Swine cysticercosis in the Karangasem district of Bali, Indonesia An evaluation of serological screening methods

tA serological assessment was undertaken on pigs from the Kubu and Abang sub-districts of Karangasemon the island of Bali, Indonesia, where earlier studies had detected patients with cysticercosis. Antigenspurified from Taenia solium cyst fluid by cation-exchange chromatography were used to evaluate antibodyresponses in the pigs and the serological tests were also evaluated using sera from pigs experimentallyinfected with T. solium eggs. A total of 392 serum samples from naturally exposed pigs were tested usingan ELISA that could be read based on both a colour change perceptible by the naked eye and an ELISAbased on absorbance values. Twenty six (6.6%) pigs were found seropositive by the naked-eye ELISAand were categorized into three groups: strongly positive (absorbance values >0.8, n = 6), moderatelypositive (absorbance values between 0.2 and 0.8, n = 7), and weakly positive (absorbance values <0.2,n = 13). Necropsies performed on 11 strongly and moderately positive pigs revealed that six stronglypositive pigs were infected either solely with T. solium cysticerci (n = 3), or co-infected with both T. soliumand Taenia hydatigena (n = 3). Four moderately positive pigs were infected solely with T. hydatigena. Nocysticerci were found in one pig that was moderately positive by the naked-eye ELISA. Two experimentallyinfected pigs became antibody positive by 6 weeks post-infection, whereas eight control pigs remainednegative. An additional 60 pigs slaughtered at authorized abattoirs on Bali were tested using the sameELISA. All 60 pigs were seronegative with no evidence of Taenia infection at necropsy. The results confirmthe presence of porcine cysticercosis on Bali and, while the serological responses seen in T. solium infectedanimals were much stronger than those infected with T. hydatigena, the diagnostic antigens are clearlynot species specific. Further studies are necessary to confirm if it is possible to draw a cut off line fordifferentiation of pig infected with T. solium from those infected with T. hydatigena