Browsing by Autor "Fernando Regla Vargas"

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A new focus of cutaneous leishmaniasis due to Leishmania amazonensis in a Sub Andean region of Bolivia
(Elsevier BV, 1998) Eliana C. Martinez; François Le Pont; M Torrez; Jenny Telleria; Fernando Regla Vargas; M Muñoz; Simonne De Doncker; Jean‐Claude Dujardin; Jean‐Pierre Dujardin
Clinical healing of antimony-resistant cutaneous or mucocutaneous leishmaniasis following the combined administration of interferon-γ and pentavalent antimonial compounds
(Oxford University Press, 1994) E Falcoff; N. J. Taranto; Carlos Remondegui; J. P. Dédet; Laëtitia Canini; C.M. Ripoll; L. Dimier-David; Fernando Regla Vargas; L. Gimenez; Jorge Guillermo Bernabó
In an open trial, longer courses of pentavalent antimonials (Sbv) at sub-optimal doses (10 mg/kg body weight), in association with recombinant human interferon-gamma (IFN-gamma) (100 micrograms/m2 of body surface area) were administered, by daily intramuscular injections, to 13 patients with diagnoses of cutaneous or mucocutaneous leishmaniasis unresponsive to Sbv. Four patients presented with large skin ulcers, and 9 had mucosal involvement as the main manifestation, the latter affecting the nose (3 cases), nose and septum (2 cases), nose and oral cavity (1 case), and nose, pharynx and larynx (3 cases). Except for one case with severe involvement of the upper respiratory tract, the lesions were fully resolved by the end of therapy (mean duration 40 +/- 12 [SD] d, range 30-60 d) in the 11 patients who completed therapy. The main side effects were headache and fever (7 cases), together with leucopenia and eosinophilia (4 cases). It is concluded that combined administration of low doses of Sbv plus IFN-gamma may provide a novel therapeutic approach for the treatment of antimony-resistant cutaneous or mucocutaneous leishmaniasis. The possible mechanisms by which IFN-gamma contributes to resolution of the disease are discussed.
Current spread of Triatoma infestans at the expense of Triatoma sordida in Bolivia
(Instituto Oswaldo Cruz, Ministério da Saúde, 1996) François Noireau; Simone Frédérique Brénière; Lucyla Cardozo; Marie France Bosseno; Fernando Regla Vargas; Carlos Peredo; Marlon Medinacelli
First evidence of transmission of Leishmania (Viannia) lainsoni in a Sub Andean region of Bolivia
(Elsevier BV, 2002) Brigitte Bastrenta; R Buitrago; Fernando Regla Vargas; François Le Pont; M Torrez; María Flóres-Chávez; N Mita; Simone Frédérique Brénière
Genetic Variability and Microdistribution of Triatoma infestans Genotypes and Trypanosoma cruzi Clones in Arequipa Region (Peru)
(Instituto Oswaldo Cruz, Ministério da Saúde, 1997) Simone Frédérique Brénière; Jenny Lopez; Fernando Regla Vargas; Christian Barnabé
The genetic variability of Triatoma infestans and Trypanosoma cruzi populations was studied by isoenzyme analysis in two distinct areas of Arequipa province (Peru); one, Santa Rita de Siguas, being an endemic area for Chagas' disease, the second, Arequipa, recently infected. Analysis of T. infestans genetic variability indicates, (i) temporal stability of genotypes found in Santa Rita de Siguas, (ii) high genetic differences between Arequipa and Santa Rita de Siguas populations suggesting minor contact between them, (iii) multiple origin of the T. infestans population in Arequipa, and (iv) poor dispersal capacity of T. infestans: the panmictic unit could be reduce to a house. Parasite isoenzyme analysis was performed in 29 Peruvian stocks of T. cruzi, mainly isolated from bugs taken in a single locality, Santa Rita de Siguas. The results show, (i) a high genetic polymorphism, (ii) nine different multilocus genotypes were detected and clustered in two different clades, (iii) most of the parasite isolates pertained to one of the clade and were genetically similar to those analyzed 12 years before. This sample allowed the study of the mating system of T. cruzi in strict sympathic conditions and gave more strength to the hypothesis of the clonal structure of T. cruzi populations.
