Seroprevalence and Associated Risk Factors of Rift Valley Fever in Livestock from Three Ecological Zones of Malawi

Henson Kainga; Marvin Collen Phonera; Elisha Chatanga; Simegnew Adugna Kallu; Prudence Mpundu; Mulemba Samutela; Herman Moses Chambaro; Masahiro Kajihara; Doreen Mainza Shempela; Jay Sikalima; Walter Muleya; Misheck Shawa; Julius Chulu; Gilson Njunga; Martin Simuunza; Ayato Takada; Hirofumi Sawa; Edgar Simulundu; Ngonda Saasa

doi:10.3390/pathogens11111349

Seroprevalence and Associated Risk Factors of Rift Valley Fever in Livestock from Three Ecological Zones of Malawi

Pathogens. 2022 Nov 14;11(11):1349. doi: 10.3390/pathogens11111349.

Authors

Henson Kainga^{1

2}, Marvin Collen Phonera³, Elisha Chatanga⁴, Simegnew Adugna Kallu^{2

5}, Prudence Mpundu⁶, Mulemba Samutela^{7

8}, Herman Moses Chambaro⁹, Masahiro Kajihara^{2

10}, Doreen Mainza Shempela¹¹, Jay Sikalima¹¹, Walter Muleya¹², Misheck Shawa¹³, Julius Chulu³, Gilson Njunga³, Martin Simuunza², Ayato Takada^{2

13}, Hirofumi Sawa^{2

12

14

15

16}, Edgar Simulundu^{2

17}, Ngonda Saasa²

Affiliations

¹ Department of Veterinary Epidemiology and Public Health, Faculty of Veterinary Medicine, Lilongwe University of Agriculture and Natural Resources, Lilongwe 207203, Malawi.
² Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia.
³ Department of Animal Health and Livestock Development, Ministry of Agriculture, Lilongwe 207203, Malawi.
⁴ Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, Lilongwe University of Agriculture and Natural Resources, Lilongwe 207203, Malawi.
⁵ College of Veterinary Medicine, Haramaya University, Dire Dawa P.O. Box 138, Ethiopia.
⁶ Department of Environmental and Occupational Health, Levy Mwanawasa Medical University, Lusaka 33991, Zambia.
⁷ Department of Paraclinical Studies, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia.
⁸ Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka 10101, Zambia.
⁹ Virology Unit, Central Veterinary Research Institute (CVRI), Ministry of Fisheries and Livestock, Lusaka 10101, Zambia.
¹⁰ Division of Global Epidemiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan.
¹¹ Churches Health Association of Zambia, Lusaka 10101, Zambia.
¹² Department of Biomedical Sciences, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia.
¹³ Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan.
¹⁴ Japan Division of International Research Promotion, International Institute for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan.
¹⁵ Japan Global Virus Network, Baltimore, ML 21201, USA.
¹⁶ One Health Research Center, Hokkaido University, Sapporo 001-0020, Japan.
¹⁷ Macha Research Trust, Choma 20100, Zambia.

Abstract

The epidemiology of Rift Valley fever (RVF) is poorly understood in Malawi. Here, a cross-sectional study was conducted (March-June 2020) to investigate the seroprevalence and potential risk factors of RVF virus (RVFV) in cattle, goats, and sheep in three ecological zones of Malawi. A total of 1523 serum samples were tested for anti-RVFV IgG and IgM antibodies by ELISA. Additionally, a questionnaire survey was used to assess potential RVF risk factors. The overall seroprevalence was 17.14% (261/1523; 95% CI = 15.33-19.11) for individual livestock and 33.24% (120/361; 95% CI = 28.18-38.11) for the livestock herd. Seroprevalence was significantly high in sheep (25.68%, 95% CI = 19.31-33.26) compared with cattle (21.35%, 95% CI = 18.74-24.22) and goats (7.72%, 95% CI = 5.72-10.34), (p = 0.047). At the individual livestock level, the risk was elevated in female livestock (OR: 1.74, 95% CI = 1.08-12.82) (p = 0.016), while at the herd level, areas receiving approximately 1001-1500 mm of rainfall (OR: 2.47, 95% CI = 1.14-5.37) (p = 0.022), areas of rainfall amount greater than approximately 1600 mm (OR: 2.239, 95% CI = 1.07-8.82) (p = 0.023), and mixed species herds (OR: 10.410, 95% CI = 3.04-35.59) (p = 0.001), were significant risk factors. The detection of IgM antibodies confirmed active circulation of RVFV in Malawi. Therefore, monitoring of RVF in animals, humans, and vectors using a "One Health" approach, along with community sensitization among the high-risk populations, could help mitigate the threat posed by this zoonotic disease in Malawi.

Keywords: ELISA; IgG; IgM; Malawi; Rift Valley fever; livestock; risk factors; seroprevalence.

Grants and funding

The study was supported in part by: The Government of the Republic of Malawi; Lilongwe University of Agriculture and Natural Resources (LUANAR), The Africa Centre of Excellence for Infectious Diseases of Humans and Animals (ACEIDHA) project (grant # P151847) funded by the World Bank; the Japan Program for Infectious Diseases Research and Infrastructure (JP21wm0125008; H.S) from Japan Agency for Medical Research and Development (AMED), and Japan International Cooperation Agency (JICA) within the framework of the Science and Technology Research Partnership for Sustainable Development (SATREPS) (JP21jm0110019). The APC was funded by Directorate of Research and Outreach, LUANAR with funds for Sustainable Food Systems project.