[1] Univ Edinburgh, Easter Bush Vet Ctr, Sir Alexander Robertson Ctr Trop Vet Med, Dept Trop Anim Hlth, Roslin EH25 9RG, Midlothian, Scotland
[2] Ctr Nacl Microbiol Virol & Inmunol Sanitarias Maja, Inst Salud Carlos III, Madrid 28220, Spain
[3] Inst Anim Hlth, Pirbright Labs, Surrey, England
[4] Univ Carabobo, Dept Parasitol, Valencia, Spain
[5] Univ Carabobo, Ctr Invest Biomed BIOMED, Maracay, Venezuela
[6] Inst Gulbenkian Ciencias, P-2780156 Oeiras, Portugal
[7] Univ Complutense Madrid, Fac Biol, Dept Microbiol 3, Madrid, Spain
[8] Univ Oxford, Sir William Dunn Sch Pathol, Oxford OX1 3RE, England