The Role of More Sensitive Helminth Diagnostics in Mass Drug Administration Campaigns: Elimination and Health Impacts.

Diagnostics play a crucial role in determining treatment protocols and evaluating success of mass drug administration (MDA) programmes used to control soil-transmitted helminths (STHs). The current diagnostic, Kato-Katz, relies on inexpensive, reusable materials and can be used in the field, but only trained microscopists can read slides. This diagnostic always underestimates the true prevalence of infection, and the accuracy worsens as the true prevalence falls. We investigate how more sensitive diagnostics would impact on the management and life cycle of MDA programmes, including number of mass treatment rounds, health impact, number of unnecessary treatments and probability of elimination. We use an individual-based model of STH transmission within the current World Health Organization (WHO) treatment guidelines which records individual disability-adjusted life years (DALY) lost. We focus on Ascaris lumbricoides due to the availability of high-quality data on existing diagnostics. We show that the effect of improving the sensitivity of diagnostics is principally determined by the precontrol prevalence in the community. Communities at low true prevalence (<30%) and high true prevalence (>70%) do not benefit greatly from improved diagnostics. Communities with intermediate prevalence benefit greatly from increased chemotherapy application, both in terms of reduced DALY loss and increased probability of elimination. Our results suggest that programmes should be extended beyond school-age children, especially in high prevalence communities. Finally, we argue against using apparent or measured prevalence as an uncorrected proxy for true prevalence.

Detecting depression after pregnancy: the validity of the K10 and K6 in Burkina Faso.

OBJECTIVE: The K10 and K6 are short rating scales designed to detect individuals at risk for depressive disorder, with or without anxiety. Despite being widely used, they have not yet been validated for detecting postnatal depression. We describe the validity of these scales for the detection of postnatal depression in Burkina Faso. METHOD: The English language version of the K10 questionnaire was translated into West African French and local languages for use in Burkina Faso. Scores for 61 women were compared with the diagnostic interview made by a local psychiatrist within 3 days of administering the K10. RESULTS: Clinical assessment found that 27 (44%) women were probable cases of depression. Internal consistency of K10 and K6 scores, defined by Cronbach's alpha coefficient, was 0.87 and 0.78, respectively, indicating satisfactory reliability. The performance of the scores was not significantly different, with areas under the curve of 0.77 and 0.75 for the K10 and K6, respectively. To estimate prevalence of depression, we suggest cut-offs of > or =14 for the K10 and between > or =9 and > or =11 for the K6 for identifying women at high risk of depression. At > or =14, the K10 has 59% sensitivity, 91% specificity; at > or =10, the K6 has 59% sensitivity and 85% specificity. CONCLUSION: This study suggests that K10 and K6 are reasonably valid measures of depression among postpartum women in Burkina Faso and can be used as relatively cheap tools for estimating prevalence of postnatal depression in developing countries.

Distance to water source and altitude in relation to active trachoma in Rombo district, Tanzania.

OBJECTIVES: To investigate the relationship between distance to water source, altitude and active trachoma in children in Rombo district, Tanzania. METHODS: In each of Rombo's 64 villages, 10 balozis (groups of 8-40 households) were selected at random and all resident children aged 1-9 years were examined for clinical signs of active trachoma. The households of these children and village water sources were mapped using differentially corrected global positioning system data to determine each household's altitude and distance to the nearest water supply. RESULTS: We examined 12 415 children and diagnosed 1171 cases of active trachoma (weighted prevalence=9.1%, 95% CI: 8.0, 10.2%). Active trachoma prevalence ranged from 0% to 33.7% across villages. Increasing distance to the nearest water source was significantly associated with rising trachoma prevalence (age-adjusted odds ratio for infection (OR) for highest quartile compared to lowest=3.56, 95% CI 2.47, 5.14, P for trend <0.0001). Altitude was significantly inversely associated with trachoma prevalence (age-adjusted OR for highest quartile compared to lowest=0.55, 95% CI 0.41, 0.75, P for trend <0.0001). These associations remained significant after adjustment in multivariate analysis. CONCLUSIONS: Trachoma is endemic in Rombo district, although the prevalence varies considerably between villages. Spatial mapping is a useful method for analysing risk factors for active trachoma.