Browsing by Author "Fenwick, Alan"

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Field Evaluation of the Meade Readiview Handheld MicroscopeFor Diagnosis of Intestinal Schistosomiasis in Ugandan School Children
(The American Society of Tropical Medicine and Hygiene, 2005) Russell Stothard, J.; Kabatereine, Narcis B.; Tukahebwa, Edridah M.; Kazibwe, Francis; Mathieson, William; P. Webster, Joanne; Fenwick, Alan
A novel, inexpensive handheld microscope, the Meade Readiview, was evaluated for field diagnosis of intestinal schistosomiasis by comparison of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) against conventional compound microscopy as part of a parasitologic survey in nine sentinel schools and a rapid mapping survey across 22 schools in Uganda. Fecal smears from 685 primary school children were examined and the overall prevalence of Schistosoma mansoni was 45%. However, prevalence by school ranged widely from 0% to 100%. For individual diagnosis the Readiview had a sensitivity of 85%, a specificity of 96%, a PPV of 95%, and an NPV of 88%. Due to the poorer movement control of the glass slide on the Readiview stage, fecal smears with less than four eggs could be overlooked. At the highest magnification (160×), egg-like objects could be confounding. Estimating prevalence by school was usually within ± 7% of that of conventional microscopy. Since the Readiview is more robust and portable, both in size and weight, and one-tenth as expensive as the traditional compound microscope, a change in the logistics and costs associated with field infection surveillance is possible. This inexpensive microscope is a pragmatic alternative to the compound microscope. It could play an important role in the collection of prevalence data to better guide anthelmintic drug delivery and also empower the diagnostic capacity of peripheral health centers where compound microscopes are few or absent.
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
(Transactions of the Royal Society of Tropical Medicine and Hygiene, 2006-06) Balena, Julie; Stotharda, J. Russell; Kabatereine, Narcis B.; Tukahebwa, Edridah M.; Kazibwee, Francis; Whawell, Sarah; Webster, Joanne P.; Utzinger, J¨urg; Fenwick, Alan
Summary: The objectives of this study were to determine the prevalence and distribution of distended abdomens among Ugandan school children across a range of eco-epidemiological settings and to investigate the relationship between distended abdomens and helminth infections, in particular Schistosoma mansoni, before and 1-year after anthelminthic treatment. A cross-sectional survey was conducted on 4354 school children across eight districts, with a longitudinal 1-year follow-up of 2644 children (60.7%). On both occasions, parasitological,biometrical and clinical data were collected for each child. Baseline prevalence of S. mansoni and hookworms was 44.3% and 51.8%, respectively. Distended abdomens, defined as an abdominal circumference ratio (ACR) >1.05, were observed in 2.5% of the sampled children,several of whom presented with particularly severe distensions necessitating hospital referral.ACR scores were highly overdispersed between districts and schools. Multivariate regression analysis revealed that S. mansoni infection accounted for only a small fraction of ACR variation,suggesting that either single point prevalence and intensity measures failed to reflectthis more chronically evolved morbidity and/or that other interacting factors were involved,
Progress towards countrywide control of schistosomiasis and soil-transmitted helminthiasis in Uganda
(Elsevier Ltd., 2005-03-09) Kabatereinea, Narcis B.; Tukahebwaa, Edridah; Kazibwea, Francis; Namwangyea, Harriett; Zarambab, Sam; Brooker, Simon; Russell Stothardd; Kamenka, Cara; Whawell, Sarah; Webster, Joanne P.; Fenwick, Alan
Schistosomiasis caused by infection with Schistosoma mansoni is a serious public health burden in 38 of the 56 districts of Uganda. This article reviews the initial experience of the national control programme. Launched in 2003, this started with a pilot phase with the main aim of utilizing the experience to formulate feasible and appropriate methods of drug delivery. Overall, 432 746 people were treated and coverage was 91.4% in schools and 64.7% in communities. The issues raised by independent evaluators included that most communities did not participate in the selection of community drug distributors (CDD) and that teachers and CDDs needed refresher training mainly on health education and the management of side effects.As a way forward, it is suggested that the Ministry of Health should integrate deworming into the existing health infrastructure so that every time a child is reached for any health service, the child is also dewormed.
Use of circulating cathodic antigen (CCA) dipsticks for detection of intestinal and urinary schistosomiasis.
(2005) Stothard, J. Russell; Kabatereine, Narcis B.; Edridah M., Tukahebwa; Kazibwe, Francis; Rollinson, David; William, Mathieson; Webster, Joanne P; Fenwick, Alan
An evaluation of a commercially available antigen capture dipstick that detects schistosome circulating cathodic antigen (CCA) in urine was conducted in representative endemic areas for intestinal and urinary schistosomiasis in Uganda and Zanzibar, respectively. Under field-based conditions, the sensitivity (SS) and specificity (SP) of the dipstick was 83 and 81% for detection of Schistosoma mansoni infections while positive predictive (PPV) and negative predictive values (NPV) were 84%. Light egg-positive infections were sometimes CCA-negative while CCA-positives included egg-negative children. A positive association between faecal egg output and intensity of CCA test band was observed. Estimating prevalence of intestinal schistosomiasis by school with dipsticks was highly correlated (r = 0.95) with Kato-Katz stool examinations, typically within ±8.5%. In Zanzibar, however, dipsticks totally failed to detect S. haematobium despite examining children with egg-patent schistosomiasis. This was also later corroborated by further surveys in Niger and Burkina Faso. Laboratory testing of dipsticks with aqueous adult worm lysates from several reference species showed correct functioning, however, dipsticks failed to detect CCA in urine from S. haematobium-infected hamsters.While CCA dipsticks are a good alternative, or complement, to stool microscopy for field diagnosis of intestinal schistosomiasis, they have no proven value for field diagnosis of urinary schistosomiasis. At approximately US $2.6 per dipstick, they are presently too expensive to be cost-effective for wide scale use in disease mapping surveys unless Lot Quality Assurance Sampling (LQAS) strategies are developed.