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 3-27) and malaria transmission information and prophylaxis recommendations. Fourteen country-specific maps of malaria transmission areas, 11 country-specific maps depicting yellow fever vaccine recommendations, and a reference map of China are included to aid in interpreting the information. 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 pretravel consultation can be found on the CDC Travelers’ Health website (www.cdc.gov/travel).
Since publication of the 2016 edition of CDC Health Information for International Travel, additional country-specific data has been made available on the geographic risk of yellow fever virus (YFV) transmission. Based on a review of these data by the WHO Scientific and Technical Advisory Group on Geographical Yellow Fever Risk Mapping (in which CDC participates), an updated yellow fever vaccination recommendation was made for Rwanda.
Revaccination against yellow fever was previously 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 amend the IHR by removing the 10-year booster dose requirement, and stipulated a 2-year transition period for this change. Consequently, as of July 11, 2016, a completed International Certificate of Vaccination or Prophylaxis (ICVP) is valid for the lifetime of the vaccinee. Moreover, countries cannot require proof of revaccination (booster) against yellow fever as a condition of entry, even if the last vaccination was more than 10 years prior.
In the United States, the Advisory Committee on Immunization Practices (ACIP) published a new recommendation in 2015 that one dose of yellow fever vaccine provides long-lasting protection and is adequate for most travelers. The recommendation also identifies specific groups of travelers who should receive additional doses and others for whom additional doses may be considered. For details, see the Yellow Fever section earlier in this chapter. For the most up-to-date information about yellow fever vaccine boosters, consult the CDC Travelers’ Health website or the specific publication posted on the ACIP website (www.cdc.gov/mmwr/pdf/wk/mm6423.pdf).
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.
NOTE: Despite the recent changes to the IHR regarding yellow fever vaccine boosters, it is uncertain when and if all countries with current yellow fever vaccination entry requirements will adopt this change. Even if countries do modify their official policies to extend the validity period of the ICVP from 10 years to the lifetime of the vaccinee, there is no guarantee that all national border officials will be aware of such policy change or be able to enforce it appropriately. CDC obtains information yearly from WHO about official country entry requirements. WHO likely will not be asking countries about yellow fever vaccine booster entry requirements in the yearly questionnaires, because it will be assumed that countries are complying with the amended IHR. This could leave a gap in the foreseeable future in accurate published information about entry requirements for yellow fever vaccine boosters for certain countries. Past experience has demonstrated that information given by consulates and embassies about vaccination requirements is often not accurate. Therefore, providers and travelers should not rely solely on such information when determining current yellow fever vaccination entry requirements for specific destinations. With the caveats described above, readers should refer to the online version of this book (www.cdc.gov/yellowbook) and the CDC Travelers’ Health website (www.cdc.gov/travel) for any reported updates to country entry requirements since publication of this edition.
Table 3-27. 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.
The following recommendations to protect travelers from malaria were developed using the best available data from multiple sources. Countries are not required to submit malaria surveillance data to CDC. On an ongoing basis, CDC actively solicits data from multiple sources, including World Health Organization (main and regional offices); national malaria control programs; international organizations, such as the International Society of Travel Medicine; CDC overseas staff; US military; academic, research, and aid organizations; and published records from the medical literature. The reliability and accuracy of those data are also assessed. If the information is available, trends in malaria incidence and other data are considered in the context of malaria control activities within a given country, or other mitigating factors such as natural disasters, wars, and other events that may affect the ability to control malaria or accurately count and report it. Factors such as the volume of travel to that country and the number of acquired cases reported in the US surveillance system are also examined. Based on all those considerations, recommendations are developed to try to accurately describe areas of the country where transmission occurs, substantial occurrences of antimalarial drug resistance, the proportions of species present, and the recommended chemoprophylaxis options.
The recommendations for malaria prevention include estimates of relative risk for US travelers. This means that compared to a hypothetical average country with malaria transmission, US travelers to some countries can be at higher than average or lower than average risk for malaria infection. The designations high, moderate, low, and very low have been used to describe the estimated relative risk for a traveler to that country.
These recommendations should be used in conjunction with an individual risk assessment, taking into account not only the destination country but also the detailed itinerary including specific cities, types of accommodation, season, and style of travel, as well as special health conditions such as pregnancy.
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.
Requirements: Required if traveling from a country with risk of YFV transmission and ≥9 months of age, including transit >12 hours in an airport located in a country with risk of YFV transmission.1
Yellow Fever 1 The official WHO list of countries with risk of YFV transmission can be found in Table 3-22. 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, Rwanda, São Tomé and Príncipe, Somalia, Tanzania, Zambia.
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 G6PD deficiency. Patients must be screened for G6PD deficiency before starting primaquine.
Yellow Fever Maps 1 This map, which aligns with recommendations also published by the world Health Organization (WHO), is an updated version of the 2010 map crated by the Informal WHO Working Group on the Geographic Risk of Yellow Fever. 2 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 (such as age or immune status).