Human and Livestock Surveillance Revealed the Circulation of Rift Valley Fever Virus in Agnam, Northern Senegal, 2021

Abstract

The mosquito-borne disease caused by the Rift Valley Fever Virus (RVFV) is a viral hemorrhagic fever that affects humans and animals. In 1987, RVFV emerged in Mauritania, which caused the first RVFV outbreak in West Africa. This outbreak was shortly followed by reported cases in humans and livestock in Senegal. Animal trade practices with neighboring Mauritania suggest northern regions of Senegal are at high risk for RVF. In this study, we aim to conduct a molecular and serological survey of RVFV in humans and livestock in Agnam (northeastern Senegal) by RT-PCR (reverse transcription real-time polymerase chain reaction) and ELISA (Enzyme-Linked Immunosorbent Assay), respectively. Of the two hundred fifty-five human sera, one (0.39%) tested RVFV IgM positive, while fifty-three (20.78%) tested positive for RVFV IgG. For animal monitoring, out of 30 sheep recorded and sampled over the study period, 20 (66.67%) showed seroconversion to RVFV IgG antibodies, notably during the rainy season. The presence of antibodies increased significantly with age in both groups (p < 0.05), as the force of RVF infection (FOI), increased by 16.05% per year for humans and by 80.4% per month for livestock sheep. This study supports the usefulness of setting up a One Health survey for RVF management.

Using the Gut Antigen HA86 as a Biomarker for Hyalomma Tick Bites, the Principal Vectors of the Crimean-Congo Hemorrhagic Fever Virus

“…The data generated were entered in Excel and the statistical analyzes were performed on the R software using the R studio interface. Using the finite mixture model on Optical Densities (OD) as previously described [13], the cut-off threshold was determined. Subsequently, the difference in antibody levels and HA86 IgG carriage between 2 groups was analyzed by logistic regression.…”

The Adaptive Immune Response against Bunyavirales

“…Human infections with RVFV, SFTSV, and TOSV lead to the development of nAbs, exhibiting similar serological kinetics across all three viruses [ 171 , 178 , 183 , 184 ]. Patients infected with these viruses generate virus-specific IgM early at symptoms onset, with IgG Abs emerging around 15–30 days from onset, which can persist for years in convalescent sera [ 180 , 181 , 185 , 186 ]. Ab responses have been proven to contribute to protection and improved clinical outcomes in SFTSV-infected human patients.…”

The increasing threat of Rift Valley fever virus globalization: strategic guidance for protection and preparation

“…However, a strong case can be made that the massive daily international movement of humans, combined with the extremely high viremias of RVFV that humans can produce, create the most vulnerable route for spread of RVFV (Gibson et al 2022). Reports of circulation of RVFV in humans (e.g., Sanderson et al 2020, Mhamadi et al 2023, Satapathy et el. 2023) are appearing more frequently in the literature.…”

“…On the other hand, increasing findings of interepizootic transmission of the virus, not only in known endemic areas but also in adjacent or land-linked nearby nonendemic regions (Lagerqvist et al 2013, de Glanville et al 2022a, Mhamadi et al 2023), may be less driven by long-term meteorological patterns such as decadal high rainfall anomalies and more driven by changes in land use and vector, virus, and vertebrate host distributions resulting from regional climate or economic shifts. With increased frequency of the opportunity for interepizootic transmission taking place in more locations the risk of expansion of RVFV could increase compared to that risk solely due to historic large epizootics and epidemics taking place at the decadal scale.…”