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J A Rioux

Publications and source records attributed to J A Rioux.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Leishmania tropica in Morocco. III--The vector of Phlebotomus sergenti. Apropos of 89 isolates].

In a Moroccan focus of cutaneous leishmaniasis caused by Leishmania tropica, 7,907 female sandflies captured with CDC traps were dissected from summer to autumn 1989. Among species of the genus Phlebotomus, only P. sergenti harbored promastigotes. Eighty-nine strains belonging to the complex L. tropica were isolated. The frequency of vector infection was zero in June, rose to 1.3% in August, and reached 9.9% in October, which indicates that the period of high risk is at the end of the hot season. Out of 89 strains isolated, 74 were completely typed and corresponded to the following four zymodemes: MON-102 (one strain), MON-107 (56 strains), MON-122 (two strains), and MON-123 (15 strains). Only the first two were observed in humans. The distribution of zymodemes MON-102 and MON-107 was very different in humans, dogs, and the vector. In one of the sites surveyed, which was strongly dominated by MON-107, the absence of human cases involving this zymodeme suggests the existence of a wild reservoir.

Animals↗
PubMed1991

[Ecoepidemiology of leishmaniases in Syria. 2--Presence, in dogs, of Leishmania infantum Nicolle and Leishmania tropica (Wright) (Kinetoplastida-Trypanonomatidae)].

In an ecoepidemiological study in the Syrian foci of human visceral (VL) and cutaneous (CL) leishmaniasis, domestic dogs infected with Leishmania infantum MON-1 and L. tropica MON-76 were found for the first time. In Syria canine leishmaniasis caused by L. infantum, occurs in the humid and sub-humid western belt from the coastal zone to the nearby mountain ranges. Sporadis cases of human VL occur in this area. Canine CL, caused by L. tropica was found in the semi-arid zone in a village with a high human infection rate. The infection causes small papules or crusted ulcers on the nose or muzzle. These observations are relevant to control. In human VL foci it is recommended not to control the dog population, unless this is linked with other activities, such as rabies control. Control of dogs in the CL areas is not justified because of the small size of the lesions and the rarity of the parasites. Indeed the role of the dog as the "true" reservoir host is questionable. Human CL infection is best controlled by active case detection and specific treatment.

Animals↗
PubMed1991

Intravectorial cycle of Leishmania in sandflies.

The development of Leishmania spp. in their vectors is a complex process involving behavioural, morphological and biochemical changes. The process differs between Leishmania species. Recent information on the developmental process and its regulation, summarised in this report, relates to possible separation of amastigotes into two separate developmental lines, development of infective forms of promastigote, attachment of certain, possibly altruistic promastigotes to the gut wall, and the possibility of genetic exchange.

Animals↗
PubMed1991

[Human cutaneous leishmaniasis caused by Leishmania Major MON-26 in the region of Damascus (Syria)].

In response to an epidemic of oriental sore around Damascus, an ecological and epidemiological survey was carried out in the village of Dmeir, 40 km NE of Damascus. Parasites isolated from six cases from Dmeir, and two other cases from Syria were identified as Leishmania major, zymodeme MON-26. This zymodeme is known as the agent of zoonotic cutaneous leishmaniasis from the Sub-Saharian Sahel to the Near and Middle East. This is the first report of L. major in Syria. In a group of 234 school children aged 5-11 years, the leishmanin skin test was positive in 37%, indicating a high transmission rate. The epidemic seems to be the result of agricultural and industrial development projects in the area: numbers of both the gerbil reservoir host and sandfly vector appear to be increased by the land improvement.

Agriculture↗
PubMed1990

Interclonal variations in molecular karyotype in Leishmania infantum imply a 'mosaic' strain structure.

The molecular karyotypes of 36 clones derived from 8 strains of Leishmania infantum were examined by pulsed-field gel electrophoresis. Although there appeared to be a high degree of genetic relatedness between the clones and the parent strain, a limited degree of polymorphism was noted in 50% of the clones, expressed mainly as the presence of an additional chromosome or as a chromosome size modification. Repeated subcloning in one strain showed that chromosomal rearrangements could occur during the cloning process. Chromosome homologies were examined by Southern analysis with chromosome-specific DNA probes. The results suggest a disomy for some chromosomes, but cannot exclude aneuploidy. The mechanisms possibly leading to such heterogeneity are discussed: they could involve frequent DNA amplification/deletion, and imply a 'mosaic' structure of the cultured strains or clones, with different individuals possessing differently sized versions of the same chromosomes.

Animals↗
PubMed1990

Taxonomy of Leishmania. Use of isoenzymes. Suggestions for a new classification.

The authors propose a new classification for the genus Leishmania Ross, 1903 based both on the use of intrinsic and extrinsic characters and on Linnean and Adansonian methods. The type of vertebrate host makes it possible to recognize the genus group: Leishmania designates Kinetoplastida parasites of mammals. Neighbouring forms which parasite reptiles are now grouped in the genus Sauroleishmania Ranque, 1973. Characteristics of the intravectorial cycle (supra- and peri-pyloric) are used to define the subgenus group (Leishmania, Viannia Lainson and Shaw, 1987). The classification uses biochemical, particularly enzymatic, characters. Elementary taxonomic units are made up of all the strains having the same isoenzyme profile, i.e. the zymodeme. The grouping of the zymodemes is usually performed through automatic techniques which lead to bush-like trees (dendrograms) showing either simple affinities between units (phenograms) or their phyletic relationships (cladograms). The branches recognized as being stable are individualized as "zymodeme complexes". They bear the name of either the previously defined species taxa or that of a specially created one. Two examples of taxonomic constructions, phenetic and cladistic, are presented. Finally, a general classification of the genus is proposed.

