Assessment of eosinophiluria using eosinophil cationic protein: Comparative study in single and mixed schistosoma infections in Kenyan school children

Abstract

Schistosomiasis is a disease of man and animals caused by digenetic trematodes of the genus Schistosoma. In Kenya, both schistosoma haematobium and S. mansoni exists. Adult worms produce eggs used as a standard method of diagnosis, however daily egg excretion varies considerably leading to incorrect estimates. Urinary eosinophilic cationic protein (ECP) have shown to be a promising marker of the eosinophilic inflamation of the bladder wall associated with perioval inflammatory reaction in S. haemotabium and hence a marker of infection and morbidity. The main objective of the study was to elucidate if co-infection with S. mansoni has any influence on the level of urinary ECP in S. haematobium infections as this could interfere with the diagnostic perfomance of the ECP test as a marker of infection and morbidity in S. haematobium infections. The study was conducted in Kilifi (S. haematobium endemic), Taveta, (S. haematobium and S. mansoni endemic) and Machakos (S. mansoni endemic). School children (4-18 years) were examined for eggs of S. haematobium and S. mansoni in urine and stool samples respectively. In Kilifi, prevalence of S. haematobium was 86% . Median egg counts and median ECP levels were significantly different for males and females (P = 0.002 and P < 0.001 respectively). A positive correlation existed between egg counts and eosinophil cationic protein levels in S. haematobium infection (r = 0.5, P < 0.001). In Taveta, the prevalence of mixed infection was 45%. The median egg counts for S. haematobium and S. mansoni, separately were statistically different for amales and females (P = 0.015 and P = 0.014 respectively). There was significant difference in median eosinophil cationic protein levels between males and females (P = 0.026). Egg counts and eosinophil cationic protein level for S. haematobium had a positive correlation (r = 0.2, P < 0.05), but this was not observed for S. mansoni (r =0.0, P > 0.05). In Machakos, the prevalence of S. mansoni was 66.2%. No correlation between egg counts and eosinophil cationic protein levels in urine was observed (r=0.0, P > 0.05). The egg excretion of S. haematobium in the children with the mixed schistosoma infections did not differ with the egg excretion of those children from the S. haematobium area (P = 0.65) and also no statistical difference was seen in the ECP levels (P = 0.08). The study concludes that ECP levels can be used as a diagnostic tool and as a morbidity marker in S. haematobium infection. In addition eosinophiluria is characteristic for S. haematobium whether in mixed or single infections. This confirms its specificity in urinary schistosomiasis.