Outbreak of type C botulism in laying hens

Investigation of a type C/D botulism outbreak in free-range laying hens in France

In 2014, a botulism outbreak in a flock of laying hens was investigated in France. In the flock of 5020 hens, clinical signs of botulism occurred at 46 weeks of age. A type C/D botulism outbreak was confirmed using the mouse lethality assay for detection of botulinum toxin in serum and a real-time PCR test to detect Clostridium botulinum in intestinal contents. The disease lasted one week with a mortality rate of 2.6% without recurrence. Botulism in laying hens has rarely been reported. Five monthly visits were made to the farm between December 2014 and May 2015 for a longitudinal study of the persistence of C. botulinum in the poultry house after the outbreak, and to assess egg contamination by C. botulinum. Several samples were collected on each visit: in the house (from the ventilation circuit, the egg circuit, water and feed, droppings) and the surrounding area. Thirty clean and 30 dirty eggs were also swabbed at each visit. In addition, 12 dirty and 12 clean eggs were collected to analyse eggshell and egg content. The samples were analysed using real-time PCR to detect type C/D C. botulinum. The bacterium was still detected in the house more than 5 months after the outbreak, mostly on the walls and in the egg circuit. Regarding egg contamination, the bacteria were detected only on the shell but not in the content of the eggs. Control measures should therefore be implemented throughout the egg production period to avoid dissemination of the bacteria, particularly during egg collection.

Investigations into an Outbreak of Botulism Caused by Clostridium botulinum Type C/D in Laying Hens

This case report describes a recent botulism outbreak in commercial laying hens with a history of increased mortality and flaccid paralysis. Routine diagnostic gross examination and microscopy from seven hens were inconclusive, but botulinum neurotoxin (BoNT) in peripheral blood was neutralized with both type C and type D antitoxins in the mouse bioassay. During a farm visit, 10 additional hens from a 34-wk-old flock on the farm were selected for clinical examination and further sampling. Nine hens were observed in sternal recumbency, with flaccid paralysis of the neck, drooping wings and tail, inability to escape, and bilateral ptosis, and one hen showed nonspecific clinical signs. Samples from cecum and liver were collected, and the gene coding for BoNT was detected by PCR in all 10 cecal samples and in four of the liver samples. Clostridium botulinum mosaic type C/D was isolated from 5 out of 10 hens from either cecum or liver, and the isolates were subjected to pulsed-field gel electrophoresis subtyping. All five isolates produced the same banding pattern, which was identical or showed >90% similarity to isolates from three different outbreaks on broiler farms in Sweden and Denmark during the 2007-10 period. However, they were clearly distinguishable from the predominantly reported pulsotype associated with avian botulism outbreaks in Europe. The authors are unaware of any previous report of C. botulinum mosaic type C/D isolates from laying hens.

Investigation of Clostridium botulinum in commercial poultry farms in France between 2011 and 2013

Between 2011 and 2013, 17 poultry botulism outbreaks were investigated in France. All cases were associated with Clostridium botulinum type C-D. Presence of C. botulinum was studied in seven areas: poultry house, changing room, ventilation system, surroundings, animal reservoirs, water, and feed. Swabs, litter, soil, darkling beetles, rodents and wild bird droppings, feed and water samples were collected. The presence of C. botulinum type C-D in the environment of affected flocks was detected in 39.5% of the 185 samples analysed by real-time polymerase chain reaction. C. botulinum type C-D was reported in each area. Four areas were more frequently contaminated, being found positive in more than one-half of farms: darkling beetles (9/11), poultry house (14/17), water (13/16) and surroundings (11/16). After cleaning and disinfection, the ventilation system and/or the soil (in the houses and the surroundings) returned positive results in four out of eight poultry farms. Consequently, darkling beetles, the drinking water, the ventilation system and the soil in the surroundings and the houses were identified as the main critical contaminated areas to consider in poultry farms to prevent recurrence of botulism outbreaks.

Multiplex real-time PCR for detecting and typing Clostridium botulinum group III organisms and their mosaic variants

Botulism is a neuroparalytic disease that can occur in all warm-blooded animals, birds, and fishes. The disease in animals is mainly caused by toxins produced by Clostridium botulinum strains belonging to group III, although outbreaks due to toxins produced by group I and II organisms have been recognized. Group III strains are capable of producing botulinum toxins of type C, D, and C/D and D/C mosaic variants. Definitive diagnosis of animal botulism is made by combining clinical findings with laboratory investigations. Detection of toxins in clinical specimens and feed is the gold standard for laboratory diagnosis. Since toxins may be degraded by organisms contained in the gastrointestinal tract or may be present at levels below the detection limit, the recovery of C. botulinum from sick animal specimens is consistent for laboratory confirmation. In this article we report the development and in-house validation of a new multiplex real-time PCR for detecting and typing the neurotoxin genes found in C. botulinum group III organisms. Validation procedures have been carried out according to ISO 16140, using strains and samples recovered from cases of animal botulism in Italy and France.

Management of animal botulism outbreaks: from clinical suspicion to practical countermeasures to prevent or minimize outbreaks

Botulism is a severe neuroparalytic disease that affects humans, all warm-blooded animals, and some fishes. The disease is caused by exposure to toxins produced by Clostridium botulinum and other botulinum toxin-producing clostridia. Botulism in animals represents a severe environmental and economic concern because of its high mortality rate. Moreover, meat or other products from affected animals entering the food chain may result in a public health problem. To this end, early diagnosis is crucial to define and apply appropriate veterinary public health measures. Clinical diagnosis is based on clinical findings eliminating other causes of neuromuscular disorders and on the absence of internal lesions observed during postmortem examination. Since clinical signs alone are often insufficient to make a definitive diagnosis, laboratory confirmation is required. Botulinum antitoxin administration and supportive therapies are used to treat sick animals. Once the diagnosis has been made, euthanasia is frequently advisable. Vaccine administration is subject to health authorities' permission, and it is restricted to a small number of animal species. Several measures can be adopted to prevent or minimize outbreaks. In this article we outline all phases of management of animal botulism outbreaks occurring in wet wild birds, poultry, cattle, horses, and fur farm animals.

Type C botulism in a commercial turkey farm: a case report

Botulism is an intoxication caused by exotoxins of Clostridium botulinum. The case of botulism described here occurred on a commercial meat turkey farm with two houses. Toms and hens were maintained in two separate houses, toms in house A and hens in house B. At 10 wk of age, an increase in mortality was observed in the toms located in house A. Clinically the animals presented with paralysis of the legs, wings, and neck. Affected birds were sitting and reluctant to move. Necropsy failed to find any specific lesions. In liver, heart, muscles, crop, and gizzard as well as in intestinal contents, DNA of C. botulinum type C was detected by PCR. The result was confirmed by a mouse lethality neutralization test. During the 2 wk after the onset of the clinical signs the mortality was about 12%. The hens kept in house B did not show any symptoms and remained healthy. Investigations of environmental samples to detect the source of the toxin were not successful. After 2 wk clinical signs and mortality abated. At 16 wk of age, toms again showed the same clinical signs accompanied by raised mortality. Again C. botulinum toxin type C was detected. Within 2 wk the total mortality reached roughly 50%. Based on the "precautionary principle" and in agreement with the local authorities, the birds were euthanatized using CO2 in order to not compromise food safety.