Yellow Fever Summary
What is Yellow fever?
Yellow fever is a short lasting viral infection that can be mild or severe. It is spread by bites from infected mosquitoes. The term "yellow" in the name refers to the jaundice that can occur. The disease is found in South America and in sub-Saharan Africa. World wide the number of yellow fever cases has increased over the past two decades. This is due to changes in immunity, deforestation, urbanization and climate change.
Image: Aedes mosquitos can carry diseases
such as yellow fever.
These are not currently present in New Zealand.
Image reproduced courtesy of the United States CDC.
There are a number of international measures in place in order to reduce the number of cases of yellow fever and to stop its spread. Since the mosquito that can carry yellow fever is not present in New Zealand, a yellow fever vaccination certificate is not required to enter New Zealand when arriving from countries that have yellow fever. A yellow fever vaccination certificate is required for entry into Australia and many other countries in the pacific region when arriving from countries that have yellow fever.
Symptoms of yellow fever will start 3 to 6 days after infection. In most cases infection is relatively mild and causes a sudden fever together with headache, chills, muscle pains and backache, nausea and vomiting. These symptoms disappear after 3 or 4 days and most patients improve.
In 15% of patients the fevers of the early stage of the infection return and the patient rapidly worsens with abdominal pains, vomiting, kidney and liver damage and jaundice. There can be bleeding from the mouth, eyes and nose, vomiting of blood can occur and there can be bleeding from the bowel. Up to half of patients who develop this toxic phase of Yellow fever die.
There is no specific cure for yellow fever. Treatment is just symptomatic; for fever, dehydration and liver and kidney damage.
Transmission - How is Yellow Fever Spread?
The yellow fever virus is transmitted through mosquito bites. This is mainly through the bite of an infected yellow fever mosquito (Aedes egyptii) but other mosquitoes can also carry and transmit the virus. Transmission of virus from one generation of mosquitoes to another via eggs and then larvae can also occur and maintains infection by causing sudden outbreaks of the disease.
The blood of someone with yellow fever is infectious to mosquitoes for the first 3-5 days of illness, starting shortly before the onset of fever.
There is no person to person spread.
Where might I catch Yellow fever?
Yellow fever is found in 32 countries in Africa and 13 in Latin America. While the risk of yellow fever is about 10 times higher in Africa than in South America, regular outbreaks have recently occurred in South America (Argentina, Bolivia, Brazil, Paraguay, Peru and Venezuela).
There are an estimated 200,000 cases of yellow fever every year and about 30,000 deaths. While the average death rate in regions where yellow fever is established in mosquito populations is 5%, it may be much higher.
Vaccination is the single most important measure for preventing yellow fever. The risk of death from yellow fever is far greater than the risks related to the vaccine. The vaccine is a live attenuated vaccine that has been in use since 1936, is almost 100% effective, and provides effective immunity within ten days of being given.
People who should not be vaccinated include:
Children aged less than 9 months for routine immunization (or less than 6 months during an epidemic).
Pregnant women – except during a yellow fever outbreak when the risk of infection is high.
People with severe allergies to egg protein, and
People with severe immunodeficiency due to symptomatic HIV/AIDS or other causes, or in the presence of a thymus disorder.
International Travel and Yellow Fever vaccination
Everyone travelling to and from a yellow fever zone needs to be aware of the risk of yellow fever and of the International health Regulation (IHR) requirements for yellow fever vaccination. Proof of yellow fever vaccination (a valid International Yellow fever Vaccination Certificate, valid for 10 years and starting 10 days after date of vaccination) is required by many countries for travelers entering or leaving a recognised yellow fever zone.
Yellow Fever Vaccination Summary
Anyone arriving at a border without a valid yellow fever vaccination certificate risks being refused entry, need medical quarantine for 6 days, or be required to required undergo vaccination.Yellow fever vaccination in New Zealand can only be performed by Ministry of Health approved IHR vaccinators at approved IHR vaccination centers.
Approved IHR (Yellow Fever) Vaccination Centres in the Auckland region
|Mairangi Medical Centre
||2 Penzance Road
||Dr Francesco Lentini
|Travel Clinic - North Shore
||101 Apollo Drive
||Dr Anwar Hoosen
|Torbay Medical Centre
||1042 Beach Road
||Quay West Bldg, Cnr Albert St and Mills Lane, CBD
||Dr Megan Corbett
|The Travel Doctor Auckland
|Level 1, Canterbury Arcade, 170 Queen Street
|Freemans Bay Medical Centre
||100 Wellington Street
|Auckland Travel Medicine Centre
||94 Remuera Road
||Dr Joan Ingram
|Worldwise Travellers Health Centre
|18 St Marks Road
|Tamaki Family Health Centre
||2-4 Clifton Court
||Dr John Clark
|Pakuranga Medical Centre
|17 William Roberts Drive
||Dr Kenneth Chin
|Silverdale Medical Centre
||4 Silverdale Street
International Health Regulations require that travelers who have a medical reason not to receive the yellow fever vaccine obtain a medical waiver. Most countries will accept such a medical waiver. Such a waiver will need a physician's note clearly stating the medical reason not to receive the vaccine. It is essential that this is written on surgery letterhead and bears the stamp used by the doctor writing the letter and preferably also a stamp from the official yellow fever immunisation centre.