Swine dysentery – Summer, the season for eradication

At a recent conference on Colonic Spirochaetal infections in Animals and Humans in the beautiful and historic city of Prague, the continued presence and isolation of Brachyspira hyodysenteriae was discused.

Brachyspira hyodysenteriae is still common in most European countries. Swine dysentery can be a severe disease damaging the large intestine (colon) of the pig and the associated diarrhoea, containing blood and mucus, can lead to mortality, a loss of bodyweight and a negative feed conversion efficiency.

In a German survey of nearly 5000 samples, the infectious organism was found in 26.4% of diarrhoeic samples and worryingly, 5.5% of normal samples or potential carriers.

Fortunately, reports from Germany and Spain showed there was little antimicrobial resistance build up to the pleuromutilin treatments, tiamulin and valnemulin, which are commonly used for swine dysentery eradication but there was some to lincomycin and especially tylosin.

In the Czech Republic however, a different picture was painted, with a steady increase in resistance to all antimicrobials including the pleuromutilins. Once Brachyspira are resistant to all the main antibiotics, the only real alternative is to completely cull out the herd, which is an expensive procedure.

The more common approach is to use partial depopulation of all the stock above weaning age and blanket medicate the breeding herd to kill the organism, as well as moving away manure and slurry, cleaning and disinfecting the farm, controlling rodents and improving biosecurity to prevent re-infection.

The summer sun can help with the environmental control (see graph). When temperatures go above 20°C, the survival time of B. hyodysenteriae drops dramatically, below 10 days, decreasing the chances of reinfection.

Graph: Survival time of Brachyspira hyodysenteriae in faeces and slurry