Investigation of the risk of exposure to antimicrobial residues present in marketed milk in Tanzania

Antibiotic Use, Awareness of Antimicrobial Resistance and Residue in Veterinary Professionals and Farmers in Selected Districts of Kellem Wollega Zone, Ethiopia

Background

Antimicrobials have a crucial role in reducing mortality and morbidity in animals, but misuse of them may cause antimicrobial resistance and residues which are challenging in animal production and public health. These problems are mostly aggravated in developing countries including Ethiopia.

Objective

Assessment of antibiotic use, awareness of antimicrobial resistance and antimicrobial residue in veterinary professionals and farmers.

Methods

A cross-sectional study was conducted from September 2021 to August 2022 in three districts (Seyo, Hawa Gelan, and Dale Sadi) of the Kellem Wollega zone, selected by purposive sampling. The study population was farmers and veterinary professionals. Data was collected from a total of 312 respondents; 230 farmers and 82 veterinary professionals using interviews and questionnaires, respectively.

Results

Out of 312 total respondents, 230 (73.71%) were farmers and 82 (26.28%) were veterinary professionals. From the farmer respondents, 127 (55.22%), 153 (66.52%), and 142 (61.74%) had an awareness of antibiotics and their usage, antimicrobial resistance, and withdrawal period, respectively. Out of 82 veterinary professional respondents, 92.68% practice dose calculation during animal treatment, 79.27% diagnose systemic infections by tentative diagnosis, 85.37% have no laboratory facility for bacterial disease, and 81.71% give broad-spectrum antibiotics for undifferentiated cases. The income type of respondents looks to have a strong association (P < 0.05) with awareness of antibiotics (OR: 3.427, SE: 1.404, CI: 1.535-7.654), antimicrobial resistance (OR: 3.536, SE: 1.339, CI: 1.683-7.430) and withdrawal periods (OR: 3.297, SE: 1.267, CI: 1.552-7.004).

Conclusion

This study shows most farmers have awareness about antibiotics and their use, antimicrobial resistance, and residue but inappropriate use of antimicrobials in farmers and lack of laboratory facilities in most veterinary professionals observed.

Antibiotics in Dairy Production: Where Is the Problem?

Antibiotics have long been used for the prevention and treatment of common diseases and for prophylactic purposes in dairy animals. However, in recent decades it has become a matter of concern due to the widespread belief that there has been an abuse or misuse of these drugs in animals and that this misuse has led to the presence of residues in derived foods, such as milk and dairy products. Therefore, this review aims to compile the scientific literature published to date on the presence of antibiotic residues in these products worldwide. The focus is on the reasons that lead to their presence in food, on the potential problems caused by residues in the characteristics of dairy products and in their manufacturing process, on the development and spread of antibiotic-resistant bacteria, and on the effects that both residues and resistant bacteria can cause on human and environmental health.

The public health issue of antibiotic residues in food and feed: Causes, consequences, and potential solutions

Antibiotics are among the essential veterinary medicine compounds associated with animal feed and food animal production. The use of antibiotics for the treatment of bacterial infections is almost unavoidable, with less need to demonstrate their importance. Although banned as a growth factor for a few years, their use in animals can add residues in foodstuffs, presenting several environmental, technological, animal health, and consumer health risks. With regard to human health risks, antibiotic residues induce and accelerate antibiotic resistance development, promote the transfer of antibiotic-resistant bacteria to humans, cause allergies (penicillin), and induce other severe pathologies, such as cancers (sulfamethazine, oxytetracycline, and furazolidone), anaphylactic shock, nephropathy (gentamicin), bone marrow toxicity, mutagenic effects, and reproductive disorders (chloramphenicol). Antibiotic resistance, which has excessively increased over the years, is one of the adverse consequences of this phenomenon, constituting a severe public health issue, thus requiring the regulation of antibiotics in all areas, including animal breeding. This review discusses the common use of antibiotics in agriculture and antibiotic residues in food/feed. In-depth, we discussed the detection techniques of antibiotic residues, potential consequences on the environment and animal health, the technological transformation processes and impacts on consumer health, and recommendations to mitigate this situation.

