to all other euleishmania. However, support for both the position basal to all euleishmania and the clustering with L. enriettii was low. The Martinique parasites may cluster with L. (Leishmania) or L. (Viannia) or form a novel clade within the euleishmania either with or without L. enriettii.

Animals↗
PubMed2002

Value of two PCR methods for the diagnosis of canine visceral leishmaniasis and the detection of asymptomatic carriers.

The value of 2 PCR methods, targeting genomic and kinetoplast minicircle DNA respectively, was investigated for both diagnosis and prevalence studies of canine visceral leishmaniasis (CVL). The first method (R) was 5000-fold less sensitive than the second (method KRV). Both were tested for diagnosis of CVL in 44 sick dogs with confirmed disease using different biological samples. Method R was highly efficient when using invasive samples, but the use of method KRV proved necessary for a 100% sensitive diagnosis using peripheral blood. This method was applied to peripheral blood and skin samples in 263 dogs during a mass survey in the Cévennes focus. PCR was compared to serology and all results were analysed according to clinical status. The 'CVL-infection' prevalence was found to be 79.8% by PCR compared with 29.6% by serology: 89.4% of symptomatic and 65.2% of asymptomatic dogs harboured parasites in peripheral blood. This study confirms the high prevalence of asymptomatic carriers of Leishmania. In total, for the diagnosis of CVL in sick dogs, method R is recommended in view of its 100% positive predictive value (compared with 30% for method KRV). A strategy best adapted for prevalence surveys might combine serology and highly sensitive PCR on peripheral blood.

Animals↗
PubMed2002

Human cutaneous leishmaniasis caused by Leishmania naiffi is wide-spread in South America.

Four human cases of localized cutaneous leishmaniasis caused by Leishmania naiffi are reported. Two of the cases were infected in French Guiana, one in French Guiana or Martinique, and the other in Ecuador or Peru. The geographical distribution of L. naiffi is clearly larger than that initially reported. Three zymodemes were represented by the four isolates, confirming that there is intraspecific polymorphism in L. naiffi.

Adult↗
PubMed2002

[Epidemiologic surveillance of cutaneous leishmaniasis in Guiana. Summary of military data collected over 10 years].

This report describes the results of epidemiological surveillance of cutaneous leishmaniasis in French military personnel in French Guiana. Data was collected regarding microscopic diagnosis, clinical manifestations, and lesion location as well as compliance with vector control measures. Year-to-year variations in the incidence in the general population have been attributed to changes in climatic conditions. Monitoring incidence and density curves, correlation of findings with local epidemiological data, and analysis of the most recent epidemic in 1998/99 (326 cases, attack rate 3.2% men years) highlight the importance of behavioral factors. The proportion of total cases involving military personnel varied widely from 20 to 85%. Investigation consistently showed that failure to apply elementary protective measures against sandfly bites was the most determinant factor in this proportion. Strict compliance with these measures appears to reduce the risk of infection considerably.

Animals↗
PubMed2001

Sudan: the possible original focus of visceral leishmaniasis.

Fifty-two Leishmania strains, obtained from human patients and dogs in a visceral leishmaniasis focus in Sudan, were characterized by isoenzyme electrophoresis (15 enzymes). The phylogenetic analysis showed that the 7 Leishmania zymodemes obtained hold ancestral positions on the phylogenetic tree, supporting the hypothesis of an East African origin of visceral leishmaniasis.

Animals↗
PubMed2001

Virulence of Leishmania infantum is expressed as a clonal and dominant phenotype in experimental infections.

