Molecular and clinicopathological diagnosis of malignant catarrhal fever in cattle, deer and buffalo in New Zealand.

Fresh and formalin-fixed tissues and blood samples in ethylenediaminetetraacetate were collected from cattle, deer and buffalo with clinical signs suggestive of malignant catarrhal fever (MCF). In addition, formalin-fixed, paraffin-embedded tissue blocks collected from these animals and retrospectively from field cases of MCF were examined. DNA samples extracted from these samples were analysed by polymerase chain reaction (PCR) assay using primers specific for the sheep-associated (SA)- and wildebeest-associated (WA)-MCF viruses. Both the SA-MCF virus and WA-MCF virus PCR yielded positive results which were in nearly complete agreement with the histopathological diagnoses of MCF in fresh and formalin-fixed, paraffin-embedded tissue from 29 cattle, 24 deer and three buffaloes. Some blood samples tested by the two assays indicated that some of the infected cattle were possible carriers.