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ISSN : 2287-7991(Print)
ISSN : 2287-8009(Online)
Journal of the Preventive Veterinary Medicine Vol.37 No.1 pp.45-48

Bovine botulism outbreak associated with incidental consumption of presumably contaminated leftover food

You-Chan Bae1,†, Jae-Won Byun1, Kyung-Hyun Lee1, Ha-Young Kim1, Soon-Seek Yoon1, Ji-Youl Jung1, Woo-Seog Jeong1, Jae-Ku Oem1, Jong-Soo Lim2, Myoung-Heon Lee1
1Animal, Plant and Fisheries Quarantine and Inspection Agency, Anyang 430-757, Republic of Korea
2Jeollanam-do Livestock Sanitation Office, Gangjin 527-822, Republic of Korea
Received 1 February 2013, accepted 18 March 2013


Nine cattle among 18 in a native Korean herd died or were euthanized within 3 days. The affected cattle showeddecreased appetite, salivation, flaccid paralysis, and recumbency. The cattle were raised with pigs and dogs in the samecowshed. The pigs and dogs had been fed leftover food originating from nearby restaurants, and the cattle could presumablyreach the contaminated food in the pig troughs. Necropsy revealed a few chicken bones and red pepper pieces as well aslarge amounts of grain and rice straw hay mixed in the rumen. Botulism type D was isolated in the ruminal contents of oneof the cattle. We speculated that the outbreak was associated with the cattle incidentally eating presumably contaminatedleftover food from the pig trough.

09 case report 배유찬_가편집_1교_저자+가제본.pdf3.30MB


 Botulism is caused by neurotoxins produced by Clostridium botulinum, a gram-positive rod and strict sporeforming anaerobe, during vegetative growth [14]. The organism produces seven known botulinum toxins: A, B, C, D, E, F, and G [20]. The toxin affects all mammals, including humans, birds, and fish [14]. Bovine botulism outbreaks occur sporadically worldwide [1, 2, 6, 13]. Cattle may be affected by types A, B, C, and D [20]. Botulism caused by type C or D is usually associated with contamination by decomposing carcasses [14]. However, the definitive diagnosis of botulism is often difficult because circulating toxin levels are often low and mouse bioassay has insufficient sensitivity [5, 17]. Reports on botulism associated with incidental intake of contaminated leftover food in cattle are rare. Botulism due to botulinum toxin type D occurred in a beef herd with incidental consumption of presumably contaminated leftover food. Therefore, we describe the clinical history and the results of laboratory tests in this case.


Four cattle (2 to 4 years old) among 18 in a Korean native herd suddenly showed decreased appetite, depression, salivation, flaccid paralysis, and recumbency at 7:30 a.m. on August 19, 2012. All four cattle died in the afternoon of the same day. Two additional cattle, which were 8 months and 1 year of age, respectively, died on the morning of August 20, 2012. Moreover, three cattle, 2 to 5 years of age, were euthanized because of exacerbation of clinical signs on August 21 and 22, 2012. A total of nine cattle died or were euthanized.

 The cattle pen was adjoined to a pig pen with two finisher pigs and dog kennels, as shown Figure 1. The pigs were introduced into the farm 2 weeks previously. Eighteen Korean native cattle were raised in the pen. Commercial grain pellets and rice straw hay from a nearby rice field had been fed to the cattle. The pigs and dogs had been fed leftover feed. However, the cattle were near the pig trough and could reach it. The owner testified that the cattle may have eaten the leftover food. The cattle were only vaccinated for foot-and-mouth disease. The cattle were denied access to the food on August 22, 2012.

Fig. 1. Diagram of the cattle and pig pens.

 The leftover food originated from restaurants near the arm. After collecting the food, it was stored at room temperature at the farm and fed to the pigs and dogs on next day. It was filtered, washed, ground, and diluted with water before feeding; however, it was not heated.

 The provincial veterinarian visited the farm from August 20 to 22, 2012 and performed a full necropsy on six of the deceased cattle. Grossly, a few chicken bones and red pepper pieces, as well as large amounts of grain and rice straw hay were mixed in the rumen of three cattle. However, no specific lesions were observed in the other organs. The tissues, ruminal contents, and sera of affected and healthy cattle, leftover feed, grain pellet, and rice straw hay, and feces of the cattle, pigs, and dogs were submitted to the Animal Disease Diagnostic Division of the Animal, Plant, and Fisheries Quarantine & Inspection Agency.

 Serum chemistry using five cattle serum samples revealed that creatine kinase (CK) levels were increased in two cattle (271 and 565 μ/l, respectively; reference range, 46~169 μ/l). Histopathological examination revealed focal pustules in the stratum corneum of the rumen and reticulum and focal chronic interstitial nephritis, which were nonspecific. Neither C. chauvoei nor Bacillus anthracis were isolated from the parenchymal tissues.

