zoonoses and communicable diseases common to ... - PAHO/WHO

BOTULISM 33and silage containing the preformed toxins (Smith, 1977). Recently, various importantoutbreaks have been recorded due to consumption of bedding silage and birddroppings. In Great Britain, 80 out of 150 stabled cattle became sick and 68 died.Type C toxin was detected in 18 of the 22 sera examined and the same toxin wasconfirmed in the remains of dead chickens found in the silage (McLoughlin et al.,1988). Similar outbreaks also occurred in Brazil and Canada because the bird beddingused to feed the cattle contained the type C toxin (Bienvenue et al., 1990;Schocken-Iturrino et al., 1990). Animal remains are usually found when botulismoutbreaks occur in cattle, especially due to silage; however, no animal remains couldbe found in the fodder in various cases in the United States and Europe.Bovine poisoning by type B is rare; outbreaks have occurred in Europe (Blood etal., 1983), the United States (Divers et al., 1986), and Brazil (Lobato et al., 1988).Botulism in sheep is due to type C and has been identified only in westernAustralia and South Africa.In horses, botulism cases are sporadic and for the most part are caused by C.botulinum type C. It has been diagnosed in various European countries, the US,Israel, Australia, and South Africa. A special form occurs in colts at 6 to 8 weeksold (“shaker foal syndrome”); it is due to the type B neurotoxin and its pathogenesisis similar to botulism in children, since apparently C. botulinum has to colonizefirst in the intestine and other sites in order to produce the neurotoxin later.Outbreaks of this form have been described in the United States and Australia(Thomas et al., 1988).Botulism in swine is rare because of the natural high resistance of this species tobotulinum toxin. Outbreaks diagnosed in Senegal and Australia were caused by typeC beta and one in the United States was caused by type B.Botulism in mink can be an important problem owing to their eating habits, if theyare not vaccinated as recommended. Mink are highly susceptible to type C, whichcauses almost all the outbreaks.Botulism in fowl occurs practically worldwide and is caused principally by typeC alpha. Outbreaks of types A and E have been recorded in waterfowl. In the westernUnited States, type C is responsible for massive outbreaks in wild ducks duringthe summer and early fall. Many other species of wild fowl are susceptible to botulismand outbreaks also occur in domestic chickens and farm-bred pheasants (Smith,1977). Botulism in domestic fowl has been related to cannibalism and the ingestionof maggots in decomposing carcasses. The explanation is that the body temperatureof fowl (41°C) favors the type C toxin, which would be produced and absorbed inthe caecum, whose pH of 7.4 also favors the toxin (Castro et al., 1988).Botulism in dogs is rare and is caused primarily by ingesting bird carcasses, withtype C being responsible for the disease (Hatheway and McCroskey, 1981).The Disease in Man: (a) Botulism poisoning by foods is produced primarily bytypes A, B, and E and rarely by F or G. Outbreaks in man described as type C havenot been confirmed, as the toxin has not been found in the patients’ blood or fecesnor in foods they ate. An outbreak of type D was identified in Chad, Africa, amongpeople who had eaten raw ham (Smith, 1977). A new toxicogenic type, C. botulinumtype G, was isolated from the soil in Argentina in 1969 (Giménez and Ciccarelli,1970). The first human cases were recognized in Switzerland (Sonnabend et al.,1981). The microorganism was isolated in autopsy specimens from four adults and