Pleuropneumonia in swine caused by Haemophilus parahaemolyticus. A study of the epidemiology of the infection

Haemophilus parahaemolyticus infection was studied in a herd with continuous production, i.e., continuous introduction of stock to replace animals delivered for slaughter. None of 30 seronegative pigs contracted the infection when exposed to contact with two pigs that were seropositive after inoculation with H. Parahaemolyticus three weeks earlier. After aerosol infection had been applied in the building an acute outbreak with a morbidity rate of 100 per cent developed in less than 24 hours. Following recovery the majority of the 16 pigs present became seropositive, and when 30 seronegative pigs were introduced 7 weeks later, antibody response occurred in three of them. The persistence of H. parahaemolyticus in pigs that had been infected during the acute outbreak was confirmed at slaughter, in that the organism was re-isolated from the tonsils of 2 of these pigs. Most serum titres persisted for several months, but some animals showed just a transient antibody response.     

Deer Fibroma: A Review

Fibromas are frequent cutaneous neoplasms of young deer of many species, characterized by proliferation of both epithelial and dermal cells. Virus particles, similar to those found in fibrous skin tumors of several wild and domestic species, have been identified in some species by electron microscopy. Attempted transmission of fibromas has not been uniformly successful using filtered preparations.     

Colostral transfer of immunity to Haemophilus parahaemolyticus in pigs.

Complement fixating antibodies for Haemophilus parahaemolyticus were shown to be transferred from immune sows to their offspring. Colostrum-fed 4-day-old piglets from immune sows resisted intranasal inoculation whereas their littermates, fed on cows' milk, were fully susceptible to the infection. Piglets inoculated later in the suckling period (3 to 8 weeks after birth) when their serumtiters had declined to very low levels, showed some degree of resistance, but the infection was not eliminated from the mucous membranes of the respiratory tract. In chronically infected breeding herds piglets are usually affected during the later part of the suckling period and clinical symptoms are often vague. Though a positive titer is indicative of resistance the results presented above show that protection is usually not complete. Further studies are required to ascertain whether the results obtained here are applicable in a rational control.     

Mercury and Mink. II. Experimental methyl mercury intoxication.

Adult female mink were fed rations containing 1.1, 1.8, 4.8, 8.3 and 15.0 ppm mercury as methyl mercury chloride over a 93 day period. Histopathological evidence of injury was present in all groups. Mink fed rations containing 1.8 to 15.0 ppm mercury developed clinical intoxication within the experimental period. The rapidity of onset of clinical intoxication was directly related to the mercury content of the ration. Mercury concentration in tissue of mink which died were similar, despite differences in mercury content of the diets and time of death. The average mercury concentration in the brain of mink which died was 11.9 ppm. The lesions of methyl mercury poisoning are described and criteria for diagnosis are discussed.     

Serology of Haemophilus (Actinobacillus) pleuropneumoniae serotype 5 strains: establishment of subtypes a and b

The serological characteristicis of 14 strains assigned to serotype 5 were examined by the slide agglutination test, the indirect haemagglutination (IHA) test and by gel diffusion.All the strains possessed identical capsular antigenic determinants of polysaccharide (PS) nature and lipopolysaccharide (LPS) nature. However, based upon a capsular antigenic determinant of PS nature the strains could be divided in two subtypes. It is therefore proposed to refer to the H. pleuropneumoniae strains of serotype 5 to two subtypes: subtype a with strain K17 as the subtype strain and subtype b with strain L20 as the subtype strain.     

Summer mastitis in heifers: observations on the effect of insect attacks on the teats of heifers

An estimation of the possible etiology behind summer mastitis in heifers includes an evaluation of the significance of various insects as hosts for the causal microorganism. Under Danish conditions, several species of insects may be considered disease-carriers, such as Simulium sp., Culicoides sp., tabanids and Hydrotaea irritans (Fall.) in particular. In contrast to the other insects mentioned, Hydrotaea irritans is not able to penetrate the skin by itself but depends on one of the species of insects able to carry out the necessary opening of the skin in order to be able to pick up a “blood meal” (cf. Hϕi Sϕensen 1979).     

A mass attack by the biting midge culicoides nubeculosus (Mg.) (Dipteria, Ceratopogonidae) on grazing cattle in Denmark. A new aspect of sewage discharge.

A consequence of sewage discharge into a shallow marsh pool was large-scale hatching of the biting midge Culicoides nubeculosus from the recipient and mass attacks by this blood-sucking insect on grazing cattle. Culicoides nubeculosus is a great nuisance due to the painful bite and in Denmark it is a potential vector of pathogenic agents. In the future, these aspects of sewage discharge must be borne in mind.     

Bordetella bronchiseptica isolations from the nasal cavity of pigs in relation to atrophic rhinitis.

The occurrence of Bordetella bronchiseptica and atrophic rhinitis was studied during a one-year period in four Danish sow herds. In three of the heards, the epidemiological studies revealed a relation between the occurrence of B. bronchiseptica in 3--10-week-old pigs and the presence and severity of atrophic rhinitis at slaughter. In the fourth herd no such relation was found.