Bacterys

202 A
bacteria. Overloading slows intestinal motility, thereby fa-
soring retention of bacteria and absorption of their toxins.
The age predilection of these diseases is due to the diet
and theinfantile digestive tract, which otten lacis en-
zymes to inactivate the toxins. Coiostral antitrypsln activ-
ity exacerbates this aspect. Clostridlunr pafrirrgens spores
are destroyed in thefunctional rumen. an organ that is
rudimentary at hirih. Type D proliferation in older lambs
appears to he favored by high-carbohydrate intalne.
Seasonal prevalence relates to the seasonal abundance
ofsusceptible populations and rich forage.
Type A-associated conditions occur worldwide. Type B
lamb dysentery occurs in Europe and South Africa, while
‘type B enteritis of sheep or goats isreported from Iran.
Type C occurs worldwide and also causes overeating-type
enterotora-mia in humans (‘pig bet"). type D is prevalent
wherever sheep are raised. Type E is found in Britain, the
UnitedStates, and Australia, and has been implicated in
enterotoxemia. A toxin similar to its iota toxin is also pro-
dured by C. spimfonne and C. diffirile (see heiow).
Immunologic Aspects
immunity isantibody-mediated and correlates with antl~
toxin levels. immunizing preparations often include bac-
terial components as well.
Passive and active immunization is important in the
control of thediseases (see under "treatment and Con-
trol.“ below).
Laboratory Diagnosis
Clostridlrmr prrfringrns ls relatively aerotolerant. it is non-
rnotile and produces a polysaecharide capsule in tissue.Spores are rarelv demonstrable in exudates obtained from
normally sterile sites.
Isolation follows inoculation of blood containing agar
media, and incubation in an anaerobic environment. if C.perfringens is to be isolated lrom a contaminated environ-
ment (e.g., intestinal contents), the sample can first be
heated to 80‘(I for I5 minutes (endospores will resist this
treatment. whereas...