At the beginning of this century, high blood pressure was virtually
non-existent among the indigenous Kenyans. This phenomenon of normotension
continued until the Second World War following which the Kenyan African began to
exhibit progressive rise in blood pressure which was age-related. Similar
changes were observed in Uganda at the same time. From about 25 years ago, high
blood pressure became established in Kenya and the neighbouring countries, in
particular Uganda. These trends have been observed in West Africa notably Ghana,
Nigeria, Cote d'Ivoire and also in Cameroon and Zaire in the Central African
region. Consumption of sodium salt and alcohol, psychological stress, obesity,
physical inactivity and other dietary factors are thought to play important
aetiologic role in the genesis of primary hypertension in the susceptible
individuals. Low blood pressure communities still exist scattered all over the
world, where blood pressure does not seem to rise with age. In Africa these have
been observed in Kenya, Nigeria, Zaire and Kalahari Desert. They also exist in
Pacific island, Australia, South America and elsewhere. Rural-urban migration
coupled with acculturation and modernization trends have some relationship with
the development of high blood pressure as observed in Kenyan and Ghanian
epidemiologic studies.