public IHttpActionResult Get()
        {
            var tree = LocalCachedProvider.Instance.Get("DiseaseTypeTree");

            if (tree != null)
            {
                return(Ok(tree));
            }
            var diseaseType = repository.GetDiseaseTypes().ToList();

            tree = CreateTree(diseaseType, 0).JsonSerialize();
            LocalCachedProvider.Instance.Set("DiseaseTypeTree", tree);
            return(Ok(tree));
        }