Human mixed infections of Leishmania spp. and Leishmania-Trypanosoma cruzi in a sub Andean Bolivian area: identification by polymerase chain reaction/hybridization and isoenzyme
(Instituto Oswaldo Cruz, Ministério da Saúde, 2003) Brigitte Bastrenta; N Mita; R Buitrago; Fernando Regla Vargas; María Flóres-Chávez; M Machane; Nina Yacsik; M Torrez; François Le Pont; Simone Frédérique Brénière
Parasites belonging to Leishmania braziliensis, Leishmania donovani, Leishmania mexicana complexes and Trypanosoma cruzi (clones 20 and 39) were searched in blood, lesions and strains collected from 28 patients with active cutaneous leishmaniasis and one patient with visceral leishmaniasis. PCR-hybridization with specific probes of Leishmania complexes (L. braziliensis, L. donovani and L. mexicana) and T. cruzi clones was applied to the different DNA samples. Over 29 patients, 8 (27.6%) presented a mixed infection Leishmania complex species, 17 (58.6%) a mixed infection Leishmania-T. cruzi, and 4 (13.8%) a multi Leishmania-T. cruzi infection. Several patients were infected by the two Bolivian major clones 20 and 39 of T. cruzi (44.8%). The L. braziliensis complex was more frequently detected in lesions than in blood and a reverse result was observed for L. mexicana complex. The polymerase chain reaction-hybridization design offers new arguments supporting the idea of an underestimated rate of visceral leishmanisis in Bolivia. Parasites were isolated by culture from the blood of two patients and lesions of 10 patients. The UPGMA (unweighted pair-group method with arithmetic averages) dendrogram computed from Jaccard's distances obtained from 11 isoenzyme loci data confirmed the presence of the three Leishmania complexes and undoubtedly identified human infections by L. (V.) braziliensis, L. (L.) chagasi and L. (L.) mexicana species. Additional evidence of parasite mixtures was visualized through mixed isoenzyme profiles, L. (V.) braziliensis-L. (L.) mexicana and Leishmania spp.-T. cruzi. The epidemiological profile in the studied area appeared more complex than currently known. This is the first report of parasitological evidence of Bolivian patients with trypanosomatidae multi infections and consequences on the diseases' control and patient treatments are discussed.
Isoenzyme profiles of Trypanosoma cruzi stocks from different areas of Paraguay
(Instituto Oswaldo Cruz, Ministério da Saúde, 2001) Nidia Acosta; Margarita Samudio; Elsa López; Fernando Regla Vargas; Nina Yaksic; Simone Frédérique Brénière; Antonieta Rojas de Árias
Twenty one Trypanosoma cruzi stocks from humans, domiciliary triatomines and one sylvatic animal of different areas of Paraguay were subjected to isoenzyme analysis. Thirteen enzyme systems (15 loci in total) were studied. MN cl2 (clonets 39) and SO34 cl4 (clonets 20) were used as references. Relationships between stocks were depicted by an UPGMA dendrogram constructed using the Jaccard's distances matrix. Among the Paraguayan stocks 14 zymodemes were identified (Par1 to Par14), Par 5 being the most frequent. Polymorphism rate and clonal diversity were 0.73 and 0.93, respectively. Average number of alleles per polymorphic locus was 2.5 (range 2-4). These measurements show a high diversity, which is confirmed by the dendrogram topology. All stocks belong to the same lineage, as MN cl2 reference strain (T. cruzi II). Moreover three distinct subgroups were identified and two of them correspond to Brazilian and Bolivian zymodemes, respectively. The third subgroup, the most common in Paraguay, is related to Tulahuen stock. The large geographical distribution of some zymodemes agrees with the hypothesis of clonality for T. cruzi populations. However sample size was not adequate to detect genetic recombination in any single locality.
