Prevalence of Human Schistosomiasis in New Halfa and Khartoum North Irrigated Agricultural Schemes with Emphasis on Evaluation of the Diagnostic Methods Used

Abstract

This study aimed to determine the sensitivity and efficiency of various techniques that are used for the diagnosis of intestinal and urinary schistosomiasis and aimed to compare the results obtained by these techniques with the routine wet preparation method. The rate of prevalence concerned with age and sex were comparable for the different methods. The study determined the levels of infection by S.mansoni in New Halfa scheme and S.haematobium in three different areas in Khartoum North during the period from January to April 2009. The study included 400 specimens (200 stool samples for S.mansoni and 200 urine samples for S.haematobium). The overall prevalence of S.mansoni in New Halfa scheme was found to be 74%, and more frequent among the school children at the age group < 15years (87.7%). The overall prevalence in Khartoum North was found to be 46% and the highest rate was found in Tibet Alahamda (61%) and more seen in school children (48.5%). Amongst the diagnostic methods used for stool examination, the formal ether concentration technique proved to be the most sensitive method (74%) for detection of infection and to determine the mean egg count, followed by the modified Kato-Katz technique (68.5%) which gave results relatively similar to that obtained by the formal ether concentration technique. Both methods are suitable for field work. Other methods showed variably less sensitivity and quantitative efficiency. The study recommended that wet preparation is not suitable for detection of mild and chronic infections. For the diagnosis of S.haematobium, the sedimentation and filtration techniques showed the same sensitivity (46%) but the filtration technique sometimes gave false positive results due to improper washing of filters. The hatching viability test gave weak results which attributed to immunity and to the fact that most of the children subjected to treatment during the past few months. So, this test can be used to assess the of the treatment and to determine the effective dose. Efficiency showed less sensitivity and can be used in qualitative diagnosis and to determine the effectiveness of treatment.