PREVALENCE AND PUBLIC HEALTH HAZARD OF SUBCLINICAL MASTITIS IN GOATS AND SHEEP IN ASSIUT GOVERNORATE

Dept. of Food Hygiene,

Fac. of Vet. Med., AssiutUniv.

PREVALENCE AND PUBLIC HEALTH HAZARD

OF SUBCLINICAL MASTITIS IN GOATS AND SHEEP IN ASSIUT GOVERNORATE

(With 6 Tables and 2 Figures)

By

T. EL-BASSIONY; ENAS EL-PRINCE;

KARIMA G. ABDEL-HAMEED;AMAL A. ABDEL-HALEEM* and ONSY A. SADEK*

*Assiut Animal Research Institute

(Received at 2/6/2008)

مدى انتشار والخطورة الصحية لمرض التهاب الضرع الغير ظاهري

فى الماعز والأغنامفى محافظة أسيوط

توفيق البسيوني ، إيناس البرنس ، کريمة جلال عبد الحميد ،

آمال على عبد الحليم ، أنسى صادق

 يعد التهاب الضرع الغير ظاهري من الأمراض التي لها تأثير خطير على الناحية الاقتصادية والصحية لما يسببه من نقص في إنتاج اللبن بالإضافة إلى نقل بعض الميکروبات الضارة التي تؤذى الإنسان صحيا. نظرا لأهمية هذا المرض فقد تضمنت هذه الدراسة تجميع عدد 395 عينة، بواقع 197 و 198 عينة ألبان من 100 حيوان من کل من الماعز والأغنام على التوالي، لفحصها بکتريولوجيا وميکولوجيا وعزل وتصنيف المسبب. بفحص عينات ألبان کل من الماعز والأغنام باختبارى الکاليفورنيا (CMT) والوايت سايد المعدل ((MWST کانت النتائج ايجابية بنسبة 34.52 ، 9.60 و34.01 ، 9.60%، أما بالنسبة لفحص الحيوانات فقد کانت النتائج ايجابية بنسبة 44 و 14% لکل منهما على التوالي. بفحص 197 و 198 عينه لبن من کل من الماعز والأغنام بکتريولوجيا وميکولوجيا کانت النتائج ايجابية بنسب 15.23 ، 8.08 و1.02 ، صفر% ، بينما في الحيوانات کانت النتائج ايجابية بنسب 27 ، 12 و2 ، صفر% علي الترتيب. بالإضافة لما سبق فقد کانت نسبة عزل البکتريا المسببة لالتهاب الضرع تحت الإکلينيکي في الماعز هي: 6.6, 6.09, 1.02, 1.02, 1.02و 4.06 % لکل من المکور العنقودي الذهبي، المکور العنقودي السالب التجلط، المکور السبحي بيوجين، المکور السبحي اجالاکتيا، الميکروب القولوني والانتيروباکتر بينما في الأغنام کانت: 4.04، 4.55، 0.51، 1.01، 0.51، 0.51 و1.52 % لکل من المکور العنقودي الذهبي، المکور العنقودي السالب التجلط، المکور السبحي بيوجين، المکور السبحي اجالاکتيا، الميکروب القولوني، الکلبسيلا نوموني والانتيروباکتر علي التوالي. بالنسبة إلي الفطريات فقد تم عزلها من الماعز فقط بنسبة 0.51% لکل من Aspergillus fumigatus و Aspergillus terreus. وقد ناقش البحث الأهمية الصحية والوبائية والاقتصادية لمرض التهاب الضرع تحت الإکلينيکي في الإنسان والحيوان والشروط الواجب إتباعها لمنع انتشاره واختباره في مزارع الألبان المختلفة لدرء خطره حفاظا على صحة المستهلک.

Summary

A total number of 395 milk samples were collected from apparently healthy she-goats and ewes at different localities in Assiut Governorate, comprising 197 halves of milk samples from 100 lactating she-goats and 198 halves of milk samples from 100 lactating ewes. Our current results showed that 34.52 & 9.60% and 34.01 & 9.60% were positive in the examined she-goats and ewes halves by using California Mastitis Test                          (CMT) and Modified Whiteside Test (MWST), respectively. While, out of tested animals 44 and 14% were positive for each test, respectively.  Moreover, screening tests used for detection of Subclinical Mastitis          (SCM), one-half and two-halves of she-goats and ewes were affected in percentages of 20 & 24 and 9 & 5%, respectively. Furthermore, out of she-goats halves examined by bacteriological and mycological examinations, 15.23 and 1.02% were positive, while in case of ewe's halves, 8.08 and 0% were positive, respectively. Concerning 100 of each she-goats and ewes animals examined bacteriologically, 27 and 12% were positive, respectively. While in case of mycological examination, 2% were positive in she-goats however, ewes gave negative results. The incidences of the isolated bacteria causing SCM in she-goat's milk samples were 6.60, 6.09, 1.02, 1.02, 1.02 and 4.06% for Staph. aureus, coagulase negative Staphylococci (CNS), Str. pyogenes, Str. agalactiae, E. coli and Ent. spp., respectively. Whereas, in ewe's milk samples they were 4.04, 4.55, 0.51, 1.01, 0.51, 0.51 and 1.52% for Staph. aureus, CNS, Str. pyogenes, Str. agalactiae, E. coli, Klebsiella pneumoniae and Ent. spp., respectively. The incidence of the isolated molds in she-goat's milk samples was 0.51% each for Aspergillus fumigatus and  A. terreus. Recommendations were suggested to eradicate and control SCM in lactating goats and sheep.

