Search

Ascariasis is of public health importance on the islands of Zanzibar (Unguja and Pemba). To shed light on the molecular epidemiology of this parasite, 68 Ascaris worms, obtained from 14 individuals in four Ungujan villages, were examined by isoenzyme analysis (ISA), DNA barcoding and microsatellite DNA profiling. ISA revealed genetic variation, which was confirmed by DNA barcoding. Nineteen worms recovered from individuals in Uganda were included for comparison. Sixteen unique DNA barcodes were identified, 15 on Unguja and three in Uganda with two shared between. These two barcodes were found in all four Ungujan villages. Worms from Tumbatu-Jongowe, an isolated village on an islet off Unguja, seemed particularly diverse. Within our barcodes, three exact matches were found with Chinese Ascaris retrieved from pigs, which is perhaps surprising given the present rarity of these animals on Unguja. Microsatellite profiling and population genetic analysis revealed further genetic diversity within our samples although population sub-structuring within Unguja was minor in comparison to that between Unguja and Uganda. As African Ascaris has not been subjected to detailed molecular scrutiny, this new diversity represents an important piece in its evolutionary jigsaw and such population markers are informative in monitoring worm dynamics during ongoing control., (Copyright © 2011 Royal Society of Tropical Medicine and Hygiene. All rights reserved.)

Background: Urinary schistosomiasis is responsible for a variety of debilitating conditions; foremost perhaps are urinary tract pathologies (UTPs). Although portable ultrasonography can be used to detect UTPs visually, there is still a need for rapid morbidity assessment (henceforth referred to as RaMA) tools that can be deployed in the field during implementation, monitoring and evaluation of control programmes. We therefore aimed to determine associations between excreted urine-albumin, as measured using a HemoCue photometer, and UTPs, as detected by ultrasonography, in children and adults from an urinary schistosomiasis endemic area in Zanzibar., Methodology/principal Findings: In a survey of 140 school-children of both sexes (aged 9 to 15 yr) and 47 adult males (> or =16 yr) on the island of Unguja, the prevalence of egg-patent urinary schistosomiasis was 36.4% (CI(95) 28.5-45.0%) and 46.8% (CI(95) 32.1-61.9%) (P = 0.14), and that of UTPs was 39.4% (CI(95) 31.0-48.3%) and 64.4% (CI(95) 48.8-78.1%) (P = 0.006), respectively. In school-children, raised urine-albumin concentrations (>40 mg/L) were associated, albeit non-significantly, with prevalence of infection (OR = 3.1, P = 0.070), but more specifically and significantly with the prevalence of micro-haematuria (OR = 76.7, P<0.0001). In adults, elevated urine-albumin excretion was associated with UTPs, particularly lesions of the bladder wall (OR = 8.4, P = 0.013). Albuminuria showed promising diagnostic performance, especially in school-aged children with sensitivity of 63.3% and specificity of 83.1% at detecting lower UTPs, i.e. bladder-wall lesions (ultrasonography as 'gold standard')., Conclusion/significance: This study indicates that albuminuria assays could be used as a RaMA tool for monitoring UTP prevalence during control programmes, as well as a tool for selecting those with more chronic bladder-wall lesions without resorting to ultrasonography.

To develop better monitoring protocols for detection of urinary schistosomiasis during ongoing control interventions, two commercially available diagnostic tests - the urine-circulating cathodic antigen (CCA) strip and the soluble egg antigen enzyme-linked immunosorbent assay (SEA-ELISA) - were evaluated for detection of Schistosoma haematobium infections in 150 schoolchildren from Zanzibar. The children originated from five primary schools representative of different levels of disease endemicity across the island; using standard urine filtration assessment with microscopy, mean prevalence of S. haematobium was 30.7% (95% confidence interval (CI)=23.4-38.7%) and a total of 35.3% (95% CI=27.7-43.5%) and 8.0% (95% CI=4.2-13.6%) children presented with micro- and macro-haematuria, respectively. Diagnostic scores of the urine-CCA strip were not satisfactory, a very poor sensitivity of 9% (95% CI=2-21%) was observed, precluding any further consideration. By contrast, the performance of the SEA-ELISA using sera from fingerprick blood was good; a sensitivity of 89% (95% CI=76-96%), a specificity of 70% (95% CI=60-79%), a positive predictive value of 57% (95% CI=45-69%) and a negative predictive value of 90% (95% CI=86-98%) were found. At the unit of the school, a positive linear association between prevalence inferred from parasitological examination and SEA-ELISA methods was found. The SEA-ELISA holds promise as a complementary field-based method for monitoring infection dynamics in schoolchildren over and above standard parasitological methods.

'Kick-out-Kichocho' is an integrated helminth-control initiative that is aimed at reducing the burden of urinary schistosomiasis and soil-transmitted helminthiases (STH) on Zanzibar Island (Unguja), in Tanzania. Like other initiatives based on preventive chemotherapy, the programme is mainly school-based and, consequently, pre-school children (aged < or =6 years) are not targeted specifically. To assess the importance of urinary schistosomiasis, STH and malaria, as well as the occurrence of anaemia and growth retardation among these younger children, an epidemiological survey has been undertaken, in a rural area of Unguja, among 152 pre-school children and their 113 mothers. In the pre-school children investigated, urinary schistosomiasis was rare because of the children's lack of contact with environmental water. Malaria was also rare in the children, probably as a consequence of the study season, the widespread use of insecticide-treated bednets and the good access to first-line antimalarial drugs. In contrast, the prevalences of infection with at least one soil-transmitted helminth and of anaemia were alarmingly high among the pre-school children, at 50.0% [95% confidence interval (CI)=40.4%-59.6%) and 73.4% (CI=?65.2%-80.5%), respectively; the corresponding values in the children's mothers were 35.2% (CI=25.4%-45.9%) and 25.9% (CI=18.0%-35.3%). In the rural study area, Kandwi was identified as a hamlet with particularly high levels of transmission of soil-transmitted helminths, and household aggregations of STH were common. To reduce the present health inequities, the future integration of pre-school children within ongoing anthelmintic-control programmes in schools is strongly recommended.