Antimicrobial Residues in Food from Animal Origin-A Review of the Literature Focusing on Products Collected in Stores and Markets Worldwide

The extensive use of antibiotics leads to antibiotic residues in frequently consumed foods. Generally, the main use of antibiotics in animals is to treat and prevent diseases and growth promotion. However, the residues and their breakdown products have several side effects on the human body and, in a broader sense, on the environment. In relation to the human body, the frequency of mutations is increased, the bone marrow is damaged (chloramphenicol), and the reproductive organs of humans are affected. Carcinogenic effects have been found with antibiotics such as sulfamethazine, oxytetracycline, and furazolidone. We summarized data from 73 scientific studies reporting antimicrobial residues in animal products that were freely available for sale. The studies were published in English starting from 1999 till 2021 and identified through the Pubmed search engine. The aims were to find out which antibiotics, legal or illegal, could be found in animal foods worldwide. Which are stable to get into the food chain and exceed the maximum residue limits (MRL) regarding the EU guidelines as a comparison. Reducing antimicrobial residues in food from animal origin and, in addition to this, fighting the tremendous growth and spread of antimicrobial resistance will undoubtedly be one of the most difficult food safety challenges in the coming years.

Antimicrobial Use, Residues, Resistance and Governance in the Food and Agriculture Sectors, Tanzania

All infections are potentially curable as long as the etiological agents are susceptible to antimicrobials. The increased rate at which antimicrobials are becoming ineffective is a global health risk of increasing concern that threatens withdrawal of beneficial antimicrobials for disease control. The increased demand for food of animal origin, in particular eggs, meat and milk has led to intensification and commercial production systems where excessive use and misuse of antimicrobials may prevail. Antimicrobials, handled and used by farmers and animal attendants with no formal education, may be predisposed to incorrect dosages, misuse, incorrect applications and non-adherence to withdrawal periods. This study was conducted to assess the regulatory roles and governance of antimicrobials, establish the pattern and extent of their use, evaluate the antimicrobial residues and resistance in the food animals and crop agriculture value chains, and relate these findings to existing strategies in place for combating the emergence of antimicrobial resistance in Tanzania. A multimethod approach (desk review, field study and interviews) was used. Relevant establishments were also visited. High levels of resistance to penicillin G, chloramphenicol, streptomycin and oxytetracycline have been reported, especially for Actinobacter pyogenes, Staphylococcus hyicus, Staphylococcus intermedius and Staphylococcus aureus from dairy cattle with mastitis and in humans. Similar trends were found in poultry where eggs and meat are contaminated with Escherichia coli strains resistant to amoxicillin + clavulanate, sulphamethoxazole and neomycin. An increasing trend of emerging multidrug resistant E. coli, Klebsiella pneumoniae, Staphylococcus aureus and Salmonella was also found in food animals. An increase in methicillin resistant Staphlococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL) in the livestock sector in Tanzania have been reported. The pathogens isolated in animals were resistant to ampicillin, augmentin, gentamicin, co-trimoxazole, tetracycline, amoxicillin, streptomycin, nalidixic acid, azithromycin, chloramphenicol, tylosin, erythromycin, cefuroxime, norfloxacin and ciprofloxacin. An increased usage of antimicrobials for prophylaxis, and therapeutics against pathogens and for growth promotion in livestock, aquaculture and crop production were observed. A One Health strategic approach is advocated to combat antimicrobial resistance (AMR) in the food and agriculture sectors in Tanzania. Practical recommendations include (a) legislation review and implementation; (b) antimicrobial use (AMU), AMR and antimicrobial residue (AR) awareness and advocacy among stakeholders along the value chain; (c) strengthening of surveillance and monitoring programs for AMU, AMR and AR; (d) enhanced development and use of rapid and innovative diagnostic tests and the promotion of biosecurity principles; and (e) good husbandry practices. The utilization of this information to improve public health policies and reduce the burden of AMR will be beneficial.

A review of microbes and chemical contaminants in dairy products in sub-Saharan Africa

Animal milk types in sub-Saharan Africa (SSA) are processed into varieties of products using different traditional methods and are widely consumed by households to support nutritional intake and diet. Dairy products contain several microorganisms, their metabolites, and other chemical compounds, some with health benefits and many others considered as potential health hazards. Consumption of contaminated milk products could have serious health implications for consumers. To access the safety of milk products across SSA, studies in the region investigating the occurrences of pathogens as well as chemical compounds such as heat stable toxins and veterinary drug residues in animal milk and its products were reviewed. This is done with a holistic view in light of the emerging exposome paradigm for improving food safety and consumer health in the region. Herein, we showed that several published studies in SSA applied conventional and/or less sensitive methods in detecting microbial species and chemical contaminants. This has serious implications in food safety because the correct identity of a microbial species and accurate screening for chemical contaminants is crucial for predicting the potential human health effects that undermine the benefits from consumption of these foods. Furthermore, we highlighted gaps in determining the extent of viral and parasitic contamination of milk products across SSA as well as investigating multiple classes of chemical contaminants. Consequently, robust studies should be conducted in this regard. Also, efforts such as development cooperation projects should be initiated by all stakeholders including scientists, regulatory agencies, and policy makers to improve the dairy product chain in SSA in view of safeguarding consumer health.

