In addition to issues of performance of tests in active and treated VL in patients from different geographical areas, there is the issue of their performance in asymptomatic individuals infected with L. infantum. Active VL, but not asymptomatic infections, are accompanied by inflammation [32,33] and polyclonal activation of B cells [34], responses which may facilitate targeting the k39 antigen, thus explaining why the tests based on this antigen do not detect asymptomatic infections. The gene discussed is KRT39; the disease is infection.