Low probability of transmission of Trypanosoma cruzi to humans by domiciliary Triatoma sordida in Bolivia
(Oxford University Press, 1997) François Noireau; Simone Frédérique Brénière; Juan C. Ordóñez; L. Cardozo; W. Morochi; T. Gutierrez; Marie France Bosseno; S. Garcia; Fernando Regla Vargas; Nina Yaksic
The role of Triatoma sordida in the domestic transmission of Trypanosoma cruzi was assessed in 7 rural localities in Velasco Province, Department of Santa Cruz, Bolivia. Tri. sordida, the only triatomine species identified in these localities, was found inside 58.0% of houses but not in large numbers (3.1 bugs per infested house on average). A total of 220 faecal samples from domiciliary bugs was examined microscopically and by the polymerase chain reaction for the presence of trypanosomes: 21.4% were infected. Analysis of blood meals of domiciliary Tri. sordida showed that humans were the commonest host (70.4%), followed by chickens and dogs. Four of 418 persons tested were seropositive for Tryp. cruzi. Only 2 of a second group of 62 persons living in dwellings infested by Tri. sordida were seropositive. Tryp. cruzi infection was demonstrated in dogs and domestic rats. Three other species of small mammals were found to be infected with trypanosomes. In our study area, domestic Tri. sordida are mainly incriminated in the transmission of Tryp. cruzi to synanthropic animals, whereas transmission to humans is very rare. The presence in houses of small populations of Tri. sordida infected with Tryp. cruzi is therefore currently insufficient for this insect to constitute a major epidemiological risk factor.
Lutzomyia nuneztovari anglesi (Le pont & Desjeux, 1984) as a vector of Leishmania amazonensis in a sub-Andean leishmaniasis focus of Bolivia.
(American Society of Tropical Medicine and Hygiene, 1999) E. Martínez; François Le Pont; M Torrez; Jenny Telleria; Fernando Regla Vargas; Jean-Pierre Dujardin; JP Dujardin
Recently, a new Leishmania amazonensis focus was described in a sub-Andean region (1,450-2,100 meters above sea level) of Bolivia. In this area, three anthropophilic sandfly species were identified: Lutzomyia nuneztovari anglesi Le Pont & Desjeux, 1984, which represented 86-99% of the captures, Lu. galatiae Le Pont et al., 1998, and Lu. shannoni Dyar 1929. Only Lu. nuneztovari anglesi was found naturally infected by flagellates (16 of 1,715 females). Three Leishmania stocks were isolated and analyzed by isoenzyme electrophoresis at 11 loci. No significant isoenzymatic differences were demonstrated between them and 7 stocks isolated from patients from the same area, and previously characterized as L. amazonensis. Moreover, in a simplified protocol, the experimental infection of Lu. nuneztovari anglesi by L. amazonensis was successful in 92% of the surviving specimens. These data are discussed in relation to the Killick-Kendrick criteria. These results strongly suggest that Lu. nuneztovari anglesi is the vector of L amazonensis at Cajuata, Inquisivi, La Paz, Bolivia.
Parasitological diagnosis of mucocutaneous leishmaniasis due to Leishmania b. braziliensis in Bolivia
(Brazilian Society of Tropical Medicine, 1991) L. Dimier-David; Christophe David; P Ravisse; R Bustillos; Susana Revollo; Philippe Lyèvre; M Muñoz; Fernando Regla Vargas; Jean-Pierre Dedet
Parasitological diagnosis, using stained smears, culture and pathological examination of biopsy, was studied in 146 patients infected with mucocutaneous leishmaniasis, in Bolivia and Peru. The most efficient parasite detecting technique appeared to be the smear examination in cutaneous lesions (33% positive) and the pathology in case of mucous lesions (28% positive). In both, cutaneous and mucous lesions, the parasites were found most frequently in old lesions.
Selection of Trypanosoma cruzi clonal genotypes (clonet 20 and 39) isolated from Bolivian triatomines following subculture in liquid medium
(Instituto Oswaldo Cruz, Ministério da Saúde, 2000) Marie-France Bosseno; Nina Yacsik; Fernando Regla Vargas; Simone Frédérique Brénière
Previous studies showed that two groups of Trypanosoma cruzi clonal genotypes named clonet 20 and clonet 39 were predominant in Triatoma infestans, the unique vector of Chagas disease in Bolivia. These groups of clones correspond to distinct genetic clusters. These clonets were detected in T. infestans and Rhodnius pictipes fecal samples before isolation and after culture by kDNA PCR (polymerase chain reaction) and hybridization of the amplified products with clonet specific kDNA probes named 20 and 39 as previously reported. Forty eight T. infestans and three R. pictipes infected insects captured at random in different Bolivian departments were proceeded. As previously reported the direct identification of the two major clonets in fecal samples allowed the detection of abundant mixed infections: 41% in the original sample, however after culture, only 6% of mixed infections were detected. Among the 21 parasite stocks isolated from digestive tracts where mixed infections were initially detected (clonet 20 + 39) clonet 20 alone was detected in 81% of them. This result clearly showed that the culture step selected clonet 20 parasites over those belonging to clonet 39. The taxonomic status of the isolated stocks was also confirmed by isoenzyme typing, and correlation was observed between clustering topology and hybridization patterns with the probes 20 and 39.
