Malady Wise

View Original

Yellow Fever

Maladywise

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

  1. Angola

  2. Argentina—Misiones Province

  3. Benin

  4. Bolivia

  5. Brazil

  6. Burkina Faso

  7. Burundi

  8. Cameroon

  9. Central African Republic

  10. Chad

  11. Colombia

  12. Congo, Democratic Republic of the

  13. Congo, Republic of the

  14. Côte d'Ivoire

  15. Ecuador (excluding the Galápagos Islands)

  16. Equatorial Guinea

  17. Ethiopia

  18. French Guiana

  19. Gabon

  20. The Gambia

MORE:

  1. Ghana

  2. Guinea

  3. Guinea Bissau

  4. Guyana

  5. Kenya

  6. Liberia

  7. Mali

  8. Mauritania

  9. Niger

  10. Nigeria

  11. Panama

  12. Paraguay

  13. Peru

  14. Senegal

  15. Sierra Leone

  16. South Sudan

  17. Sudan

  18. Suriname

  19. Togo

  20. Trinidad

  21. Uganda

  22. Venezuela

RESOURCES:

WHO - Fact sheet on Yellow Fever

Aus Health dot gov information and factsheet

CDC Yellow Fever section