Clinical communication — Kliniese mededeling Atypical dermatophilosis of sheep in Kenya

INTRODUCTION Ovine dermatophilosis, commonly called ‘dermo’ or ‘lumpy wool’, is an acute or subacute, chronic exudative dermatitis of sheep of all age groups. It causes economic loss to producers through lowered production, lowered wool value, treatment costs, poor-quality skins, restriction of management options such as shearing and death in severe cases. It is caused by a bacterium, Dermatophilus congolensis, which is pleomorphic, Gram-positive, non-acid-fast, facultative anaerobe belonging to the order Actinomycetales. Two characteristic morphological forms, filamentous hyphae and motile zoospores are recognised during the life cycle of the bacterium. The filamentous hyphae become transversely and longitudinally septate to form parallel rows of small coccoid zoospores, which are motile. The organism persists in dry scabs and crusts from healed lesions and can survive for several months in the lesions and transmission can occur through contact with the latently infected animals. The host spectrum for Dermatophilus congolensis includes cattle, sheep, horses, donkeys, pigs, goats, wild animals, laboratory animals and humans. The causative organism does not invade an intact skin and the disruption of the skin barrier, by continued wetting due to wet weather, thorny or spiny forage, tick and insect bites, dipping and shearing is necessary for the disease to occur. The disruption of the skin integrity provides the zoospores with access to living epidermal layer resulting in serous exudation which together with epithelial debris and the mycelial form of the organism dry to form a characteristic matting of hair that progresses to scab and crust formation on the skin. The lesions of ovine dermatophilosis can be localised or generalised, depending on the predisposing factor. Spiny plants are associated with lesions on the lips, brisket, legs and feet and heavy rainfall and shearing are associated with lesions on the back of the sheep. Several different forms of ovine dermatophilosis have been described. In Africa ovine dermatophilosis has been reported in several countries and it is likely to occur in many other countries where predisposing factors pertain. In Kenya, there is no report of natural ovine dermatophilosis. This paper highlights some clinical features of atypical ovine dermatophilosis and we believe that this is the 1st published report of an outbreak of ovine dermatophilosis in Kenya.