Assessing the WHO 50% Prevalence Threshold in School-Aged Children as Indication for Treatment of Urogenital Schistosomiasis in Adults in Central Nigeria

Abstract

Abstract. Preventive chemotherapy with praziquantel is recommended in adults by the World Health Organization when prevalence of schistosomiasis in school-aged children (SAC) is 50%. This study ascertained the value of this threshold in predicting prevalence and intensity of Schistosoma hematobium (SH) infection in adults in central Nigeria. We evaluated urogenital schistosomiasis prevalence in 1,164 adults: 659 adults in 12 communities where mean hematuria among SAC in 2008 was 26.6% and 505 adults in 7 communities where the mean hematuria among SAC in 2008 was 70.4%. No statistically significant differences were found between the two groups of adults in prevalence of hematuria, prevalence of SH eggs, or intensity of infections. We conclude that, in this setting, the SAC threshold is not useful for treatment decisions in adults. Given the increased risk of subtle morbidity or urogenital schistosomiasis as a risk factor for human immunodeficiency virus (HIV), more liberal treatment of adults with praziquantel is warranted.

Predictive Value of School-Aged Children's Schistosomiasis Prevalence and Egg Intensity for Other Age Groups in Western Kenya

“…27 By contrast, the study of Evans and others of S. haematobium infections in Nigeria demonstrated similar adult levels of infection and hematuria in villages with SAC prevalence between 20% and 49% as in villages with SAC prevalence > 50%. 14 However, in both settings the median adult prevalence was lower than for SAC (~20% for both groups) whereas in our study the adult prevalence was more similar to the SAC prevalence. This may represent differences in the longevity of S. haematobium and S. mansoni worms, increased resistance to reinfection in adults infected with S. haematobium, or simply differences in age-related water contact patterns between the two study settings.…”

“…The WHO recommendations may not be always applicable to the reality in some settings if the 6-to 15-year-old age group does not truly reflect the prevalence of the disease and the need for intervention in the community as a whole. 14 In Kenya, the current control strategy for STHs and schistosomiasis is school-based mass chemotherapy with albendazole (since 2009) and PZQ (since 2012), administered in prioritized areas by a national control team with cascaded support at the county and subcounty levels. Prioritization of targeted areas is based on historical data generated from these areas, and implementation is accompanied by baseline surveys.…”

Comparison of community-wide, integrated mass drug administration strategies for schistosomiasis and soil-transmitted helminthiasis: a cost-effectiveness modelling study

“…Although many studies have reported greater prevalence of helminths in school-aged children than in adults, growing scientifi c literature supports our fi nding that adults can often have equivalent or greater disease burden than children, especially for hookworm infections and schistosomiasis. 56,57 To the best of our knowledge, the empirical data used in our study came from communities that had not received MDA, but there is still a potential undocumented exposure to anthelmintics.…”

Performance of three rapid screening methods in the detection ofSchistosoma haematobiuminfection in school-age children in Southeastern Nigeria

“…10 According to WHO, 26 school-age children and adults of special risk group in MPA should be treated every 2 years but there is a growing discussion that adults in general contribute to community transmission of schistosomiasis and should be included in mass treatment. 27 More important is the fact that this MPA has been known to be endemic for schistosomiasis since 1986-1987. 28 Chemotherapeutic control was given in 1987 and 1995 and since then no mass treatment had been done in the area.…”