Challenges of Congenital HHV6 Infection Diagnosis and Treatment: Two Case Reports and Literature Review.

Introduction: Congenital human herpesvirus 6 (HHV6) infection occurs in 1% of the general population and may result from the transmission of an inherited chromosomally integrated HHV6 (iciHHV6) or transplacental infection. It is mostly asymptomatic.

Case Reports: Case 1: a 29th-week-old female preterm newborn, admitted to the neonatal intensive care unit, became clinically unstable and irritable on the 20th day of hospitalization. Cranial ultrasound, revealed a significant posthemorrhagic tetraventricular dilation, with signs of ventriculitis. Investigations revealed HHV6 positivity on cerebrospinal fluid polymerase chain reaction multiplex panel testing and HHV6-DNA high viral loads in plasma samples. Case 2: a female late preterm newborn was admitted to the neonatal intensive care unit due to early-onset sepsis. Investigations revealed group B streptococcus positive blood cultures and cerebrospinal fluid HHV6 positivity on polymerase chain reaction multiplex panel testing, with negative bacterial culture. After 3 days of adequate antibiotic treatment, she maintained persistent moaning, which motivated a cranial ultrasound, revealing mild brain edema. Clinical improvement was observed only after beginning antiviral treatment in both newborns. Due to the persistency of high viral loads in both cases, despite antiviral treatment and clinical improvement, an iciHHV6 was suspected and posteriorly confirmed.

Discussion/conclusion: Congenital iciHHV6 infection diagnosis is challenging because the presence of an iciHHV6 results in persistently high viral loads, even in the absence of active infection. Only a few diagnostic techniques can confirm active replication; unfortunately, these are not available in most countries. The decision to initiate antiviral treatment should be based on clinical judgment. Better ways for the diagnosis of active infection are needed.