Clostridial Diseases in Pigs and Public Health Concerns

C. difficile from pigs might be a serious public health concern and needs to be further investigated, according to R. Friendship, J. Gallant, K. Warriner and S. Weese of the University of Guelph. They presented a written paper at the 28th Centralia Swine Research Update.

7 July 2009

5 minute read

There are several species of clostridia that are very commonly found in the intestines of pigs. The extent of disease associated with these bacteria is not well known and their impact in Ontario maybe under-estimated. They are reported to be the most frequently diagnosed cause of diarrhea in suckling piglets in the swine producing areas of the United States. One type of clostridia – C. difficile – is also a concern from a public health standpoint. C. difficile in hospitals has created major problems.

Clostridium perfringens type A is a normal inhabitant of the pig intestine but is also occasionally a cause of diarrhoea in piglets during their first week of life. One reason it may escape diagnosis is that this bacteria does not cause gut damage. It is believed that beta-2 toxin plays a role in causing the diarrhoea and generally the bacteria isolated from disease cases produce this toxin.

Clostridium difficile is also a cause of diarrhea in piglets during the first week of life, and is sometimes associated with antibiotic use as a predisposing factor. On post mortem examination the lining of the colon is swollen with fluid (oedema) and the contents of the large intestine is pasty-to-watery and yellow. Piglets generally do not die from the diarrhoea but as in most cases where piglets are sick the lack of nursing may cause the sow to develop a swollen udder and milk production is reduced, and weaning weights of piglets are negatively affected.

Research Findings

There are no formal studies examining the prevalence of clostridial diarrhea in the Canadian pig population, however there are anecdotal reports from swine practitioners that the problem has increased recently or is becoming more commonly diagnosed. Gallant Custom Laboratories report that in 2007 there were seven swine clients who requested autogenous Clostridium bacterins and that number jumped to 40 in 2008. Most vaccines were for C. perfringens type A strains that produced beta 2 toxin, but a few bacterins also included C. difficile.

Longitudinal evaluation of Clostridium difficile in piglets on one farm

The objective of this study was to characterise the prevalence of C. difficile colonisation in piglets over time on a commercial swine farm.

Sows were sampled 30, 23 and 15 days prior to farrowing and rectal swabs were collected from piglets from positive and negative sows on days 2, 7, 30, 44 and 62 for enrichment culture.

C. difficile colonisation rates were high initially and decreased over time. C. difficile was isolated on one or more occasions from 97 per cent (117/121) of piglets. The prevalence of C. difficile colonization on days 2, 7, 30, 44 and 62 was 74 per cent, 56 per cent, 40 per cent, 23 per cent and 3.7 per cent, respectively. The reason for the change in prevalence over time is unclear and requires investigation to determine whether factors can be modified to reduce the risk of transmission.

The use of a single farm limits making broad conclusion, but this study provides insight into age-related effects on colonisation that should be considered in future studies. While colonisation status of the sow influences the piglets, there is not an absolute relationship and other sources of infection need to be considered.

Prevalence of C. difficile in 52 Ontario herds

Faecal and effluent samples (133) were collected from 52 farms located within Southern Ontario.

C. difficile was recovered from 15 farms (28 per cent prevalence). The majority of isolates recovered belonged to ribotype 078 (16/20 isolates) with ribotype 027 being less prevalent (1/20). All the isolates produced toxin A & B, in addition to binary toxin confirming potential pathogenicity towards neonatal pigs and humans.

The prevalence of C. difficile is high within Ontario pig herds and a shift from the dominance of ribotype 027 to the strain implicated in community acquired CDAD (ribotype 078) has occurred providing further evidence of a foodborne link.

Implications

This preliminary work suggests that Clostridium perfringens and Clostridium difficile are extremely common in Ontario pig herds and that they are likely both associated with piglet diarrhoea at times but more importantly C. difficile from pigs might be a serious public health concern and needs to be further investigated.