Serological diagnosis of canine alveolar echinococcosis.

Canine alveolar echinococcosis (AE) is a rare liver disease caused by the larval stage (metacestode) of E. multilocularis. Its diagnosis so far is rather difficult and invasive. Imaging techniques for the diagnosis have been described recently and in this study, the serological diagnosis of canine AE was evaluated in 30 dogs with confirmed AE using ELISA based on seven different antigens (E. multilocularis-antigens: Em2G11, EmII/3-10, protoscolex (EmP), excretory/secretory and adult integument (EmAd/I); E. granulosus antigens: hydatid fluid (EgHF) and antigen B (EgAgB)) and by the detection of circulating Em2G11-antigen. EmII/3-10 and Em2G11-based tests detected AE in 50 and 53%. The combined serological investigation for specific circulating Em2G11-antigen and specific antibodies against this antigen showed a sensitivity of 77%. This strategy is useful in animals with large parasite masses and ascites. The highest sensitivities for AE were obtained by the EmAd/I and the EmP antigens (97 and 93% sensitivity) with high specificities in the control group of 76 dogs (100 and 98.7%, respectively). Heterologous E. granulosus antigens (EgHF and EgAgB) showed low sensitivities (43 and 50%, respectively) with high numbers of unspecific reactions (>16%) in the control group. In the follow-up of four dogs, the serological reaction patterns against the antigens Em2G11, EmP and EmAd/I showed some correlations with the development of the parasite mass. Intestinal infections cannot be differentiated from AE by most antigens (except EmII/3-10) and have to be excluded by the absence of coproantigens or DNA of E. multilocularis in faecal samples.