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Alan Fenwick

Publications and source records attributed to Alan Fenwick.

24 records · Page 2Linked to original sources
PubMed2005

Rapid assessment of Schistosoma mansoni: the validity, applicability and cost-effectiveness of the Lot Quality Assurance Sampling method in Uganda.

Rapid and accurate identification of communities at highest risk of morbidity from schistosomiasis is key for sustainable control. Although school questionnaires can effectively and inexpensively identify communities with a high prevalence of Schistosoma haematobium, parasitological screening remains the preferred option for S. mansoni. To help reduce screening costs, we investigated the validity of Lot Quality Assurance Sampling (LQAS) in classifying schools according to categories of S. mansoni prevalence in Uganda, and explored its applicability and cost-effectiveness. First, we evaluated several sampling plans using computer simulation and then field tested one sampling plan in 34 schools in Uganda. Finally, cost-effectiveness of different screening and control strategies (including mass treatment without prior screening) was determined, and sensitivity analysis undertaken to assess the effect of infection levels and treatment costs. In identifying schools with prevalences > or =50%, computer simulations showed that LQAS had high levels of sensitivity and specificity (>90%) at sample sizes <20. The method also provides an ability to classify communities into three prevalence categories. Field testing showed that LQAS where 15 children were sampled had excellent diagnostic performance (sensitivity: 100%, specificity: 96.4%, positive predictive value: 85.7% and negative predictive value: 92.3%). Screening using LQAS was more cost-effective than mass treating all schools (US$218 vs. US$482/high prevalence school treated). Threshold analysis indicated that parasitological screening and mass treatment would become equivalent for settings where prevalence > or =50% in 75% of schools and for treatment costs of US$0.19 per schoolchild. We conclude that, in Uganda, LQAS provides a rapid, valid and cost-effective method for guiding decision makers in allocating finite resources for the control of schistosomiasis.

Adolescent↗
PubMed2005

Efficacy of myrrh in the treatment of human Schistosomiasis mansoni.

Myrrh (Mirazid) has been produced and marketed as an antischistosomal drug since 2001. The current study was designed to assess the efficacy of a commercially available product of myrrh. One hundred four individuals, infected with Schistosoma mansoni, were randomized in two groups, one for myrrh and the second for praziquantel. Treatment-whether myrrh or praziquantel-was given twice with a 3-week interval. The cure rate with myrrh was very low, 15.6% after the first treatment, and 8.9% after the second treatment. Egg reduction among uncured persons was also very low, being 17.2% after the first treatment, and 28% after the second treatment. Praziquantel cure rate was 73.7% and 76.3%, and individuals still passing S. mansoni ova after praziquantel treatment showed a substantial reduction in the geometric mean egg counts (84% and 88.2% after the first and second treatments, respectively). When 34 individuals-uncured after two myrrh treatments-were offered praziquantel in the standard dose, 32 of them stopped passing S. mansoni eggs when tested 4 weeks post-treatment. The results of the current study raise serious doubts about the antischistosomal properties of Mirazid.

Adolescent↗
PubMed2005

Field evaluation of the Meade Readiview handheld microscope for diagnosis of intestinal schistosomiasis in Ugandan school children.

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 (160x), 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.

Animals↗
PubMed2004

Evaluating the epidemiological impact of national control programmes for helminths.

During the past decade, there has been renewed commitment to programmes for helminth control, and several international initiatives have been launched. Scientific evaluation of large-scale interventions to reduce the incidence of infection and associated morbidity and mortality is vital, not only to demonstrate health benefits, but also to assess cost-effectiveness to show that monies from donor agencies have been used wisely. Using the example of schistosomiasis, this article outlines a framework for the evaluation of the impact of national control programmes, highlighting the important epidemiological and practical issues that must be addressed.

Animals↗