[1] Ross Univ, Sch Vet Med, POB 334, Basseterre, St Kitts & Nevi
[2] Univ Johannesburg, Dept Zool, ZA-2006 Auckland Pk, South Africa
[3] Bayer Pty Ltd, Div Anim Hlth, ZA-1600 Isando, South Africa
[4] Onderstepoort Vet Inst, ZA-0110 Onderstepoort, South Africa
[5] Ctr Dis Control & Prevent, Div Parasit Dis, Natl Ctr Infect Dis, Atlanta, GA 30341 USA
[6] Vet Serv Eastern Cape Prov, Dept Agr, ZA-5605 Bhisho, Eastern Cape, South Africa
[7] Agr Res Council, Biometry Unit, ZA-0127 Pretoria, South Africa
[8] Inst Trop Med, Dept Anim Hlth, B-2000 Antwerp, Belgium
[9] Univ Edinburgh, Royal Dick Sch Vet Studies, Div Vet Clin Sci, Ctr Trop Vet Med,Easter Bush Vet Ctr, Roslin EH25 9RG, Midlothian, Scotland
[10] Univ Zurich, Inst Parasitol, CH-8057 Zurich, Switzerland
[11] Univ Copenhagen, Danish Ctr Expt Parasitol, Fac Life Sci, WHO FAO Collaborating Ctr Parasit Zoonoses, DK-1870 Frederiksberg, Denmark