Key words: Subclinical Mastitis, Screening Tests, Microbiological, Mycological examination, Goats and Sheep

Introduction

In small ruminant, mastitis, particularly in its subclinical and chronic forms, is a serious risk both to obtain milk of good hygienic quality and to farm profitability (Gonzalo, 1996). So, the study of mammary pathogens involved in intramammary infection (IMI) is basic to knowledge of the disease and the design of mastitis control programs. In dairy industry, the economic impact of both clinical and subclinical forms of mastitis is large as losses occur from decreased milk production due to reduced its quality and price, treatment and labor costs, veterinary fees, increased risk of subsequent mastitis and increased risk of culling or death of the animal (Harmon, 1994). Furthermore, SCM remains an important cause of reduced milk production and poor quality of products such as cheese or casein (Roux, et al., 1995). Diagnosis of acute mastitis presents little difficulty as compared to subclinical by ordinary clinical tests. Also, more attention has been given for the diagnosis of SCM by indirect tests (Joshi, et al., 1976). Bacteriological culture is a test, similar to the CMT and Somatic cell count (SCC), which are extremely useful tools for monitoring udder health status and for problem-solving (Radostits, et al., 1994). Simply the bacteriological culture of milk is essential to determine the presence and type of pathogen involved in cases of IMI. Some studies have identified the main pathogenic organisms responsible for SCM in small ruminant (Marco, 1994 and Las Heras, et al., 1999). They found that the most prevalent etiological group is represented by staphylococci and particularly Staph. aureus, CNS,  Str. pyogenes and Str. agalactiae. In mastitic milk from severe clinical mastitis, the gross abnormalities of milk are readily observed and milk is discarded by the producers. Such milk normally would not enter the food chain, but with SCM infected milk with no visible changes accidentally mixed into bulk milk and also enters food chain and poses a human health hazards. Although pasteurization is likely to destroy all human pathogens, there is concern when raw milk is consumed or when pasteurization is faulty. As a result of the economic and public health significance of SCM, the objective of this work was to detect its prevalence in goats and sheep by using screening tests and microbiological examination.

Materials and Methods

Milk samples:

A total number of 395 milk samples were collected from apparently healthy she-goats and ewes at different localities in Assiut Governorate, comprising 197 halves of milk samples from 100 lactating she-goats and 198 halves of milk samples from 100 lactating ewes.

I- Screening tests to detect SCM:

a- CMT as described by Schalm, et al. (1971).

b- MWST according to Murphy and Hanson (1941).

II- Microbiological examination of SCM milk samples:

a- Isolation of members of Family Enterobacteriaceae according to Finegold and Martin (1982); Collee, et al. (1989); Carter and Cole (1990) and Koneman, et al. (1992).

b- Isolation of Staph. aureus (Bailey and Scott, 1994) .

c- Isolation and identification of Streptococci (Quinn, et al.1994).

d- Isolation and identification of Molds: Fungal cultures were kindly identified by staff members of the Assiut University Mycological Centre (AUMC), Assiut, Egypt, using the following references: Kwon-Chung and Bennett (1992), Moubasher (1993), Odds and Bernaerts (1994) and Hoog, et al. (2000).

Results

          The obtained results were illustrated in Tables 1-6 and Figures 1-2

Table 1: Half-wise incidence of subclinical mastitis in she-goat's and ewe's milk samples based on the results of CMT and MWST.

Table 2: Animal-wise incidence of subclinical mastitis in she-goat's and ewe's milk samples based on the result of CMT and MWST.

Table 3: Quarter-wise incidence of subclinical mastitis in she-goat's and ewe's milk samples based on the results of bacteriological and mycological examinations.

Table 4: Animal-wise incidence of subclinical mastitis in she-goat's and ewe's milk samples based on the results of bacteriological and mycological examinations.

Table 5: Incidence of the isolated bacteria causing subclinical mastitis in the examined she-goat's and ewe's milk samples.

* Coagulase negative Staphylococci

Fig. 1: Incidence of the isolated bacteria causing subclinical mastitis in the examined she-goat's and ewe's milk samples.

                   CNS= Coagulase negative Staphylococci

Table 6: Incidence of the isolated molds causing subclinical mastitis in she-goat's and ewe's milk samples.

Fig. 2: Incidence of the isolated molds causing subclinical mastitis in she-goat's and ewe's milk samples.

