Minimal training of fieldworkers in resource-poor settings for rapid assessment of scabies prevalence: a diagnostic accuracy study in Mopeia, Mozambique

BackgroundScabies is endemic in many tropical, resource-poor areas, causing significant morbidity. Our understanding of the true burden of scabies in Africa is very limited, and we lack tools to accurately assess its prevalence, given our reliance on highly qualified doctors and microscopy for diagnosis. The primary objective of this study was to assess the accuracy of minimally trained fieldworker diagnosis of scabies, compared to diagnosis by experienced medical doctors. MethodologyWe trained 62 fieldworkers with a minimum of secondary school education in the diagnosis of scabies (categorized as either clinical or suspected), and in terms of severity, based on lesion count. Immediately after the training, we assessed their knowledge based on written assessments. We also assessed the diagnostic accuracy of a sub-sample of the fieldworkers in the field compared to the reference standard (experienced medical doctors). 193 individuals were assessed for scabies. The sensitivity, specificity, PPV and NPV were calculated, as well as agreement (kappa coefficients) between medical doctors and between fieldworkers. ResultsThe overall median results in written assessments were around 80%. Of the 193 people assessed for scabies, 27% were classified as having scabies according to the reference standard. The sensitivity of fieldworker diagnosis compared to the reference standard was 95% (95%CI 93 -100), and the specificity was 99% (95%CI 99-100). The sensitivity for severe scabies was lower at 64% (95%CI 51-75), and the mean specificity was 100%. Kappa coefficients were 1.00 between medical doctors and 0.95 between fieldworkers. ConclusionsFieldworkers without medical qualifications were capable of diagnosing scabies to a similar level of accuracy as experienced medical doctors, after a short period of focal training. This may facilitate rapid assessments of scabies prevalence for public health purposes and decisions about MDA implementation in similar settings. Author summaryO_ST_ABSWhat is already known on this topicC_ST_ABSScabies is a disease that causes intense itchiness which can affect peoples wellbeing and ability to attend work or school, and if left untreated it can lead to further, more severe complications. Typically, scabies is diagnosed by specialist medical doctors using microscopy. However, many countries lack these resources and therefore there is a paucity of data on scabies prevalence. What this study adds-In our study, we trained people with no previous medical training in the diagnosis of scabies over a few days through presentations and assessments. We demonstrated that they were able to diagnose scabies to a similar degree of accuracy compared to experienced medical doctors. How this study might affect research, practice or policy-Understanding that minimally trained fieldworkers are able to diagnose scabies to a similar degree of accuracy as medical doctors, may facilitate the collection of data for survey purposes in resource-poor areas, which in turn may promote advocacy for the disease.