Infectious Bovine Keratoconjunctivitis: A Review

Abstract

The economic impact of infectious bovine keratoconjunctivitis (IBK) warrants continued investigation of the mechanisms by which Moraxella bovis survives on and colonizes the corneal surface. Virulent strains of M bovis produce hemolysin and exhibit different plasmid profiles than nonvirulent strains. Interactions among host, environment, vector, season, and concurrent infection influence the prevalence of IBK. Mycoplasma sp. or infectious bovine rhinotracheitis virus may enhance or hasten the disease process. The manifestations of IBK may range from mild conjunctivitis to severe ulceration, corneal perforation, and blindness. Treatment of IBK is dictated by economic considerations, intended animal use, and feasibility of administration. Antibiotic therapy is aimed at achieving drug concentrations in tears to meet or exceed the minimum inhibitory concentration for prolonged periods. At present, IBK is not a preventable disease. Affected animals must be separated from the herd and vector control vigorously instituted. Carrier animals must be identified and removed from the herd. Vaccination trials have been unsuccessful because of pili antigen crossreactivity, variable strains, and uncontrolled environmental factors. Recent investigations have determined that M bovis may utilize host iron sources via iron-repressible outer membrane proteins and siderophores for growth. Elucidation of normal defense mechanisms of the bovine eye may lead to new strategies to enhance the immune response against M bovis.Key words: Bovine pinkeye; IBK.he first reports of infectious bovine keratoconjunctivitis EpizoologyAlthough M bovis is the pathogen most commonly isolated from IBK, various factors are involved with the pathogenesis of this disease. The environment, season, concurrent pathogens, M bovis strain, and host immune system play integral roles in the occurrence and clinical severity of IBK. IBK is a highly contagious disease that spreads rapidly within a herd.6 The yearly and seasonal prevalence of the disease in different geographic regions varies greatly.l0." The isolation rate of M bovis infection gradually increases during the spring (21.4%) and summer (29.3%) months to reach a maximum in the fall at 45%.12 Peak IBK prevalence is preceded by the highest values of ultraviolet (UV) radiation.I3J4 IBK can occur during any time of the year, but outbreaks are more common during summer months. Nonetheless, heavy snowfall and UV radiation have been individually associated with outbreaks of IBK.M. bovis is spread by direct contact, nasal and ocular discharges, and by mechanical vectors. The most important vector is considered to be the face fly (Musca a~turnnalis).~~ The house fly (Musca dornestica) and barn fly (Stomoxys calcitrans) may also transport the organism. In addition to physically irritating the eye, insects may harbor the organism on their legs for up to 3 days.Is A positive correlation exists between the number of flies per animal and M bovis infection,I8 and disease prevalence is reduced by rigorous fly control pr...

Surto de ceratoconjuntivite infecciosa bovina e hemoncose causando mortalidade em bezerros

“…Os sinais clínicos observados inicialmente são lacrimejamento, conjuntivite, blefaroespasmo e fotofobia (Baptista 1979, Punch & Slatter 1984, Brown et al 1998. Após 2-4 dias do início dos sinais clínicos há edema de córnea associado ao aparecimento de um foco opaco e brancacento ou amarelo-azulado no centro da córnea.…”

Genetic and environmental factors associated with incidence of infectious bovine keratoconjunctivitis in preweaned beef calves1

“…Infection by IBK significantly lowers calf growth rate (Thrift and Overfield, 1974;Ward and Nielson, 1979). The most common bacterial pathogen to cause IBK is Moraxella bovis (Brown et al, 1998). Pathogenesis of the disease is influenced by many factors, such as season, mechanical irritation (dust, grass, weeds, etc.…”

“…Control of M. autumnalis is the general approach to IBK prevention. Vaccination for M. bovis has not been success-ful (Brown et al, 1998). Results of treatment including tropical, subconjunctival, and i.m.…”

“…Results of treatment including tropical, subconjunctival, and i.m. administration of antibiotics or antimicrobial drugs have varied according to the severity of IBK (Brown et al, 1998).…”

Bacteria and Nematodes in the Conjunctiva of Mule Deer from Wyoming and Utah

“…Infectious keratoconjunctivitis (IKC) has been extensively studied in cattle (Brown et al, 1998) and domestic sheep (Dagnall, 1994a, b), but little is known in free-ranging ruminants (e.g., Loison et al, 1996;Taylor et al, 1996). Infectious keratoconjunctivitis can cause temporary blindness in affected individuals, increasing the likelihood of predation and fatal accidents due to impaired vision.…”