Animals↗
PubMed1990

[Ecoepidemiology of leishmaniasis in Syria. 1. Leishmania major Yakimoff and Schokhor (Kinetoplastida-Trypanosomatidae) infestation of Psammomys obesus Cretzschmar (Rodentia-Gerbillidae)].

During an epidemiological survey of zoonotic cutaneous leishmaniasis in South-West Syria, Leishmania major zymodème MON-26 was isolated from a reservoir host, Psammomys obesus terraesanctae (Rodentia-Gerbillidae). The abundance of this rodent, its close contact with infected villages and the high prevalence of the infection (63,1%) indicate that this is the main reservoir host of oriental sore in the semi desert area of this country.

Animals↗
PubMed1990

[Cell fusion in Leishmania (Kinetoplastida, Trypanosomatidae)].

Cell fusion in Leishmania infantum and L. tropica was recorded by means of a camera and a video system. Promastigotes were obtained from cultures in both cases. Fusion began with attachment of the posterior extremities of two ovoid flagellates. Complete fusion, with disappearance of adjacent cell membranes took about five minutes. In parallel, the flagella appear larger and shorter. These observations support the hypothesis of genetic exchanges suggested by analysis of DNA and enzymatic proteins.

Animals↗
PubMed1989

Chromosome size and number polymorphisms in Leishmania infantum suggest amplification/deletion and possible genetic exchange.

We have studied the molecular karyotypes of 21 strains and 14 clones of Leishmania infantum using pulsed field gel electrophoresis (PFGE). We detected a high degree of polymorphism within this species, with 'strain-specific' patterns for most isolates, even within a restricted endemic area. Variations relate to both the size of chromosomes (270-2600 kb) and their number, which can vary from 24 to 31 between closely related isolates. This polymorphism does not correlate with isoenzyme analysis. Small size variations between homologous chromosomes of different strains are suggestive of DNA amplification/deletion events. Strains are also shown to be multiclonal, with slight differences between most clones, but with a predominant clone concealing the others in PFGE analysis. The analysis of these data leads to the hypothesis of occasional genetic exchange by nuclear fusion in Leishmania, as recently shown in the related protozoan Trypanosoma brucei.

Animals↗
PubMed1989

[Eco-epidemiology of visceral and cutaneous leishmaniasis in the Yemen Arab Republic. I. Presence, in sympatric condition, of Leishmania infantum and Leishmania donovani complexes].

In complement to a previous survey, the authors proceed to the analysis of strains isolated from visceral human and canine leishmaniasis. Finally, among eight human strains isolated and identified with an enzymatic method, seven belong to the Leishmania donovani complex and one to the L. infantum complex. The L. donovani complex is represented by the MON-31 and MON-83 zymodem. The first one is also present in Saudi Arabia and Ethiopia. The second one, corresponding to a small variant, pleads for an intrafocal polymorphism phenomenon which was until now unknown in the L. donovani complex. The L. infantum complex is observed: 1) in sympatria with L. donovani in mountainous areas; 2) alone in the Tihama coastal plain. As for human cutaneous leishmaniasis present in the same focuses it is caused by L. tropica MON-71 and not by the above mentioned complexes.

Animals↗
PubMed1989

[Eco-epidemiology of visceral and cutaneous leishmaniasis in the Arab Republic of Yemen. II. A survey using intradermal reaction to leishmanin in a zone of mixed infestation with Leishmania tropica, L. donovani and L. infantum].

Frequency distribution of leishmanin test survey in Dhamran valley around Taez (Yemen Arab Republic) is reported. It was carried out on 174 school children from 6 to 12 years old. Three schools located at 950 m, 1,100 m and 1,430 m of altitude were visited. The maximum of positivity is observed in the lower range where L. tropica, L. donovani and L. infantum are rife. In the upper valley, where cutaneous leishmaniasis is rare and visceral leishmaniasis absent, the rate of positivity is a little bit lower. The conjugated influence of the three parasites is suggested.

Animals↗
PubMed1989

[Eco-epidemiology of visceral and cutaneous leishmaniasis in the Arab Republic of Yemen. III. Inventory and dynamics of Phlebotomus].

The systematic inventory and annual following of Phlebotomus population is established by the authors in a transmission area of visceral (human and canine) and cutaneous (human) leishmaniasis in the Yemen Arab Republic (province of Taez). Seven species of Phlebotomus and nine species of Sergentomyia are thus identified. Among them, four are considered as potential vectors: on the one hand, P. orientalis (s.g. Larroussius) and, probably P. arabicus (s.g. Adlerius) for L. infantum and L. donovani, in the other, P. sergenti and P. saevus (s.g. Paraphlebotomus) for L. tropica.

Animals↗
PubMed1989

[Leishmania braziliensis Vianna, 1911 in French Guiana].

A new case of cutaneous Leishmaniasis to L. braziliensis Vianna, 1911, contracted in French Guyana is reported. The parasite, isolated in culture, is identified by enzymatic typing (13 zymoden). The identified zymodem is zymodem MON-43. It is the same of the WHO reference strain L. braziliensis s. st.

Adult↗