Variasie in die Schistosoma haematobium-ovagetalle wat deur mense onder verskillende toestande ge-ekskreteer word asook verwante morbiditeitsverskynsels

Abstract

Several methods exist for the identification of schistosome infections in humans, of which the most common and accurate is the demonstration of schistosome eggs in the urine. However, several reports have indicated that there is a daily fluctuation, as well as a circadian rhythm in the excretion of Schistosoma haematobium eggs in the urine, and that these variations differ between various endemic and geographical areas. The impact of these factors on a positive diagnosis of S. haematobium eggs in the urine, based solely on a single urine analyses, will therefore decrease the accuracy of such a diagnosis. It is therefore necessary to establish the degree of daily variation in egg excretion, as well as the peak in egg excretion (circadian rhythm) in the population in the geographical area that is studied. The present study was undertaken to establish the effect that the circadian rhythm and daily variation in egg excretion has on the accuracy of a schistosome diagnosis by demonstration of eggs in the urine. A baseline study was performed after which 120 schistosome-infected individuals were selected for further study. This study was carried out in the Mamitwa Village in the Limpopo Province of South Africa. Urine samples were collected five times a day from both males and females to determine whether a circadian cycle of egg excretion was present. This method was repeated for a total of six days. This was done in order to establish if there were any daily fluctuations in egg counts found in the urine on these consecutive days. Reagent strips were used for the detection of haematuria and proteinuria. The following conclusions were made from the results obtained in this study: * The variation in the number of eggs passed per individual, per timeframe during the whole of the collection period, was great. It is obvious that infected individuals did not continuously pass the same number of eggs in the urine. * Individuals in the 10 to 14 year old age group showed a higher intensity of infection than individuals in the other two age groups. * Individuals in the 15 to 22 year old age group had a lighter degree of infection than individuals in the four to nine year old age group. * A circadian rhythm of egg excretion was found in all of the age groups. Individuals in the four to nine year old age group showed a peak in egg excretion during the 12:30 time interval, whereas the 10 to 14 year and 15 to 22 year old age groups showed a peak in egg excretion at the 14:30 and 16:30 time intervals respectively. It seems that there is a variation in the circadian rhythm of egg excretion between the age groups. * The majority of individuals in all three age groups, irrespective of the degree of infection, showed great variation in the demonstration of blood in the urine (ranging from negative to 1.0 mg/di). It seems possible that the excretion of blood in the urine also follows a circadian rhythm . * The occurrence of no blood in the urine was more prevalent in the four to nine year old age group, however the occurrence of 1.0 mg/di (+++) blood in the urine was more prevalent in the 10 to 14 and 15 to 22 year old age groups. It seems that the older age groups show a higher degree of morbidity related symptoms such as haematuria. * The occurrence of haematuria was more prevalent in the afternoon. * Proteinuria occurred less frequently than haematuria. * Individuals in the four to nine year old age group demonstrated more protein in the urine than individuals in the other two age groups. * The occurrence of group C (0, 30 and 100 mg/di) degree of proteinuria was more prevalent in the four to nine year old age group.

* Group B (0 and 30 mg/di) degree of proteinuria was more prevalent in individuals in the 10 to 14 year old age group that showed a light intensity of infection, whereas group C (0, 30 and 100 mg/di) degree of proteinuria showed a medium to heavy intensity of infection. * Group B (0 and 30 mg/di) degree of proteinuria was more prevalent in individuals that showed a light to medium intensity of infection, whereas group C (0, 30 and 100 mg/di) degree of proteinuria was more prevalent in individuals that showed a heavy intensity of infection. * It seems that the intensity of infection plays a part in morbidity related symptoms like proteinuria in all of the age groups. * The highest arrhythmic mean of egg excretion in the four to nine year old age group occurred at the ++ degree of haematuria. On the other hand the highest arrhythmic mean of egg excretion in the other two age groups occurred at the +++ degree of haematuria. * The highest arrhythmic mean of egg excretion in all three the age groups occurred at group C (0, 30 and 100 mg/di) degree of proteinuria * The sensitivity of haematuria in the diagnosis of schistosome infections, as determined by reagent strips, did not vary between the age groups. The mean sensitivity was 70 % for all three the age groups, which means that the reagent strips can be used with confidence in the geographical area in question. * The sensitivity of proteinuria in the diagnosis of schistosome infections, as determined by reagent strips, did not vary between the age groups. The mean sensitivity was 56 % for all the age groups, which was markedly lower than the sensitivity for haematuria.

* The mean specificity for haematuria in all of the age groups was 18 %, while it was 43 % for proteinuria. It is obvious that the sensitivity for haematuria was higher than that of proteinuria; however, the specificity for proteinuria was higher than that of haematuria. * If both haematuria and proteinuria are used as an indirect measurement tool in the diagnosis of schistosome infections, their diagnostic value will be enhanced.