Combined diagnostic methods identify a remarkable proportion of asymptomatic Leishmania (Leishmania) chagasi carriers who present modulated cytokine profiles.
Peripheral blood samples of 138 co-habitants from 25 families with recently diagnosed cases of visceral leishmaniasis in the Metropolitan Region of Belo Horizonte, Minas Gerais, Brazil, were analyzed by indirect fluorescent antibody test (IFAT), rK39 and Leishmania chagasi Enzyme Linked Immunosorbent Assay (ELISA), intradermal skin-test and Polymerase Chain Reaction (PCR) over a 12-month period. The cumulative positivity was significantly higher by PCR (29.7%) than by IFAT, rK39 ELISA, L. chagasi ELISA and intradermal skin-test (5.1%, 6.5%, 14.5% and 2.9%, respectively). In addition, the cytokine profile was measured in 16 of the 138 volunteers, of whom eight were asymptomatic carriers and eight were non-infected co-habitants. The innate immunity cells from asymptomatic carriers displayed, upon in vitro antigenic stimulation, a modulated increase in cytokine synthesis that was distinct from that observed in non-infected volunteers. This study suggests that the identification of a large proportion of asymptomatic carriers is facilitated when more than one diagnostic method is applied and that a mixed pattern of immune response is correlated with clinical status of asymptomatic individuals. These observations suggest also that asymptomatic infection by L. chagasi is a frequent event and that control programs could benefit by including this indicator in their interventions.
de Gouvêa Viana
Luciana
L
Laboratório de Pesquisas Clinicas, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, MG, Brazil.
de Assis
Tália Santana Machado
TS
Orsini
Marcela
M
da Silva
Alexandre Rotondo
AR
de Souza
Guenael Freire
GF
Caligiorne
Rachel
R
da Silva
Aline Christiane Louredo
AC
Peruhype-Magalhães
Vanessa
V
Marciano
Ana Paula Vieira
AP
Martins-Filho
Olindo Assis
OA
Rabello
Ana
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology*; D000953:Antigens, Protozoan / Q000097:blood / Q000276:immunology*; D001938:Brazil / Q000453:epidemiology; D002353:Carrier State / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D006801:Humans; D007223:Infant; D007428:Intradermal Tests / Q000379:methods; D007891:Leishmania / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000097:blood / Q000175:diagnosis*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D015800:Protozoan Proteins / Q000097:blood
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015800:Protozoan Proteins