Until recently medical practitioners in sub-Saharan Africa had to rely for many conditions on literature written in environments very different from those in the tropics. There is no doubt, however, that some diseases have different patterns, symptoms, incidences, etc. in the tropics than in temperate climates.
Doctors in the tropics must be well-informed about the differences between medical practice in tropical and temperate climates. This article reviews the characteristics of some gastrointestinal illnesses in tropical (sub-Saharan) Africa. In particular, those pathologies are discussed where the differences in disease characteristics between the tropics and other regions are significant, e.g. peptic ulcer and certain malignancies of the gastrointestinal tract. The limitations of the review are acknowledged since the problems discussed are much more complex and have many other aspects than those dealt with here. It does, nevertheless, provide an account of these conditions as they present in tropical Africa.
As with all diseases, reporting the true incidence of peptic ulcer depends on two factors:
-- satisfactory case-history data; and
-- good diagnostic facilities.
Both these requirements are difficult to meet in Africa since detailed case histories are sometimes very difficult to obtain because doctors often have to use interpreters, and because diagnostic investigations are limited in many parts of the continent. Usually hospitals in major towns are equipped with X-ray equipment but gastroscopy and endoscopy are costly and therefore generally unavailable in most African countries.
Gastric ulcers are rare in some African countries, but have been reported from all parts of the continent (1). Their incidence is much lower than that of duodenal ulcers in all developing countries. Gastric ulcers are probably commoner in East than in West Africa and in general their incidence is low in the continent as a whole (2).
Gastric ulcers affect men more frequently than women in Africa and seem to be a disease of the lower social strata; the majority of the patients are in their fifth or sixth decades of life (3).
The presentation of gastric ulcers in sub-Saharan Africa is no different from that in developed countries, although gastric retention seems to be commoner, presumably because of the chronicity of the condition (4).
Not more than 40 years ago duodenal ulcers were considered to be uncommon in tropical Africa (5), although there is evidence that they have become commoner since the beginning of the 20th century (6).
At present the epidemiology of duodenal ulcers in tropical Africa is as described below.
In West Africa their incidence is relatively high in Nigeria, Cameroon, and Ghana. There are also high incidences in the Nile--Congo watershed, Burundi, Rwanda, eastern Democratic Republic of Congo (Lake Kivu area), south-western Uganda, and the Ethiopian highlands (7).
Barton & Cockshott considered duodenal ulcers to be as common in Nigeria as in the United Kingdom (8), drawing attention to the fact that in Nigeria it is the rural farmer who is usually affected. They also reported a male: female ratio of 4.5:1, but it should be remembered that it is often especially difficult for women to get to hospital in rural Africa.
Reports from Nairobi and from other parts of Kenya indicate that nowadays duodenal ulcers are not uncommon (9). Stenosis is a frequent complication and the ratio of duodenal to gastric ulcers is about 12:1 (10, 11).
In the literature it is commonly stated that genetic factors play a part in determining the incidence of duodenal ulcers. In Uganda there is no doubt that the condition is commoner among Hamites than Bantu tribes, while in Nigeria there are marked differences in incidence between the north and south of the country. …