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
opacity and ulceration
. This disease is highly contagious and occurs worldwide. Younger animals are more susceptible but recovery with minimal damage is usual, if they are treated early. The disease is better known as pinkeye
is a gram-negative
. These bacteria are obligate intracellular parasites
of the mucous membranes
and can usually be isolated from the respiratory tract
and conjunctiva of healthy animals. Transmission of IBK is through direct and indirect contact where flies act as a mechanical vector.
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.
Pinkeye is most prevalent in summer and early autumn.
A recent Meat & Livestock Australia (MLA) report "estimates that the disease costs Australian beef producers $23.5 million annually in lost production and treatment costs".
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
. 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.