Introduction

Yersinia enterocolitica is a common pathogen for both human and animals, the predominant clinical feature is abdominal pain and diarrhea with or without fever ₁ . The emergency of Yersinia enterocolitica 0:3 and 0:9 in Europe and Japan in the 1970s and in North America by the end of the 1980s has been characterised as an example of a global pandemic ₂ . The number of infection due to Yersinia enterocolitica in humans has increased considerably over the past years ₃ . These infections are often linked to pork consumption ₄ .

There is a strong indirect evidence that swine constitute an important reservoir for human infection with Yersinia enterocolitica ₅,₆,₇,₈ .

The pig is the only food animal which regularly harbours pathogenic Yersinia enterocolitica ₉ . Epidemiological surveys have shown that Yersinia enterocolitica in healthy carriers do exist and certainly may represent an important factor in the spread of this infection. Yersinia enterocolitica has been isolated from a variety of environmental sources but pigs are recognised to be the main reservoir of the different Yersinia enterocolitica serotypes (0:3, 0:9, 0:5, and 0:8) which are also known pathogens prevalent in human infections ₃,₁₀ The apparently low incidence of the infection in Islamic countries where consumption of pork is restricted buttresses the fact that pork is the main sources of human infections.

In Nigeria, ₁₁ and ₁₂ reported the oocurrence of Yersinia enterocolitica in pigs in Zaria and Jos respectively. Gastroentritis and diarrhoea associated with Yersinia enterocolitica have been similarly documented by ₁₃ and ₁₄ .

This study was aimed at establishing the frequency and profiles of pathogenic Yersinia enterocolitica among apparently healthy pigs in selected herds in Jos and its environ.

Materials And Methods

Three pig herds (Kaduna Vom, Kuru, and Vwang) located in Jos South Local Government Area and one large weekly pig market in Kafanchan, Kaduna State (neighbouring Local Government Area to Jos) were selected for this study (Fig.1). A total of 320 tonsil and faecal samples were screened for the presence of Yersinia enterocolitica.

Cold enrichment

Bacterial isolation and identification

Serotyping

Biotyping

Antimicrobial susceptibility

Data management and analysis

Results

Samples from the three pig farms visited in Jos and the weekly pig market in Kafanchan, Kaduna State were all positive for Yersinia enterocolitica. A total of 56 (17.5%) Yersinia enterocolitica strains (Table 1) were isolated from 320 samples of tonsils and faeces. Kafanchan study area gave a high prevalence rate of 7.8%. Of the 160 tonsil samples screened from all study areas 32 (20%) were positive for Yersinia enterocolitica (Table 2) while 24 (15%) of faecal samples were positive for Yersinia enterocolitica (Table 3).

All isolates belonged to predominant human and animal serotypes in Nigeria ₁₄,₂₀ , 18 and 14 Yersinia enterocolitica strains were biotyped 1 and 4 respectively among the tonsil samples while 8 and 16 Yersinia enterocolitica strains were biotyped 1 and 4 among the faecal samples

(Table 4). All strains of Yersinia enterocolitica were susceptible to ciprofloxacin, tarivid, gentamycin and but resistant to amoxicillin, ampicillin, and erythromycin (Table 5). No significant differences were observed among the samples analysed (P<0.5).

Figure 1

Table 1: Percentage distribution of from different study areas

Figure 2

Table 2: Percentage prevalence of in Tonsil samples

Figure 3

Table 3: Percentage prevalence of in faecal samples

Figure 4

Table 4: Phenotypic profiles of pathogenic

Figure 5

Table 5: Antimicrobial Susceptibility Pattern Of Strains

Figure 6

Figure 1: Species of pigs investigated

Discussion

Our findings are further proof that the pig population in the study areas are reservoir of human infections as serotypes and biovars isolated in these herds have been found to be responsible for most epizootics diseases as documented in a similar study by ₂₁ . This is perhaps the only biogroups present among swines in this part of the world. The prevalence rate (17.5%) found in this study are consistent with the rates found by ₂₂ in Denmark and Norway ₂₃ . These findings are also similar to reports in other parts of the world particularly in India ₂₄ and Finland ₂₅ where Yersinia enterocolitica was frequently isolated from intestinal contents of slaughtered pigs and rectal swabs of apparently healthy pigs. The occurrence of Yersinia enterocolitica in pigs investigated in this study seems to be a global problem ₂₆,₂₇ . Unlike other countries where Yersinia enterocolitica serotype 0:3 is frequently encountered in animals and human ₂₆,₂₈ our studies has identified serotype 0:9 as the most prevalence strain in this part of the world ₁₄ .

Although this study can not give complete information about the true prevalence of Yersinia enterocolitica 0:9 in the whole of Nigeria but it can be considered to represent the figures in the middle belt of Nigeria with certain limitations. It is also note worthy that profile of Yersinia enterocolitica isolates were seen to be similar within all the study areas. This suggest that all the herd investigated harboured common strain of Yersinia enterocolitica and in accordance with the findings of ₂₀ .

Prevalence rates of 15% and 20% recorded for faecal and tonsil samples in our studies confirms previous studies that have identified this bacteria (Yersinia enterocolitica) more frequently in tonsils than in faeces ₁₀,₂₇,₂₈,₂₉,₃₀,₃₁ .

Exceptionally high susceptibility to spectrum of antibiotics such as ciprofloxacin, tarivid and gentamycin as documented in our finding has been similarly reported in Nigeria by ₁₄,₂₀ .

Our results support the assumption that the use of conventional cultivation methods may lead to considerable underestimation of pathogenic Yersinia enterocolitica in pork products/samples ₉ . The reported rate of Yersinia enterocolitica isolation from faeces specimen is usually far below the actual incidence ₂₁ . Highly Selective culture media such as CIN used in this study is highly recommended for future studies. This study did not take into consideration seasonal differences in occurrence of Yersinia. This may be necessary in future investigation.

Overall, our findings implicated tonsils as the most volunerable tissue to Yersinia enterocolitica infection ₃₂ . Hence the removal of this tissue during the slaughter process should be considered in order to minimize the possibility of contamination of meat products.