MILK Symposium review: Microbiological quality and safety of milk from farm to milk collection centers in Rwanda

The aim of this study was to generate knowledge on the most important milk quality and safety attributes, including somatic cell count (SCC), total bacterial count (TBC), Escherichia coli, Salmonella, and Brucella spp. antibodies and antibiotic residues in milk in the chain from farm to milk collection center (MCC) in Rwanda. In addition, we investigated farm and management factors associated with high TBC, SCC, and Salmonella counts. Raw milk was sampled at the farm and MCC levels. Milk samples were taken from dairy farms linked to 2 selected MCC in each of the 4 provinces in Rwanda. In total, 406 bulk milk samples from 406 farms and 32 bulk milk samples from 8 MCC were collected and analyzed. Farm milk average SCC varied between 180 × 10³ and 920 × 10³ cells/mL, whereas average SCC in milk samples at MCC varied between 170 × 10³ and 1,700 × 10³ cells/mL. The mean milk TBC of different farms per MCC varied between 1.1 × 10⁶ and 1.6 × 10⁷ cfu/mL, whereas in milk samples from different MCC, the mean TBC ranged between 5.3 × 10⁵ and 2.4 × 10⁸ cfu/mL. The high TBC in milk from MCC suggests proliferation or recontamination of milk by bacteria during transportation. Escherichia coli was detected in 35 of 385 farm milk samples and ranged between 5 cfu/mL and 1.1 × 10⁴ cfu/mL, whereas in milk samples from the MCC, it was detected in 20 out 32 samples varying between 5 cfu/mL and 2.9 × 10³ cfu/mL. Overall farm prevalence of Salmonella in milk samples was 14%, but no milk samples from MCC were positive for Salmonella. Five out of 22 bulk milk samples from different MCC were positive for Brucella spp. antibodies, but no Brucella antibodies were detected in milk samples from farms. The prevalence of antibiotic residues as detected by the Delvotest SP NT (DSM, Delft, the Netherlands) was low: 1.3% in farm milk samples and undetected in MCC milk samples. Lack of a separate milking area was associated with high TBC, whereas offering of supplemental feeds, keeping data of past diseases, and an unhygienic milking area were associated with high SCC. Lack of teat washing before milking was the only factor associated with Salmonella contamination of milk at the farm level. This study indicated high TBC and SCC of milk samples at the farm and MCC levels, which indicates both microbial contamination of milk and poor udder health in dairy cows. Presence of E. coli, Salmonella, and Brucella antibodies in milk was common, but finding antibiotic residues in milk was uncommon.

Comparison of Tick Control and Antibiotic Use Practices at Farm Level in Regions of High and Low Acaricide Resistance in Uganda

Uganda has experienced tick acaricide resistance in the livestock sector. With increase in incidence of tick-borne diseases (TBDs), use of antibiotics for control of TBDs and other opportunistic diseases has raisedserious concerns. The purpose of this study was to compare the farmers' tick control and antibiotic use practices on farms in regions of low (LARA) and high (HARA) tick acaricide resistance in Uganda, determine the prevalence of antibiotic residues in milk from both regions, and identify factors associated with antibiotic residues in milk. One representative district was selected from each region from which 10 farms were randomly selected. Delvotest SP-NT® test kit was used to detect antibiotic residues in milk. Half-body tick counts and acaricide efficacy tests were performed. Majority (70%) of HARA's respondents reported a corresponding increase in a monthly incidence of TBDs with an average of 3.2 cases of TBDs treated per farm compared to 0.2 cases in LARA. East Coast fever (ECF) was identified as the most common TBD in both regions, though cases of coinfection were more common in HARA. Half of HARA's respondents reported a corresponding increase in the use of antibiotics on their farms due to tick resistance compared to LARA. Antibiotics were the most used drugs on farms in both regions with oxytetracycline being the commonly used antibiotic. Ticks from HARA were resistant to deltamethrin, amitraz, and coformulation (chlorpyriphos and cypermethrin) while resistance against deltamethrin was confirmed in LARA. HARA farms had a significantly higher prevalence of antibiotic residues (21.25%) in raw milk than in LARA (4%) farms (p <  0.05). Acaricide resistance and practice of reading drug use instructions were significantly associated with antibiotic residues in milk at farm level. Overall, the study provides vital information linking acaricide resistance to antibiotic use practices, consequently leading to antibiotic residues in milk.

