Serological evidence for infection of sheep with Leptospira interrogans serotype hardjo

Leptospiral infeotion of cattle in New Zealand is caused in decreasing order of frequency by serotypes hardjo, pomona, copenhageni and ballum (Anim. Hlth Div., MAF, unpubl. data). In spite of the high prevalence in cattle of serological reactors to hardjo, symptoms are usually either absent or not observed. Therefore, it appears that the pathogenicity for cattle of this serotype is low. The same cannot be said for man, for hardjo now accounts for some two-thirds of all human cases notified annually in this country (Christmas et al 1974b). Leptospirosis in sheep in New Zealand has been described previously by Hartley (1952) and by Webster and Reynolds (1955), who reported a disease of sheep (especially lambs) caused by serotype pomona. No other serotypes have been associated with sheep in this country, but recently serological evidence was obtained that hardjo infection occurs in sheep…