Annual report of the Australian National Enterovirus Reference Laboratory 2010-2011

Australia conducts clinical surveillance for cases of polio-like illness in children in accordance with the World Health Organization (WHO) recommended surveillance criteria for acute flaccid paralysis (AFP). AFP cases are ascertained either by clinicians notifying the Australian Paediatric Surveillance Unit or designated nurses enrolling cases as part of the Paediatric Active Enhanced Disease Surveillance system at four sentinel tertiary paediatric hospitals. The National Enterovirus Reference Laboratory (NERL), formerly the National Poliovirus Reference Laboratory, is accredited by the World Health Organization (WHO) for the testing of faecal specimens from cases of AFP and operates as a Poliovirus Regional Reference Laboratory for the Western Pacific Region. In 2010 and 2011, for the 3rd and 4th consecutive years, Australia met the WHO AFP surveillance performance indicator. This is indicative of a sensitive surveillance system capable of detecting an imported case of polio in children. However, the faecal collection rate for the virological investigation of AFP cases was below the WHO surveillance performance indicator in both years and represented a gap in Australia's polio surveillance. Enterovirus and environmental surveillance were established in Australia as virological surveillance to complement the clinical surveillance schemes. No poliovirus was detected by the clinical or virological surveillance schemes in 2010 or 2011 and Australia maintained its polio-free status. India was declared polio-free in January 2012, a significant step towards global polio eradication, leaving Afghanistan, Nigeria and Pakistan as the remaining countries endemic for wild poliovirus.

Annual report of the Australian National Enterovirus Reference Laboratory 2012

In 2012 no cases of poliomyelitis were reported through clinical surveillance in Australia, and poliovirus was not detected through virological surveillance. Australia conducts surveillance for cases of acute flaccid paralysis (AFP) in children less than 15 years as the main mechanism to monitor its polio-free status in accordance with World Health Organization (WHO) recommendations. Cases of AFP in children are notified to the Australian Paediatric Surveillance Unit or the Paediatric Active Enhanced Disease Surveillance System. In 2012 Australia reported 1.2 non-polio AFP cases per 100,000 children, meeting the WHO performance criterion for a sensitive system for the fifth year in a row. However the faecal specimen collection rate from AFP cases was 29%, which was well below the WHO target of 80%. Virological surveillance for poliovirus consists of two components. Firstly, the Enterovirus Reference Laboratory Network of Australia (ERLNA) reports on the typing of enteroviruses detected in or isolated from clinical specimens. Secondly, environmental surveillance is conducted at sentinel sites. These surveillance systems are co-ordinated by the National Enterovirus Reference Laboratory (NERL).

Comparison of automated and manual nucleic acid extraction methods for detection of enterovirus RNA

Automated nucleic acid extraction is an attractive alternative to labor-intensive manual methods. We compared two automated methods, the BioRobot M48 instrument (Qiagen, Inc.) and MagNA Pure (Roche Applied Sciences) methods, to two manual methods, the QIAamp Viral RNA Mini kit (Qiagen) and TRIzol (Invitrogen), for the extraction of enterovirus RNA. Analytical sensitivity was assessed by dilution analysis of poliovirus type 2 Sabin in cerebrospinal fluid. The sensitivity of PCR was equivalent after RNA extraction with QIAamp, BioRobot M48, and MagNA Pure. All 18 replicates of 100 PFU/ml were detected after extraction by the four methods. Fewer replicates of each successive dilution were detected after extraction by each method. At 10(-1) PFU/ml, 17 of 18 replicates were positive by QIAamp, 15 of 18 replicates were positive by BioRobot M48, and 12 of 18 replicates were positive by MagNA Pure; at 10(-2) PFU/ml, 4 of 17 replicates were positive by QIAamp, 2 of 18 replicates were positive by BioRobot M48, and 0 of 18 replicates were positive by MagNA Pure. At 10(-3) PFU/ml, no replicates were detected. Evaluation of TRIzol was discontinued after nine replicates due to a trend of lower sensitivity (at 10(-3) PFU/ml eight of nine replicates were positive at 100 PFU/ml, four of nine replicates were positive at 10(-1) PFU/ml, and zero of nine replicates were positive at 10(-2) PFU/ml). Concordant results were obtained in 24 of 28 clinical specimens after extraction by all methods. No evidence of contamination was observed after extraction by automated instruments. The data indicate that the sensitivity of enterovirus PCR is largely similar after extraction by QIAamp, BioRobot M48, and MagNA Pure; a trend of decreased sensitivity was observed after TRIzol extraction. However, the results of enterovirus PCR were largely concordant in patient samples, indicating that the four extraction methods are suitable for detection of enteroviruses in clinical specimens.

Frequency, viral loads, and serotype identification of enterovirus infections in Scottish blood donors

BACKGROUND

Enteroviruses are non-enveloped, frequently pathogenic RNA viruses infecting humans. Infection is potentially transmissible through blood or blood component transfusion from donor in the viremic phase before seroconversion for antibody. To investigate the threat to blood safety from enteroviruses, a large-scale survey of frequency and levels of viremia in blood donors was conducted.

STUDY DESIGNS AND METHODS

Blood donations from Scotland over a period of 22 calendar months were screened for enterovirus RNA sequences by PCR. Positive samples were quantified, and serotypes were identified by nucleotide sequencing of VP1.

RESULTS

From a total of 3658 pools of 95 donations tested, 73 samples that were enterovirus-positive were identified (corrected annual frequency 0.024% or 1 in 4000). The highest rates of viremia were in late summer months (e.g., 0.055%, 1 in 1800 in July) and lowest from January to May (0.009 and 0.012%). Viral loads ranged from 500 (the lower cutoff of the assay) to greater than 100,000 amplifiable enterovirus template copies per mL. Coxsackievirus A16, echoviruses 11 and 30, and enterovirus 71 were most often identified.

CONCLUSIONS

The detection of enterovirus-positive blood units indicates the potential for enteroviral transmission by blood components. Although the infrastructure established for PCR-based screening for HCV RNA would allow parallel screening for enteroviruses, any decision concerning donor testing would require further information on the outcome of transfusion-acquired enterovirus infections.

The classification of viruses infecting the respiratory tract

Following the boom in respiratory virology in the 1960s, species of rhinoviruses, coronaviruses, enteroviruses, adenoviruses, parainfluenza viruses and respiratory syncytial virus were added to influenza and measles viruses as causes of respiratory tract infection. In restricted patient groups, such as the immunocompromised, members of the family of herpesviruses including herpes simplex, cytomegalovirus, varicella-zoster virus, Epstein-Barr virus and human herpes virus 6 have also been associated with respiratory disease. This list of pathogens was extended last year with the discovery of a novel virus, the human metapneumovirus. More than 200 antigenically distinct viruses have been documented as causes of sporadic or epidemic respiratory infections in infants, children and adults. However, this varied and diverse group can be divided among six distinct families. Understanding some of the basic biology of these families gives an insight into possible strategies for diagnosis, control and therapy.