- Reason for surveillance
- Case definition
- Notification criteria and procedure
- The disease
- Managing notifications
1. Reason for surveillance
- To identify of outbreaks of Salmonella, to determine the source of the infection and to prevent further cases through control measures
- To detect the emergence of new strains of Salmonella
- To monitor the epidemiology of S. Enteritidis to enable early detection of S. Enteritidis in poultry in Australia
- To inform the development of better prevention strategies.
2. Case definition
Only confirmed cases should be notified
A confirmed case requires laboratory definitive evidence only.
Laboratory definitive evidence
Isolation or detection of Salmonella species (excluding S. Typhi, S.Paratyphi A, S. Paratyphi B (with the exception of S. Paratyphi B biovar Java) and S. Paratyphi C which are notified separately under Enteric Fever.
3. Notification criteria and procedure
Salmonella infection is to be notified by:
- Laboratories on isolation of Salmonella.
Only confirmed cases should be entered onto NCIMS.
4. The disease
There are many different serotypes of Salmonella that cause human disease.
Mode of transmission
Salmonella infection is transmitted by:
The typical incubation period can vary from 6 hours to 3 days, (and occasionally longer), but is commonly 12 to 36 hours. Salmonellosis is infectious while the case's stools are positive, which can vary from several days to several weeks after infection. A temporary carrier state occasionally continues for months, particularly in infants, the elderly and immunocompromised people. Long term permanent carriage occurs in <1% of the population.
Salmonella infection usually presents as acute gastroenteritis, with sudden onset of headache, abdominal pain, diarrhoea, nausea and sometimes vomiting. In rare cases, Salmonella can cause septicemia or focal infections such as abscesses or arthritis.
5. Managing notifications
Begin follow-up investigation on same day of notification for
- a cluster of cases of any untyped Salmonella cases, Salmonella serotype or MLVA type, or
- a single case of Salmonella Paratyphi bioser Java), or
- a single case of S. Enteritidis.
- a single case of unusual or emerging Salmonella serotypes.
- if asked by the Communicable Diseases Branch.
Notify the Communicable Disease Branch on the day a cluster of cases of any Salmonella serotype or MLVA type is identified. Local clusters should be investigated by the Public Health Unit in whose area the cases reside, using the hypothesis generating questionnaire on the NSW Health website.
Investigations of state-wide outbreaks will be centrally coordinated in close collaboration with the PHUs.
Within 3 working days of notification enter confirmed cases on NCIMS. Serotype and MVLA type will be automatically uploaded into NCIMS by the enterics team.
The response to a notification will normally be carried out in collaboration with the case's health carers. Where the PHU undertakes follow up, it should ensure that action has been taken to:
- confirm the onset date and symptoms of the illness
- confirm results of relevant pathology tests, or recommend the tests be done
- find out if the case or relevant care-giver has been told what the diagnosis is before beginning the interview
- seek the doctor's permission to contact the case or relevant care-giver
- review case and contact management
- identify whether the case is in a high risk occupation
- identify the likely source of infection.
Investigation and treatment
For case treatment, refer to Therapeutic Guidelines: Antibiotic. For non-invasive and uncomplicated cases, treatment is usually supportive only. Antibiotics given in the acute stage may prolong the carrier state, but may be indicated in the very young, the elderly or debilitated.
- Single cases of S. Paratyphi bioser Java infection should be followed up to ascertain exposures such as overseas travel, sandpits (associated with outbreaks on the Northern beaches of Sydney), aquariums in the home and imported seafood (both associated with multi-antibiotic resistant S. Paratyphi bioser Java organisms).
- Single cases of S. Enteritidis need to be followed up to ascertain overseas travel during their exposure period. If the case was unlikely to have been acquired overseas, the case should be interviewed with the Salmonella hypothesis generating questionnaire to ascertain a possible local source. S. Enteritidis is transmitted through consumption of contaminated eggs where transovarial transmission has occurred. While S. Enteritidis is endemic in commercial poultry farms in most countries it is not endemic in chicken flocks for egg-laying or meat production in Australia. Understanding the epidemiology of locally acquired S. Enteritidis infection in humans may assist in the detection of S. Enteritidis in poultry.
- If the case has recently travelled overseas, determine what countries were visited during their exposure period. An interview with the hypothesis generating questionnaire is not necessary for cases that were most likely infected while overseas.
- Investigation into single cases of infections of other serotypes of Salmonella is dependent on local epidemiology and at the discretion of the Public Health Unit Director. The identification of unusual or emerging pathogens may prompt an investigation.
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission. Emphasise the importance of correct food handling and hygienic practices, particularly hand washing before eating and preparing food and after going to the toilet.
Isolation and restriction
- Cases who are food handlers should not attend work until 48 hours have elapsed after symptoms resolve. The case should be provided with information regarding hand washing and hygiene before returning to work.
- Other people with Salmonella infection should not attend work while diarrhoea is present
- Cases who reside in an institution should be cohorted (separated from non-infected residents) if possible. Contact precautions should be used when caring for infected residents
- Children in childcare should be excluded until 24 hours after diarrhoea ceases. It is not necessary for them to be excluded if they have a positive stool sample but do not have symptoms.
Where a food source is suspected on epidemiological grounds, immediately notify the NSW Food Authority to conduct an environmental assessment and consider control measures.