SUMMARY

Drug residues in foods of animal origin are drugs and their metabolites which are found in edible

tissues and milk of animals following their medication with specific drugs whose prescribed

withdrawal period are not observed. Chloramphenicol (CAP) residues in the food chain are

potential hazards to public health. Such hazards include: allergy, antibacterial resistance,

carcinogenicity, genotoxicity, aplastic anemia and leukemia. Globally, aplastic anemia affects 1

in 10,000 to 50,000 patients receiving a typical course of CAP therapy and about 280,000

patients are susceptible to the development of aplastic anemia in Nigeria.9,10 CAP has therefore

been banned globally by FAO/WHO and considered a drug of zero-tolerance in food-producing

animals. This study was carried out to determine the occurrence of CAP residues in chicken eggs

in the FCT and to assess the usage and awareness of its ban amongst poultry farmers.

A cross-sectional survey using structured questionnaires was conducted on poultry farmers and a

survey of commercial chicken eggs from poultry farms and government owned markets in FCT,

Nigeria was also carried out using CAP ELISA kits to test for the presence of CAP in eggs.

Frequencies and proportions were obtained by univariate analysis and odds ratios and Fischer‟s

exact p-values at 95% confidence intervals were also obtained using OpenEpi and EpiInfo

version 3.5.3 softwares.

Of the 57 questionnaire respondents, 30 (52.6%) were farm managers out of which 48 (84.2%)

were males, and 27 (47.4%) were between ages 36-50 years. Pooled egg samples (10 eggs make

a sample, n=288 i.e. 2880 eggs) were analyzed using CAP ELISA kits and 20 (7%) of the

samples tested positive for CAP residues. Poultry farmers use both human (8.8%) and veterinary

drug preparations containing CAP (43.9%) on their birds. Most poultry farmers (71.9%) were not

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CHAPTER ONE – INTRODUCTION

1.1BACKGROUND

Drug residues in foods of animal origin are drugs and their metabolites which are found in

edible tissues and milk of animals following their medication with specific drugs whose

prescribed withdrawal period are not observed. 1, 2 Drug residues eventually make their way

to the food chain where they can potentially pose a risk to human health. Such health

problems include development of allergic reactions, emergence of multiple resistant strains

of pathogenic bacteria, development of cancer and mutations, aplastic anemia and leukemia

in humans.3 This has resulted in the global ban of the use of chloramphenicol in Veterinary

Medicine to non-food use due to potential public health risks posed by its traces in edible

tissues and was therefore considered a drug with an established zero-tolerance.4

Chloramphenicol (CAP) was first isolated in 1947 from the soil bacterium Streptomyces

venezuelae, and synthetic production began in 1949.5 Due to its outstanding antibacterial

properties, CAP is an often used antibiotic in the production of milk, meat and eggs. It is an

inexpensive broad-spectrum antibiotic recommended for the treatment of salmonella

infections and for the prevention of secondary infections associated with chronic respiratory

disease and blue comb in poultry.6 It is well absorbed by both oral and parenteral routes.

CAP usually acts as a bacteriostatic, but at higher concentrations or against some very

susceptible organisms it can be bactericidal. It is used in the treatment of human infection

with Salmonella typhi and other forms of salmonellosis and other threatening infections of

the central nervous system and respiratory tract.7

1

In Nigeria, many poultry farmers use CAP to control poultry diseases because of its claimed

efficacy. 8 This situation could result from a state of very low and absolute lack of awareness