1. Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi 62, 51014 Tartu, Estonia
2. Veterinary and Food Laboratory, Kreutzwaldi 30, 51006 Tartu, Estonia
3. Laboratory of Parasitology, Department of Bacteria, Parasites & Fungi, Infectious Disease Preparedness, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark
4. Department of Infectious Diseases, Istituto Superiore di Sanita, Viale Regina Elena 299, 00161 Rome, Italy