Implementation and evaluation of different eradication strategies for Brachyspira hyodysenteriae

Abstract

Background Brachyspira infections are causing major losses to the pig industry and lead to high antimicrobial use. Treatment of Brachyspira (B.) hyodysenteriae infections may be problematic due to the high level of antimicrobial resistance. The present study implemented and evaluated farm-specific eradication programmes for B. hyodysenteriae in 10 different infected pig farms in Belgium. Results Ten pig farms clinically infected with B. hyodysenteriae volunteered to implement a farm-specific eradication programme. The programme depended on the farm and management characteristics, antimicrobial susceptibility of the B. hyodysenteriae strain and the motivation of the farmer. Two farms practiced total depopulation, six farms partial depopulation and two farms antimicrobial medication without depopulation. In addition, all farms implemented biosecurity measures, and faeces samples were tested for the presence of B. hyodysenteriae at 6, 9 and 12 months after the start of the program. Single Brachyspira isolates from before and after the programme were typed using multilocus sequence typing (MLST). Eradication was successful in four farms. Two of them (farrow-to-finish and finishing herd) had applied total depopulation and respected a vacancy period of at least 3 weeks. A third farm (gilt farm) practised partial depopulation, the rooms remained empty for 28 days and changed the source of breeding gilts. The fourth farm practised partial depopulation, the stables remained empty for 3 weeks, and used antimicrobial medication. The eradication programme was not successful in six farms. Two of the latter farms only used medication without partial depopulation. Four farms practiced partial depopulation, one of them combined it with antimicrobial medication. The cleaning and disinfection procedures, rodent control, stand-empty period and/or other biosecurity measures in the six farms were not always implemented properly. In two of three farms, isolates belonging to the same MLST type were found before and after eradication. Conclusions Total depopulation or partial depopulation combined with implementing strict biosecurity measures allowed eradication of B. hyodysenteriae from clinically infected pig farms. Programmes based on antimicrobials without depopulation or partial depopulation without strictly adhering to all suggested biosecurity measures were not successful. Stockmanship and motivation of the farmer to permanently maintain high biosecurity standards are essential for success.

Combined in-vitro and on-farm evaluation of commercial disinfectants used against Brachyspira hyodysenteriae

“…Within biosecurity schemes, implementation of effective cleaning and disinfection protocols are mandatory as part of those strategies, which aim at breaking the disease transmission among batches [ 11 ]. This fact is supported by observational studies such as the one carried out by Neirynck et al [ 2 ], who only found successful eradication programmes for B. hyodysenteriae on the four farms, which implemented properly cleaning and disinfection procedures, among other biosecurity measures. This efficacy relies on the selection of the most appropriate compounds [ 14 , 15 ] and their application through effective protocols.…”

“…Swine dysentery (SD) is a severe mucohaemorhagic enteric disease, which causes important losses in the pig industry due to mortality and sub-optimal performance [ 1 , 2 ]. The disease is more frequently observed in the growing and finishing stages [ 3 ].…”

“…High standards in biosecurity are crucial in prevention and amelioration of diseases in pig production [ 11 , 12 ] and management strategies such as all-in /all-out (AI/AO) attempt to be effective firewalls to prevent the transmission of diseases such as SD. Undoubtedly the effectiveness of AI/AO depends on the efficacy of cleaning and disinfection protocols put in place [ 2 , 3 , 11 ].…”

“…Field studies also reveal the need to implement efficient protocols, which remove the pathogens from the environment successfully [ 16 ]. Despite the environmental component in SD epidemiology, there are no studies which particularly combine the assessment of the in-vitro susceptibility of B. hyodysenteriae to disinfectants and the efficacy of these agents under the usual cleaning and disinfection protocols implemented in field conditions [ 2 , 17 , 18 ]. With this aim in mind, this study evaluates the in-vitro efficacy of an array of different commercial disinfectants against a collection of ten field isolates of B. hyodysenteriae and the efficacy of hygiene protocols, under field conditions, on farms with SD.…”

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): antimicrobial‐resistant Brachyspira hyodysenteriae in swine

“…The disease is characterised by various degrees of mucoid and haemorrhagic diarrhoea, fever, dehydration, loss of body condition, depression and apathy, and sometimes disease is followed by death (Bellgard et al, 2009 ). Once a pig herd is infected with B. hyodysenteriae , elimination of the pathogen is extremely difficult therefore often resulting in long‐term losses and continued use of antimicrobials (Neirynck et al, 2020 ). As described in the following sections, several other animal species have been reported to be subclinical carriers of B. hyodysenteriae .…”