Infectious bovine keratoconjunctivitis

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Infectious bovine keratoconjunctivitis, or IBK, is a veterinary infection of cattle caused by Moraxella bovis, a species of bacteria. It is spread by direct contact or by the common fly serving as a vector. It is the most common ocular disease of cattle (mostly beef). IBK is similar to human pink eye and causes severe infection of the conjunctiva, edema, corneal opacity and ulceration. This disease is highly contagious and occurs worldwide. Younger animals are more susceptible but recovery with minimal damage is usual.

1 Cause
2 Predisposing factors
3 Treatment and control
4 External links

[edit] Cause

Moraxella bovis is a gram-negative rod-shaped aerobe. These bacteria are obligate intracellular parasites of the mucous membranes and can usually be isolated from the respiratory tract, vagina and conjunctiva of healthy animals. Transmission of IBK is through direct and indirect contact where flies act as a mechanical vector.

[edit] Predisposing factors

Ultraviolet radiation is implicated in cattle with no pigmentation around the eyelids and cattle with prominently placed eyes. Exudates from the sun-burnt skin around the eyes become a culture media for bacteria and attract flies. UV also directly damages the corneal epithelium leading to a break-down in host innate immunity.

Dust, dried up plants and long vegetation causes mechanical damage to the eye and facilitate bacterial colonization.

Concurrent infection with viruses such as infectious bovine rhinotracheitis virus (bovine herpesvirus 1) or adenovirus, bacteria such as Mycoplasma boviculi or Listeria monocytogenes, or Thelazia, a nematode, complicates the disease

Vitamin A deficiency is also implicated.

Disease is most prevalent in summer and early autumn.

[edit] Treatment and control

Shade, insect repellent impregnated ear tags, and lower stocking rate may help prevent IBK. Early identification of the disease also helps prevent spread throughout the herd. Treatment is with early use of a long acting antibiotic such as tetracycline or florfenicol. Topical corticosteroids reduce pain by relieving inflammation.

M. bovis uses several different serotyped fimbriae as virulence factors, consequently pharmaceutical companies have exploited this to create vaccines. However, currently available vaccines are not reliable.