Poster Presentation The 3rd Prato Conference on the Pathogenesis of Bacterial Diseases of Animals 2014

Serological investigation in a persistent outbreak of bovine botulism (#11)

Luca Bano 1 , Elena Tonon 1 , Ilenia Drigo 1 , Alexander Tavella 2 , Giacomo Berto 1 , Katia Capello 3 , Cedric Woudstra 4 , Fabrizio Agnoletti 1
  1. Special Bacteriology Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Villorba di Treviso, Italy
  2. Veterinary Diagnostic Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Bolzano, Italy
  3. Epidemiological Unit, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy
  4. Food Safety Laboratory, French Agency for Food, Environmental and Occupational Health Safety (ANSES), Maisons-Alfort, France

Animal botulism is a neuro-paralytic disease caused by neurotoxins (BoNT) produced by a gram-positive, sporeforming anaerobic bacterium named Clostridium botulinum. BoNTs are classified into 7 serotypes from A to G on the basis of their antigenic properties. An additional serotype (known as BoNT/H) has been proposed, but its confirmation as a novel toxin serotype requires further experimental validation1. Although serology showed to be a useful tool to discriminate vaccinated from unvaccinated cows, some studies demonstrated that non-fatal natural exposure results inadequate to cause seroconversion to type D toxin2,3.
In 2012, slight signs referable to botulism were observed in a dairy cattle herd of ten lactating Simmental cows, four pregnant heifers and seven calves of the same breed. The disease spread over a period of 11 weeks with a low mortality rate (one cow). The majority of the affected animals recovered after five to eight weeks since the beginning of the symptoms. The diagnosis of botulism type C was assessed by PCR type-specific protocols, bacteriological examination and BoNT detection. An in-house ELISA was developed, validated on a vaccinated herd and applied in the studied clinical case. The ROC analysis provided a specificity of 95% and a sensitivity of 90% for the developed ELISA. All ELISA positive animals (8/14) tested positive also by PCR and neurotoxin gene characterization showed that the strain was a non-chimeric type C.
Contrary to what demonstrated for type D, our findings suggest that non-chimeric type C BoNTs can provide a seroconversion in cattle. This could be due to the fact that type C neurotoxin is less lethal to bovine than type D/C or C/D. This possibility has already been demonstrated in chicken where type C/D showed to be more toxic than type C4. This difference in toxicity could explain the slight clinical signs and the seroconversion.

  1. Dover, N., Barash, J. R., Hill, K. K., Xie, G. & Arnon, S. S. 2014. Molecular characterization of a novel botulinum neurotoxin type H gene J. Infect. Dis. 209, 192–202.
  2. Steinman A., Chaffer M., Elad D. & Shpigel N. Y. 2006. Quantitative analysis of levels of serum immunoglobulin G against botulinum neurotoxin type D and association with protection in natural outbreaks of cattle botulism. Clinical and Vaccine Immunology : CVI 13, 862-868.
  3. Mawhinney I., Palmer D., Gessler F., Cranwell M., Foyle L., Otter A., Payne J., Strugnell B. 2012. Investigation of serology for diagnosis of outbreaks of botulism in cattle. The Veterinary Journal 192, 382–384.
  4. Takeda M., Tsukamoto K., Kohda T., Matsui M., Mukamoto M. & Kozaki S. 2005. Characterization of the neurotoxin produced by isolates associated with avian botulism. Avian Diseases 49, 376-381.