11 Francisco A. Uzal and J. Glenn Songer Infections by Clostridium perfringens type B have been described in the Middle East, Europe, and South Africa. No cases of this infection have been reported from Australasia or the Americas, although anecdotal evidence suggests that infections by this microorganism have been occasionally diagnosed in North and South America. Disease has most frequently been reported in lambs, occasionally in calves, and very rarely in foals. C. perfringens type B isolates carry the genes encoding beta (CPB) and epsilon (ETX) toxins, but different strains can also encode several other non-typing toxins. It is assumed, however, that the two main virulence factors of type B strains are CPB and ETX. CPB is very sensitive to the action of proteases (for example, intestinal trypsin), while ETX needs one or more proteases to become fully activated; however, it seems likely that only one of these toxins is the main virulence factor in the pathogenesis of type B disease at a given time. Clinical signs and lesions are expected to be very different when ETX or CPB action predominates. This, however, has not been demonstrated and remains speculative. In young lambs (from birth to approximately 14 days of age), C. perfringens type B causes a condition known as “lamb dysentery”, which is characterized clinically by acute abdominal pain, a distended abdomen, and hemorrhagic diarrhea. Older lambs may have a more chronic form of the disease, which in the UK is known as “pine,” and is characterized by loss of condition, depression, and reluctance to suckle. Neurological signs including opisthotonus, blindness, and lack of coordination may be observed occasionally and are thought to be produced by the brain lesions caused by ETX. However, it is possible that at least some of these signs are associated with CPB. In calves, the disease caused by C. perfringens type B is clinically similar to that described in lambs, with animals less than 10 days of age being mostly affected; a few cases have been reported in older animals. Although little information is available in this regard, it has been suggested that calves are more likely to recover than similarly affected lambs. Rare cases of C. perfringens type B infection with hemorrhagic diarrhea have been described in foals within the first few days of life. In lambs, intestinal gross lesions associated with infection by C. perfringens type B are essentially the same as those seen in C. perfringens type C necrotizing enteritis (Chapter 12
Infections by Clostridium perfringens type B
Introduction
Etiology
Clinical signs
Gross changes
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
