Norovirus RT-PCR Testing - Laboratory Guidelines©

This service is available to help rapidly identify potential outbreaks of diarrhoea and vomiting in hospitals or institutions. Testing may also be performed on samples referred from private practitioners if an outbreak situation exists. An outbreak is defined as two or more cases of illness linked to a common cause. Testing of isolated cases is not recommended.

Testing criteria

Samples should only be submitted for testing if there is a suspect outbreak with the following:

• Incubation period between 10 and 50 hours (mean 24 hours).
• Predominant symptoms vomiting and/or diarrhoea (usually last less than 24 to 48 hours).
• Clinical samples negative for bacterial or other viral pathogens (optional).

Sample type

Stool samples are preferred for testing. Vomitus is accepted only if the patient has vomited 2 or more times and a stool sample cannot be obtained. Both sample types should be placed in sterile stool collection container and be at least one third full.

Timing of specimen

It is recommended that samples be collected during the symptomatic phase of the illness.

Number of samples from an outbreak

It is recommended that for each outbreak that up to 6 samples are sent per outbreak area. Once the presence of norovirus is confirmed in two cases, specimens from subsequent cases will not be tested.

Two positive samples from each clearly defined outbreak will be forwarded by Virology, CHL to The Norovirus Reference Laboratory at ESR, for further analysis for epidemiological purposes.

Sample transport and storage

Samples should be stored at 4°C and sent on wet ice.

Request form information

Specimens submitted without the information detailed below will NOT be tested unless the requestor provides further information.

• Name of institution/ward that patient is located.
• Number of cases in suspected outbreak.
• Symptoms.
• Duration of illness.
• Contact details of requestor.

Turn around time

Samples will be processed Monday to Friday. Samples are batch tested and must be received in the Virology laboratory by 9.00 am to be processed that day, results will be available by 4.00 pm. Specimens received after the 9.00 am cut-off will be processed the following working day. If consultation is required in relation to testing or testing of isolated cases please contact one of the Microbiologists or Microbiology registrars at Microbiology, CHL Ph. (03) 364 0300 or 0800 THE LAB.

For further information please contact Lance Jennings, Kevin Barratt in the Microbiology-Virology Section of , . Phone: 03 364 0356. Fax: 03 364 0750.

Version 1 Issued by: on 8-February-2007