Diagnosis of human parechovirus infections of the central nervous system with a commercial real-time reverse transcription–polymerase chain reaction kit and direct genotyping of cerebrospinal fluid specimens

Epidemic and Inter-epidemic Burden of Pediatric Human Parechovirus Infection in New South Wales, Australia, 2017-2018

BACKGROUND

Human parechovirus (HPeV) typically infects young children, and although infection is often asymptomatic, some types (eg, HPeV3) are associated with severe clinical manifestations, including central nervous system infection or sepsis-like syndrome, particularly affecting young infants. The third documented national epidemic of HPeV occurred in Australia in 2017-2018.

METHODS

Four public laboratories that perform almost all of the HPeV PCR testing in New South Wales provided data regarding HPeV tests performed from July 1, 2017 to June 30, 2018. Limited demographic and clinical data were obtained from electronic medical records for laboratory test-positive cases that presented to each of the 3 pediatric hospitals in New South Wales.

RESULTS

Five hundred eighty-one HPeV-positive samples obtained from 395 cases were included in the analysis. The peak of the outbreak occurred in late November 2017 (approximately 35 new cases each week), with the main HPeV epidemic occurring between the spring and summer months of September 2017 to January 2018; although this seasonality was observed primarily in infants less than 12 months of age. Among the 388 pediatric cases, almost half were younger than 2 months (188; 47%) and only 10 were children older than 2 years. The annualized estimated incidence of laboratory confirmed HPeV infection in children was approximately 142.4 cases per 100,000 children younger than 5 years in New South Wales during the epidemic season.

CONCLUSIONS

The large burden of HPeV infection and disease identified in young infants in this and previous Australian studies highlight the need for more comprehensive national surveillance of HPeV infections and improved prevention strategies.

Enteroviruses and Parechoviruses

Infections with enteroviruses and human parechoviruses are highly prevalent, particularly in neonates, where they may cause substantial morbidity and mortality. Individuals with B-cell-related immunodeficiencies are at risk for severe enteroviral infections, usually a chronic and fatal meningoencephalitis. In transplant recipients and patients with malignancy, enterovirus infections typically involve the respiratory tract, but cases of severe, disseminated infection have been described. The mainstay of diagnosis for enterovirus and human parechovirus infections involves the use of molecular diagnostic techniques. However, routine nucleic acid-detection methods for enteroviruses will not detect human parechoviruses. Laboratory diagnosis of these viral infections is important in determining a patient's prognosis and guiding clinical management.

Relevance of human parechovirus detection in cerebrospinal fluid samples from young infants with sepsis-like illness

BACKGROUND

The human parechoviruses (HPeVs) were recently recognized as important viral pathogens involved in various illnesses in young children. However, routine detection is not performed in most clinical laboratories. Therefore, in this study, we aim to assess the relevance of HPeV detection in cerebrospinal fluid (CSF) of infants, according to clinical presentation.

METHODS

A total of 120 CSF specimens collected during 2012 from infants aged less than 1 year and previously reported negative for Herpes simplex virus (HSV) and enterovirus were selected. HPeV detection was performed with a commercially available real-time RT-PCR and HPeV strains from positive samples were subsequently genotyped by sequencing.

RESULTS

HPeV RNA was detected in nine (7.5%) CSF samples. The median age of infected children was 41 days (range: 19-122 days). HPeV genotyping could be performed on five samples and three HPeV-3, one HPeV-1, and one HPeV-4 were identified. Hyperthermia associated with mottled skin was the predominant clinical presentation. Most clinical presentations of HPeV-infected infants were mild with a final diagnosis of sepsis-like illness. The median hospital stay was 3.5 days and five children received antibiotics.

CONCLUSION

Routine detection of HPeV in CSF may allow differential diagnosis of enterovirus infection and improve etiologic identification of sepsis-like illness in children.