Seasonal and Climatic Drivers of Lassa Fever Transmission in Nigeria: A Multi-Year Ecological Analysis (2020–2025)
DOI:
https://doi.org/10.54536/ajbb.v5i1.8094Keywords:
Climate Variability, Epidemiology, Humidity, Lassa Fever, Negative Binomial Regression, Nigeria, Rainfall, Seasonality, TemperatureAbstract
Lassa fever remains a major public health challenge in Nigeria, where recurrent outbreaks continue to impose substantial health and socioeconomic burdens. Although climatic variability has been implicated in disease transmission, the relative contributions of key environmental factors to outbreak occurrence remain insufficiently quantified. This study examined the influence of temperature, rainfall, humidity, and seasonality on Lassa fever epidemiology in Nigeria using national surveillance and meteorological data collected between 2020 and 2025. A total of 1,404 observations comprising confirmed cases and associated climatic variables were analysed using descriptive statistics, Pearson correlation analysis, and Negative Binomial Regression to account for overdispersion in disease counts. The findings revealed a pronounced seasonal pattern, with 77.1% of confirmed cases occurring during the dry season and peak transmission observed between January and March. Temperature was positively associated with disease incidence, whereas rainfall exhibited a significant inverse relationship. Negative Binomial Regression identified temperature (IRR = 1.024, p < .001), rainfall (IRR = 0.987, p < .001), humidity (IRR = 1.007, p = .001), and seasonality (IRR = 2.131, p < .001) as significant predictors of Lassa fever occurrence. After adjusting for climatic factors, disease incidence during the dry season was approximately 113% higher than during the wet season. These patterns suggest that climatic conditions influence transmission through their effects on environmental suitability, rodent ecology, and opportunities for human exposure. This study provides updated national-level evidence on the climatic determinants of Lassa fever transmission in Nigeria and demonstrates the dominant role of seasonality in shaping outbreak dynamics. By simultaneously quantifying the independent effects of multiple environmental drivers using a modelling framework appropriate for overdispersed disease count data, the study advances understanding of climate-sensitive Lassa fever epidemiology and provides an evidence base for climate-informed surveillance, early warning systems, and outbreak preparedness strategies.
Downloads
References
Adesola, M., Kazeem, O., Dayo, L., Abideen, S., Fewajesuyan, A., Wakilat, T., Abass, A., & Babatunde, S. (2024). Modelling seasonal variation and Lassa fever outbreak in Nigeria: A predictive approach. International Journal of Data Science and Analysis, 10(5), 100–108. https://doi.org/10.11648/j.ijdsa.20241005.12
Alao, J. O. (2026). Public genomic visibility of Lassa virus in West Africa: mapping sequence availability, ecological risk, and surveillance gaps. Critical Public Health, 36(1). https://doi.org/10.1080/09581596.2026.2676344
Akhmetzhanov, A. R., Asai, Y., & Nishiura, H. (2019). Quantifying the seasonal drivers of transmission for Lassa fever in Nigeria. Philosophical Transactions of the Royal Society B: Biological Sciences, 374(1775), 20180268. https://doi.org/10.1098/rstb.2018.0268
Bonwitt, J., Kelly, A. H., Ansumana, R., Agbla, S., Sahr, F., Saez, A. M., Borchert, M., Kock, R., & Fichet-Calvet, E. (2017). Rat-atouille: A mixed method study to characterize rodent hunting and consumption in the context of Lassa fever. EcoHealth, 13(2), 234–247. https://doi.org/10.1007/s10393-016-1098-8
Arotolu, T.E., Olayinka-Olagunju, J. & Dosumu, A.A. Modelling the effects of climate and human factor on Lassa fever distribution in Ondo State Nigeria. Int J Biometeorol 69, 2553–2565 (2025). https://doi.org/10.1007/s00484-025-02996-3
Al-Mustapha, A. I., Adesiyan, I. M., Orum, T. G., Ogundijo, O. A., Lawal, A. N., Nzedibe, O. E., Onyeka, L. O., Muhammad, K. U., Odetayo, L., Oyewo, M., Muhammad, S. O., Atadiose, E. O., Adebudo, L. I., Adetunji, D. A., Jantiku, H. J., Akintule, A. O., Nwachukwu, R. C., & Abubakar, A. T. (2024). Lassa fever in Nigeria: epidemiology and risk perception. Scientific reports, 14(1), 27669. https://doi.org/10.1038/s41598-024-78726-3
Cadmus, S., Akinseye, V., Cadmus, E.,Famokun, G., Fagbemi, S., Ogunde, G., et al. (2025).Drivers of Lassa fever in an endemic area of southwestern Nigeria (2017–2021): An epidemiological study. PLoS ONE, 20(6), e0327143.
