[The etiology and epidemiology of malignant catarrh--a review]

It is generally accepted that both, the wildebeest-derived malignant catarrhal fever (WD-MCF), and the circumstantially evidenced sheep-associated form of the disease (SA-MCF), may be explained as autoimmune disease of various ruminants, namely cattle and farmed deer. The disease follows infection with related herpesviruses being shed by the respective healthy carrier animals. This has convincingly be shown to apply for WD-MCF (Alcelaphine herpesvirus 1, AlcHV1). SA-MCF, however, remains to be controversial with both respects. In Switzerland, a serological study indicated that a herpesvirus(es) was highly prevalent among cattle and sheep, inducing antibody that cross-react with AlcHV1 and bovine herpesvirus 4 (BHV4). The latter is known as a largely innocuous agent. A relationship can be demonstrated between the presence of MCF in this country and concurrent serological reactions to both viruses. However similar results may be obtained with healthy animals. Healthy cattle and sheep from farms with or without incidences of MCF displayed the same antibody profiles. It is thus not possible to effectuate meaningful diagnostic tests for (SA-)MCF, nor to confirm any relationship between presumed carrier sheep and the appearance of MCF.