A practical method for the production of Brucella skin test antigen.

Skin test antigens for the diagnosis of brucellosis were produced from the rough Brucella abortus strain 45/20. The production of two products termed Brucellin B and Brucellin W are described. The method described for the production of Brucellin W is recommended as an improved practical method of Brucellin production. The Brucellin products described were equal in sensitivity to that of a commercially available product, Brucellergen, which is used in New Zealand. Brucellin B was extensively tested in non-infected cattle and its specificity was equal to that of Brucellergen. Recommendations for the standardisation of skin test reagents for the diagnosis of brucellosis are made. Intradermal testing for brucellosis in cattle should be used only for the identification of infected herds and not as an individual animal test.

Prototheca zopfii mastitis in a herd of dairy cows.

Mastitis caused by the colourless alga Prototheca zopfii was diagnosed in 17 of 120 cows in a dairy herd. Infection occurred in animals varying from 3-14 years old and was present in one to four quarters of each cow. Nine cases were associated with clinical mastitis characterised by the presence in milk of flakes or small clots. Somatic cell counts consistent with subclinical mastitis (>500 x 10(3) cells/ml) were recorded in five of the eight remaining cows. Histological examination of udder tissue showed the presence of granulomatous lesions associated with the presence of Prototheca. The problem was identified and controlled by repeated microbiological examination of milk samples from all lactating cows and immediate culling of infected animals. P. zopfii was also recovered from environmental water samples on this farm. It is suggested that infection may have occurred as a result of teat sores caused by trauma from a milking machine, and the tendency for cows to lay down on a race, the surface of which was sometimes flooded by drain water in which Prototheca were present.

Anaemia and deaths in red deer (Cervus elaphus) fawns associated with heavy infestations of cattle tick (Haemaphysalis longicornis).

In late December/early January 1979/80, deaths occurred in 30 red deer (Cervus elaphus) fawns. Evidence is presented to suggest that these deaths most likely resulted from heavy infestations of ticks (Haemaphysalis longicornis).