Comparison of the Polymerase Chain Reaction and Serology for the Detection of Canine Visceral Leishmaniasis

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  • Department of Tropical Public Health, Harvard School of Public Health, Instituto de Biofisica, Carlos Chagas Filho, Universidade Federal de Rio de Janeiro, Universidade Federal da Bahia, Fundacao Oswaldo Cruz-Bahia, Cornell University Medical College, Fundacao Oswaldo Cruz-Rio de Janeiro, Boston, Massachusetts, Brazil
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The polymerase chain reaction (PCR) and serology was evaluated for the diagnosis of canine visceral leishmaniasis in Bahia, Brazil in a study of 125 dogs. The PCR was 100% sensitive in 25 dogs that had Leishmania demonstrated by either culture or hamster inoculation. It was 100% specific for 35 dogs from the northeastern United States, all were PCR negative. However, 22 of 54 Brazilian dogs that were culture-hamster inoculation-negative were positive by PCR. The nature of the PCR product was identified by hybridization with specific Leishmania probes. Whereas the sensitivity of serology in relationship to infection, as determined by hamster or culture assay was more than 80%, sensitivity of serology was only 63% when compared with PCR. These results raise questions about the use of serology to detect Leishmania infection in dogs, and suggest that the PCR might serve as a better gold standard to define Leishmania infection than culture or hamster inoculation.