Discussion

I- Screening tests for detection of SCM:

Data presented in Table 1 showed that out of 197 halves she-goat's milk samples examined by CMT, 68 (34.52%) were positive. Extremely lower results were estimated by Salem, et al. (1993) (9.56%) and Hassanain & Zaabal (2004) (1.66%), however, higher percentage was recorded by Guha, et al. (1989) (48.44%). With regard to ewe's milk, out of 198 halves examined, 19 samples (9.60%) were positive. Somewhat, similar result was estimated by Salem, et al. (1993) (10.11%), while, Moawad and Osman (2005) stated extremely higher incidence of 55.6%. Regarding MWST it was found that 67 samples (34.01%) of she-goat's milk samples were positive and extremely lower result was reported by Salem, et al. (1993) (8.47%) while, higher result was stated by Guha, et al. (1989) (57.8%). Concerning ewe's milk samples, 19 samples (9.60%) were positive while, Salem, et al. (1993) estimated lower percentage (7.81%).

The animal-wise incidence of SCM in she-goat's and ewe's milk samples based on the result of CMT and MWST was illustrated in Table 2. Out of each 100 she-goat's and ewes examined, 44 animals (44%) & 14 (14%) were positive, respectively. Higher results with a great extent in ewes stated by Al-Hawary (2005) and Moawad & Osman (2005) (26.7 and 53.98%), respectively.

II- Microbiological examination of milk for detection of SCM:

The half-wise incidence of SCM in she-goat's and ewe's milk samples based on the result of bacteriological and mycological examination was illustrated in Table 3. 30 (15.23%) of examined she-goat's halves, were bacteriologically positive and extremely higher results were estimated by Salem, et al. (1993) (79.36%) and Hassanain & Zaabal (2004) (20%). In case of ewe's halves, 16 (8.08%) were positive and 182 (91.22%) were negative. Extremely higher result was incriminated by Salem, et al. (1993) (80.45%). Additionally, it was found that two halves (1.02%) of she goats halves examined mycologically were positive however; in ewes no half gave positive result.

The obtained results in Table 4 revealed the animal-wise incidence of SCM based on the result of bacteriological and mycological examination. Out of 100 she-goats examined bacteriologically, 27 animals (27%) were positive. Somewhat lower result was recorded by Hassanain & Zaabal (2004) (23.33%). While, in ewes 12 animals (12%) were positive. Moreover, 2 (2%) of she-goats animals were mycologically positive, but in case of ewes, animals gave negative results.

Staph. aureus were isolated from she-goat's milk samples in      13 (6.60%) and this is higher than that obtained by Salem, et al. (1993) (3.7%). However, extremely higher incidences were recorded by Mishra, et al. (1996) (22.7%) and Hassanain & Zaabal (2004) (58.33%). Concerning CNS, 12 isolates (6.09%) were recovered and relatively higher incidence of 11.36% was estimated by Mishra, et al. (1996). Two species (1.02%) each of Str. pyogenes and Str. agalactiae were recovered in relatively similar result of Salem, et al. (1993) (1.6%). Also, 2 (1.02%) isolates of E. coli was isolated and it is somewhat higher than that stated by Salem, et al. (1993) (0.623%). However, higher results were recorded by Guha, et al. (1989), Mishra, et al. (1993), Hassanain & Zaabal (2004) and Bayoumi, et al. (2005) (5.26, 9.09, 41.67 and 15%, respectively). In addition, 8 strains (4.06%) of Ent. spp. were isolated. In examined ewe's milk samples, 8 isolates (4.04%) of Staph. aureus were obtained and Salem, et al. (1993) stated lower incidence of 1%. Moreover, extremely higher results were stated by Moawad & Osman (2005) (30.65%) and Al-Hawary (2005) (84.38%). Concerning CNS, 9 isolates (4.55%) and one isolate (0.51%) of          Str. pyogenes were recovered. Moreover, 2 strains (1.01%) of             Str. agalactiae were isolated in lower incidences than that reported by Moawad and Osman (2005) (7.69%). Also, one strain (0.51%) of E. coli was isolated and this is lower than that estimated by Salem, et al. (1993) (1.2%) and Moawad & Osman (2005) (14.10%). Klebsiella pneumoniae and Ent. spp. were isolated in percentages of 0.51 and 1.52%, respectively, as shown in Table 5 and Fig. 1. It is clear that, Staph. aureus was the highest microorganism isolated from she-goat's and ewe's milk samples. This could be attributed to the capacity of this microorganism to produce exo-polysaccharides (slime), which form a protective barrier that restricts the efficiency of both immune responses and chemotherapy (Baselga, et al., 1994).

Results illustrated in Table 6 and Fig. 2 showed that one mold isolate (0.51%) of each Aspergillus fumigatus and A. terreus were recovered from she-goat's milk samples, however, no yeasts were obtained. On the contrary neither yeast nor mold could be isolated from ewe's milk samples.

Under the condition of this investigation, it can be concluded that, CMT and MWST were highly sensitive for detection of SCM and their application lead to earlier detection of infected animal and its isolation either for culling or therapy. Staphylococci either Staph. aureus or CNS were the most causative agents causing SCM followed by      Ent. spp. Ewes more resist to mycotic SCM than goats.

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