Drivers of Antibiotic Resistance Transmissionin Low- and Middle-Income Countriesfrom a "One Health" Perspective-A Review

Antibiotic resistance is an ecosystem problem threatening the interrelated human-animalenvironmenthealth under the "One Health" framework. Resistant bacteria arising in onegeographical area can spread via cross-reservoir transmission to other areas worldwide either bydirect exposure or through the food chain and the environment. Drivers of antibiotic resistance arecomplex and multi-sectoral particularly in Lower- and Middle-income countries. These includeinappropriate socio-ecological behaviors; poverty; overcrowding; lack of surveillance systems; foodsupply chain safety issues; highly contaminated waste effluents; and loose rules and regulations. Inorder to examine the drivers of antibiotic resistance from a "one health" perspective, a literaturereview was conducted on three databases including PubMed, Medline and Google Scholar. A totalof 485 studies of potential relevance were selected, out of which 182 were included in this review.Results have shown that the aforementioned market failures are the leading cause for the negativeexternality of antibiotic resistance that extends in scope from the individual to the global ecosystem.Incremental and sustainable global actions can make the change, however, the problem willcontinue to prevail if governments do not prioritize the "One health" approach and if individual'saccountability is still denied in a world struggling with profound socio-economic problems.

Screening for tylosin and other antimicrobial residues in fresh and fermented (nono) cow milk in Delta state, South-South, Nigeria

BACKGROUND AND AIM

Milk is a food that contains almost all the essential nutrients needed for growth and maintenance for both young and old animals and man. Since quite nutritious and in high demand, dairy products should be free of both chemical and biological contaminants. Unfortunately, antibiotics used in the treatment of infectious diseases in dairy cattle are often seen in their products if withdrawal periods of those drugs are not observed before milking. This study aimed to detect the presence of antibiotics and the level of tylosin in fresh and fermented (nono) milk from cows in Delta state, Nigeria.

MATERIALS AND METHODS

Two hundred and five samples comprising 126 fresh milk and 79 fermented milk (nono) were sampled from Kwale, Ozoro, and Oleh representing one senatorial district of Delta state, South-South Nigeria. They were screened for the presence of tylosin and other antimicrobial residues using four-plate test and tylosin was confirmed with high-performance liquid chromatography.

RESULTS

Antibiotic residues were obtained in 76% and 85% of fresh milk and nono, respectively. Tylosin residue was also detected in 24% fresh milk and 11% nono samples at mean concentrations of 14.64±0.69 µg/l and 7.97±0.23 µg/l, respectively. The mean concentrations of tylosin from both milk types were below the recommended maximum residue limit (MRL) of 50 µg/l in dairy.

CONCLUSION

High prevalence of antimicrobial residues in fresh milk and nono shows that consumers in the study area are predisposed to health hazards due to the presence of residues of different antibiotics in fresh milk and nono. Although tylosin was confirmed in both milk products, the mean concentrations were below the MRL. However, it is still very vital to resort to the observance of withdrawal periods and avoid gross misuse of antimicrobials. It is also necessary to emphasize the need for effective prevention of infectious diseases and most importantly create awareness and establish a national antibiotic residue monitoring program in Nigeria.

Assessment of Raw Cow Milk Quality in Smallholder Dairy Farms in Pemba Island Zanzibar, Tanzania

