Clint Lichty from Southwest Ontario Veterinary Service Vomitoxin As A Disease “Tipping Point”

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Listeria (L.) monocytogenes is occasionally   involved   in   food   borne disease  outbreaks  in  humans.  Sometimes the L. monocytogenes get hung up in some meat  processing  equipment  and  can  be  a  bit  pesky when   it   comes   to   completely   cleaning   the equipment.  The  organism  can  survive  in  a  wide range  of  environments  as  well  as  in  the  gut  and manure    of    healthy    pigs.    On    occasion    L. monocytogenes  can  cause  septicaemia  and  bloody

diarrhea  in  growing  pigs.  Austrian  veterinarians described  an  outbreak  of  listeriosis  in  a  450  head finishing  pig  site  where  the  mortality  rate  reached 7.8%.  Clinical  signs  included  off  feed,  bloody diarrhoea and increased body temperature. L. monocytogenes was isolated from internal tissue of  the pigs  and  was present  in  high  numbers  in  the digestive    tract    lymphatic    drainage    system. Interestingly, L. monocytogenes was also isolated in

the maize silage that was being fed on the farm. One animal    was    also    positive    for    Brachyspira hyodysenteriae,  and  this  disease  agent  may  have also  been  involved  in  the  development  of  bloody diarrhea.  The  L.  monocytogenes  isolates  from  pigs and   maize   silage   showed   an   identical   DNA-fingerprint  assigned  to  sequence  type  (ST)  21.  The plot  further  thickened  with  additional  diagnostics that  showed  a  very  high  content  of  vomitoxin  or deoxynivalenol DON (3000 parts per billion) in the maize silage.

 

Take Home Message

  1. monocytogenes  can  cause  clinical  disease  in finishing pigs.

 

  1. monocytogenes  is  rarely  seen  as  a  clinical issue  in  finishing  pigs.  In  this  case  you  would have to be very suspicious that the high levels of vomitoxin  in  the  face  of  infectious  challenge from  the  maize  silage  was  enough  of  a  “tipping point” to allow clinical expression of the disease.

 

In a year with increased vomitoxin contamination of  feed  in  Ontario  any  number  of  otherwise usually rare health issues can start to bubble up to the surface.

 

Submitted by Clint Lichty, DVM

Ref: Stein H, Stessl B, Brunthaler R, Loncaric I, Weissenböck H, Ruczizka U, Ladinig  A,  Schwarz  L.  Listeriosis  in  fattening  pigs  caused  by  poor  quality silage –  a case  report. BMC  Vet Res. 2018  Nov  21;14(1):362.  doi: 10.1186/

s12917-018-1687-6.

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