Surveys in Papua New Guinea to detect the presence of Trypanosoma evansi infection

Abstract

Objective: To confirm serological evidence that Trypanosoma evansi is present in Papua New Guinea. Design: Three surveys were undertaken in PNG during 1997/1998. Animals were selected for sampling on the basis of convenience. Samples of blood were examined for the presence of T evansi by the haematocrit centrifugation technique (HCT) and mouse inoculation test (MI). Sera were tested in the field using the card agglutination test for trypanosomiasis/T evansi (CATT). Bovine sera were tested at James Cook University using an antibody-detection ELISA (Ab-ELISA). Results from testing bovine sera with the Ab-ELISA and sera from wallabies with the CATT were analysed using FreeCalc to determine the probability that animals in these populations were infected with T evansi. Results: A total of 545 serum samples were collected. during the three surveys of which 39 cattle, two pig and three agile wallaby samples were positive with the CATT. All bovine sera collected were negative when tested with an Ab-ELISA. T evansi was not isolated using the HCT or the MI from any of these animals. Conclusion: Based on the Ab-ELISA results it was concluded that T evansi infection was not present in cattle in villages around Balimo at a minimum expected prevalence of 10% (P < 0.05) and, based on the CATT results, that infection was not present in wallabies on the Bula plain at a minimum expected prevalence of 10% (P < 0.1). These results indicate that it is unlikely that T evansi is endemic in PNG.