Mark D. Gershman, Emily S. Jentes, Rhett J. Stoney (YELLOW FEVER) Kathrine R. Tan, Paul M. Arguin, Stefanie F. Steele (MALARIA)
The following pages present country-specific information on yellow fever vaccine requirements and recommendations (see Table 3–26) and malaria transmission information and prophylaxis recommendations. Fifteen country-specific maps of malaria transmission areas, 10 country-specific maps depicting yellow fever vaccine recommendations, and reference maps of 2 countries are included to aid in interpreting the recommendations. The information was accurate at the time of publication; however, this information is subject to change at any time as a result of changes in disease transmission or, in the case of yellow fever, changing country entry requirements. Updated information, reflecting changes since publication, can be found in the online version of this book (www.cdc.gov/yellowbook) and on the CDC Travelers’ Health website (www.cdc.gov/travel). General recommendations for other vaccines to consider during the pre-travel consultation can be found on the CDC Travelers’ Health website (www.cdc.gov/travel).
Since publication of the 2014 edition of CDC Health Information for International Travel, additional country-specific data on the geographic risk of yellow fever virus (YFV) transmission was provided by certain countries and the Pan American Health Organization (PAHO). Based on a review of these data by CDC, the World Health Organization (WHO), PAHO, and other yellow fever and travel medicine experts, updated yellow fever vaccination recommendations were made for Argentina, Colombia, Peru, and Venezuela. Furthermore, an updated recommendation for the Democratic Republic of the Congo was made after an outbreak of yellow fever was confirmed in Katanga Province in early 2014.
Revaccination for yellow fever has been required by certain countries at 10-year intervals to comply with International Health Regulations (IHR). In 2014, the World Health Assembly (of WHO) adopted the recommendation to remove the 10-year booster dose requirement from the IHR as of June 2016. Once this change is instituted, a completed International Certificate of Vaccination or Prophylaxis will be valid for the lifetime of the vaccinee. It is uncertain when and if all countries with current yellow fever vaccination entry requirements will adopt this change.
In the United States, the Advisory Committee on Immunization Practices (ACIP) is considering the issue of the continued need for yellow fever vaccine boosters. In February 2015, ACIP approved a new recommendation that one dose of yellow fever vaccine provides long-lasting protection and is adequate for most travelers. The recommendations also identify specific groups of travelers who should receive additional doses and others for whom additional doses may be considered. The official recommendations were published after this edition went to press. For the most up-to-date information about yellow fever vaccine boosters, consult the CDC Travelers’ Health website or the ACIP website (www.cdc.gov/vaccines/hcp/acip-recs/).
Ultimately, the clinician’s decision whether or not to vaccinate any traveler must take into account the traveler’s risk of being infected with YFV, country entry requirements, and individual risk factors for serious adverse events after yellow fever vaccination (such as age and immune status). For a thorough discussion of yellow fever and guidance for vaccination, see the Yellow Fever section earlier in this chapter.
The recommendations for malaria prevention include estimates of malaria risk to US travelers. These estimates are based on numbers of malaria cases reported in US travelers and the estimated volume of travel to these countries. In some instances, the risk may be low because the actual intensity of transmission is low in that country. In other instances, malaria transmission may occur only in small focal areas of the country where US travelers seldom go. Thus, even though the risk for the average traveler to that country may be low, the risk for the rare traveler going to the areas with higher transmission intensity will be higher. For some countries rarely visited by US travelers, insufficient information exists to make a risk estimate. Information about malaria species present in each country is based on the best available data from multiple sources.
Several medications are available for malaria chemoprophylaxis. When deciding on which drug to use, clinicians should consider the specific itinerary, length of trip, cost of the drugs, previous adverse reactions to antimalarials, drug allergies, and medical history.
For a thorough discussion of malaria and guidance for prophylaxis, see the Malaria section earlier in this chapter.
Table 3-26. Categories of recommendations for yellow fever vaccination
YELLOW FEVER VACCINATION CATEGORY
RATIONALE FOR RECOMMENDATION
Vaccination recommended for all travelers ≥9 months of age to areas with endemic or transitional yellow fever risk, as determined by persistent or periodic YFV transmission.
Generally not recommended
Vaccination generally not recommended in areas where the potential for YFV exposure is low, as determined by absence of reports of human yellow fever and past evidence suggestive of only low levels of YFV transmission. However, vaccination might be considered for a small subset of travelers who are at increased risk for exposure to YFV because of prolonged travel, heavy exposure to mosquitoes, or inability to avoid mosquito bites.
Vaccination not recommended in areas where there is no risk of YFV transmission, as determined by absence of past or present evidence of YFV circulation in the area or environmental conditions not conducive to YFV transmission.
Abbreviation: YFV, yellow fever virus.
Requirements: Required if traveling from a country with risk of YFV transmission.1
Areas with malaria:All.
Estimated relative risk of malaria for US travelers:High.
Malaria species:P. falciparum 60%, P. vivax 35%–40%, P. ovale <1%.
Recommended chemoprophylaxis:Atovaquone-proguanil, doxycycline, or mefloquine.
Yellow Fever 1 The official WHO list of countries with risk of YFV transmission can be found in Table 3-21. Proof of yellow fever vaccination should be required only if traveling from a country on the WHO list, unless otherwise specified. The following countries, containing only areas with low potential for exposure to YFV, are not on the WHO list: Eritrea, São Tomé and Príncipe, Somalia, Tanzania, Zambia. 2 An elevation of 2,300 m is equivalent to 7,546 ft.
Malaria 3 This risk estimate is based largely on cases occurring in US military personnel who travel for extended periods of time with unique itineraries that likely do not reflect the risk for the average US traveler. 4 Refers to P. falciparum malaria unless otherwise noted. 5 Primaquine can cause hemolytic anemia in people with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Patients must be screened for G6PD deficiency before starting primaquine.
Yellow Fever Maps 1 Yellow fever (YF) vaccination is generally not recommended in areas where there is low potential for YF virus exposure. However, vaccination might be considered for a small subset of travelers to these areas who are at increased risk for exposure to YF virus because of prolonged travel, heavy exposure to mosquitoes, or inability to avoid mosquito bites. Consideration for vaccination of any traveler must take into account the traveler’s risk of being infected with YF virus, country entry requirements, and individual risk factors for serious vaccine-associated adverse events (e.g., age, immune status). 2 Current as of September 2014. This map, which aligns with recommendations also published by the World Health Organization (WHO), is an updated version of the 2010 map created by the Informal WHO Working Group on the Geographic Risk of Yellow Fever.