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Yellow fever virus is a mosquito-borne flavivirus that causes yellow fever, an acute infectious disease that occurs in South America and sub-Saharan Africa. Most patients with yellow fever are asymptomatic, but among the 15% who develop severe illness, the case fatality rate is 20%-60%. Effective live-attenuated virus vaccines are available that protect against yellow fever. An outbreak of yellow fever began in Brazil in December 2016; since July 2017, cases in both humans and nonhuman primates have been reported from the states of Sao Paulo, Minas Gerais, and Rio de Janeiro, including cases occurring near large urban centers in these states. Yellow fever is a potentially fatal illness that is preventable by vaccination. Yellow fever vaccination is recommended for all eligible persons aged ≥9 months, traveling to many areas in Brazil, including the states of Sao Paulo and Rio de Janeiro (especially Ilha Grande).
On March 16, 2018, this report was posted as an MMWR Early Release on the MMWR website (https://www.cdc.gov/mmwr).
Yellow fever virus is a mosquito-borne flavivirus that causes yellow fever, an acute infectious disease that occurs in South America and sub-Saharan Africa. Most patients with yellow fever are asymptomatic, but among the 15% who develop severe illness, the case fatality rate is 20%-60%. Effective live-attenuated virus vaccines are available that protect against yellow fever (1). An outbreak of yellow fever began in Brazil in December 2016; since July 2017, cases in both humans and nonhuman primates have been reported from the states of Sao Paulo, Minas Cerais, and Rio de Janeiro, including cases occurring near large urban centers in these states (2). On January 16, 2018, the World Health Organization updated yellow fever vaccination recommendations for Brazil to include all persons traveling to or living in Espirito Santo, Sao Paulo, and Rio de Janeiro states, and certain cities in Bahia state, in addition to areas where vaccination had been recommended before the recent outbreak (3). Since January 2018, 10 travel-related cases of yellow fever, including four deaths, have been reported in international travelers returning from Brazil. None of the 10 travelers had received yellow fever vaccination.
Five of the 10 cases were reported by ProMED since January 15, including two from Argentina and three from Chile; two of the travelers from Chile died. In addition, during January 1-March 15, 2018, five confirmed cases of yellow fever in unvaccinated travelers returning from Brazil were reported by GeoSentinel (http://www.istm.org/geosentinel), the global clinician-based sentinel surveillance system for travel-related illness among international travelers and migrants (4). These five yellow fever cases represent the first such cases identified by GeoSentinel (Table), which was initiated in 1995 by the International Society of Travel Medicine with support from CDC and now consists of 70 specialized travel and tropical medicine clinical sites around the world. The first of the GeoSentinel-reported cases occurred in a Dutch man aged 46 years who traveled to Sao Paulo state for 3 weeks during December 2017-January 2018. The second case occurred in a French woman, aged 42 years, who traveled to Minas Gerais state in Brazil for 4 weeks during December 2017-January 2018. She received a diagnosis of yellow fever in Brazil and was examined at a GeoSentinel site after returning to France to convalesce. The third and fourth cases occurred in a Romanian man, aged 34 years, and a Swiss man, aged 44 years, each of whom visited Brazil for approximately 2 weeks in February 2018. The fifth case was in a German man, aged 33 years, who spent a week in Brazil in late February. The Swiss and German travelers died from their illness (Table).
Among the 10 international travelers reported with yellow fever acquired in Brazil, eight acquired the disease on Ilha Grande, a forested island off the Rio de Janeiro coast, where one human and one nonhuman primate yellow fever case were reported in early February 2018 (5); of the eight patients who acquired the disease on Ilha Grande, four died. Another travel-related case of yellow fever was reported recently outside of Brazil (6).
Yellow fever is a potentially fatal illness that is preventable by vaccination. Yellow fever vaccination is recommended for all eligible persons aged >9 months, traveling to many areas in Brazil, including the states of Sao Paulo and Rio de Janeiro (especially Ilha Grande). Unvaccinated travelers should avoid traveling to areas where vaccination is recommended (https:// wwwnc.cdc.gov/travel/notices). Travelers planning to visit areas in Brazil or elsewhere where yellow fever transmission is occurring should receive yellow fever vaccine at least 10 days before travel and follow recommendations for avoiding mosquito bites (https://www.cdc.gov/yellowfever/prevention/index.html). The Food and Drug Administration-approved yellow fever vaccine, YF-VAX, is currently unavailable in the United States because of manufacturing difficulties (7). An alternative yellow fever vaccine, Stamaril, is available through a limited number of U.S. yellow fever vaccination clinics. U.S. travelers should therefore plan ahead to obtain Stamaril because it might take more time to access one of these clinics. Clinicians assessing returned travelers should be aware of yellow fever signs and symptoms and maintain vigilance regarding the possibility of yellow fever exposure in travelers returning from Brazil or other areas with ongoing transmission of yellow fever.
Acknowledgments
Marion Koopmans, Department of Viroscience, Erasmus MC, Rotterdam, Netherlands; Ana Maria Bispo de Filippis, Laboratorio de Flavivirus do Instituto Oswaldo Cruz, Rio de Janeiro, Brazil; Cornelia Svetlana Ceianu, Ani Ioana Cotar, Laboratory for Vector-Borne Infections, Cantacuzino National Institute for Research, Bucharest, Romania; Mike Jacobs, Royal Free Hospital, London, United Kingdom; Eleni Nastouli, University College London Hospitals, London, United Kingdom; Andrew Simpson, Rare and Imported Pathogens Laboratory, Public Health England, Wiltshire, United Kingdom; Institute of Intensive Care and Division of Infectious Diseases, University Hospital Zurich, Switzerland; Alexandra Trkola, Institute of Medical Virology, University of Zurich, Switzerland; Laurent Kaiser, Virology Laboratory, University Hospital Geneva, Switzerland.
Conflict of Interest
No conflicts of interest were reported.
References
1. CDC. Yellow fever. Atlanta, GA: US Department of Health and Human Services, CDC; 2018. https://www.cdc.gov/yellowfever/symptoms/index.html
2. World Health Organization. Yellow fever-Brazil. Disease outbreak news. Geneva, Switzerland: World Health Organization; 2018. http://www.who. int/csr/don/27-february-2018-yellow-fever-brazil/en/
3. World Health Organization. Updates on yellow fever vaccination recommendations for international travelers related to the current situation in Brazil. Geneva, Switzerland: World Health Organization; 2018. http:// www.who.int/ith/updates/20180116/en/
4. Harvey K, Esposito DH, Han P, et al. Surveillance for travel-related disease-GeoSentinel Surveillance System, United States, 1997-2011. MMWR Surveill Summ 2013;62(No. SS-3).
5. Prefeitura Angra, página inicial, noticias. Atençao-febre amarela [Portuguese]. https://www.angra.rj.gov.br/noticia.asp?vid_noticia=53727&indexsigla=imp
6. Newman AI] Becraft R, Dean AB, et al. Notes from the field: fatal yellow fever in a traveler returning from Peru-New York, 2016. MMWR Morb Mortal Wkly Rep 2017;66:914-5. https://doi.org/10.15585/mmwr.mm6634a5
7. Gershman MD, Angelo KM, Ritchey J, et al. Addressing a yellow fever vaccine shortage-United States, 2016-2017. MMWR Morb Mortal Wkly Rep 2017;66:457-9. https://doi.org/10.15585/mmwr.mm6617e2
Copyright U.S. Center for Disease Control Mar 23, 2018