- Reason for surveillance
- Case definition
- Notification criteria and procedure
- The disease
- Managing single notifications
- 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
In the event of an outbreak or enhanced public health investigation, additional data points may be required.
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
Yellow fever is a listed human disease under Australia’s Biosecurity (Listed Human Diseases) Determination 2016. All travellers are recommended to be vaccinated for yellow fever if travelling to or from a yellow fever risk country. People entering Australia who are one year of age or older will be asked to provide an international vaccination certificate if, within six days before arriving in Australia, they have stayed overnight or longer in a yellow fever risk country. People unable to provide a certificate will still be able to enter Australia.
Unvaccinated people entering Australia will still be permitted to enter Australia however a biosecurity officer from the Department of Agriculture and Water Resources will reinforce the seriousness of the disease and provide a Yellow Fever Action Card. The card provides instructions on what to do if symptoms of yellow fever develop in the six-day period following departure from a yellow fever risk country.
Further information is available at Department of Health and Aged Care Yellow Fever Factsheet, and National Guidelines for Yellow Fever Vaccination Centres and Providers.
Entry into other countries
Other countries may have different yellow fever vaccination legislation and requirements to enter their jurisdiction. Travellers should be aware of these requirements prior to travel.
Change in yellow fever vaccination requirements since June 2016
The Australian Government has adopted the World
Health Organization amendment to the International Health Regulations
(2005) regarding the period of
protection afforded by yellow fever vaccination, and the term of validity
of the certificate. The period of protection and term of validity
has changed from 10 years to the duration of the life of the person vaccinated.
This means that international yellow fever vaccination certificates presented
at Australia’s border will be accepted even if the vaccination was given more
than ten years previously.
6. Appendices
Appendix 1. Yellow fever factsheet
Appendix 2: Disease investigation form
Appendix 3. Mosquitoes are a health hazard Factsheet
Appendix 4. Staying safe and healthy overseas