A cross-sectional study was conducted from October 2014 to July 2015 to determine the prevalence and populations of
Outbreaks of VTEC infections involving serogroup O157 have been reported from different countries of the world including United States, Canada, Asia, Australia, Europe, and Africa through various sources of infection and different case fatality [
Food borne diseases are common in developing countries, including Ethiopia, because of the prevailing poor food handling and sanitation practices, inadequate food safety laws, weak regulatory systems, lack of financial resources to invest in safer equipment, and lack of education for food-handlers. The National Hygiene and Sanitation Strategy program reported that about 60% of the disease burden was related to poor hygiene and sanitation in Ethiopia. Unsafe sources, contaminated raw food items, improper food storage, poor personal hygiene during food preparation, inadequate cooling and reheating of food items, and a prolonged time lapse between preparing and consuming food items have been identified as contributing factors for outbreaks of food borne diseases [
The consumption of raw milk and its derivatives is common in Ethiopia, which is not safe from a consumer health point of view as it may lead to the transmission of various diseases [
Even though milk represents an important food in consumers’ nutrition as well as in the nutrition and income of producers, there is limited work so far undertaken regarding the assessment of the bacteriological quality and safety of raw cow milk in western Ethiopia, in general, and in Assosa town, in particular. Therefore, the aim of the present study was to determine the prevalence and antimicrobial susceptibility pattern of
Asosa is a town found in Asosa zone in western Ethiopia and the capital of the Benishangul-Gumuz Regional State, Ethiopia. The town is located at latitude and longitude of 10°04′N 34°31′E, with an elevation of 1570 meters, at 476 km distance from the capital city of the country, Addis Ababa. In this area, the mixed farming system is dominant, in which about 92.5% of the population is engaged in agriculture as a major means of subsistence. The region is bordered with the Sudan in the west, Amhara Regional State in the east and north, Oromia Regional State in the east and south east, and Gambella Regional State in the south. Three administrative zones, one special woreda, 19 woredas, and 425 kebeles exist in the region. It covers a total area of about 5,038,100 hectares. Plain undulating slopes and mountains characterize the topography of the region. The agroclimatic zone of the region is categorized as 75% “
The rainfall distribution pattern is monomodal, commencing towards the end of April and ending in October. The topography of the woreda is mainly plain [
A cross-sectional study was conducted from October 2014 to July 2015 to determine the prevalence and populations of
The prevalence of the selected bacteria at the study area was not known; hence, the required sample size was calculated considering a previously published prevalence estimate of 44.4% [
First, a baseline survey was conducted to identify the total number of farms, farm size, farming system, and the status and number of vendors in and around the Asosa town. According to the results of the survey all farms were at the household/smallholder level, with farm size not more than 4 cows per farm. Then, a total of 60 small farms and 25 small vendors were identified as main sources of milk for consumers in and around the town and included in the study using stratified sampling methods. A simple random sampling technique was applied to collect raw milk samples from each group of vendors. Then all individuals involved directly or indirectly in milk production and marketing were communicated to allow us permission to obtain samples and provide us with relevant information. After that, 178 milk samples were collected aseptically using sterile test tubes from milking buckets immediately after milking and 202 raw milk samples were collected from vendors’ containers. The samples were transported to the Asosa Regional Veterinary Research Laboratory under refrigeration (using ice boxes) for bacteriological analysis. The examination of milk samples was conducted within 4 hours after collection. Isolation and identification of
In addition to this, questionnaires and observation check lists were used as a tool to gather information (data) on the hygienic practices during milking, handling, storage, transportation, duration of transportation, and storage of the milk by the stakeholders and their knowledge regarding diseases associated with milk, in order to assess the associated risks.
