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Detection of Leishmania infantum by PCR, serology and cellular immune response in a cohort study of Brazilian dogs

Published online by Cambridge University Press:  07 May 2002

R.J. QUINNELL
Affiliation:
School of Biology, University of Leeds, Leeds LS2 9JT Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT
O. COURTENAY
Affiliation:
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT Present address: Department of Biological Sciences, University of Warwick, Coventry CV4 7AL.
S. DAVIDSON
Affiliation:
School of Biology, University of Leeds, Leeds LS2 9JT
L. GARCEZ
Affiliation:
Instituto Evandro Chagas, Belém, Pará 66090-000, Brazil
B. LAMBSON
Affiliation:
Molteno Institute for Parasitology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP
P. RAMOS
Affiliation:
Instituto Evandro Chagas, Belém, Pará 66090-000, Brazil
J.J. SHAW
Affiliation:
Instituto Evandro Chagas, Belém, Pará 66090-000, Brazil Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP 05508-900, Brazil
M.-A. SHAW
Affiliation:
School of Biology, University of Leeds, Leeds LS2 9JT
C. DYE
Affiliation:
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT Present address: Communicable Diseases Control, Prevention and Eradication, World Health Organization, CH-1211 Geneva 27, Switzerland.

Abstract

The sensitivity and specificity of PCR, serology (ELISA) and lymphoproliferative response to Leishmania antigen for the detection of Leishmania infantum infection were evaluated in a cohort of 126 dogs exposed to natural infection in Brazil. For PCR, Leishmania DNA from bone-marrow was amplified with both minicircle and ribosomal primers. The infection status and time of infection of each dog were estimated from longitudinal data. The sensitivity of PCR in parasite-positive samples was 98%. However, the overall sensitivity of PCR in post-infection samples, from dogs with confirmed infection, was only 68%. The sensitivity of PCR varied during the course of infection, being highest (78–88%) 0–135 days post-infection and declining to around 50% after 300 days. The sensitivity of PCR also varied between dogs, and was highest in sick dogs. The sensitivity of serology was similar in parasite-positive (84%), PCR-positive (86%) and post-infection (88%) samples. The sensitivity of serology varied during the course of infection, being lowest at the time of infection and high (93–100%) thereafter. Problems in determining the specificity of serology are discussed. The sensitivity and specificity of cellular responsiveness were low. These data suggest that PCR is most useful in detecting active or symptomatic infection, and that serology can be a more sensitive technique for the detection of all infected dogs.

Type
Research article
Copyright
2001 Cambridge University Press

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