Urolithiasis in Sahelian Africa

Renal stones in the tropics

Urolithiasis is a problem that is generally increasing in the tropics as it is in most Western countries. There are 2 main types of the disorder-bladder stones in children, a form of the disorder that disappeared from Europe in the late 19th and early 20th centuries, and upper urinary tract stones in adults. The former has been decreasing in most countries in the so-called endemic bladder stone belt with gradual improvements in levels of nutrition. However, as living standards increase, particularly in the urban areas of the more affluent developing countries, so the incidence of upper urinary tract stones in adults is increasing. The types of stones formed depend mainly on the composition of urine, which, in turn, reflects the type of diet consumed in the countries concerned. The main factor that leads to the formation of bladder stones in children is a nutritionally poor diet that is low in animal protein, calcium, and phosphate, but high in cereal and is acidogenic. This leads to the formation of urine with a relatively high content of ammonium and urate ions and consequently to the formation of ammonium acid urate crystals and stones. In countries where there is also a high intake of oxalate from local leaves and vegetables, urinary oxalate is increased and, as a result, the ammonium acid urate stones often contain calcium oxalate as well. The stone problem in the tropics is compounded by low urine volumes resulting in some areas from poor drinking water, which causes chronic diarrhea, and in others from the hot climate and fluid losses through the skin. As nutrition improves in these countries, the formation of bladder stones gives way to upper urinary tract stones consisting of calcium oxalate, often mixed with calcium phosphate or uric acid, such as are formed in most Western countries.

Epidemiology and socioeconomic aspects of urolithiasis

This epidemiologic study reveals that the occurrence of urolithiasis in the nineteenth century population in Europe is quite similar to that of the twentieth century in Asia. The analogy is demonstrated for age distribution, stone localization, male/female ratio, and stone composition. The distribution of urolithiasis in a low socioeconomic level population is defined by: highest frequency in childhood, more than 40% bladder stones, less than 20% female patients, less than 40% calcium-oxalate stones, and more than 30% uric acid/urate stones. Typical for a population with a high level these characteristics of urolithiasis are: highest frequency among adults, less than 10% bladder stones, more than 25% female patients, more than 60% calcium oxalate stones, and less than 20% uric acid/urate stones. In partially developed countries those values fall in between.

Urinary calculus in Zambia: its incidence and relationship to Schistosoma haematobium infection and vesicovaginal fistula

Radiological, cystoscopic and histological observations were made on 41 cases of urinary stones in a hospital in Zambia. The results of biochemical analysis of 31 of these stones are presented. The possible role of Schistosoma haematobium in the causation of urinary stones has been analysed; associated schistosomiasis was diagnosed in 17 cases (41.4%). It is concluded that there is no significant causal association between the two disorders and urolithiasis is an uncommon disease in Zambians.