The patient is a 14 months old Caucasian male with a known history of a myelosarcoma with affected bone marrow, recurrent HHV6 pneumonia, and multiple hospitalisations for several reason. Of note, the patient also suffers from a secondary immunodeficiency with predominant global lack of Immunoglobulins A, G, and M, which origin is not yet determined.
In January 2011 the patient was hospitalized for severe pneumonia accompanied by Norovirus-induced gastroenteritis with severe diarrhoea. Thereby the hospitalisation was required as the symptoms of diarrhoea were recurring since November 2010 and resulted in a stop of weight gain with the risk of dehydration. The patient was released from the hospital 3 days later but was re-hospitalized after four weeks due to aggravation of the gastrointestinal disease.
Despite reduced body weight the patient's general condition was classified as good, however accompanied by moderate anaemic but partially irritated flaked skin, reduced turgor, and wheezing, with radiological signs of an atypical pneumonia (banded shadows in the right upper lope and moderately reduced ventilation). Antibody levels and the blood lymphocyte count were extremely low, whilst monocytes and eosinophiles were significantly increased. Serologically, the patient was tested negative for CMV, EBV, parvovirus B19, and adenoviruses but positive for HHV6 with a viremia increasing from 5.3 × 106 to 7.8 × 106 copies per ml serum. Stool samples were tested negative for rotavirus, adenoviruses, norovirus, Clostridium difficile (strains and toxins), Salmonella, Shigella, Yersinia, and Campylobacter coli/jejuni as well as enteropathogenic E. coli.
Due to the ongoing and severe diarrhoea further analyses and pathological investigations were initiated. Thereby, the human herpes virus 6 (HHV6) infection was confirmed in blood, duodenum, and colon biopsies. Instead, human bocavirus was detected in stool and, surprisingly, in duodenum biopsies but not in blood or colon biopsies. Sequencing analyses and subsequent blastN revealed that HBoV1 was present with an E-value of 5 × 10-68 to 3 × 10-65 and a total matching score ranging between 292 and 297. No further signs for a pathological disorder were detected. Based on the pathological and virological diagnoses antiviral therapy was started with Cidofovir. During this therapy, the HHV6 viremia decreased but remained detectable in both serum and stool samples taken in two intervals of 14 days; thereby, most surprisingly, during the Cidofovir therapy HBoV became undetectable in the stool samples 2 weeks after the onset of the antiviral therapy while HHV6 remained positive.