Public health priority: High
PHU response time: Respond to 2 or more probable cases in an institution. Respond within 1 working day of notification.
Case management: Advise cases who are healthcare workers, food
handlers, children in childcare or those who care for children, the elderly or
patients to stay away from work until at least 48 hours after symptoms cease.
Contact management: Where food is possible vehicle, ask the NSW Food Authority to identify the likely source and mode of transmission. Review infection control procedures. Introduce control measures.
Clusters of two (or
more) conﬁrmed cases or probable cases should
within an institution who develops vomiting or diarrhoea within an incubation
period of when at least one other person at the institution was infectious with
vomiting or diarrhoea (i.e. overlapping infectious and incubation periods).
Isolation of a pathogen consistent with the aetiology of illness from a vomitus or stool specimen in a probable case.
Any two (or more) conﬁrmed cases or probable cases in
the same institution where one case develops vomiting or diarrhoea within
an incubation period* following when at least one other person at the
institution was infectious* with vomiting or diarrhoea.
and incubation periods are given in ‘Section 4. The disease’ (table page 4).
PHU investigation and assessment should be based on the appropriate timeframes
for the suspected pathogen, given the clinical presentation of cases. However,
to help facility staff understand when an outbreak may be occurring, the
following time frames are given in the respective Gastro Packs:
Any residential environment or organisation with
a responsibility to care for a defined group of individuals, such as:
Gastroenteritis among two or more people of any age in an institution is to be notified by:
notifications should be made by phoning the local PHU on 1300 066 055.
enteric pathogens, including viruses, bacteria and parasites, as well as toxins
produced by bacteria, can produce gastroenteritis outbreaks. Noroviruses are
the most common cause of large outbreaks in institutions.
Gastroenteritis is transmitted in different modes, including:
Incubation periods and clinical features of selected agents of gastroenteritis are presented in the table1 below.
Symptoms of viral gastroenteritis usually last between 24 and 48 hours but can sometimes be longer. Cases are usually infectious for at least 48 hours after symptoms cease. Outbreaks where diarrhoea was the
only/predominant symptom are unlikely to be caused by norovirus or rotavirus,
and consideration of a food or other sources is important.
Clinical symptoms vary depending on the causal agent and may include nausea, vomiting, diarrhoea, abdominal pain, myalgia, headache, malaise and low-grade fever.
On same working day of notification of two or more probable or confirmed cases in an institution, begin follow-up investigation.
Notify the Communicable Diseases Branch (email NSWH-Enteric@health.nsw.gov.au)
within one working day of notification. If within a licensed aged care
facility, include the Aged Care Quality and Safety Commission (ACQSC, email@example.com)
in the email notification.
On the same working day of notification ensure that the initial
information is entered into NCIMS and notified to CDB.
Notify CDB (and ACQSC if a licensed ACF) by using the “institutional
outbreak summary” template from NCIMS. Although the template will mostly
auto-populate, the PHU should check that the following fields have been
To close an outbreak,
complete the “Date outbreak / exposure closed” field in NCIMS (General
question package) and change the event/cluster status to “closed”. This should
be completed within one month of notification if cases are no longer occurring,
or within one month of the last case in outbreaks which last longer.
Note: An institutional
outbreak summary form from NCIMS does not need to be re-submitted to CDB at the
closure of an outbreak of gastroenteritis.
The response to a notification will be carried out in collaboration with the cases' health carers and the institution that has been affected. But regardless of who does the follow up, PHU staff should ensure that action has been taken to:
Where food is suspected as the cause of the outbreak, request the NSW Food Authority to conduct an environmental investigation. A joint inspection of the facility is recommended. Refer to Foodborne Illness Outbreak protocol and seek advice from Communicable Diseases Branch.
Treatment of cases is the responsibility of the health care provider.
to a notification should be carried out in collaboration with the cases' health
carers and the institution that has been affected. The following steps are a
guide to the investigation of gastroenteritis outbreaks in institutions. The
response to the outbreak will depend on the suspected mode of transmission,
cause of illness and whether there is ongoing risk of transmission. Steps marked with an asterisk (*) should
is suspected as the cause of the outbreak, request the NSW Food Authority to
conduct an environmental investigation by sending a completed Environmental
Investigation Request Form to firstname.lastname@example.org.
A joint inspection of the facility is recommended. Refer to the Foodborne
Illness Outbreak Protocol and seek advice from CDB.
If a notifiable
medical condition is detected in a case, create separate event(s) for each case
and for each confirmed result in NCIMS and link it to the NCIMS record for the
outbreak. If applicable, complete the standard public health response for the
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission. Emphasise the importance of hand washing, particularly after going to the toilet, changing nappies, before eating and preparing food.
Letters and resources
for facilities are available in the Gastro
Pack for Hospitals and Aged Care Facilities, and Gastro
Pack for Child Care Centres, as well as in the ID
Complementary Operating Procedures on PopNet (see 8. Additional
Provide a verbal or written report for the manager of the institution or facility which details control and prevention measures.
environmental evaluation is recommended for all outbreaks. Most evaluations may
be completed over the phone. Occasionally, a site visit by PHU staff may be
warranted to aid investigations into the source of infection and review control
measures. An investigation tool (template) has been developed to assist this
process and is available in the ID
Complementary Operating Procedures on PopNet (see 8. Additional
The end of
an outbreak should be determined on a case-by-case basis, and will be decided
by the PHU leading the investigation by considering all available evidence. Considerations
decision to close an outbreak deviates from 72 hours after the last episode of
vomiting or diarrhoea in the last case, the PHU should communicate the
rationale to the institution (i.e. specific pathogen, vulnerability of
residents, good control, etc.) to avoid any confusion about how this decision
may differ from previous advice.
outbreak is declared over, provide advice to the manager of the institution to:
Secondary cases should be anticipated in persons exposed to the faeces or vomitus of cases. Staff and residents should be given information about the outbreak and how to prevent infection and placed under surveillance.
No specific treatment is recommended for asymptomatic contacts.
Where available data indicates that an unidentified source remains an ongoing risk, then a cohort or case-control study may be required to identify the source.
Refer to Foodborne Illness Outbreak protocol and seek advice from Communicable Diseases Branch.
following fact sheets and guidelines are available to assist in managing
gastroenteritis in various institutional settings: