immunology of infectious and parasitic diseases - XXXVII Congress ...

IDENTIFICATION OF M. LEPRAE DNA IN HOUSEHOLD CONTACTS
RESIDENT IN GOVERNADOR VALADARES – MG, BRAZIL
RAFAEL SILVA GAMA(1); THALISSON ARTUR RIBEIRO GOMIDES(1);
EUZENIR NUNES SARNO(2); MILTON OZÓRIO MORAES(2); GULNARA
PATRICIA BORJA CABRERA(1); LUCIA ALVES DE OLIVEIRA FRAGA(1).
(1). Núcleo de Pesquisa em Imunologia – Faculdade de Ciências da Saúde -
Universidade Vale do Rio Doce – UNIVALE – Gov Valadares, MG;
(2). Fundação Oswaldo Cruz –FIOCRUZ/RJ.
Introduction: Classical bacteriological methods for identification of pathogenic
bacteria can not be applied to the diagnosis of leprosy, especially the inability of
in vitro cultivation of M. leprae. The histopathology and smear microscopy has
been used as auxiliary methods for the clinical classification of cases. The
advent of molecular biology techniques with good specificity and high sensitivity
has been evaluated as tools for early diagnosis of leprosy. Objective: The
objective of this study was to evaluate the qPCR as a tool to identify M. leprae,
and to compare the levels of bacterial DNA in samples of dermal scrapings and
blood of patients with leprosy and their household contacts. Methodology and
Results: The qPCR was performed to amplify 16S rRNA fragments, specific for
the M. leprae. A total of 156 individuals participated in this study, 43 index
cases and 113 household contacts. PCR was positive with 16S rRNA primer in
21 (48.84%) of 43 patients diagnosed with leprosy while the baciloscopic
method was positive in only 13 (30.23%) patients. In relation to household
contacts 27 (23.89%) of 113 subjects had bacterial DNA. The levels of bacterial
DNA contacts were similar to those of DNA of PB. We conclude that qPCR was
able to detect bacterial DNA in biological samples in which the baciloscopic
method was negative. Furthermore, a positive qPCR smear was higher than in
index cases under 5 lesions. We found that 23.89% of the contacts showed M.
leprae DNA in qPCR and that the level of bacterial DNA in these subjects was
similar to the group level CPB, DM 1 and DM 2. Rather, the level of bacterial
DNA was significantly lower than in group MB. Conclusion: We suggest the
incorporation of this technique in the health system, as well as monitoring and
prophylactic treatment of contacts positive qPCR as strategies for early
diagnosis and control of leprosy.
Financial support: CNPq-DECIT/2008, FIOCRUZ/RJ.