Each raw cow milk sample was enriched using EC-broth at 37°C for 24 hours, inoculated on MacConkey agar, and then incubated at 37°C for 24 hours. Typical colonies on MacConkey agar (pink, due to their ability to ferment lactose) were stained using gram stain and observed for their staining and morphological characteristics and transferred to eosin-methylene-blue (EMB) agar. The colonies with metallic sheen on EMB agar which is typical feature of
The
Milk samples (25 ml) were diluted in buffered peptone saline water (225 ml); serial dilution of 10−1, 10−2, and 10−3 was applied in order to quantify this microbial group. Most probable number (MPN) method was used after serial dilutions to estimate the populations of
Mueller-Hinton agar media were used for susceptibility testing according to the criteria of the National Committee for Clinical Laboratory Standards [
The data obtained was coded and entered in Excel 2010 for storage and then entered in to data editor view of SPSS (Version 20) for statistical analysis. Cross tabulation was used to calculate the frequencies of the parameters of the variables. In some cases, the chi-square statistic was used to test for significant difference in prevalence of
Out of the 380 raw cow milk samples collected in the present study,
Prevalence of
Tested samples | Presence of | Presence of | |||
---|---|---|---|---|---|
Negative | Positive | Negative | Positive | ||
Farm | 178 (46.8%) | 128 (71.9%) | 50 (28.1%) | 177 (99.4%) | 1 (0.6%) |
Vendor | 202 (53.2%) | 123 (60.9%) | 79 (39.1%) | 192 (95.0%) | 10 (5%) |
| 5.12 | 6.48 | |||
| 0.02 | 0.01 | |||
Good | 150 (39.5%) | 112 (74.7%) | 38 (25.3%) | 149 (99.3%) | 1 (0.7%) |
Poor | 230 (60.5%) | 139 (60.4%) | 91 (39.6%) | 220 (95.7%) | 10 (4.3%) |
| 8.20 | 4.38 | |||
| 0.004 | 0.04 | |||
Plastic | 234 (66.2%) | 154 (60.6%) | 100 (39.4%) | 245 (96.5%) | 9 (3.5%) |
Steel | 126 (33.2%) | 97 (77.0%) | 29 (23.0%) | 124 (98.4%) | 2 (1.6%) |
| 10.05 | 1.15 | |||
| 0.002 | 0.28 | |||
<1 hour | 197 (51.8%) | 136 (69.0%) | 61 (31.0%) | 195 (99%) | 2 (1%) |
1–4 hours | 96 (25.3%) | 43 (44.8%) | 26 (27.1%) | 93 (96.9%) | 3 (3.1%) |
>4 hours | 87 (22.9%) | 45 (51.7%) | 42 (48.3%) | 81 (93.1%) | 6 (6.9%) |
| 13.2 | 4.81 | |||
| 0.001 | 0.09 | |||
| |||||
Total | 380 (100%) | 251 (66.1%) | 129 (33.9%) | 369 (97.1%) | 11 (2.9%) |
The variation that was seen in prevalence in different studies may be due to difference in sample size, farming system, farm size, milking equipment, milking technique, geography, ecology, duration of milk transportation, and hygienic conditions [
The frequency of contamination of
In this study, the methods of production, transportation, handling, and sale of milk are prone to contamination. Hence, milk can be easily contaminated from different sources including the contaminated udder, milk handlers with poor personal hygiene, water of poor quality, and inappropriately cleaned and/or sanitized containers, all of which contribute to milk contamination [
In the current study, the overall prevalence of
Most probable number (MPN) is one of the most commonly used methods to estimate the microbial load from milk and milk products. The mean MPN value of
Mean (±SE) count (log10/ml) of
Range | Mean | 95% CI for mean value | SE | ||
---|---|---|---|---|---|
Lower | Upper | ||||
Sources | |||||
Farmer | 1.10–7.00 | 4.720 | 4.312 | 5.127 | 0.203 |
Vendors | 1.10–7.00 | 4.978 | 4.620 | 5.336 | 0.180 |
Hygienic condition | |||||
Good | 1.10–7.00 | 4.556 | 3.983 | 5.111 | 0.278 |
Poor | 1.81–7.00 | 5.016 | 4.416 | 5.316 | 0.151 |
Containers | |||||
Plastic | 1.10–7.00 | 4.926 | 4.615 | 5.238 | 0.157 |
Stainless steel | 1.10–6.13 | 4.710 | 4.170 | 5.250 | 0.264 |
Time ranges | |||||
<1 hour | 1.10–7.00 | 4.258 | 4.214 | 4.902 | 0.173 |
1-2 hours | 5.35–7.00 | 4.425 | 3.336 | 5.513 | 0.481 |
2:01–4 hours | 1.81–6.13 | 5.779 | 5.028 | 6.529 | 0.354 |
4:01–5 hours | 1.81–7.00 | 6.161 | 4.103 | 8.218 | 0.478 |
>5 hours | 1.81–7.00 | 5.239 | 4.626 | 5.853 | 0.297 |
According to an earlier report, the
In the study area, milking animals were kept with the rest of the stock in a shade or enclosure during the night. Milking was done in the shaded grazing field in front of the homestead, or under trees. However, as these areas were not generally kept clean enough, cows usually become soiled with dung and urine. Moreover, cleaning of the udder and of the hind quarters of the cows was not a common practice among milkers. This, coupled with the unhygienic cleaning and handling of milk containers, resulted in microbial contamination of milk [
The bacterial counts in milk probably reveal the general conditions of sanitation and temperature control under which milk was produced, handled, and held [
Possible reasons for the high counts could be due to infected udders of the cows, use of unclean equipment, poor personal hygiene, lack of cooling after milking, and lack of heat treatment, which contribute to the poor hygienic quality of raw milk. Therefore, training and guidance in general milking hygienic practices and in keeping milk at low temperature should be given to the farmers to avoid microbial growth and lengthen the shelf life of milk [
The average values (ranging from 4.258 to 6.161, Table
Antimicrobial resistance profile of
Susceptible | Intermediate | Resistant | |
---|---|---|---|
Streptomycin | 0 (0%) | 2 (18.2%) | 9 (81.8%) |
Trimethoprim- | 2 (18.2%) | 6 (54.5%) | 3 (27.3%) |
Cefoxitin | 1 (9.1%) | 4 (36.4%) | 6 (54.5%) |
Kanamycin | 0 (%) | 4 (36.4%) | 7 (63.6%) |
Gentamycine | 4 (36.4%) | 3 (27.3%) | 4 (36.4%) |
Tetracycline | 0 (0%) | 2 (18.2%) | 9 (81.8%) |
Norfloxacin | 1 (9.1%) | 4 (36.4%) | 6 (54.5%) |
The susceptibility of the
A total of 125 respondents were included in the study to collect relevant information regarding their knowledge about keeping the quality of the milk, the hygienic status, the type of milk containers, and the elapsed time for the milk to reach the market. Respondents were categorized into 4 groups including farmers (32.0%) (40), venders (32.0%) (40), cafeteria (12.0%) (15), and household consumers (24.0%) (30).
