1. Reason for surveillance
   
2. Case definition
3. Notification criteria and procedure
4. The disease
5. Managing single notifications
   
6. Appendices​
   

1. Reason for surveillance

• To identify and control cases of disease
• To monitor the epidemiology and so inform the development of better prevention and control strategies. 
  

2. Case definition

Only a confirmed case should be notified.

Confirmed case

A confirmed case requires either:

• Laboratory definitive evidence and clinical evidence or
• Laboratory suggestive evidence and clinical and epidemiological evidence.

Laboratory definitive evidence

• Isolation of yellow fever virus or
• Detection of yellow fever virus by nucleic acid testing or
• Seroconversion or a four-fold or greater rise in yellow fever virus-specific serum IgM or IgG levels between acute and convalescent samples in the absence of vaccination in the preceding 3 weeks or
• Detection of yellow fever virus antigen in tissues by immunohistochemistry

Laboratory suggestive evidence

• Yellow fever virus-specific IgM detected in the absence of IgM to other relevant flaviviruses, in the absence of vaccination in the preceding 3 months.
• Confirmation of laboratory results by a second arbovirus reference laboratory is required in the absence of travel history to areas with known endemic or epidemic activity.

Clinical evidence

A clinically compatible illness.

Epidemiological evidence

History of travel to a yellow fever endemic country in the week preceding onset of illness.

3. Notification criteria and procedure

Yellow fever is to be notified by:

• Hospital Chief Executives (ideal reporting by telephone within 1 hour of diagnosis)
• Laboratories on diagnosis (ideal reporting by telephone within 1 hour of diagnosis).

Enter confirmed cases into NCIMS within one day of notification. Yellow fever is subject to the Commonwealth Biosecurity Act 2015.​

4. The disease

Infectious agent

The Yellow Fever virus, is a ribonucleic acid (RNA) virus, belonging to the genus Flavivirus. It is related to the West Nile and Japanese encephalitis viruses.

Mode of transmission

Urban yellow fever is transmitted from person to person by the Aedes aegypti mosquito. Jungle yellow fever is a zoonosis transmitted among non-human hosts (mainly monkeys) by various forest mosquitoes that may also bite and infect humans. Aedes aegypti are not established in NSW however are found in tropical climates, such as north, central and southern Queensland. Rarely, yellow fever can follow as an idiosyncratic reaction to the yellow fever vaccination.

Timeline

The typical incubation period is 3 to 6 days. The blood of cases is infective for mosquitoes shortly before onset of fever and up to five days after onset.

Clinical presentation

The usual clinical presentation is as an acute viral disease of short duration and varying severity. The mildest cases are clinically indeterminate. Typical attacks are characterised by sudden onset fever, chills, headache, backache, generalised muscle pain, prostration, nausea and vomiting. The majority of infections resolve at this stage. Approximately 15% of infected people go on to experience jaundice, haemorrhagic symptoms and melaena.

Prevention​

Yellow fever prevention is via vaccination and avoiding being bitten by mosquitoes.

Yellow fever vaccination information is available at HealthDirect and at the Commonwealth Department of Health and Aged Care yellow fever webpage. Vaccination is recommended for people who work with yellow fever virus in laboratories or are aged over 9 months and are travelling to an area with a risk of yellow fever.

Avoid being bitten by mosquitoes by:

• closing windows and using insecticide sprays indoors
• wearing light-coloured, long-sleeved shirts, long trousers and enclosed shoes
• using an insect repellent containing DEET (diethyl toluamide) or picaridin
• using mosquito nets or screens
• ensuring there is no stagnant water around e.g., in discarded containers, fallen palm fronds or gutters.

People travelling to yellow fever prone areas should speak to their doctor or healthcare professional about yellow fever prevention. Yellow fever vaccination entry requirements may differ between countries, and this can be discussed with their doctor depending on travel plans. 

For further information, see Healthdirect and NSW Health Factsheets: Yellow Fever and Mosquitoes are a health hazard.​

5. Managing single notifications

Response time

Investigation and Data Entry

On same day of notification begin follow-up investigation and notify the One Health Branch of the details of the case.

Data entry

Within 1 working day of notification enter confirmed cases on NCIMS. When entering potential exposures on NCIMS, the following variables are considered minimum data requirements:

• ​Place of exposure/acquisition including country -  enter data in Clinical and Risk History packages in NCIMS
  
• Yellow fever vaccination history - enter data in Clinical Package in NCIMS​

Response procedure

The response to a notification will normally be carried out in collaboration with the case's health carers. But regardless of who does the follow-up, PHU staff 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 caregiver has been told what the diagnosis is before beginning the interview
• Seek the doctor's permission to contact the case or relevant caregiver
• Identify the likely source of infection and ensure proper control measures are in place.

If no overseas travel is identified, contact One Health Branch.

Case management

Investigation and treatment

Identify the source of the infection, such as a location visited and exposures during recent overseas travel, and vaccination history.

Education

The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission and the reason for and duration of quarantine. Provide the Yellow Fever fact sheet.

Isolation and restriction

Standard precautions. Prevent access to the patient by mosquitoes for 5 days after onset (care for case in a screened room, or using a mosquito net and insect spray).

Environmental evaluation

None usually required.

Contact management

Identification of contacts

Any unimmunised person who has travelled through a Yellow Fever-endemic country with the case. Contacts should be placed under surveillance. This involves monitoring for symptoms within six days, seeking testing if symptoms develop, and avoiding mosquito bites.​

Education

Advise susceptible contacts (or parents/guardians) of the risk of infection and the reason for and duration of quarantine. Provide the Yellow Fever fact sheet.

Entry into Australia