CHAPTER ONE
INTRODUCTION
Malaria is a very old disease since Anopheles mosquito that transmits the disease is as old as mankind. The writings of the Samarians, Egyptians, Ancient Chinese, Homer, Aristotle, Plato and Shakespeare some dating 3,500 to 4,000 years ago, described intermittent fevers and splenomegaly; characteristic of malaria. Malaria is believed to have originated from West Africa (Plasmodium falciparum), West and Central Africa (P. vivax) (on the basis of the presence of homozygous alleles for hemoglobin C and red blood cell (RBC) duffy negativity that confer protection against P. falciparum and P. vivax respectively) and transported to other parts of the world through trans-pacific voyages, slave trade and man’s migration (Kakkilaya, 2006). It was reported that man and malaria seemed to have evolved together, and that the ancestors of malaria parasite probably existed at least half a billion years ago (WHO, 1982). At present, about 100 countries or territories in the world are considered malarious almost half of which are in Africa, south of the Sahara. Although this number is considerably less than it was in the mid 1950s (140 countries or territories) more than 2,400 million of the world’s populations are still at risk (Greenwood et al., 2008). The manifestation of the disease in different populations varies across the continent. In many parts of Africa, young children and pregnant women are most affected while in Asia adults as well as children are equally affected (Onaku et al., 2011). In Nigeria, there is an element of uniform distribution and prevalence of the disease in both rural and urban areas. This may be due to the vectors, Anopheles gambiae, A. arabiensis and A. funestus breeding in fairly clean sun lit water pools e.g. water storage tanks and wells which are found in both rural and urban areas. Malaria in Nigeria is holoendemic i.e. there is an intense all-year round transmission with greater intensity in the wet season than dry season (Onaku et al., 2011). The world health organization (WHO) reported that there were an estimated 246 million malaria cases distributed among 3.3 billion people at risk in 2006, causing at least a million deaths. These were mostly children under five years. One hundred and nine countries were endemic in 2008 and 45 within the African region. Approximately 80% of malaria cases in the world are estimated to be in Africa, where the disease is endemic (WHO, 2008). The disease is a major cause of the continents high infant mortality, killing 1 in every 20 children below 5 years of age (Goose, 1993). Nigeria accounts for a quarter of all malaria cases in the WHO African region (WHO, 2008).
In Africa and other countries where malaria is endemic, medicinal plants are frequently used to treat or cure malaria (Gessler et al., 1994; Jenett-Siems et al., 1999). The use of antimalarial drugs and other means have not been fruitful over the years, this is due to the alarming rate at which P. falciparum has developed resistance to chloroquine and other synthetic antimalarial drugs makes it necessary to search for more effective antimalarial compounds (Bhat and Surolia, 2001). However, the use of herbal medicine in combating malaria has been reported by many researchers as a good alternative (WHO, 2002), but little has been done in examine the chemical composition of these herbs, safety and the effectiveness of the claims from scientific bases.
