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Friday, May 7, 2010

Yellow Fever in Latin America

World map of Yellow Fever endemic regions (click to enlarge)
The following countries are considered at risk of yellow fever transmission:
South America: Bolivia, Brazil, Colombia, Ecuador, French Guyana, Peru, Venezuela.
Africa: Angola, Benin, Burkina Faso, Cameroon, Gabon, The Gambia, Ghana, Guinea,
Liberia, Nigeria, Democratic Republic of Congo, Sierra Leone, Sudan

The last 24 hours have been spent researching yellow fever and its vaccination requirements, as we traverse through Ecuador, Colombia, Panama and Costa Rica. I have previously had Yellow Fever vaccination and never had any side effects and the disease is generally deadly, once you go past the more common flu-like episode and get the symptoms of liver and organ failure, but we are only touching on the endemic areas in Latin America and we have to balance the risks against the risks of the vaccination itself.

We got drawn into this only because we began it check whether we would be barred from entering any country as a result of not having the official vaccination certificate. So far as we have been able to ascertain:

1. Colombia has no entry restrictions according to COPA and the gist of the CDC statement below.
2. Panama says it is recommended but not required for people over 9 months coming from endemic areas.
3. Costa Rica says it is required for people between 9 months and 60 years coming from endemic areas.

Here are come of the detailed risks, focusing on countries we are passing through.

Yellow Fever Cases in Travelers
• During 1970–2002, a total of nine cases of yellow fever were reported in unvaccinated travelers from the United States and Europe who traveled to West Africa (five cases) or South America (four cases). Eight of these nine travelers died.
• Only one documented case of yellow fever has occurred, which was in a vaccinated traveler from Spain, who visited several West African countries during 1988.

Risk Estimates for Travelers
• The risk of acquiring yellow fever is difficult to predict because of variations in ecologic determinants of virus transmission. For a 2-week stay, the risks for illness and death due to yellow fever for an unvaccinated traveler traveling to an endemic area of
• 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
• These estimates are a rough guideline based on the risk to indigenous populations, often during peak transmission season. Thus, these risk estimates may not accurately reflect the true risk to travelers, who may have a different immunity profile, take precautions against getting bitten by mosquitoes, and have less outdoor exposure.
• The risk of acquiring yellow fever in South America is lower than that in Africa because the mosquitoes that transmit the virus between monkeys in the forest canopy do not often come in contact with humans, and there is a relatively high level of immunity in local residents secondary to vaccine use.

Yellow Fever vaccine is live vaccine and is generally safe and has few side effects, but there is a small incidence of serious side effects, mimicking the actual disease, occurring at levels similar to the risk of a two-week visit to a Latin American endemic country.

Yellow Fever Vaccine-Associated Neurologic Disease (YEL-AND)
• YEL-AND represents a conglomerate of different clinical syndromes, including meningoencephalitis, Guillain–Barré syndrome (GBS), acute disseminated encephalomyelitis (ADEM), bulbar palsy, and Bell’s palsy.
• Historically, YEL-AND was seen primarily among infants as encephalitis, but more recent reports have been among persons of all ages.
• The onset of illness for documented cases ranges 3–28 days after vaccination, and almost all cases were in first-time vaccine recipients.
• YEL-AND is rarely fatal.
• The incidence of YEL-AND in the United States is 0.8 per 100,000 doses administered. The rate is higher in persons ≥60 years of age, with a rate of 1.6 per 100,000 doses in persons 60–69 years of age and 2.3 per 100,000 doses in persons ≥70 years of age.

Yellow Fever Vaccine-Associated Viscerotropic Disease (YEL-AVD)
• YEL-AVD is a severe illness similar to wild-type disease, with vaccine virus proliferating in multiple organs and often leading to multisystem organ failure and death.
• Since the initial cases of YEL-AVD were published in 2001, more than 40 confirmed and suspected cases have been reported throughout the world.
• The onset of illness for YEL-AVD cases averaged 3.5 days (range: 1–8 days) after vaccination. YEL-AVD appears to occur after the first dose of yellow fever vaccine rather than with booster doses.
• The case–fatality ratio for reported YEL-AVD cases is 53%.
• The incidence of YEL-AVD in the United States is 0.4 cases per 100,000 doses of vaccine administered. The rate is higher for persons ≥60 years of age, with a rate of 1 per 100,000 doses in persons 60–69 years of age and 2.3 per 100,000 doses in persons aged ≥70 years of age.

