Avian botulism in winter and spring and the stability of Clostridium botulinum type C toxin

Thermal sensitivity ofClostridium botulinumtype C toxin

“…This could enable 'overwintering' of type C botulinum toxin, if it is produced in a sufficient quantity during warm weather within a generally mild climatic zone. Graham et al (1978) demonstrated experimentally that the toxin (initial concentration -105 mouse MLD/ml) might well be stable over 10 months in semi-natural circumstances.…”

“…mink, cattle), poultry and free-living water birds (Roberts et al 1972; Smith, 1976Smith, , 1977 Haagsma, 1979;Roberts & Gibson, 1979;. In addition to numerous typical outbreaks of avian botulism in warm summer and early autumn seasons, sporadic cases or even small epizootics have been recorded in early spring (Graham et al 1978;Wobeser et al 1983;Rachac, 1986). The origin and source of botulinum toxin in these cases remain obscure.…”

The relevance of Clostridium botulinum type C in public health and food processing

“…botulinum type C is more resistant to physical stress than the other types of Cl. botulinum, although type C toxin may be more resistant to dilution in water (PrCvot & Brygoo, 1953;Haagsma, 1973;Graham et al, 1978), and more resistant than types A, B and E to heat (PrCvot & Brygoo, 1953). However heating for 2 min at 90°C was sufficient to destroy type C toxin from an initial concentration of 4--10 x lo4 MLD/ml (PrCvot & Brygoo, 1953).…”

“…botulinum type C toxin, produced experimentally, to an area of severe botulism outbreaks among waterfowl, the toxin remained stable even after 9 months, although toxin was not found in mud and water samples collected from areas of high botulism mortality. Graham et al (1978) reported that type C toxin retained 1% of its toxicity after 344 days in screw-capped bottles in lake water.…”

“…A temperature of 90°C for 2 min must be reached to destroy Brygoo, 1953 *Tap water (pH not stated) stored at 'room temperature' was used by Brygoo, 1953. Lake water (pH not stated) in 'natural surroundings' was used by Graham et al, 1978. Brygoo, 1953), and 99.9% toxicity of type A is lost after heating at 60°C for 2 min.…”