Milk quality depends on the physicochemical characteristics, hygienic standards, and nutritional quality; however, animal husbandry practices, unhygienic harvesting and processing, may affect its quality. A cross-sectional study was conducted between August 2010 and July 2011 to assess the hygiene of cow milk production environment, raw cow milk physicochemical characteristics, and microbial quality and estimate the prevalence of antimicrobial residues using standard methods in Pemba Island. A total of 98 raw cow milk samples from selected smallholder dairy farms were analyzed, and the judgement on the quality used the East African Standards. Generally, the milk production chain was done under the unhygienic condition, and dirty plastic containers were used for collection and storage of milk under room temperature. Some milk samples had abnormal colour (2.1%), abnormal smell (7.1%), and pH below normal (35.7%), clotted on alcohol test (9.2%), and had the specific gravity below normal (13.3%). All the milk samples had mineral contents within the recommended range. Milk samples with butterfat below normal were 29.6%, while 14.3% had total solids below recommended values. The mean total viable count (TVC) of milk container surfaces was 9.7 ± 10.5 log CFU/100 cm2, while total coliform count (TCC) was 7.8 ± 8.5 log CFU/100 cm2. Up to 55.1% of milk had TVC beyond the recommended levels. The milk mean TVC was 11.02 ± 11.6 log CFU/ml and TCC was 6.7 ± 7.3 log CFU/ml. Up to 26.5% of milk samples had the TCC beyond levels. Results on physicochemical characteristics and nutritional analysis show that the raw cow milk in Pemba Island is of inferior quality. Microbiological results of this study imply heavy contaminations of milk. Antimicrobial residues were detected in 83% of the samples and most of them were from Wete District. Unhygienic milk production chain accelerates microbial contaminations, and antimicrobial residues in milk are a big problem that needs urgent attention from the responsible authority.

Antimicrobial residues and compositional quality of informally marketed raw cow milk, Lamu West Sub-County, Kenya, 2015

Introduction

unadulterated milk, free of antimicrobial residues is important for industrial processing and consumers’ health. Antimicrobial residues in foods of animal origin can cause adverse public health effects like drug resistance and hypersensitivity. Milk produced in Lamu West sub-county is sold raw directly to consumers. We estimated the compositional quality and prevalence of antimicrobial residues in informally marketed raw cow milk in Lamu West Sub-County, Kenya.

Methods

we randomly recruited 152 vendors and 207 farmers from four randomly selected urban centers in a cross-sectional study and interviewed them using a pretested standardized questionnaire. A100-ml raw milk sample was aseptically collected from each vendor and farm and tested for antimicrobial residues using Charm Blue Yellow II kit following the European Union Maximum Residue Limits (EU-MRLs) while an Ekomilk® Analyzer was used to measure compositional quality where samples with either solid not fat (SNF) < 8.5 or added water ≥ 0.01% or both were considered adulterated. We analyzed data using univariate analysis and unconditional logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI).

Results

thirty-two of the 207 (15.5%) samples from farmers and 28 (18.4%) of the 152 samples from vendors tested positive for antimicrobial residues. Thirty-six (17.4 %) samples from farmers and 38 (25.0%) from vendors were found to be adulterated with water. Farmers’ awareness of the danger of consuming milk with antimicrobial residues and farmers having training on good milking practices were protective against selling milk with antimicrobial residues (adjusted OR and 95% CI 0.20, 0.07-0.55 and 0.33, 0.11-0.99, respectively).

Conclusion

the antimicrobial residues above EU MRLs and adulteration of raw marketed cow milk observed in this study provide evidence for routine testing of marketed milk and educating farmers to observe antimicrobial withdrawal period.

Contamination Levels and Identification of Bacteria in Milk Sampled from Three Regions of Tanzania: Evidence from Literature and Laboratory Analyses

Milk in Tanzania has been reported to be contaminated with large number of bacteria. This is because (1) milk is obtained from animals with unknown health status, (2) good milking and handling practices are to a large extent not observed, and (3) marketing and distribution are done in informal channels. These factors are potential causes of milk-borne diseases and milk quality loss. The aim of this study was to assess nutritional risks in milk as reported in literature over a period of 20 years and through analyses of samples collected during the present study. The issues highlighted in literature were high bacteria and coliform counts exceeding standard levels in East Africa, prevalence of bacteria and drug residues in milk, and adulteration. Based on performed analyses, total bacterial count 1.0 × 10⁷ colony forming units per millilitre (cfu/ml) and total coliform count 1.1 × 10⁷ cfu/ml, also greater than recommended levels, were found. Ten bacteria types were isolated from milk samples (five, Pseudomonas aeruginosa, Listeria monocytogenes, Listeria innocua, Listeria ivanovii, and Klebsiella spp. are reported in Tanzanian for the first time). Two drugs tetracycline and sulphur were detected. Therefore, it is worth noting that integrated research is needed to evaluate the situation and address these challenges.

