Conference Abstract | Volume 8, Abstract ELIC2025329 (Oral 082) | Published:  11 Aug 2025

Pattern of occurrence of yellow fever cases and vector carrier determinants of the viral transmission in Imo State, South Eastern Nigeria: A case study of 2019-2023 One Health outbreak response

Egbuna Hyacinth Chukwuebuka1,&, Nwachukwu Williams2, Francis Ola2, Oparaocha Evangeline Tochi3, Iwuala Chimezie3, Dozie Winnie Ugonna3

1Imo State Ministry of Health, Owerri, Imo State, 2,Nigeria Centre for Disease Control, Federal Capital Territory, Abuja, Nigeria 3Federal University of Technology Owerri, Imo State, Nigeria

&Corresponding author: Egbuna Hyacinth Chukwuebuka, Imo State Ministry of Health, Owerri, Imo State, Nigeria. Email: egbuhyacinth@gmail.com

Received: 31 Mar 2025, Accepted: 09 Jul 2025, Published: 11 Aug 2025

Domain: Infectious Disease Epidemiology

This is part of the Proceedings of the ECOWAS 2nd Lassa fever International Conference in Abidjan, September 8 – 11, 2025

Keywords: Yellow fever, mosquito vectors, vector-borne disease, IgM, flavivirus, viral hemorrhagic fevers

©Egbuna Hyacinth Chukwuebuka et al. Journal of Interventional Epidemiology and Public Health (ISSN: 2664-2824). This is an Open Access article distributed under the terms of the Creative Commons Attribution International 4.0 License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Cite this article: Egbuna Hyacinth Chukwuebuka et al., Pattern of occurrence of yellow fever cases and vector carrier determinants of the viral transmission in Imo State, South Eastern Nigeria: A case study of 2019-2023 One Health outbreak response. Journal of Interventional Epidemiology and Public Health. 2025;8(ConfProc5):00082. https://doi.org/10.37432/jieph-confpro5-00082

Introduction

Yellow Fever is an acute viral hemorrhagic disease caused by the yellow fever virus, an arthropod-borne virus (arbovirus) of the genus Flavivirus (family Flaviviridae) that has continued to pose epidemic risks in Africa despite the availability of effective vaccines. This study aimed to assess the pattern of occurrence of yellow fever cases and to determine the vector carrier driving the viral transmission in Imo, southeastern Nigeria

Methods

A descriptive study was conducted using suspected yellow fever cases confirmed through IgM detection and further testing at Institut Pasteur Dakar. Adult mosquitoes, field-collected or reared from larvae, were preserved via freezing or ethyl acetate and identified morphologically using Edward (1941) and Gillet (1972) taxonomic keys. Specimens were stored in RNAlater at -20ºC until testing. Sociodemographic and epidemiological data were recorded in SORMAS. Yellow fever cases were identified across all 27 LGAs based on standard definitions (fever and jaundice within 14 days). The data were exported from SORMAS and analyzed using Microsoft Excel.

Results

Among 420 suspected cases tested from January 2019 to December 2023, 7 (1.7%) were confirmed cases. 50% were male, and those aged 0-10 years, and they were all unvaccinated. All suspected and confirmed cases had high fever with jaundice. Of the 27 LGAs, 20 had at least one suspected case of unvaccinated. Among 61 households visited in the communities, there was the presence of Aedes aegypti 35%, Aedes albopictus 55%, Cx quinquefasciatus 10% of mosquito species, while Aedes species accounted for 90%, which indicates the presence of vector of yellow fever.

Conclusion

Enhanced surveillance was performed. A vector control approach should be applied in the state, and the testing laboratory should be equipped to perform integrated testing for all viral hemorrhagic fevers because all negative results met the case definition.

 
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