Merkus' research interest has always been focused on development and improvement of childfriendly, noninvasive diagnostic techniques, and of the treatment for children with asthma and cystic fibrosis. This includes clinical intervention trials, descriptive and randomized studies into the quality of life of children with Asthma and Cystic Fibrosis, but also testing and evaluating existing pulmonary function tests, and assessment of biomarkers in exhaled breath of patients for early detection of respiratory infections with Pseudomonas Aeruginosa or Aspergillus Fumigatus.; A further aim is to enhance the prognosis and quality of life of children with asthma and cystic fibrosis. This is achieved through the use of an extensive network. This involves very important and productive collaborations with other departments within Radboudumc, other faculties within Radboud University, and in numerous research institutes and clinics within the Netherlands. The focus of our medical research has gradually shifted more towards respiratory infections (fungal, viral and bacterial), inflammation patterns and host response, while the other focus of our group is nowadays more emphasizing adherence to treatment, quality of life and the role of e-health in optimizing patient satisfaction and adherence to treatment.