Measuring morbidity in schistosomiasis mansoni: relationship between image pattern, portal vein diameter and portal branch thickness in large‐scale surveys using new WHO coding guidelines for ultrasound in schistosomiasis

Abstract

Summaryobjective World Health Organization consensus meetings on 'Ultrasound in Schistosomiasis' in 1996 and 1997 anticipated further challenges in the global implementation of a standardized protocol for morbidity assessment in schistosomiasis mansoni. We evaluated the performance of the qualitative and quantitative components of the new Niamey criteria.method Use of the Niamey protocol among 3954 subjects in two linked, cross-sectional ultrasound surveys of Schistosoma mansoni-endemic populations in Egypt and Kenya.results There were significant differences between Egyptian and Kenyan sites in prevalence and age distribution of S. mansoni-related hepatic fibrosis (36% vs. 3%, P < 0.001). Protocol image pattern scoring could be performed quickly and was stable to interobserver variation. However, there were unintended but systematic differences between study sites in the measurement of portal vein diameter (PVD) and wall thickness. By Niamey criteria, a high prevalence of portal dilation was scored for normal Egyptian subjects, which reduced the predictive value of image pattern for portal hypertension. Using alternative height-indexing of PVD, image pattern plus PVD findings predicted 15% of Egyptians and 2.5% of Kenyans were at risk for variceal bleeding, whereas locally derived PVD norms estimated 25% of Egyptians and 12% of Kenyans to be at possible risk.conclusion Niamey scoring criteria performed acceptably as a relative grading system for disease in schistosomiasis mansoni, but failed to account fully for site-to-site variation in test performance and morbidity prevalence. Consequently, standardized image pattern scoring appears to provide the most useful tool for detection and comparison of S. mansoni-associated morbidity in large-scale surveys.keywords Schistosoma mansoni, schistosomiasis, portal vein, Egypt, Kenya, risk factors, diagnostic imaging/ultrasonography, mass screening/ standards, predictive value of tests correspondence Dr

Schistosoma mansoni: magnetic resonance analysis of liver fibrosis according to WHO patterns for ultrasound assessment of schistosomiasis-related morbidity

“…However, the quantitative assessment of periportal thickness of portal vein walls, particularly of the secondary branches, proved to be difficult in everyday use. In addition, it is considered time-demanding and complex, leading to low reproducibility , Hoffmann et al 2001, Richter et al 2001, Ruiz et al 2002, King et al 2003.…”

Morbidity due to Schistosoma mansoni: an epidemiological assessment of distended abdomen syndrome in Ugandan school children with observations before and 1-year after anthelminthic chemotherapy

“…Whilst clinical investigations with ultrasound and/or abdominal palpation methods can better describe morbidity associated with Schistosoma mansoni infection, for example hepatosplenomegaly, liver fibrosis and/or organ texture (Hatz, 2001;King et al, 2003), these require specialist equipment and well trained staff (Nooman et al, 1995;Ruiz et al, 2002). As a consequence, large-scale community screening of morbidity has been limited and broad geographic comparisons are rarely made.…”

High Schistosoma mansoni Disease Burden in a Rural District of Western Zambia

“…32 As has been observed in other S. mansoni-endemic countries, the prevalence of fibrosis was shown to increase with increasing age. 20,[32][33][34] We also observed in our study population that adults were more likely to present with portal fibrosis on ultrasound than children. Although this is sometimes reported in children, severe forms of the disease are rarely observed in younger populations.…”

“…This finding contrasts with some studies that have that the intensity of infection correlates with disease severity. 20,23,[32][33][34] The lack of association observed in our study could be explained by other possible factors, including the observed high prevalence of S. mansoni infection in this study population, suggesting that the studied participants have repeated exposure.…”