Yellow fever (YF) is a mosquito-borne viral disease endemic in 34 sub-Saharan African and 13 Central/ South American countries. YF affects humans and non-human primates (1), with human transmission  occurring when infected mosquitoes, in jungle (sylvatic), rural or urban areas, bite humans and transmit  the virus. In addition, occupational transmission may potentially occur due to mishandling of infected  biological specimens, in particular in non-vaccinated infection (2).An infected bite may initially produce nonspecific febrile symptoms, and some individuals remain  asymptomatic or experience mild symptoms. Severe viscerotropic disease can occur (jaundice, liver and  multi-organ failure, death), with a case-fatality rate of 40-50% in persons with severe disease. The disease  incidence is difficult to assess due to limitations in detection and reporting, jointly leading to overall  underreporting (3).A safe, inexpensive vaccine confers lifelong immunity (4), but low vaccine coverage and the presence of  infected non-human primates in some regions mean there is an ongoing risk of YF outbreaks. Strong  surveillance programmes can minimize this risk, and laboratory diagnosis of YF is integral to that effort,  enabling swift identification of cases and subsequent response to mitigate disease spread. 

YF virus belong to the genus Flavivirus and shares many characteristics with other closely related viruses  including dengue (DEN), Zika (ZIK) and West Nile (WN) viruses. These flaviviruses have similar  structural resemblances, mode of transmission, early clinical presentation, and reactions in serological  tests (5). Clinical presentation of YF can be misleading and can also result in clinical misdiagnosis in  favour of unrelated diseases, such as malaria, which can cause delays in diagnosis and response. Accurate  and timely identification of YF is therefore critical. The Eliminate Yellow Fever Epidemics (EYE) Strategy’s Laboratory Technical Working Group (EYE  LTWG) is responsible for devising and coordinating efforts to improve YF laboratory capacity throughout  affected areas with funding support from Gavi, the Vaccine Alliance (Gavi).