Viremic co-infections in children with allogeneic haematopoietic stem cell transplantation are predominated by human polyomaviruses.

Koskenvuo, Minna; Rahiala, Jaana; Sadeghi, Mohammadreza; Waris, Matti; Vuorinen, Tytti; Lappalainen, Maija; Norja, Päivi; Toppinen, Mari; Saarinen-Pihkala, Ulla; Allander, Tobias; Söderlund-Venermo, Maria; Hedman, Klaus; Ruuskanen, Olli; Vettenranta, Kim

BACKGROUND Viral infections remain the cause of key complications following haematopoietic stem cell transplantation (HSCT). The impact of multiple, concurrent viral reactivations/infections remains to be delineated. METHODS The clinical correlates of single or multiple viremic infections following HSCT and especially the occurrence of respiratory viruses in the bloodstream were investigated. We retrospectively searched for 23 viruses in a total of 184 sera from 53 paediatric patients. The time-points of interest were pre-HSCT, one, two and three months post-HSCT, and at discharge or death. The viruses were analyzed by quantitative or qualitative PCR. RESULTS Of the 53 patients, 13 (25%) had viraemias by multiple viruses and 27 (51%) by a single virus. Thirteen patients (25%) had no viruses detected by PCR during the study period. In the children with viremic co-infections, polyomaviruses predominated over herpes viruses. Nearly half the patients, 24/53 (45%) had a polyomavirus in their serum at one or more time-points. At 12/15 time-points and in 11/13 patients with co-infections polyomaviruses were involved, compared with 6/15 time-points and 6/13 patients for cytomegalovirus. Acute graft-versus-host disease (GvHD) and steroid use were significant risk factors for the viraemias caused by more than one virus. CONCLUSIONS Viral co-detection is a common finding in children undergoing HSCT. With large-scale viral screening also viruses other than CMV could be found as potential pathogens. In this study, BKPyV predominated over CMV as a contributor in viraemias caused by multiple viruses in children receiving HSCT.