Infections with Clostridium perfringens
Necrotic enteritis of suckling pigs
In intensive pig husbandries Clostridium perfringens type C causes haemorrhagic diarrhoea in suckling pigs. Exotoxins (alpha and beta toxins, N1 toxin) induce necrosis and bleeding of the mucous membrane of the jejunum. Morbidity from 15 to 80 % can occur.
Catarrhal enteritis of suckling pigs
The significance of infections with Clostridium perfringens type A (alpha toxin, beta 2 toxin, M toxin, N1 toxin) is increasing. Morbidity is very high, mortality is mostly lower compared to infections with Clostridium perfringens type C.
Infections with E. coli
Diarrhoea caused by E. coli is a very important infection of suckling and weaner piglets. Economic losses are huge.
There are two forms:
Coli diarrhoea of suckling pigs
With fimbriae ETEC strains (predominantly F4 and subtypes (K88) as well as F18 and subtypes (F102)) bind to the mucosa of the gut. Diarrhoea is caused by formation of enterotoxins.
Colienteritoxemia of weaner piglets, edema disease
STEC strains (shiga toxin E. coli) produce shiga toxin (or vero toxin), which is neurotoxic and necrotizing. In particular, type F18 (F102) damages the vascular walls.
Infections with Actinobacillus pleuropneumoniae (App)
In fattening farms, respiratory disorders like haemorrhagic-necrotizing pleuorpneumonia due to App cause huge economic losses worldwide. Sixteen different serotypes known so far are present in different geographical patterns. In the USA, serotype 1, 5 and 7 predominate, in Europe serotype 2 followed by 3, 5, 6, 7 and 9. Different combinations of virulence factors (capsule antigens, LPS, exotoxins Apx I-IV) lead to different degrees of virulence of each serotype. Poor cross protection is due to poor cross immunity within the serovars. An infection only induces serotype-specific immunity, which means that another infection with another serotype is possible.
Latent infections are problematic, too.
Infections with Haemophilus parasuis
Glässer´s disease is characterised by fibrinous inflammation of the serosa in the chest and abdominal cavities. Most of the time, the organs are not affected to the same degree.
Fifteen different serotypes of different degrees of virulence are described so far, the majority cannot be standardised. Apathogenic strains can colonise the upper respiratory tract.
Infections with Pasteurella multocida, Bordetella bronchiseptica
Both pathogens induce respiratory diseases. Rhinitis atrophicans is due to Bordetella bronchiseptica and certain strains of Pasteurella multocida type D, which produce a dermonecrotic toxin.
Pasteurella multocida type A and some strains of type D, which do not produce dermonecrotic toxins, induce pneumonia.
Infections with Staphylococcus hyicus
Staphylococcus hyicus, which is common on the skin of swine, can induce inflammation as a consequence of immune depression or injuries of the skin.
Infections with Erysipelothrix rhusiopathiae
Serovars 1 and 2 cause the most frequent and serious infections. Apathogenic serovars can be isolated by healthy pigs.
Infections with Streptococcus suis
Meningitis is pathognomonic. Other clinical manifestations can be arthritis, endocarditis, abortus and stillbirth due to septicaemia. Two types are described (type 1 and 2).
Infections with Arcanobacterium (Actinomyces) pyogenes
A. pyogenes is pyogenic and can primarily be found in arthritis.