ABSTRACT
AIM: To test for antibodies to rabbit haemorrhagic disease (RHD) virus (RHDV) in sera from mammals and birds associated with rabbit populations infected with RHDV. METHODS: Sera from feral and domestic cats, feral ferrets, stoats, hedgehogs, hares, harrier hawks, and black-backed gulls were taken (apart from some of the hares) from areas in New Zealand where RHD was active among rabbit populations. The presence of antibodies to RHD was investigated using a competition enzyme-linked immunosorbent assay (ELISA). RESULTS: Some individual animals of all species were seropositive. Thirty eight of 71 feral cats, but only 1/80 domestic cats were seropositive at a 1:40 dilution. The latter had not been exposed to RHDV. Also reactive in the ELISA were 2/8 stoats; 11/115 ferrets, with significantly more females having antibodies than males; 4/73 hedgehogs; 2/18 hawks, and 1/30 gulls. Three of 66 hares, comprising 3/14 from one population, were seropositive. CONCLUSIONS: Apart from the hares, all these species are known to prey upon rabbits or scavenge their carcasses, a possible means of exposure to RHDV. The possibility that the positive test reactions were due to cross-reactions with other caliciviruses cannot be ruled out, especially for the hares. Nor could the study differentiate whether the positive results were due to an antigenic reaction to ingestion of RHDV, as suggested by overseas work, or to infection of new species by RHDV. These possibilities are being investigated further.
ABSTRACT
AIM: To determine the aetiology of a recurring and severe form of infectious keratoconjunctivitis (IKC) in sheep. METHODS: Five sheep flocks that had experienced a severe form of IKC were examined. Clinical history, conjunctival swabs and blood samples were collected from affected animals. Culture for bacteria, and also specifically for Mycoplasma and Chlamydophila spp, and detection of Mycoplasma conjunctivae DNA by polymerase chain reaction (PCR) were attempted. Serum samples were tested for antibodies to M. agalactiae, M. capricolum, M. conjunctivae and Chlamydophila spp. RESULTS: Mycoplasma conjunctivae DNA was detected using PCR in 3/5 flocks, and in all flocks antibodies to M. conjunctivae were detected in sera. A pure growth of Branhamella ovis was cultured from conjunctival swabs from a small proportion of sheep in two flocks. No other pathogens were detected. CONCLUSIONS: This investigation demonstrated that M. conjunctivae was a primary pathogen causing severe IKC in sheep, and is the first report of detection of this organism in sheep in New Zealand. Introduction of clinically normal carrier sheep appeared to have caused the outbreaks. KEYWORDS: Infectious keratoconjunctivitis, Mycoplasma conjunctivae, Chlamydophila pecorum, Branhamella ovis, polymerase chain reaction, ELISA, complement fixation test.
