By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
Dr. Deresinski reports no financial relationships relevant to this field of study.
SYNOPSIS: Yellow fever currently is epidemic in Brazil, and there is concern of further spread.
SOURCE: Paulus CI, Fauci AS. Yellow fever — Once again on the radar screen in the Americas. N Engl J Med 2017; DOI: 10.1056/NEJMp1702172)
In December 2016, cases of yellow fever began appearing in the Brazilian state of Minas Gerais, which is north of Rio de Janiero.2 Soon, additional cases appeared to the west in the state of Sao Paulo and to the east in the coastal state of Espirito Santo.1 Additional presumed cases now have been reported in other surrounding states. Since the beginning of the outbreak, there have been 1,368 cases of yellow fever reported (326 confirmed, 125 discarded, and 916 suspected cases remain under investigation), including 220 deaths (109 confirmed, six discarded, and 105 under investigation) as of March 2, 2017. The case fatality rate (CFR) among confirmed cases is 33% and is 11% among cases that remain only suspected. Transmission to date has been sylvatic, but some cases have occurred in areas adjacent to large urban centers, raising concerns about an urban epidemic. A large urban outbreak of yellow fever that began in Angola in December 2015, with subsequent spread to the Democratic Republic of Congo, led to 961 confirmed cases and 137 deaths. As we are reminded by Paules and Fauci, the outbreak led to the exhaustion of the world’s emergency stockpiles of yellow fever vaccine, without which the epidemic would have continued.
CDC recommends that anyone > 9 months of age traveling to affected areas be vaccinated against yellow fever and that those who have never been vaccinated against yellow fever should not travel to areas with ongoing outbreaks.3 While the CDC no longer recommends booster doses of yellow fever vaccine for most travelers, a booster dose may be given to travelers who received their last dose of yellow fever vaccine at least 10 years ago and who will be in a higher-risk setting, including areas with ongoing outbreaks. Thus, because of the ongoing outbreak, travelers to the Brazilian states of Minas Gerais, Espirito Santo, and parts of Bahia, Sao Paulo, and Rio de Janeiro states may consider getting a booster if their last yellow fever vaccination was more than 10 years ago.
However, vaccine shortage is again of concern. The CDC reports that the manufacturer of yellow fever vaccine (YF-Vax), Sanofi Pasteur, has informed the CDC that supplies of all preparations of YF-Vax are limited, and ordering restrictions have been implemented. Healthcare providers may no longer place orders for YF-Vax vaccine online. They must call Sanofi Pasteur at 1-800-VACCINE (1-800-822-2463), and a customer service representative will work with them to determine how many doses can be shipped and which vial sizes (single-dose or five-dose). YF-Vax doses will be prioritized for patients who are traveling in the next 30 days to an area where yellow fever vaccine is required or recommended.
Paules and Fauci point out that yellow fever is only one of a total of five arboviruses present in the Americas, with the other four being dengue virus, West Nile virus, chikungunya virus, and Zika virus. While the likelihood of yellow fever taking hold in the continental United States is low, it is not impossible and, of course, there is historical precedence for its occurrence here. Thus, in Philadelphia in early August 1793, two recent immigrants died of yellow fever, marking the beginning of an epidemic that killed at least 10% of the city of 50,000. By the end of September, 20,000 residents had fled, and among these was much of the federal government, including George Washington, who left on Sept. 10 for a scheduled vacation. The Federal Congress was not scheduled to meet in the city until November, and the epidemic largely subsided by the end of October. The U.S. capital was moved to New York City in 1789.
REFERENCES
- Available at: http://s13.postimg.org/jumnalk87/map_of_Brazil.gif. Accessed March 10, 2017.
- PAHO/WHO Epidemiological Update Yellow Fever. 2 March 2017. Available at: http://www.paho.org/hq/index.php?option=com_docman&task=doc_view&Itemid=270&gid=38466&lang=en. Accessed March 10, 2017.
- Centers for Disease Control and Prevention. Clinical Update Announcement: Yellow fever vaccine shortage. Available at: https://wwwnc.cdc.gov/travel/news-announcements/yellow-fever-vaccine-shortage-2016. Accessed March 10, 2017.
Yellow fever currently is epidemic in Brazil, and there is concern of further spread.
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