Document Type : Original Article


1 World Health Organization Ondo State Office, Akure, Nigeria

2 Ondo State Ministry of Health, Akure, Nigeria

3 Ondo State Primary Health Care Development Agency, Akure, Nigeria


Background: Yellow fever (YF) is an acute viral hemorrhagic fever caused by the yellow fever virus and transmitted by Aedes mosquito species. Despite the availability of a very effective vaccine, yellow fever virus (YFV) remains a public health threat across Africa. Enhanced disease surveillance, vector control, and high vaccination coverages are key to the prevention and control of YF. This paper aimed to describe yellow fever surveillance in Ondo state and the outbreak investigation activities conducted in the LGAs where outbreaks occurred in the year 2021.
Methods: This is a retrospective cross-sectional study. We conducted an epidemiological investigation of yellow fever suspected and confirmed cases in Ondo State in Nigeria in 2021, using the YF case-based surveillance data. We described outbreak investigation and response activities carried out in affected LGAs, where the outbreaks were confirmed.
Results: A total of 62 suspected YF cases were reported from January to December 2021, with no record of mortality. More than half (53%) of the cases were between the age of 15 to 29 years. About three-quarter of the reported cases (73%) had received the YF vaccine. The overall attack rate was 1.33 cases per 100,000 population. Only 3 out of the 62 reported cases were confirmed as yellow fever cases.
Conclusion: The resurgence of yellow fever in the state puts the state at high-risk for yellow fever transmission. To reduce the immediate risks to the health of the population, specific activities should be tailored towards increasing awareness on yellow fever transmission, prevention, and control. These include activities on risk communication and community engagement, active surveillance, vector control, strengthening of routine immunization, as well as continued implementation of preventive mass vaccination campaigns.


  1. Zuckerman AJ. Principles and practice of clinical virology. John Wiley & Sons; 2009.
  2. Organization WH. District guidelines for yellow fever surveillance. World Health Organization; 1998.
  3. Organization WH. Yellow fever fact sheet. Fact sheet number 100. Geneva: WHO; 2011.
  4. Litvoc MN, Novaes CTG, Lopes MIBF. Yellow fever. Revista da Associação Médica Brasileira. 2018;64:106–13.
  5. Agwu EJ, Igbinosa IB, Isaac C. Entomological assessment of yellow fever-epidemic risk indices in Benue State, Nigeria, 2010–2011. Acta Trop. 2016;161:18–25.
  6. NCDC 2017 Viral Haemorrhagic Fevers Preparedness and Response Plan https:// .
  9. Pan AHO. Control of yellow fever: field guide. Washington, DC: Paho Scientific and Technical Publication. 2005;
  10. (PAHO) PAHO. Epidemiological Update: Yellow Fever. 2018;
  11. Nigeria Centre for Disease Control. National guidelines for yellow fever preparedness and response. 2019.
  12. YELLOW FEVER SITUATION REPORT. Nigeria Centre for Disease Control.
  13. National Population Commission and MEASURE DHS ICF Macro, 2009.
  14. Olaoye I, Fatiregun AA, Opeyemi E, Adeleke D, Jacdonmi T, Fagbemi S, et al. An Epidemiological Evaluation of Acute Flaccid Paralysis Surveillance Performance in Ondo State, Nigeria from 2016 to 2020. 2000;
  15. Umar UY, Sabitu K, Mohammed SS, Karaye NY, Balogun MS. Descriptive Characterization of Suspected Yellow Fever Cases in Kano state, Nigeria, 2015-2018. Journal of Interventional Epidemiology and Public Health. 2021;4(1).
  16. Goldani LZ. Yellow fever outbreak in Brazil, 2017. Vol. 21, Brazilian Journal of Infectious Diseases. SciELO Brasil; 2017. p. 123–4.
  17. Lilay A, Asamene N, Bekele A, Mengesha M, Wendabeku M, Tareke I, et al. Reemergence of yellow fever in Ethiopia after 50 years, 2013: epidemiological and entomological investigations. BMC Infect Dis. 2017;17(1):1–6.
  18. Babaniyi OA, Mwaba P, Mulenga D, Monze M, Songolo P, Mazaba-Liwewe ML, et al. Risk assessment for yellow fever in western and North-Western provinces of Zambia. Journal of Global Infectious Diseases. 2015;7(1):11.
  19. Reiter P. Global-warming and vector-borne disease in temperate regions and at high altitude. The Lancet. 1998;351(9105):839–40.
  20. Mulchandani R, Massebo F, Bocho F, Jeffries CL, Walker T, Messenger LA. A community-level investigation following a yellow fever virus outbreak in South Omo Zone, South-West Ethiopia. PeerJ. 2019;7:e6466.
  21. Sanders EJ, Marfin AA, Tukei PM, Kuria G, Ademba G, Agata NN, et al. First recorded outbreak of yellow fever in Kenya, 1992-1993. I. Epidemiologic investigations. Am J Trop Med Hyg. 1998;59(4):644–9.
  22. National Health Management Information System,Nigeria.
  23. Barnett ED. Yellow fever: epidemiology and prevention. Clinical Infectious Diseases. 2007;44(6):850–6.
  24. Hamrick PN, Aldighieri S, Machado G, Leonel DG, Vilca LM, Uriona S, et al. Geographic patterns and environmental factors associated with human yellow fever presence in the Americas. PLoS Negl Trop Dis. 2017;11(9):e0005897.
  25. Kaul RB, Evans M v, Murdock CC, Drake JM. Spatio-temporal spillover risk of yellow fever in Brazil. Parasit Vectors. 2018;11(1):1–12.
  26. Agha SB, Tchouassi DP, Bastos ADS, Sang R. Dengue and yellow fever virus vectors: seasonal abundance, diversity and resting preferences in three Kenyan cities. Parasit Vectors. 2017;10(1):1–10.
  27. Wamala JF, Malimbo M, Okot CL, Atai-Omoruto AD, Tenywa E, Miller JR, et al. Epidemiological and laboratory characterization of a yellow fever outbreak in northern Uganda, October 2010–January 2011. International Journal of Infectious Diseases. 2012;16(7):e536–42.
  28. Monath TP, Vasconcelos PFC. Yellow fever. Journal of clinical virology. 2015;64:160–73.
  29. Yellow Fever.
  30. Kallas EG, Zanella LGFABD, Moreira CH v, Buccheri R, Diniz GBF, Castiñeiras ACP, et al. Predictors of mortality in patients with yellow fever: an observational cohort study. The Lancet Infectious Diseases. 2019;19(7):750–8.
  31. Gould LH, Osman MS, Farnon EC, Griffith KS, Godsey MS, Karch S, et al. An outbreak of yellow fever with concurrent chikungunya virus transmission in South Kordofan, Sudan, 2005. Trans R Soc Trop Med Hyg. 2008;102(12):1247–54.