Whole viral genome sequencing has the potential to provide physicians the ability to track outbreaks, particularly in the nosocomial setting, according to research published in The Journal of Infectious Diseases.1

Researchers from the University College London in the United Kingdom reported a case study that used sequencing to identify nosocomial transmission of varicella zoster virus.

The researchers discussed 3 patients, including a 55-year-old woman with end-stage renal failure and a 61-year-old man with advanced renal failure due to IgA nephropathy with secondary focal segmental glomerulosclerosis, who developed varicella following renal transplant.

The female patient, identified only as Patient 1, was VZV IgG negative prior to transplant and had not received a varicella vaccine, the researchers noted. She later died of varicella pneumonitis 3 three days after being admitted to intensive care.

The male patient, Patient 2, was IgG VZ negative prior to transplant despite having had chickenpox as a child. He was initially diagnosed with diagnosis of disseminated shingles, though a retrospective review later determined that he should have been diagnosed with recurrent varicella.

The researchers later determined that both patients had been on the same transplant ward as Patient 3, a 67-year-old man who had cough and deteriorating renal function 4 weeks after dual cadaveric renal transplant. He was placed into respiratory isolation and treated with antibiotics. He later developed shingles on his right leg and was transferred to intensive care after the rash became generalized and he developed respiratory failure.

Despite the presence of the second patient’s shingles, clinicians did not suspect nosocomial transmission at first because Patient 3 was isolated and did not initially have a rash. To determine whether there was a connection, the researchers genotyped and sequenced samples from all 3 patients and 2 unrelated cases that occurred in the hospital at the same time.

Genotyping identified virus from all 3 patients and 2 control patients as clade 1. All 5 had identical origin of replication sequences. Whole genome sequencing showed the virus present in Patients 1 and 2 to be identical to that of Patient 3, the index case, but not the controls.

Reference

1.    Depledge DP, Brown J, Macanovic J, Underhill G, Breuer J. Viral genome sequencing proves nosocomial transmission of fatal varicella. J Infect Dis. 2016; doi: 10.1093/infdis/jiw398.