Browsing by Autor "Nina Yaksic"

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High correlation between Chagas' disease serology and PCR-based detection of<i>Trypanosoma cruzi</i>kinetoplast DNA in Bolivian children living in an endemic area
(Oxford University Press, 1994) Patrick Wincker; Marie-France Bosseno; Constança Britto; Nina Yaksic; Micaela Cardoso; Carlos MÃ©dicis Morel; Simone FrÃ©dÃ©rique BreniÃ ̈re
The detection of Trypanosoma cruzi kinetoplast DNA by polymerase chain reaction (PCR) amplification is a potentially powerful tool for the parasitological diagnosis of Chagas' disease. We have applied this technique in a field situation in Bolivia, where 45 children from a primary school were subjected to serological testing, buffy coat analysis and PCR diagnosis. 26 of the 28 serology-positive individuals were also positive by PCR. In addition, two serology-negative children gave a positive result by PCR, including one who was positive in the buffy coat test. These results suggest that PCR detection of T. cruzi DNA in blood can be a very useful complement to serology in Chagas' disease diagnosis in Bolivia.
Immune Response to Trypanosoma cruzi Shed Acute Phase Antigen in Children from an Endemic Area for Chagas' Disease in Bolivia
(Instituto Oswaldo Cruz, Ministério da Saúde, 1997) Simone Frédérique Brénière; Nina Yaksic; Jenny Telleria; Marie-France Bosseno; François Noireau; Patrick Wincker; Daniel O. Sánchez
A field study of the immune response to the shed acute phase antigen (SAPA) of Trypanosoma cruzi was carried out in the locality of Mizque, Cochabamba department, Bolivia. Schoolchildren (266), with an average of 8.6 +/- 3.6 years, were surveyed for parasitological and serological diagnosis, as well as antibodies directed against SAPA using the corresponding recombinant protein in ELISA. The antibodies against SAPA were shown in 82% of patients presenting positive serological diagnosis (IgG specific antibodies). The positive and negative predictive values were 0.88. Antibodies anti-SAPA were shown in 80.8% of the chagasic patients in the initial stage of the infection (positive IgM serology and/or positive buffy coat (BC) test) and in 81.4% of the patients in the indeterminate stage of the infection (positive IgG serology with negative BC and IgM tests). These results show that the anti-SAPA response is not only present during the initial stage of the infection (few months) but extends some years after infection.
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.
Lutzomyianuneztovarianglesi (Diptera: Psychodidae) as a probable vector of Leishmaniabraziliensis in the Yungas, Bolivia
(Elsevier BV, 1998) M Torrez; Martha López; François Le Pont; E. Martínez; M Muñoz; David Abril Hervàs; Nina Yaksic; Jorge Arévalo; David Sossa; Jean-Pierre Dedet
PCR-based diagnosis for Chagas' disease in Bolivian children living in an active transmission area: comparison with conventional serological and parasitological diagnosis
(Cambridge University Press, 1997) Patrick Wincker; Jenny Telleria; M. F. Bosseno; Micaela Cardoso; Patrícia Marques; Nina Yaksic; Christine Aznar; P. LIEGEARD; Mireille Hontebeyrie; François Noireau
A large field study has been performed in the Cochabamba region of Bolivia with the aim of comparing the polymerase chain reaction (PCR) with other diagnostic methods for Chagas' disease. The amplification of Trypanosoma cruzi-specific kinetoplast DNA sequences in blood samples was compared with classical serological methods, specific IgM detection and direct parasite visualization for 268 school children in a single village where Chagas' disease transmission is active. Of 113 children positive by classical serology or buffy coat examination, 106 were detected by PCR (sensitivity: 93.8%). We did not observe any significant difference of PCR sensitivity between initial (IgM and/or buffy coat positive) and indeterminate stage (only IgG positive) patients. Among the remaining 155 children unconfirmed as chagasic (who were either only IgM positive, IgG-, IgM-, and buffy coat-negative) only 1 case was PCR positive. This case may be due to DNA contamination, or to a very recent infection not detected otherwise, or to specific immune depression. These results show that PCR is a very sensitive parasitological test for Chagas' disease in active transmission regions. The future follow-up of the possibly infected patients who were only IgM-positive should clarify the interest of PCR and IgM tests in the detection of starting infections.
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