A. Wiseman

Reactivation and shedding of bovine herpesvirus 1 following Dictyocaulus viviparus infection

Three groups of 4 bullocks which had recovered from infectious bovine rhinotracheitis (IBR) were infected 5 months later with Dictyocaulus viviparus larvae. Bovine herpesvirus 1 was recovered from days 7 to 21 post-infection from the nasal secretions of the group given 50 larvae per kilogram and on one occasion from those given 1000 larvae per animal (less than 5 L3 per kg). Virus was not isolated from the animals given 1000 irradiated larvae. Typical clinical signs and lesions of IBR developed in the group from which the virus was isolated regularly.

Precipitins to Micropolyspora faeni in the adult cattle of selected herds in Scotland and north‐west England

Sera from all housed adult cattle in twelve herds were examined for precipitating antibody to Micropolyspora faeni at the beginning of winter and approximately 5 months later in the spring; during this time they had been fed hay. Six of these herds were owned by farmers with farmers lung. The average incidence of precipitins was 33% on the first occasion and 47% on the second occasion. After the winter there was a statistically significant increase in the number of animals with precipitins in five herds. A positive correlation was shown between the incidence of precipitins and age.

Fog fever in cattle: cytology of the hyperplastic alveolar epithelium.

Abstract Alveolar epithelial hyperplasia is a prominent pulmonary lesion in fog fever, which is an acute respiratory distress syndrome of adult cattle. The hyperplastic cells are cuboidal in shape, rest on a basement membrane, form tight cell junctions with their neighbours, possess microvilli on their free surface, and contain lamellated, irregularly electron-dense inclusion bodies in their cytoplasm. These features enable the cells to be characterized as type 2 pneumonocytes.

Studies on the incidence and titres of precipitating antibody to Micropolyspora faeni in sera from adult cattle

Abstract Over 2 consecutive years, serum samples, taken in autumn and spring from all housed adult cattle in 16 herds, were examined for the presence and amount of precipitating antibody to Micropolyspora faeni. Exposure to the allergen over the winter months resulted in a rise in the number of cattle with antibody and in the serum titres. Over the summer the number of positive cattle and titres fell but this period of non-exposure was insufficient to restore some of the herds to their original state, showing that the effects of exposure can be cumulative from one year to the next. Studies on paired serum samples clarified the seasonal changes in antibody in herds and showed the importance of titre in determining whether antibody is liable to be retained over the summer. Some measure of the amount of exposure to which a herd has been subjected can be obtained from the percentage of positive cattle and the titres of the sera. From this data it is also possible to identify herds liable to be at risk if subjected to further heavy exposure. Culling of high titre animals in such herds is suggested as a possible control measure.

The prevalence of serum precipitating antibody to Aspergillus fumigatus in adult cattle in Britain

The prevalence of precipitating antibody to A. fumigatus in 3509 sera from adult cattle in 44 herds was 25 per cent. Only 19 per cent of sera from grazing or recently housed animals were positive compared with 30 per cent of those taken towards the end of the winter. Mouldy hay was the most likely source of A. fumigatus antigens although a positive correlation between the prevalence of precipitins and either the mouldiness of the hay or the frequency of coughing in the springtime was not established. However, there was a positive correlation between the age of cattle sampled and the prevalence of antibodies. Mycotic abortion had been confirmed in only one of 6 herds in which more than 80 per cent of the cows were seropositive and so it can be inferred that the presence of serum precipitating antibody is of very little value in the diagnosis of mycotic abortion resulting from A. fumigatus infection.

Fog fever: Provocation tests with Dictyocaulus viviparus

Abstract There have been many suggestions that fog fever of cattle is the result of a hypersensitivity to Dictyocaulus viviparus . However, when 7 adult cattle that had recovered from fog fever were challenged orally with 30 000 third-stage larvae of D. viviparus , the acute respiratory signs did not recur. Pulmonary lesions comparable to those of reinfection husk and unlike those of fog fever were found at post mortem examination of the 7 animals, one month after challenge. It is concluded that there is no evidence that fog fever occurs as the result of a hypersensitivity reaction in sensitized cattle to oral reinfection with d. viviparus larvae.