Overview of Emerging Arboviruses

Ann M. Powers


Future Virology. 2009;4(4):391-401. 

In This Article

Sporadic Re-emergence of Yellow Fever Virus in South America

Yellow fever virus is the type species in the Flavivirus genus of the family Flaviviridae. Endemic transmission of YFV occurs continuously in South America, with nonhuman primates serving as the major vertebrate reservoirs in this jungle cycle.[2] By contrast, prior to recent activity, no urban YFV had been reported in South America since 1942. During late 2007 and early 2008, human YFV cases were detected in a cluster, including areas of Brazil, Paraguay and Argentina.[3] This was the first time that human cases had been recorded in Argentina or Paraguay since the 1970s. By mid-2008, approximately 75 human cases had been confirmed in these three countries, with an overall mortality rate of 45%. Prior to the emergence of these human cases, a dramatic increase in the number of nonhuman primate cases had been reported,[3,4] serving as a warning that epidemics were possible. The appearance of jungle human cases after increased levels of epizootic activity is not unexpected. However, significantly, the cases in Paraguay were revealed to be urban-acquired cases,[5] making this outbreak in Asunción the first urban YFV outbreak in South America in over 65 years. While fewer than 30 confirmed cases were documented in this area, the event was a reminder that a YFV epidemic in a major urban center of South America is a real possibility that could have catastrophic public health consequences. Further epizootic activity with sporadic human cases has been reported since late 2008 and into 2009 in Argentina, Brazil, Trinidad, Venezuela and Colombia;[201] the outcomes of this current activity remain to be determined.