 Ruminal contents and sera of affected and healthy cattle, leftover feed, grain pellet, and rice straw hay, and feces of cattle, pigs, and dog were used for C. botulinum isolation and detection of botulinum toxin. Samples were stored in containers and transported on ice to QIA. Toxin testing was performed on all samples by intraperitoneal inoculation of mice according to the protocol of the Centers for Disease Control and Prevention (CDC) with minor adaptations (CDC 1998) [3]. Toxin types were confirmed using a mouse neutralization assay. Specific antisera were incubated with the positive sample at 37℃ for 30 minutes and inoculated intraperitoneally.

In addition, anaerobic broth culture was performed in cooked meat medium (BD, USA) after heat shock (80℃, 30 min). The presence of C. botulinum organisms was confirmed by detecting the presence of toxins in the broth culture according to the CDC protocol with minor adaptations. Botulinum type D was isolated in the contents of one of three rumens. Polymerase chain reaction (PCR) was performed to detect toxin genes of C. botulinum type A to D using the elute from ruminal contents [19]. The amplified DNA product was sequenced and confirmed to be botulinum type D toxin. The mouse bioassay was approved by the institute’s ethical committee.

PCR was performed for viral agents, such as arboviruses (Akabane virus, Aino virus, Chuzan virus, Ibaraki virus, and bovine ephemeral fever virus), bovine viral diarrhea virus, bovine herpesvirus-1, and bovine herpesvirus-5; however, no viral genomes were detected. Analysis for organophosphate chemicals was performed using ruminal contents, but no organophosphate chemicals were detected. In addition, bovine spongiform encephalopathy tests using the brain stem were negative in all cases.


Type B botulism is usually associated with contaminated forage, whereas type C and D botulism is associated with carrion-associated botulism or ensiled poultry litter [4, 5, 8, 10, 12, 13]. However, type D botulism in cattle has been shown to occur due to feeding contaminated bakery waste or haylage [7, 9]. Moreover, type C bovine botulism due to carcass-contaminated non-acidified silage has been reported [11]. We suspect that the affected cattle in this case may have consumed the leftover food because chicken bones and red pepper pieces were observed at necropsy. As a result, this outbreak was associated with incidentally eating the presumably contaminated leftover food in a pig trough. The isolation of C. botulinum type D in the ruminal contents supports this presumption, although no spore or toxin was detected in the food. Uneven distribution of the toxin in clinical samples or a small amount of toxin in samples can result in failure of toxin detection [12]. The warm and humid weather in August may promote the growth of C. botulinum and production of botulinum toxin in the food.

 In one human botulism outbreak, botulinum toxin was detected in 11.4% and 9.9% of clinical samples and food samples, respectively [15]. The contaminated foods were home-canned meat or home-canned vegetables [15, 18]. Botulism outbreaks in humans are mainly associated with improper food handling practices that facilitate the germination and growth of C. botulinum with subsequent toxin production [18]. Leftover food should be hygienically processed before feeding to pigs. In addition, cattle should not be exposed to leftover food.

 No pigs were affected in this case; authentic reports of botulism in pigs are rare because this species resistant to the disease [14].

 The clinical signs in affected cattle and the mortality rate (50%) in this case are consistent with those in previous botulism reports [2, 5, 16]. Moreover, no specific gross or histopathological lesions were observed in this study, which is also consistent with typical botulism [14]. The elevation in serum CK in this study was attributed to muscle damage caused by prolonged recumbency [7].

 For differential diagnoses, organophosphate poisoning, hypocalcemia, and arbovirus infection (e.g., Akabane virus and BSE) were considered, but these diseases were ruled out by laboratory tests. Based on epidemiological data, clinical signs, finding of chicken bones and pepper pieces, isolation of C. botulinum type D from ruminal contents, and the absence of specific pathological lesions, this case was confirmed as botulism. The fact that no further cattle out-breaks occurred after preventing access to the food supports this diagnosis. Bovine botulism causes serious economic damage, as shown in this case; therefore, preventive measures should be available to veterinarians and farmers.

Fig. 2. A downer cow with botulism. Note the mild salivation.

Fig. 3. The rumen of a downer cow with botulism. Note the red pepper piece (blue arrow), chicken bones (white arrow), and large amount of rice straw hay mixed in the lumen.


 A total of 9 cattle among 18 in a Korean native cattle herd died or were euthanized. The affected cattle showed decreased appetite, salivation, flaccid paralysis, and recumbency. The cattle had contacted presumably contaminated leftover food. Based on clinical signs, the presence of chicken bones and pepper pieces, detection of C. botulinum type D toxin from ruminal contents, and the absence of specific pathological lesions, this case was confirmed as botulism.


 This research was supported by a grant from the Animal, Plant, and Fisheries Quarantine and Inspection Agency, Ministry for Food, Agriculture, Forestry, and Fisheries, Anyang, Republic of Korea. The authors thank Dr. Albert Byungyun Jeon for bacterial isolation and also thank Drs. Woo-Hee Park and Moon-Young Rhyoo for necropsy support.


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