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

Objective To confirm serological evidence that Trypanosoma evansi is presen t 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 ex amined for the presence of T evansi by the haematocrit centrifugation techn ique (HCT) and mouse inoculation test (MI). Sera were tested in the field u sing the card agglutination test for trypanosomiasis/T evansi (CATT). Bovin e sera were tested at James Cook University using an antibody-detection ELI SA (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 tha t 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 e vansi 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 inf ection was not present in cattle in villages around Balimo at a minimum exp ected prevalence of 10% (P < 0.05) and, based on the CATT results, that inf ection 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 th at T evansi is endemic in PNG.