Is Leishmania (Viannia) braziliensis parasite load associated with disease pathogenesis?
BACKGROUND
Leishmania (Viannia) braziliensis is the main etiological agent of tegumentary leishmaniasis in the Americas. Parasite molecular diversity and host immune status contribute to extensive variations in its clinical presentation within endemic areas of Brazil. Pentavalent antimonials have been used for more than 60 years as the first-line drug for all cases, despite the potential for severe side effects and refractoriness. In Rio de Janeiro, Brazil, most L. (V.) braziliensis infections are benign with a scarcity of parasites, although metastasis and refractory infections can arise. In this scenario, the use of novel molecular tools can be useful for diagnosis and to assess tissue parasitism, and is of benefit to clinical and therapeutic management.


METHODS
In this study, parasite load was assessed by real-time PCR based on the leishmanial small subunit ribosomal RNA gene.


CONCLUSIONS
The data revealed a tendency to higher tissue parasitism in the skin compared to mucous lesion sites and a reduction with disease progression. Parasite load was lower in poor compared to good responders to antimonials, and was also reduced in recurrent lesions compared to primary ones. However, parasite load became higher with sequential relapses, pointing to an immune system inability to control the infection. Therefore the parasite burden does not seem to be a good predictor of disease progression.
Laboratório de Pesquisa em Leishmaniose, IOC, FIOCRUZ, Rio de Janeiro, RJ, Brazil. Electronic address: luizaper@ioc.fiocruz.br.
Luiza de Oliveira Ramos
LOR
Pereira
Laboratório Interdisciplinar de Pesquisas Médicas, IOC, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Regina Barbosa
RB
Moreira
Laboratório Interdisciplinar de Pesquisas Médicas, IOC, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Márcia Pereira
MP
de Oliveira
Laboratório Interdisciplinar de Pesquisas Médicas, IOC, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Soraya de Oliveira
SO
Reis
Instituto Nacional de Infectologia Evandro Chagas, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Manoel Paes
MP
de Oliveira Neto
Laboratório Interdisciplinar de Pesquisas Médicas, IOC, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Claude
C
Pirmez
D000818:Animals; D002478:Cells, Cultured; D018450:Disease Progression; D006801:Humans; D007892:Leishmania braziliensis / Q000302:isolation & purification*; D016773:Leishmaniasis, Cutaneous / Q000209:etiology* / Q000469:parasitology; D059208:Parasite Load; D060888:Real-Time Polymerase Chain Reaction
Leishmania (Viannia) braziliensis; Parasitic load; Small subunit ribosomal RNA gene; Therapeutic failure