Human Leishmania infantum infection results in a spectrum of clinical expressions ranging from cutaneous to either asymptomatic or fatal visceral disease. In this context, characterization of parasite virulence appears to be relevant as a biological marker of intrinsic parasitic factors that can affect the pathology of leishmaniasis. Since parasite populations in naturally infected hosts are likely to be composed of multiclonal associations, we first explored the biodiversity of parasite virulence at the intrastrain level in vitro and in vivo by using 11 clones isolated from three strains previously known to express different virulence phenotypes in mice. Subsequently, we studied the course of infection in mice inoculated simultaneously or successively with strains or clones showing various virulence phenotypes. Analysis of in vitro growth characteristics showed no differences among clones from the different parental strains. By contrast, in vivo experiments evidenced a marked intrastrain heterogeneity of virulence to mice. One out of five clones obtained from a virulent strain showed a typical virulence phenotype, while the remaining four clones had low-virulence profiles, as did the six clones isolated from two low-virulence strains. In mixed multiclonal infections, the virulence phenotype was expressed as a dominant character over the associated low-virulence clones. After a challenge with either a homologous or a heterologous strain or clone, virulence phenotypes were conserved and expressed as in naive mice independently from the preexisting population. These results strongly suggest that parasite virulence in L. infantum visceral leishmaniasis is clonal and dominant in nature.

Animals↗
PubMed2001

[Infantile visceral leishmaniasis caused by Leishmania infantum zymodeme MON-24 in Algeria].

In Algeria, visceral leishmaniasis is caused principally by Leishmania infantum MON-1, a common agent of the disease on the edges of the mediterranean basin. Other zymodemes (MON-34 and MON-80) of the same complex have also been isolated from immunologically competent patients. In the present study, the authors report the presence of Leishmania infantum MON-24, the main agent of cutaneous leishmaniasis in northern Algeria, in five children with visceral leishmaniasis.

Animals↗
PubMed2001

[Visceral leishmaniasis in Cameroon. Seroepidemiologic survey in the Kousseri region, north Cameroon].

A sero-epidemiological survey of school children was carried out in Kousseri, a focus for visceral leishmaniasis. Sero-immunological assays for the detection of anti-Leishmania antibodies were based on the indirect immunofluorescence assay test and counter-immunoelectrophoresis. 9 out of 223 school children tested positive for visceral leishmaniasis (seroprevalence rate of 4%). These 9 cases had no history of the disease. The data obtained confirm the endemicity of visceral leishmaniasis in this focus and call for extensive studies in order to determine the prevalence of the disease in the entire population as well as the main components of the transmission cycle.

Animals↗
PubMed2000

[Leishmaniasis: update].

PARASITE IDENTIFICATION: Leishmaniases are a group of parasitic diseases affecting 88 countries in four continents. Isoenzymatic electrophoresis, presently the gold standard technique for Leishmania identification, has led to the development of the phenetic and phylogenetic classifications commonly in use. Study of the genome of these parasites is particularly important because of the features it presents. PARASITE CYCLE: Parasite transmission to mammals is facilitated by sandfly saliva. The parasite invades the human dermis by complex mechanisms involving molecular interactions allowing the parasite to survive after intracellular penetration. CLINICAL EXPRESSION: Clinical outcome of leishmaniases depends on both the Leishmania species tropism and the host's immune response. Immunosuppressive status, whatever its origin, facilitates Leishmania infection and worsens the clinical picture. TREATMENT: No new developments have occurred for a long time in the treatment of leishmaniases. Individual prophylactic measures are limited to insecticide impregnated bednets for human use and insecticide collars for prevention of canine leishmaniases.

Animals↗
PubMed2000

Optimized PCR using patient blood samples for diagnosis and follow-up of visceral Leishmaniasis, with special reference to AIDS patients.

We developed a highly sensitive PCR method that enables the diagnosis and posttherapeutic follow-up of visceral leishmaniasis with patient blood. The PCR assay was thoroughly optimized by successive procedural refinements to increase its sensitivity and specificity. It was compared to in vitro cultivation as well as to direct examination of bone marrow and to serology. Two hundred thirty-seven patients presenting with clinical signs compatible with visceral leishmaniasis were included in the study. Thirty-six were diagnosed as having Mediterranean visceral leishmaniasis (MVL). Twenty-three of them, including 19 AIDS patients, were monitored during and after treatment over a period from 2 weeks to 3 years. Our PCR assay proved more sensitive than in vitro cultivation, direct examination, and serology for all patients. It is simple and can be adapted to routine hospital diagnostic procedures. For the primary diagnosis of MVL, the sensitivity of PCR versus that of cultivation was 97 versus 55% with peripheral blood and 100 versus 81% with bone marrow samples. Regarding posttherapeutic follow-up, overall, 48% of positive samples were detected by PCR only. Seven patients presented with a clinical relapse during the study; six relapses were detected at first by PCR only, sometimes a few weeks before the reappearance of signs or symptoms. We conclude that an optimized and well-mastered PCR assay with a peripheral blood sample is sufficient to provide a secure diagnosis for all immunocompromised patients and most immunocompetent patients. We also suggest systematic posttherapeutic monitoring by PCR with peripheral blood for immunocompromised patients.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Treatment of Old World cutaneous leishmaniasis by pentamidine isethionate. An open study of 11 patients.

