In the first two patients, the IgM response was delayed, while the quantitative real-time RT-PCR for PUUV RNA was positive, suggesting it as a valuable tool to hasten the aetiological diagnosis [18] . Notably, in patient 1 PUUV RNA was found in serum from three weeks prior to the acute onset of disease, that is, in incubation phase and consistent with hantavirus incubation time ranging from one to four weeks [3, 24] .