Cadmus, S., Taiwo, O. J., Akinseye, V., Cadmus, E., Famokun, G., Fagbemi, S., Ansumana, R., Omoluabi, A., Ayinmode, A., Oluwayelu, D., Odemuyiwa, S., & Tomori, O. (2023). Ecological correlates and predictors of Lassa fever incidence in Ondo State, Nigeria 2017–2021: An emerging urban trend. Scientific Reports, 13(1), Article 20855. https://doi.org/10.1038/s41598-023-47820-3
Dan-Nwafor, C., Dalhat, M. M., Olayinka, A., Meremikwu, M. M.,., Iniobong, A., Ntoimo, L. F., Onoh, I., Mba, S., Ohonsi, C., Arinze, C., Esu, E. B., Nwafor, O., Oladipupo, I., Onoja, M., Ilori, E., Okonofua, F., Ochu, C. L., Igumbor, E. U., & Adetifa, I. (2022). Epidemiological trends of Lassa fever in Nigeria, 2018-2021. PloS one, 17(12), e0279467. https://doi.org/10.1371/journal.pone.0279467
Eneh, S. C., Obi, C. G., Ikpongifono, U. E., Dauda, Z., Udoewah, S. A., Anokwuru, C. C., Onukansi, F. O., Ikhuoria, O. V., Ojo, T. O., Madukaku, C. U., Orabueze, I. N., & Chizoba, A. F. (2025). The resurgence of Lassa fever in Nigeria: Economic impact, challenges, and strategic public health interventions. Frontiers in Public Health, 13, Article 1574459. https://doi.org/10.3389/fpubh.2025.1574459
Fichet-Calvet, E., & Rogers, D. J. (2009). Risk maps of Lassa fever in West Africa. PLoS Neglected Tropical Diseases, 3(3), e388. https://doi.org/10.1371/journal.pntd.0000388
Fuwape, I., Ogunjo, S., Erinfolami, F., Osunmakinwa, O., Ajanaku, O., Akerele, A., Akinlami, A., Akinsusi, J., Olayinka-Olagunju, J., & Asubiaro, O. (2026). Quantifying the climatic influence on Lassa fever incidences in six high-risk Nigerian states using multilinear regression and generalized additive models. Discover Public Health, 23(1), Article 276. https://doi.org/10.1186/s12982-026-01550-9
Gibb, R., Moses, L. M., Redding, D. W., & Jones, K. E. (2017). Understanding the cryptic nature of Lassa fever in West Africa. Pathogens and Global Health, 111(6), 276–288. https://doi.org/10.1080/20477724.2017.1369643
Grace, J. A., Egoh, I. J., & Udensi, N. (2021). Epidemiological trends of Lassa fever in Nigeria from 2015-2021: A review. Therapeutic advances in infectious disease, 8, 20499361211058252. https://doi.org/10.1177/20499361211058252
Ilori, E. A., Furuse, Y., Ipadeola, O., Dan- Nwafor, C. C., Abubakar, A., Womi-Eteng, O., Olayemi, A., & Okoli, A. (2019). Epidemiologic and clinical features of Lassa fever outbreak in Nigeria, January 1–May 6, 2018. Emerging Infectious Diseases, 25(6), 1066–1074. https://doi.org/10.3201/eid2506.181035
John, O. N., Akyala, A. I., Eleojo, G. I., Aremu, S. O., Matthew, A. O., Elam, O. P., Ezeobi, A. J., Augustine, O., Barnabas, S., Augustine, U., Ayo, O. J., Mohammed, K., Ameh, A. J., Ohize, M. S., Thankgod, O. S., & Barkhadle, A. A. (2026). Impact of seasonal changes on the epidemiology of Lassa fever in a state in North Central, Nigeria. Tropical diseases, travel medicine and vaccines, 12(1), 12. https://doi.org/10.1186/s40794-026-00294-3
Nigeria Centre for Disease Control and Prevention. (2025). Lassa fever situation reports. Abuja, Nigeria: NCDC.