BACKGROUND: Pentavalent antimonial derivatives (PAD), especially meglumine antimoniate (Glucantime((R))), are usually considered as the first-line drugs for Old World leishmaniasis, but their potential toxicity and the number of required injection, either intralesional or intramuscular, prompt to search for alternative treatments. OBJECTIVE: To evaluate the efficiency and tolerance of pentamidine isethionate in Old World leishmaniasis. METHODS: An open pilot study included 11 patients from two regional academic centers, with varied parasitological forms of Old World leishmaniasis, treated with three strictly intramuscular injections of 4 mg/kg of base-pentamidine every other day. RESULTS: Tolerance was good overall, and 8/11 (73%) of patients responded well with a quick healing of their lesions, little scarring and no relapse. CONCLUSION: Pentamidine isethionate is a safe and effective first-line treatment for Old World leishmaniasis. Larger-scale prospective studies comparing several dosage regimens of pentamidine and pentamidine isethionate to PAD are warranted.

Adolescent↗
PubMed2000

[Infantile visceral leishmaniasis from Leishmania infantum MON-24: a reality in Tunisia].

The authors report the first documented observation of infantile visceral leishmaniasis due to Leishmania infantum MON-24 zymodeme in Tunisia. This zymodeme was isolated from a non-immunodepressed two-year-old child, with visceral leishmaniasis, originating from Zaghouan, in northern Tunisia. This case shows that beside L. infantum MON-1 and MON-80, L. infantum MON-24, the usual parasite of cutaneous leishmaniasis, there exists also a causative agent of visceral leishmaniasis in our country.

Animals↗
PubMed1998

Conserved linkage groups associated with large-scale chromosomal rearrangements between Old World and New World Leishmania genomes.

The genus Leishmania can be taxonomically separated into three main groups: the Old World subgenus L. (Leishmania), the New World subgenus L. (Leishmania) and the New World subgenus L. (Viannia). The haploid genome of Old World Leishmania species has been shown to contain 36 chromosomes defined as physical linkage groups; the latter were found entirely conserved across species. In the present study, we tried to verify whether this conservation of the genome structure extends to the New World species of Leishmania. 300 loci were explored by hybridization on optimized pulsed field gel electrophoresis separations of the chromosomes of polymorphic strains of the six main pathogenic Leishmania species of the New World. When comparing these New World karyotypes with their Old World counterparts, 32 out of 36 linkage groups were found conserved among all species. Four chromosomal rearrangements were found. All species belonging to the L. (Viannia) subgenus were characterized by the presence (i) of a short sequence exchange between chromosomes 26 and 35, and (ii) more importantly, of a fused version of chromosomes 20 and 34 which are separated in all Old World species. 69 additional markers were isolated from a plasmid library specifically constructed from the rearranged chromosomes 20+34 in an attempt to detect mechanisms other than a fusion or breakage: only two markers out of 40 did not belong to the linkage groups 20 and 34. On the other hand, all strains belonging to the New World subgenus L. (Leishmania) were characterized by two different chromosomal rearrangements of the same type (fusion/breakage) as above as compared with Old World species: chromosomes 8+29 and 20+36. Consequently, these two groups of species have 35 and 34 heterologous chromosomes, respectively. Overall, these results show that large-scale chromosomal rearrangements occurred during the evolution of the genus Leishmania, and that the three main groups of pathogenic species are characterized by different chromosome numbers. Nevertheless, translocations seem particularly rare, and the conservation of the major linkage groups should be an essential feature for the compared genetics between species of this parasite.

Animals↗