Requirements by Country (See US CDC world listing)

Ecuador (US CDC)
The vaccine is required for travelers greater than one year of age arriving from a yellow-fever-infected country in Africa or the Americas. Yellow fever vaccine is recommended for the following provinces in the Amazon Basin - Morona-Santiago, Napo, Orellana, Pastaza, Sucumbios, and Zamora-Chinchipe - and for all areas along the eastern slopes and to the east of the Andes Mountains (see the CDC map for details). This does not include the cities of Quito and Guayaquil or the Galapagos Islands, though travelers to the Galapagos who make intermediate stops east of the Andes should be vaccinated against yellow fever. In recent years, yellow fever has been reported from the provinces of Morona-Santiago, Napo, Pastaza, Sucombios, and Zamora-Chinchipe. In April 2005, the Ecuadoran authorities announced a yellow fever alert in the province of Sucombios, due to a yellow fever outbreak in neighboring areas of Colombia.

Colombia (US CDC)
Not required. Yellow fever vaccine is recommended for all travelers greater than nine months of age, except that travelers whose itinerary is limited to the cities of Bogota, Cali, and Medellin are at lower risk and may consider foregoing immunization. Yellow fever vaccine is required for visitors to the country's national parks along the Atlantic coast. In January 2004, a yellow fever outbreak was reported from the departments of Guajira, Magdalena, Meta, and Cesar, including Sierra Nevada and Tyrona parks (see "Recent outbreaks" below). In recent years, yellow fever has also been reported from the departments of Antioquia, Boyaca, Caqueta, Casanare, Choco, Cundinamarca, Santander, Norte Santander, and Vichada, and the intendencias of Arauca, Cucuta, Guaviare, and Putumayo.

Panama (US CDC)
CDC yellow fever vaccination recommendation for travelers to Panama: For all travelers ≥9 months of age traveling to the provinces of Darien, Kuna Yala (old San Blas), Comarca Emberá, and Panama east of the Canal Zone, EXCLUDING the Canal Zone, Panama City, and San Blas Islands Panama requires travelers arriving from countries where yellow fever is present to present proof of yellow fever vaccination. Vaccination should be given 10 days before travel and at 10-year intervals if there is ongoing risk.

However Lonely Planet Thorn Tree states as of 2010: "Panama officially requires a certificate of anyone arriving from a country where YF occurs. That does not include the US or Costa Rica. However, the ministry of health says that the requirement is a recommendation, not a requirement." (See also Panama backtracks on Yellow Fever shot Requirement)

The Panamanian government official documentation states the same position:


"¿La ausencia del Certificado Internacional de Vacunación ó Profilaxis será impedimento para que los viajeros ingresen al país? NO, la ausencia del Certificado Internacional de vacunación o profilaxis no será impedimento para que los pasajeros ingresen al país ni para abordar aeronaves, embarcaciones y transportes terrestres interfronterizos, ya que en la República de Panamá, la aplicación de la vacuna contra la Fiebre Amarilla es una RECOMENDACIÓN Y NO UNA OBLIGACION, para los viajeros internacionales proveniente de los países enunciados en el punto 4."

Translated this roughly reads:

"The absence of the Certificate the International of Vaccination or Prophylaxis will be impediment so that the travellers enter the country? NO, the absence of the Certificate the International of vaccination or prophylaxis will not be impediment so that the passengers enter the country nor to approach transfrontier airships, boats and terrestrial transports, since in the Republic of Panama, the application of the vaccine against the Yellow Fever is a RECOMMENDATION AND NOT an OBLIGATION, for the international travellers originating of the countries enunciated in point 4."

In South America, these are: Bolivia, Brasil, Colombia, Ecuador, Perú and Venezuela.

Costa Rica (US CDC)
Required from travelers coming from countries with risk of yellow fever transmission. No certificate is required for travelers

Nicaragua, Honduras, Guatemala (US CDC)
Required if traveling from a country with risk of yellow fever transmission and ≥1 year of age.

We are still trying to decide whether to inject or wait till Panama, given our age over 60 and the high cost of the vaccine here ($100 US each).

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