Detection ofLeishmaniaDNA by Polymerase Chain Reaction in Scars of Treated Human Patients

Abstract

Leishmaniasis is an endemic disease in developing countries. The efficacy of therapy is usually evaluated through clinical parameters. To define the parasitologic cure, 20 patients were biopsied before and 1 month to 8 years after treatment. Paraffin-embedded tissue was used for DNA isolation. All patients had a positive polymerase chain reaction (PCR) result before therapy, except 1, for whom no histopathologic material was available. The causative agent was identified as belonging to the Leishmania (Viannia) subgenus by hybridization. Despite clinical healing and absence of reactivation or development of mucosal lesions, PCR was positive in scars of 16 patients (80%). The results suggest that parasites persist in the skin for many years despite treatment. Depending on specific pathogenetic features of the parasite and the immune status of the host, this phenomenon might result in mucosal lesions. Alternatively, it could have a role in the maintenance of immunologic memory in patients living in areas in which leishmaniasis is endemic.

Estudo comparativo entre miltefosina oral e antimoniato de N-metil glucamina parenteral no tratamento da leishmaniose experimental causada por Leishmania (Leishmania) amazonensis

“…Quanto à discordância entre a negatividade da pesquisa de amastigotas em relação à positividade das culturas, sem dúvida a leitura das culturas é mais fácil porque requer menor habilidade técnica. Também, a cultura de leishmânia tem mais alto percentual de positividade que a pesquisa de amastigotas em esfregaço, e o achado de DNA de leishmânia, em cicatrizes de pacientes tratados com antimonial, é referido na literatura 17 .…”

First encounter of subclinical human Leishmania (Viannia) infection in State of Rio Grande do Sul, Brazil

“…Some studies have shown that the persistence of Leishmania DNA in blood or bone marrow of treated visceral leishmaniasis patients is associated with disease relapse or the appearance of post-kala azar dermal leishmaniasis (Osman et al 1997). Furthermore, PCR permitted the detection of Leishmania (Viannia) DNA in scars of clinically cured cutaneous leishmaniasis patients, demonstrating the persistence of the parasite (Schubach et al, 1998). Likewise, the scar of one of these patients was also positive by culture (Schubach et al 1998).…”

“…A positive control, consisting of 100 pg DNA extracted from an axenic culture of Leishmania braziliensis, was also performed. The DNA from the agarose gels was transferred to nylon membranes by capillary blotting using 0.4 N NaOH and hybridized against Leishmania (Viannia)-specific probes as described elsewhere (Schubach et al 1998, Pirmez et al 1999). …”

“…Furthermore, PCR permitted the detection of Leishmania (Viannia) DNA in scars of clinically cured cutaneous leishmaniasis patients, demonstrating the persistence of the parasite (Schubach et al, 1998). Likewise, the scar of one of these patients was also positive by culture (Schubach et al 1998). Assuming that a positive PCR corresponds to the presence of viable parasites, it might be considered to be an indicator of active infection (Tarleton et al 1999).…”

Innovación y desarrollo de productos

“…Because L. panamensis and L. braziliensis are the most prevalent species among human cases innovación y dEsarrollo dE productos XV Congreso Colombiano de Parasitología y Medicina Tropical of cutaneous leishmaniasis and infection is not eliminated by treatment (Schubach, et al, 1998;Vergel, et al, 2006), decades of monotherapeutic use of antimonial drugs is likely to have selected tolerant and even resistant populations of these species that could have been disseminated in circumstances of anthroponotic transmission.…”