According to the findings summarized in Table
Summary of questionnaire data.
Risk factors | Cafeteria | Household | Vender | Farmer | Total |
---|---|---|---|---|---|
Knowledge about keeping quality of milk | |||||
Nonsatisfactory | 12 (80.0%) | 24 (80.0%) | 37 (92.3%) | 38 (95.0%) | 111 (88.8%) |
Satisfactory | 3 (20.0%) | 6 (20.0%) | 3 (7.7%) | 2 (5.0%) | 14 (11.2%) |
Water for sanitation | |||||
Well | 2 (10.0%) | 0 (0%) | 13 (65.0%) | 5 (25.0%) | 20 (16.0%) |
Pipe | 10 (73.4%) | 13 (77.5%) | 20 (30%) | 14 (45%) | 57 (45.6%) |
Both | 3 (6.20%) | 17 (35.4%) | 7 (14.6) | 21 (43.8) | 48 (38.4%) |
Frequency of sanitation | |||||
Usually | 10 (67.5%) | 12 (40.0%) | 19 (47.5%) | 16 (40.0%) | 57 (45.6%) |
Sometimes | 5 (33.5%) | 18 (60.0%) | 21 (52.5%) | 24 (60.0%) | 68 (54.4%) |
Washing equipment | |||||
Only water | 4 (26.7%) | 12 (86.7%) | 23 (82.5%) | 24 (87.5%) | 63 (50.4%) |
Water & detergents | 11 (17.7%) | 18 (29.0%) | 17 (27.4%) | 16 (25.8%) | 62 (49.6%) |
Containers | |||||
Plastic container | 10 (11.5%) | 24 (27.6%) | 24 (27.6%) | 29 (33.3%) | 87 (70.7%) |
Stainless steel | 5 (13.2%) | 6 (15.8%) | 16 (42.1%) | 11 (28.9%) | 28 (29.3%) |
Sources of milk | |||||
Town | 3 (5.1%) | 16 (27.1%) | 0 (0%) | 40 (67.8%) | 59 (47.2%) |
Village | 12 (18.2%) | 14 (21.2%) | 40 (60.6%) | 0 (0%) | 66 (52.8%) |
Knowledge of keeping quality of milk gained | |||||
From parents | 3 (33.3%) | 11 (53.3%) | 15 (27.5%) | 17 (57.5%) | 46 (36.8%) |
Observations | 8 (14.0%) | 11 (19.3%) | 22 (38.6%) | 16 (28.1%) | 57 (45.6%) |
Formal training | 4 (13.4%) | 8 (10%) | 3 (12.5%) | 7 (7.5%) | 22 (17.6%) |
Time required to reach the market | |||||
≤1 hour | 2 (4.0%) | 7 (14.0%) | 6 (12.0%) | 35 (70.0%) | 50 (40.0%) |
1-2 hours | 4 (16.7%) | 6 (25.0%) | 9 (37.5%) | 5 (20.8%) | 24 (19.2%) |
2:01–5 hours | 4 (15.4%) | 14 (53.8%) | 8 (30.8%) | 0 (0%) | 26 (20.8%) |
>5 hours | 5 (20.0%) | 3 (12.0%) | 17 (68.0%) | 0 (0%) | 25 (20.0%) |
Most of the milk supplied to the consumer in the town was managed under poor hygienic conditions at ambient temperatures with poor levels of sanitation in plastic containers. Most of the stakeholders were managing the raw milk with limited awareness and knowledge on milk contamination and on the public health impact of milk-borne pathogens. The sources of
The authors declare that there is no conflict of interests.
The authors would like to extend sincere thanks to Asosa regional research laboratory for their kind cooperation and willingness to support the study providing laboratory materials and equipment. The authors also like to thank Asosa administrative, agricultural sector for their assistance in gathering farm data/information during baseline survey including facilitation of sample collection.