Application of Cognitive Engineering Principles to the Redesign of a Dichotomous Identification Key for Parasitology

Dichotomous identification keys are used throughout biology for identification of plants, insects, and parasites. However, correct use of identification keys can be difficult as they are not usually intended for novice users who may not be familiar with the terminology used or with the morphology of the organism being identified. Therefore, we applied cognitive engineering principles to redesign a parasitology identification key for the Internet. We addressed issues of visual clutter and spatial distance by displaying a single question couplet at a time and by switching to the appropriate next couplet after the user made a choice. Our analysis of the original paper-based key versus the Web-based approach found that of 26 applicable cognitive engineering principles, the paper key did not meet 4 (15%) and partially met 11 (42%). In contrast, the redesigned key met 100% of 32 applicable cognitive engineering principles.

Population-based cross -sectional survey on intestinal helminth infections with a focus on taeniasis among residents of El Paso, Texas and Ciudad Juarez, Mexico

Few studies have been conducted on the epidemiology of enteric infectious diseases of public health importance in communities along the United States-Mexico border, and these studies typically focus on bacterial and viral diseases. The epidemiology of intestinal helminth infections along the border has not recently been explored, and there are no published reports for El Paso and Ciudad Juarez, both of which are high traffic urban areas along the Texas-Mexico border. The purpose of this research project was to conduct a cross-sectional epidemiologic survey for enteric helminths of medical importance along the Texas-Mexico border region of El Paso and Ciudad Juarez and to evaluate risk factors for exposure to these parasites. In addition, an emphasis was placed on the zoonotic tapeworm, Taenia solium. This tapeworm is especially important in this region because of the increasing incidence of neurocysticercosis, a severe disease spread by carriers of intestinal T. solium. Fecal samples were collected from individuals of all ages in a population-based cross-sectional household survey and evaluated for the presence of helminth parasites using fecal flotations. In addition, a Taenia coproantigen enzyme linked immunosorbent assay (ELISA) was performed on each stool sample to identify tapeworm carriers. A standardized questionnaire was administered to identify risk factors and routes of exposure for enteric helminth infections with additional questions to assess risk factors specific for taeniasis. The actual prevalence of taeniasis along the Texas-Mexico border was unknown, and this is the first population-based study performed in this region. Flotations were performed on 395 samples and four (1%) were positive for helminths including Ascaris, hookworms and Taenia species. Immunodiagnostic testing demonstrated a prevalence of 2.9% (11/378) for taeniasis. Based on the case definition, a 3% (12/395) prevalence of taeniasis was detected in this area. In addition, statistical analyses indicate that residents of El Paso are 8.5 times more likely to be a tapeworm carrier compared to residents of Juarez (PR=8.5, 95% CI=2.35, 30.81). This finding has important implications in terms of planning effective health education campaigns to decrease the prevalence of enteric helminths in populations along the Texas-Mexico border. ^