Canine visceral leishmaniasis in northeast Brazil: assessment of serodiagnostic methods.

Domestic dogs are considered to be a major reservoir of Leishmania donovani chagasi in northeast Brazil, and the elimination of infected dogs is an important part of the control program. We assessed 2 serological methods, IFA and ELISA. Of 405 dogs, 8% were positive by IFA obtained from blood collected by drying onto filter paper followed by elution, 17% were positive by IFA performed using sera, and 38% were positive by ELISA on the same sera. Thirty-five dogs, seropositive by 1 or more of the above tests, were killed and touch preparations were made of liver, spleen, and mesenteric lymph nodes. Samples were cultured in enriched NNN media. The ELISA recognized all dogs with proven infection; IFA detected 10 of 12. Eleven dogs were positive by touch preparations and 7 by culture. In addition, kDNA hybridization was undertaken with probes to L. donovani chagasi, L. braziliensis ssp., and L. mexicana amazonensis. Positive results were obtained from tissue in 19 instances, but 10 culture positive specimens were not recognized.