CHAPTER ONE
1.0 INTRODUCTION
Nigeria’s biodiversity is rich in medicinal plants. The World Health Organization (WHO) reported that 70─90 % of the world’s population relies chiefly on traditional medicine and a major part of the traditional therapies involve the use of plant extracts or their active constituents. Many plants have therefore become
sources of important drugs and as such the pharmaceutical industries have exploited traditional medicine as a source of bioactive agents that can be used in the preparation of synthetic medicines. Natural products play important roles in drug discovery and development process, particularly in the field of infectious diseases, where 75 % of these drugs are of natural origin. Trypanosomiasis, a disease of major importance in human and animals has continued to threaten human health and economic development. Trypanosoma brucei gambiense and Trypanosoma brucei rhodensiense as the etiological agents of trypanosomiasis affect millions of people in sub-Saharan Africa and are responsible for the death of about half a million patients per year. In Africa where
trypanosomiasis is endemic, plants have been used for generations. Natural products derived from them offer novel possibilities to obtain new drugs that are active against trypanosomes. The disease is caused by flagellate parasites – protozoa belonging to the genus trypanosome and family trypanosidae.
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1.1Human African Trypanosomiasis African trypanosomiasis or sleeping sickness is a parasitic disease of humans and other animals.
[1] It is caused by protozoa of the species Trypanosoma brucei [2].
There are two types that infect humans; Trypanosoma brucei gambiense (T.b.g.) and Typanosma brucei rhodesiense (T.b.r). T.b.g is usually transmitted by the bite of an infected tse tse fly and is most common in rural areas. Initially, in the first stage of the disease, there are fevers, headaches, itchiness, and joint pains [2].
This begins one to three weeks after the bite
[3]. Weeks to months later the second stage begins with confusion, poor co-ordination, numbness and trouble
sleeping [1, 3]. Diagnosis is via finding the parasite in a blood smear or in the fluid of a lymph
node [3]. A lumber puncture is often needed to tell the differences between first and second stage disease.
History of Discovery Although the symptoms of African sleeping sickness were documented by Atkins
in 1742, the association of the clinical syndrome with its etiological agent, the trypanosome, was not documented until 1902 by Forde [4]. In the School of tropical medicine, Forde chronicled his treatment of a 42 year –old European male colonialist who presented to his practice in the Gambia colony in May 1901.
The patient complained of fever and malaise, bading Forde to make a preliminary diagnosis of malaria. He initiated anti-malaria treatment, but days later the patient’s condition had yet to improve. Slides of the patient blood were prepared.
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This examination ruled out malaria due to lack of malaria parasites found in the blood. Only later, Dutton a second physician from the Liverpool School of Tropical Medicine, made the identification of Trypanosoma brucei in the patients blood . Due to the probable location of the patient’s inoculation, this case can be
attributed to the species T.b gambiense.
The identification of T.b rhodesiense as another species of trypanosome to cause African sleeping sickness was not documented until 1910. Stephens and Fantham