Clostridium perfringens type C infections

M W ODENDAAL, N P J KRIEK AND P HUNTER

GENERAL INTRODUCTION: ENDOSPORE-FORMING GRAM-POSITIVE RODS AND COCCI Clostridium perfringens group infections

Introduction

Clostridium perfringens type C has been regarded since 1931 as the cause of struck, which is an acute infectious but non-contagious and rapidly fatal disease of adult sheep first described on the Romney Marsh in Kent, England. Struck is characterized by an acute enteritis, peritonitis and toxaemia, and has a seasonal occurrence.¹⁹More recently, C. perfringens type C has become associated with haemorrhagic enterotoxaemia in young lambs,^{12, 15, 17, 43} haemorrhagic enteritis or enterotoxaemia in calves,^{16, 46} haemorrhagic necrotizing enteritis or necrohaemorrhagic enterocolitis in foals,^{7, 27, 48, 51} and necrotizing or haemorrhagic enteritis in neonatal piglets^{4, 22–26, 29, 30} and in weaner, fattening and breeding pigs.³⁵ In humans, C. perfringens type C has been isolated from patients suffering from a similar condition described in Germany as ‘Darmbrand’ ⁶¹ and in Papua New Guinea, as enteritis necroticans.^{8, 9, 41} It is possible that the young of all animal species may be susceptible to C. perfringens type C infection, which is possibly dependent on those factors favouring bacterial colonization in the intestine, such as digestive malfunctions. Present indications are that the number of animal species which may be affected by a fatal infection of type C is greater than that by any of the other C. perfringens types.⁴⁵ The infection is rarely diagnosed in South Africa in calves, lambs and piglets.²¹

Aetiology

Clostridium perfringens type C produces alpha and beta toxins as major toxins, whereas minor toxins such as theta and delta toxins are produced less consistently by different strains (see the introduction, Clostridium perfringens group).

There can be little doubt that C. perfringens type C is a cause of haemorrhagic or necrotic enteritis, or enterotoxaemia in very young animals under natural conditions; type C enterotoxaemia has also been experimentally reproduced in piglets,^{11, 29} lambs⁴³ and guinea pigs.³⁶

Five subtypes of type C have been recognized, their identity being based on their ability to produce certain minor toxins. These subtypes have a specific geographic distribution and affinity for certain species of livestock, and include those associated with classical struck in sheep, the Colorado variety from lambs and calves, human necrotic enteritis, and porcine enteritis. All type C isolates produce beta toxin. The classical subtype, isolated from struck in sheep, produces all three haemolysins (alpha, theta and delta toxins), a number of other minor toxins as well as the beta toxin. The presence or absence of the delta toxin⁴⁵ is one of the distinguishing characteristics between the type C subtypes, as opposed to the presence of the alpha and theta toxins, which are present in most of the other C. perfringens strains, including type C.^{40, 44, 57} Strains isolated from typical C. perfringens type C enterotoxaemia in pigs share the biochemical characteristics common to C. perfringens (see the introduction, Clostridium perfringens group). All these strains also produce alpha and beta toxins and some of the minor toxins including the theta toxin. None of the porcine strains produces the delta toxin.²³

The morphological and biochemical properties of C. perfringens type C are identical to those of the other types (see the introduction, Clostridium perfringens group). The biochemical and morphological identification of type C isolates can be performed according to the procedures described by Harmon¹⁸ and the toxin typing to those described by Sterne and Batty.⁵⁵

Epidemiology

Diseases caused by C. perfringens type C are largely unknown in South Africa and the organism is rarely isolated.²¹

Few cases of necrotic enteritis have been encountered in pigs but it is not considered to be of economic importance. Struck also is not a recognized entity in South Africa though it may be confused with pulpy kidney disease.³ The disease in sheep has mostly been reported from the UK, Germany, Sardinia, New Zealand and the USA.

Epidemiological data on the disease in the various animal species are scant. The neonatal disease may be sporadic and affect individual animals, as in foals,²⁷ or occur in outbreaks of varying extent annually or during successive farrowings as it does in pigs,⁴ calves and lambs. It is estimated that in an endemic area up to 25 per cent of piglets, under five days of age, can develop a clostridial diarrhoea.²² Struck occurs on a seasonal basis, mainly during the winter or spring.²⁰

The disease appears to be transmitted per os. Clostridium perfringens type C can live for long periods in the intestine of carrier animals without causing clinical disease. It appears that, of the animal species investigated, pigs carry the largest numbers of the bacterium in their intestinal tracts; in one study, ⁸⁷ per cent of all C. perfringens type C isolated were obtained from pigs, while less than 4 per cent were obtained from sheep and less than 2 per cent from cattle. Clostridium perfringens type C can also be isolated from faeces of pigs from farms where outbreaks have not occurred. These animals, as well as diseased animals, are responsible for disseminating the type C organism through their faeces. Predisposing factors to disease in piglets include...