STUDIES OF THE PREVALENCE OF RENAL DISEASE AND HYPERTENSION IN RELATION TO SCHISTOSOMIASIS: A CROSS SECTIONAL SURVEY OF OMI-ADIO, A COMMUNITY OF HIGH BILHARZIA ENDEMICITY AND OFFA-TEDO, ONE WITH LOW ENDEMICITY

Abstract

Two rural communities in the environs of Ibadan, Western State of Nigeria, one with sustained high endemicity of urinary schistosomiasis as the test, the other with a low endemicity as control have been studied for the following: (a) Symptoms of urinary tract involvement, of possible aetiology and of severe nephron failure; (b) few signs of significant renal failure and its complications viz. mucosal pallor and hypertension; (c) laboratory evidence of urinary tract involvement in renal disease viz. Proteinuria, Cellular excretion and Bacteriuria (d) Radiological evidence of urinary tract disease by intravenous pyelography. The two communities were pooled and examined for the prevalence of certain items in the rural community. Care was taken to ensure accurate data collection especially in relation to age, certain standard symptoms recording of blood pressure and collection of mid stream specimen of urine. Examining for the influence of schistosomiasis on these, items it has been found that (I) Certain symptoms viz: Nocturia, Haematuria, poor urinary stream, smarting sensation at micturition , previous history of continuous urinary incontinence, previous history of suprapubic discomfort and attacks of renal colic are more marked in the community where bilharzias endemicity is higher in both sexes. Previous history of loin pains showed up in significant relationship to shistosomiasis only in females. None of the other symtoms seem to be positively influenced by schistosomiasis. In fact in quite a number of them, they were less marked in the test than in the control community. (2) Mucosal pallor was also not associated with endemic schistosomiasis. (3) Mean blood pressure is not higher in the test than control population, the reverse being the case for female diastolic, male, systolic blood pressure. This difference is probably a reflection of age since there are more elderly people in control than in the test community. Pregnancies and parity might also be contributory. 4) Laboratory findings confirmed that schistosomiasis is more endemic in the test population and that in relation to thus haematuria, proteinuria, pyuria and bacteriuria are accordingly more common. However, it was found that bacteriuria in school boys did not differ in the two communities suggesting that increased prevalence rate of bacteriuria in schistosomiasis is not associate with egg exretion but may be due to other defects caused on the urinary tract. (5) Intravenous pyelography like the laboratory results, showed that urinary tract distortion and calculi formation are more common in the test than the control population. These findings arc discussed against current literature on the subject and it is concluded that, (1) our area of study, which is in the environs of Ibadan, is a focus of relatively mild endemicity of schistosomiasis when compared with a zone like Egypt and even Rhodesia. (2) that at a such a level of endemicity although it predisposes to evidence of nephron failure and bacterialogic Involvement of the urinary tract, such effects are not gross enough to intensify symptoms of renal failure or its complications beyond what could be expected in a less endemic zone. In particular, hypertension as a cause or effect of renal disease does not seem to be significantly influenced by schistosomiasis. Pooling the two population, data were analysed for the prevalence of certain items. Among others it has been found that in the rural setting; (1) During the day average frequency of micturition is 3 - 6 times. (2) Nocturia is a very common symptom in apparently normal population. (3) Smarting sensation, unlike bacteriuria is more common among males than females. This may be a distortion by schistosomiasis. (4) Loin pain is very frequently admitted to by both males and females, occurring in roughly 20 percent of subjects. (5) Urinary symptoms in pregnancy i.e. loin pain and smarting sensation with or without feverishness or rigors, occurs in approximately 20 percent of women. The majority did not receive adequate treatment. (6) Symptoms of outlet obstructive uropathy occurred in approximately 10 percent of the male population about 5 percent of females.

(7) Headache appears to be a universal symptom occurring in 90 percent of the people but is much less frequent when subjects were asked to locate it to specific areas. (8) Systemic hypertension was found to be consistently more common in females in all age groups. This trend was particularly marked in the child bearing age group. Using statistical analysis hypertension was found to be related to weight, live birth, abortions. Proteinufria among females may also be related but this requires further studies. It is established that at least in the rural community, headache. palpitations, poor sleep are not symptoms of hypertension. Attention has been drawn to the difficulties encountered in an epidemiological study of a largely illiterate population. The limitations imposed by such on this studied have been outlined. Findings are discussed against this background and the following conclusions are made. (l) Nocturia of once would appear to be normal among `Nigerians, but before any answer can be given, further studies are required. (2) Compared with other parts of the world dysuria (Smarting sensation at micturition) would seem to be much lower in the rural Nigerian women. This symptom is more common among Nigerian males. Unlike other studies however it has no relation to hypertension, nor does it correlate with the prevalence of bacteriuria. (3) Ureteric and renal symptoms are surprisingly very common inspite of the very low prevalence of urinary calculi. (4) History of gonorrhoea would seem to be a reliable indication of neisseria infection among males but perhaps not among females. (5) Sore throat, swelling of the face and gross protenuiria seem to correlate when the gross effect of schistosomiasis is excluded. This is in contrast to hospital experience in adults; suggesting that a large proportion of cases of possible acute nephritis do not present to hospital. (6) Systolic and diastolic hypertension has a predilection for the female sex and pregnancy might be the enhancing factor.