Smallness of the Panmictic Unit of Triatoma infestans (Hemiptera: Reduviidae)
(Oxford University Press, 1998) Simone Frédérique Brénière; Marie-France Bosseno; Fernando Regla Vargas; Nina Yaksic; François Noireau; Sébastien Noël; Jean‐Pierre Dujardin; Michel Tibayrenc
The population genetic structure of Triatoma infestans (Klug), the principal vector of the causative agent of Chagas disease in Bolivia, was investigated by enzyme electrophoresis at 15 loci, of which 3 were polymorphic. A total of 1,286 adults and nymphs was collected from 19 localities of the Cochabamba (high endemicity) and La Paz (low endemicity) departments. Previous results were confirmed, including a low level of polymorphism (0.20), low genetic distance between geographic areas, and a population structure compatible with an isolation by distance model. However, a high proportion (26.3%) of the surveyed localities showed a significant excess of homozygotes, disputing previous conclusions that considered the village as the probable panmictic unit. The excess of homozygotes was reduced when smaller subunits, such as individual houses or chicken coops, were considered, indicating a Wahlund effect.
Sylvatic Triatomines (Hemiptera: Reduviidae) in Bolivia: Trends Toward Domesticity and Possible Infection with Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae)
(Oxford University Press, 1995) François Noireau; Marie-France Bosseno; Roxana Carrasco; Jenny Telleria; Fernando Regla Vargas; Clara Camacho; Nina Yaksic; Simone Frédérique Brénière
The risk of domestic transmission of Trypanosoma cruzi (Chagas) by sylvatic triatomines was assessed in an isolated area of the subandean region of Bolivia. None of the 390 residents examined had serological evidence of infection. Two sylvatic triatomine species, Eratyrus mucronatus (Stål) and Triatoma sordida (Stål), were found in houses and in peridomestic structures. The collection of nymphal instars of both species from some houses indicated possible domesticity. Microscopic examination of feces from 92 insects showed no parasites, and cultures from the guts of 30 insects were negative. Nevertheless, a polymerase chain reaction (PCR) test performed on the same fecal samples showed the presence of T. cruzi DNA in 19.1 and 12.5% of E. mucronatus and T. sordida, respectively. These 16 PCR-positive samples were hybridized with 2 T. cruzi-specific probes known from the domestic cycle in Bolivia (clones 20 and 39). At least 1 of these clones was identified in 7 bugs (5 E. mucronatus and 2 T. sordida). Moreover, no hybridization was observed with these probes in S E. mucronatus and 1 T. sordida samples that showed an amplified band by PCR. These data indicated that T. cruzi clones, genetically unrelated to clones 20 and 39, also were circulating in this area. Based on these results, the 2 sylvatic triatomine species encountered in Apolo should not be overlooked as possible local vectors of T. cruzi.
Trypanosoma cruzi genotypes associated with domestic Triatoma sordida in Bolivia
(Elsevier BV, 1998) Simone Frédérique Brénière; W. Morochi; Marie-France Bosseno; J.A. Ordóñez; Teresa de Jesús Molina Gutiérrez; Fernando Regla Vargas; Nina Yaksic; François Noireau
Trypanosoma cruzi:Study of the Distribution of Two Widespread Clonal Genotypes in BolivianTriatoma infestansVectors Shows a High Frequency of Mixed Infections
(Elsevier BV, 1996) Marie-France Bosseno; Jenny Telleria; Fernando Regla Vargas; Nina Yaksic; François Noireau; Annie Morin; Simone Frédérique Brénière