SOME INVESTIGATIONS ON RABBIT VIRAL HAEMORRHAGIC DISEASE IN UPPER EGYPT

Rabbit hamorrhagic disease (RHD) outbreaks were observed during winter and spring, 1993 in most rabbitaries of Upper Egypt (Minia, Assiut and Sohage Provinces) with mortality rate of 26.7 up to 100% in4-16 month-old rabbits. Clinico-pathological manifestations of natural outbreaks are described. Viral hemagglutinins were detected in 117 out of 206 tested tissue homogenate from dead rabbits representing 19 rabbitaries with hemagglutination (HA) titres of 1:160 - 1:5120. The viral hemagglutination inhibition (HI) test against reference RHD-antiserum. Cross protection test, cross HI-test, HA-activity to mammalian and avian erythrocytes and experimental infection to rabbit, rat, mice and guinea pig of two field isolates (from outbreaks with high and low mortalities). Results revealed that both isolates are identical viruses and represent only one serotype of RHD virus. Seroepidemiological study of different rabbitaries revealed that 79 (22.9%) of 374 rabbit sera were positive. These positive sera were From 8 (27. 6%) of 29 examined rabbitaries (7-11 month old, and without history of RHD) had naturally HI-antibodies.