Assessment of raw milk quality and stakeholders' awareness on milk-borne health risks in Arusha City and Meru District, Tanzania

A cross-sectional study was conducted to assess the quality of raw milk and stakeholders' awareness on milk-borne health risks and factors for poor milk hygiene in Arusha City and Meru District, Tanzania between October and December 2012. A total of 105 smallholder dairy farmers, milk vendors and milk retailers were interviewed, and milk samples were collected for physical, microbial and antibiotic residue analysis using standard procedures. Questionnaire results indicated high level of awareness (94 %) that drinking raw milk can predispose consumers to milk-borne diseases; nevertheless, 65 % of respondents consumed raw milk. Physicochemical analyses showed some of the milk had sediments (20 %), bad smell (21 %) and had clotted on alcohol test (27 %). About 36 % of milk samples had pH below 6.6, and 25 % had specific gravity below 1.028 g/ml. The mean total viable count (TVC) of milk from vendors is significantly (P < 0.05) higher than that from retailers and smallholder dairy farmers. Generally, 65 % of milk samples assessed had a higher TVC than the level recommended (2.0 × 10(5) cfu/ml) by the East African Community (EAC) standards. Up to 91 % of the milk samples had bacterial growth that included Eschericia coli (66 %), Staphylococcus aureus (33 %), Corynebacterium (11 %) and Pseudomonas (10 %). All smallholder dairy farmers were aware of drug residues, but majority (57 %) were unaware of human health effects caused by veterinary drug residues in milk. Up to 97 % of respondents reported to comply with drug withdrawal periods. This possibly led to all milk samples analysed to be negative from detectable levels of antibiotic residues. It is concluded that the level of awareness on milk quality is high, although practices associated with milking and post-harvest handling predispose milk to bacterial contamination which is a public health risk to milk consumers.

Microbiological quality and antibiotic residues in informally marketed raw cow milk within the coastal savannah zone of Ghana

OBJECTIVES

To investigate the microbiological quality and the presence of antibiotic residues in raw cow milk and in some indigenous milk products produced and marketed by the informal sector in the coastal savannah zone of Ghana.

METHODS

Milk samples were aseptically collected from 224 kraals and samples of 26 indigenous milk products were purchased from processors and retailers. Total plate counts, total coliform counts and the presence of Escherichia coli and E. coli O157:H7 were determined in all 250 samples. Milk samples were also tested for antibiotic residues.

RESULTS

Total plate counts exceeded 10⁵ CFU/ml in 45.2% of the samples while coliforms exceeded 10³ CFU/ml in 66.0% and E. coli was detected in 11.2%. E. coli was present in raw cow milk but not in the indigenous products and all E. coli isolates were negative for E. coli O157:H7. Antibiotic residues were detected in 3.1% of the raw cow milk samples.

CONCLUSION

Bulk milk contains unacceptable levels of hygiene indicators and antibiotic residues and is a potential source of milk-borne infections. The detection of E. coli and antibiotic residues raises public health concerns about the safety of fresh unpasteurized cow milk in the coastal savannah zone of Ghana and calls for improved farm hygiene, the need for milk pasteurization and the sensible use of antibiotics in the milk industry.

Assessment of antimicrobial usage and residues in commercial chicken eggs from smallholder poultry keepers in Morogoro municipality, Tanzania

Occurrence of antimicrobial residues in commercial chicken eggs was determined in Morogoro municipality between January and February 2007. Twenty smallholder farmers were interviewed on the types of antimicrobials, reasons of use and their awareness on antimicrobial withdrawal period. Seventy egg samples were collected for qualitative antimicrobial drug residues analysis by use of agar well diffusion and Delvotest SP assays. It was found that farmers use antimicrobial drugs as prophylaxis and treatment of common chicken diseases namely fowl typhoid (85%), infectious bursa disease (Gumboro) (65%) infectious coryza (65%), collibacilosis (55%), coccidiosis (54%), Newcastle disease (50%), helminthosis (20%) and fowl pox (15%). Antimicrobials accounted for 85% of the drugs commonly used. It was also found that 65% of the farmers treat their chicken themselves. The common drugs were oxytetracycline (75%), egg booster (50%), amprolium (35%), sulphamethoxypyridazine (35%), sulphanilamide (25%), chlortetracyclines (10%), chloramphenicol (10%), sulphadiazine-trimethoprim (20%), duoxycycline (20%), sulphadiazine (25%) and flumequine (10%). Eighty per cent of the farmers had knowledge on antimicrobial withdrawal period sold eggs before withdrawal period and almost 85% were unaware of possible effects of antimicrobial residues in humans. All 70 eggs were positive to antimicrobial residues by Delvotest kit, but 21.4% positive with agar well diffusion test. It was concluded that the presence of antimicrobial residues in table eggs could be of public health significance to the egg consumers in Morogoro municipality.