Olayemi, A., Cadar, D., Magassouba, N., Obadare, A., Kourouma, F., Oyeyiola, A., Fasogbon, S., Igbokwe, J., Rieger, T., Bockholt, S., Jérôme, H., Schmidt-Chanasit, J., Garigliany, M., Lorenzen, S., Igbahenah, F., Fichet-Calvet, E., & Günther, S. (2016). New hosts of the Lassa virus. Scientific Reports, 6, 25280. https://doi.org/10.1038/srep25280
Okoro, O. A., Bamgboye, E., Dan-Nwafor, C., Umeokonkwo, C., Ilori, E., Yashe, R., Balogun, M., Nguku, P., & Ihekweazu, C. (2020). Descriptive epidemiology of Lassa fever in Nigeria, 2012-2017. The Pan African medical journal, 37, 15. https://doi.org/10.11604/pamj.2020.37.15.21160
Oyeyiola, A., Adesina, A. S., Obadare, A., Igbokwe, J., Fasogbon, S. A., Abejegah, C., Akhilomen, P., Asogun, D., Tobin, E., Ayodeji, O., Osoniyi, O., Pahlmann, M., Günther, S., Fichet-Calvet, E., & Olayemi, A. (2025). Impact of seasonal change on virus-rodent dynamics in Nigeria’s Edo-Ondo hotspot for Lassa fever. Current research in parasitology & vector-borne diseases, 7, 100271. https://doi.org/10.1016/j.crpvbd.2025.100271
Redding, D. W., Gibb, R., Dan-Nwafor, C. C., Ilori, E. A., Yashe, R. U., Oladele, S. H., Amedu, M. O., Iniobong, A., Attfield, L. A., Donnelly, C. A., Abubakar, I., Jones, K. E., & Ihekweazu, C. (2021). Geographical drivers and climate-linked dynamics of Lassa fever in Nigeria. Nature communications, 12(1), 5759. https://doi.org/10.1038/s41467-021-25910-y
Siddle, K. J., Eromon, P., Barnes, K. G., Mehta, S. B., Oguzie, J. U., Odia, I., Schaffner, S. F., Winnicki, S. M., Shah, R. R., Qu, J., Okogbenin, S., Akpede, G., Akpede, N., Ogbaini-Emovon, E., Folarin, O., Ehiane, P. E., Etebu, E. N., Agbebaku, E., Airende, M., ... Happi, C. T. (2018). Genomic analysis of Lassa virus during an increase in cases in Nigeria in 2018. New England Journal of Medicine, 379(18), 1745–1753. https://doi.org/10.1056/NEJMoa1804498
World Health Organization. (2024). Lassafever fact sheet. Geneva, Switzerland: WHO.
Zhao, S.,Musa, S. S., Fu, H., He, D., & Qin, J. (2020).Large-scale Lassa fever outbreaks in Nigeria: quantifying the association between disease reproduction number and local rainfall. Epidemiology and infection, 148, e4. https://doi.org/10.1017/S0950268819002267
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Akpensuen Shiaondo Henry, Kazeem Eyitayo Lasisi, Hamisu Idi, Akpan Alphonsus Emmanuel
This work is licensed under a Creative Commons Attribution 4.0 International License.
