Yellow Fever
SUMMARY: These are my notes on Yellow Fever as part of the workup for accreditation in order to be able to vaccinate in Australia.
CAUSE: Yellow fever virus (YFV) is a single-stranded RNA virus that belongs to the genus Flavivirus.
TRANSMISSION: Mosquito borne
EPIDEMIOLOGY: See Table 4-23 on CDC here.
MAP: CDC Maps
VACCINE: Live attenuated. Indicated for people >9 months of age travelling in areas at risk for YFV or as a requirement for entry. The vaccine certificate becomes valid 10 days after vaccination and remains valid for the duration of the life of the person vaccinated.
RISK: YFY transmission in West Africa is Seasonal, elevated risk during end of rainy season and beginning of dry season (July-October). South America risk is highest during rainy reason (Jan-May). Risk of illness and death respectively of a 2 week stay (based on indigenous populations and peak season).
West Africa are 50 per 100,000 and 10 per 100,000, respectively
South America are 5 per 100,000 and 1 per 100,000, respectively
Current disease outbreaks are reported by the WHO at http://www.who.int/csr/don/en/
PREVENTION: Personal protection measures. The Yellow Book contains more detail about HERE: protection against mosquitoes
Wearing a mosquito repellent containing DEET, picaridin, IR-3535 or oil of lemon eucalyptus (always follow product directions)
Applying permethrin-containing repellents to clothing
Minimising skin exposure by wearing light coloured, long-sleeved shirts and long pants
Avoiding areas where mosquitoes breed
Preventing mosquitoes entering your accommodation
Staying in air-conditioned or well-screened quarters. If not available, sleep under a mosquito net. Insecticide treated nets provide better protection.
DIAGNOSIS: Serology for IgM and IgG
TREATMENT: Supportive
SYMPTOMS:
Incubation periods is typically 3–6 days.
Patients may be asymptomatic
For patients that show clinical signs of yellow fever infection, disease onset is typically abrupt and is characterised by:
Fever
Chills
Malaise
Headache
Lower Back Pain
Weakness
Nausea
Vomiting
Dizziness
The heart rate may be slow relative to fever (Faget sign)
Average fever is 39°C and lasts for 3-4 days
After a brief remission of hours to a day, approximately 15% to 25% of patients progress to a more serious or toxic form of the disease
This is known as the ‘toxic’ stage’ and is characterised by:
Fever
Vomiting
Epigastric pain
Relative bradycardia
Liver failure
Jaundice
Renal failure
Haemorrhagic complications (such as petechiae, epistaxis, melaena, haematemesis)
The case-fatality rate of patients for those with the severe form ranges from 20-50%
Death typically occurs 7-10 days after disease onset.
ADVERSE: 10-30% report mild systemic adverse events.
Adverse events following yellow fever vaccine are generally mild and may include:
Low-grade fever
Myalgia
Mild headache
Malaise
Asthenia
Injection site inflammation
Begin after vaccination and last 5 to 10 days.
1% of vaccinees curtail regular activities because of symptoms.
1 in 100,000 have hypersensitivity reaction / anaphylaxis.
YEL-AND incidence 1 in 100,000 including GBS, Bell’s Palsies.
YEL-AVD is 1 in 200,000.
CONTRAINDICTIONS:
Infants <6months (9 months Aus Immunisation Handbook).
Sensitivity to components including Eggs, Chicken, Gelatin.
Thymus disorder.
Hypersensitivity/anaphylaxis to a previous dose of the vaccine.
Immunocompromised due to disease or medical treatment.
Women currently breastfeeding infants aged less than nine (9) months should not be vaccinated, except in situations where exposure to yellow fever virus cannot be avoided.
ELDERLY: Though the occurrence is rare, adults 60 years of age or older have a higher risk of severe adverse events following yellow fever vaccination, and this risk appears to increase with increasing age.
STORAGE: +2 to +8c, needs reconstitution. Do NOT freeze. Protect from light. Reconstituted vaccine must be used within 1 hour.
EXEMPTION: At times it is not considered safe to proceed with yellow fever vaccination. This may be if
The vaccine is contraindicated; or
There is a precaution present where risks of the vaccine outweigh the potential benefits.
CAUTION:
6-8 months.
Age >60.
Pregnancy.
HIV infection.
VISA: Travellers from these countries are not prevented from entering Australia if they fail to produce a valid yellow fever certificate. view most recent list
Angola
Argentina—Misiones Province
Benin
Bolivia
Brazil
Burkina Faso
Burundi
Cameroon
Central African Republic
Chad
Colombia
Congo, Democratic Republic of the
Congo, Republic of the
Côte d'Ivoire
Ecuador (excluding the Galápagos Islands)
Equatorial Guinea
Ethiopia
French Guiana
Gabon
The Gambia
MORE:
Ghana
Guinea
Guinea Bissau
Guyana
Kenya
Liberia
Mali
Mauritania
Niger
Nigeria
Panama
Paraguay
Peru
Senegal
Sierra Leone
South Sudan
Sudan
Suriname
Togo
Trinidad
Uganda
Venezuela
RESOURCES:
WHO - Fact sheet on Yellow Fever
Aus Health dot gov information and factsheet
CDC Yellow Fever section