Offender: virus or parasite or both.

Sir,

A very interesting report has been described by the authors, in which a toddler developed hemophagocytic lymphohistiocytosis (HLH) after coinfection with Epstein-Barr virus (EBV) and Leishmania.[1] We also had experience with EBV infection where the clinical profile was suggestive of acute leukemia in two patients, but ultimately one was diagnosed as having infectious mononucleosis while the other was found to have HLH.[2] The case described by the authors is unique in many aspects. Primary HLH is more commonly seen in infants as compared to adults although the latter are not immune from HLH secondary to infections. The toddler here had a coinfection with EBV as well as leishmania. A workup for secondary immunodeficiency should also have been done, including serology against human immunodeficiency virus (HIV). Antibody to rK39 antigen carries a sensitivity and specificity above 90% for diagnosis of visceral leishmaniasis and can help to avoid costly tests like polymerase chain reaction (PCR).[3] It is not mentioned whether Antibody against rK39 antigen was done or not. Whether HLH was due to EBV or Leishmania or was a combined effect of both is difficult to say as both are common etiological agents of HLH, though EBV is more common. Moreover, fever can respond to amphotericin in febrile neutropenia due to acquired infections, apart from leishmania.