Canine leishmaniasis: use of serological tests in three non-endemic areas from Northern Argentina.

MORÉ, G.; SÁNCHEZ, R.; SCODELLARO, C. F.; LÓPEZ, G.; DESIMONE, M.; EIRAS, D.F.

Buenos Aires

Congreso; The 23rd International Conference of the World Association for the Advancement of Veterinary Parasitology (WAAVP 2011); 2011

WAAVP

Canine infection with Leishmania chagasi (syn. Leishmania infantum) can cause serious disease (CanL: canine visceral leishmaniasis) and infected dogs are important for human disease epidemiology. Accurate diagnosis of canine infections is essential to veterinarians and leishmaniasis surveillance programs. Diagnosis in asymptomatic dogs is usually difficult due to the low level of parasites in tissues and detectable antibodies in serum. Moreover, cross reactions in serological tests among Leishmania and Trypanosoma species has been reported. During the last years the northeast area of Argentina became an endemic area of CanL. A total of 131 serum samples from CanL-asymptomatic dogs were taken during 2010 in Taco Pozo (n: 37), Concordia (n: 50) and Salta suburbs (n: 44) from Chaco, Entre Rios and Salta provinces respectively. The sampled area is currently considered non-endemic for CanL, and Salta and Chaco provinces are endemic for chagas disease. All samples were evaluated for anti-Leishmania antibodies by IFAT and RK39 Immunochromatographic strip test and for anti-Trypanosoma antibodies by IFAT. Serum dilutions 1/40 or greater were considered positive in both IFATs. Positive results for IFAT-Leishmania, RK39 and IFAT-Trypanosoma were respectively as follows: 2.3%, 11.3% and 7% in Salta; 11.4%, 16% and 22.2% in Chaco and 26%, 18% and 32% in Entre Rios. Regarding IFAT results, positive animals had titer 40, except one with titer 80 to Leishmania and another with titer 160 to Trypanosoma. Agreement between test for all samples was estimated and Kappa values were obtained: IFAT-Leishmania and RK39: 0.200; IFAT-Trypanosoma and RK39: 0.303; IFAT-Leishmania and IFAT-Trypanosoma: 0.388. The three locations showed similar seropositivity for each serological test. Surprisingly seropositivity by IFAT was always higher for Trypanosoma than Leishmania antigen. This fact is especially interesting in Entre Ríos province, considered chagas vector transmission-free since 2004. The agreement between tests was low and both Leishmania tests show the lowest value. Considering all these facts, the accuracy of these tests to diagnose CanL and/or chagas disease in Argentinean asymptomatic dogs can be questioned. Additional studies are needed in order to determine if the protozoans are present in areas considered non-endemic or in asymptomatic animals.