A nosocomial outbreak of hepatitis B virus infection in a paediatric haematology and oncology unit in South Africa

Abstract

Background: Nosocomial outbreaks of hepatitis B virus (HBV) have beenwell described. Horizontal transmission plays an important role in the epidemiology of HBV in sub-Saharan Africa, but the mechanisms of transmission are poorly understood. Currently, South Africa has no national guidelines for prevention of hepatitis B in paediatric oncology units. Methods & Materials: A retrospective descriptive study of a HBV outbreak that started in March 2012, was performed at the Paediatric Haematology and Oncology Unit of a large tertiary hospital. Results: Thirty-eight cases were identified of which 16/38 (42%) presented with clinical or biochemical features of hepatitis. The asymptomatic group (58%) was identified by contact tracing through plotting transmission events. The mean age was 9.7 years (range 1.4 to 17.3 years) with a male:female ratio of 1:0.65. The underlying diagnoses were haematological malignancies (27/38, 71%), non-haematological malignancies (9/38, 24%) and non-malignant haematology (2/38, 5%). One patient was HIVinfected. In all patients theHepatitis B surface antigenwas negative at first contact with the oncology service. The HBV viral load, available for 28 patients at initial diagnosis, had a median value of 68 739 713 IU/ml (x (1) =94 IU/ml; Q 1=668 544 IU/ml; Q 3≥170 000 000 IU/ml; x (28)≥170 000 000 IU/ml). Twenty nine patients (76%) wereHBeAgpositive. Phylogenetic analysiswas done on 7 samples, using the precore/core gene. All sequences belonged to HBV genotype E and formed a separate cluster (97% bootstrap value). The index case of the outbreak could not be identified with certainty but on-going transmission was suspected to be through contaminated multiple-dose vials and intravenous access toppers. There were no HBV related deaths, 11/38 (29%) had spontaneous resolution, 18/38 remain chronic carriers and six patients died due to non-HBVrelatedcauses.Only threepatients (8%)were lost to follow up. Conclusion: Nosocomial transmission of HBV infection remains problematic, especially in vulnerable patient groups needing prolonged hospitalisation. Continued vigilance, repeated screening and correct infection prevention and control measures need to be standard of care in paediatric oncology units. This outbreak highlights the need for guidelines to prevent similar outbreaks from recurring.