Epidemiological and microbiological study of an outbreak of infectious keratoconjunctivitis in sheep

Abstract

After several thousand sheep had been imported from Australia and New Zealand to Croatia during 1995, many native sheep that had been in contact with the imported animals acquired a severe ocular disease closely resembling infectious keratoconjunctivitis. In affected flocks glucose-fermenting mycoplasma were isolated from 48 per cent of conjunctival swabs and Branhamela ovis from 58 per cent. Twelve of 42 culturally and biochemically identical isolates were identified as Mycoplasma conjunctivae by polymerase chain reaction. From the conjunctivae of two animals M conjunctivae and M arginini were isolated in mixed culture. For many reasons most farmers removed the imported animals from their flocks and only sporadic cases of the disease were recognised in 1996. At the end of 1997, six flocks which were clinically free of the disease but had been affected during 1995, and five flocks with no history of the severe ocular disease were examined clinically and microbiologically, and were found to be free of M conjunctivae infection. At the time, B ovis was cultured almost exclusively from sheep originating from flocks which had been affected during 1995 and/or 1996. It was usually isolated in pure culture or as the predominant bacterial species, and was often accompanied by mild conjunctivitis. There were no microbiologically confirmed new cases of infectious keratoconjunctivitis during 1998 and 1999.

Molecular Epidemiology ofMycoplasma conjunctivaein Caprinae: Transmission across Species in Natural Outbreaks

“…The DNA sequence heterogeneity in the variable part of lppS was also used as a phylogenetic marker for the different M. conjunctivae strains. Hence, the six M. conjunctivae isolates from Croatia that are presumed to originate from imported Australian sheep (19) clearly show a cluster that is distinct from the other strains that are generally found in the European Alpine region (Fig. 2).…”

Postepizootic Persistence of Asymptomatic Mycoplasma conjunctivae Infection in Iberian Ibex

“…Both epidemiological situations (i.e., IKC outbreak and endemic asymptomatic infections) have been described in other domestic (16,25) and wild free-ranging (12,20,26,27) hosts. The results of the present study show how both epidemiological situations can occur consecutively in a host population, depending on M. conjunctivae circulation, its maintenance in the population, and the progression of the host-pathogen interactions.…”

Effects ofMoraxella(Branhamella)ovisCulture Filtrates on Bovine Erythrocytes, Peripheral Mononuclear Cells, and Corneal Epithelial Cells

“…Microscopically, the M. ovis isolates were gram-negative cocci (0.6 to 1.0 m) arranged in pairs. All M. ovis isolates were aerobic and oxidase and catalase positive, and they reduced nitrate but did not ferment carbohydrates or liquefy gelatin (8,13,22,30).…”

“…From 1999 to 2002, M. ovis was isolated three times more often from field cases than M. bovis. Isolation of M. ovis from cases of keratoconjunctivitis has previously been reported in sheep, goats, deer, and moose (3,14,16,17,30,33,40,41). In cattle, M. ovis has been isolated from IBK cases (17, 31); but the significance of its isolation is currently unclear because, in one study, experimental inoculation of calves with M. ovis isolated did not cause keratoconjunctivitis (17).…”

“…Microscopically, the M. ovis isolates were gram-negative cocci (0.6 to 1.0 m) arranged in pairs. All M. ovis isolates were aerobic and oxidase and catalase positive, and they reduced nitrate but did not ferment carbohydrates or liquefy gelatin (8,13,22,30).Preparation of culture supernatants. Aliquots of each isolate from frozen stock cultures were streaked onto blood agar and incubated at 37°C for 24 h. Culture for hemolysin production during early-logarithmic-phase growth was performed as described previously (20) but with modification.…”