Morel’s Disease and Caseous Lymphadenitis: a Literature Review with Special Reference to Saudi Arabia

Abstract

Morel’s disease (MD), caused by Staphylococcus aureus subspecies anaerobius and caseous lymphadenitis (CLA), caused by Corynebacterium pseudotuberculosis are two of the major constraints of sheep and goats industry. CLA is prevailing in most parts of the world including USA and Europe, while MD is prevailing in some African and Asian countries including Kingdom of Saudi Arabia (KSA), plus some reports of outbreaks in some European countries. In spite of some differences in epidemiology and characteristics of abscesses in the two diseases and easy microscopic differentiation, MD is greatly misdiagnosed as CLA in KSA and elsewhere. Chronic and generally subclinical and contagious nature of infections and in-efficiency of drug therapy besides poor response to available vaccines which are targeting only CLA make the control difficult and prevalence high. This article reviews the main features of epidemiology, virulence factors, clinical manifestations, diagnosis and control measures of these two diseases. It is intended to display the differences between the two diseases and that the MD is at least should have the same importance as CLA in KSA; and to ensure the importance of development of a bivalent vaccine. Quality of the putative vaccine is discussed here. This review is the first for MD and for MD and CLA together