'Retrospective" case-control study?? Berihun Megabiaw Zeleke, University of Gondar 17 February 2015 I am very happy to read such a study on a neglected tropic epidemic infectious disease. Have few comments on the article 1. Case-control study is always retrospective by its very nature! hence, no need to say retrospect since no prospective case-control study exists. 2. This study is a typical survey followed by an internal comparison group (created after enough number of the two groups were obtained). What would the investigators have done if there were very few co-infections or almost all were con-infected. That would have stoped at survey stage and case control was optional at the start. Similarly, it was stated as ....multicenter retrospective survey!" survey is not retrospective (does it mean the data was already collected in the past and investigators used a secondary data?). Case-control study is done to identify determinant factors, the conclusion lacks such components. Competing interests No competing interest at all and strongly believe that my comments will improve the paper and will by no means have any impact on the fact that it is published.