pathogens Article First Serological Evidence of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in Ruminants in Tunisia Khaoula Zouaghi 1 , Ali Bouattour 1 , Hajer Aounallah 1 , Rebecca Surtees 2 , Eva Krause 2 , Janine Michel 2 , Aymen Mamlouk 3 , Andreas Nitsche 2 and Youmna M’ghirbi 1, *   Citation: Zouaghi, K.; Bouattour, A.; Aounallah, H.; Surtees, R.; Krause, E.; Michel, J.; Mamlouk, A.; Nitsche, A.; M’ghirbi, Y. First Serological Evidence of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in Ruminants in Tunisia. Pathogens 2021, 10, 769. https://doi.org/ 10.3390/pathogens10060769 Academic Editors: Natasha N. Gaudreault and Anna Honko Received: 27 March 2021 Accepted: 9 June 2021 Published: 18 June 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Laboratory of Viruses Vectors and Hosts (LR20IPT02), Institute Pasteur of Tunis, University of Tunis El Manar, Tunis 1002, Tunisia; khawlazouaghi@gmail.com (K.Z.); ali.bouattour@pasteur.tn (A.B.); aounallahhajer@gmail.com (H.A.) 2 Division Highly Pathogenic Viruses, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestraße 10, 13353 Berlin, Germany; SurteesR@rki.de (R.S.); KrauseE@rki.de (E.K.); MichelJ@rki.de (J.M.); NitscheA@rki.de (A.N.) 3 Service de Microbiologie et Immunologie, Ecole Nationale de Médecine Vétérinaire, Université de Manouba, Sidi Thabet 2020, Tunisia; aymen.mamlouk@enmv.uma.tn * Correspondence: youmna.mghirbi@pasteur.tn or youmna.mgh@gmail.com Abstract: Crimean-Congo hemorrhagic fever virus (CCHFV, Nairoviridae family) and Rift Valley fever virus (RVFV, Phenuiviridae family) are zoonotic vector-borne pathogens with clinical relevance worldwide. Our study aimed to determine seroprevalences of these viruses and potential risk fac- tors among livestock (cattle, sheep, and goats) in Tunisia. Sera were tested for antibodies against CCHFV (n = 879) and RVFV (n = 699) using various enzyme-linked immunosorbent assays (ELISAs) and indirect immunofluorescence assays (IIFA). The overall seroprevalence of IgG antibodies was 8.6% (76/879) and 2.3% (16/699) against CCHFV and RVFV, respectively. For CCHF seropositivity bioclimatic zones and breed were potential risk factors for the three tested animal species; while the season was associated with cattle and sheep seropositivity, tick infestation was associated with cattle and goats seropositivity and age as a risk factor was only associated with cattle seropositiv- ity. Age and season were significantly associated with RVFV seropositivity in sheep. Our results confirm the circulation of CCHFV and RVFV in Tunisia and identified the principal risk factors in ruminants. This knowledge could help to mitigate the risk of ruminant infections and subsequently also human infections. Keywords: Crimean-Congo hemorrhagic fever virus; Rift Valley fever virus; enzyme-linked im- munosorbent assays; indirect immunofluorescence assay; risk factors; ruminants; Tunisia 1. Introduction Crimean-Congo hemorrhagic fever virus (CCHFV, Nairoviridae family) and Rift Valley Fever virus (RVFV, Phenuiviridae family) are the causative agents of Crimean-Congo hemor- rhagic fever (CCHF) and Rift Valley fever (RVF), respectively. These viruses belonging to the Bunyavirales order have clinical relevance worldwide [1]. CCHFV of the Orthonavirus genus is transmitted to large and small mammals and birds(with the exception of ostriches), by ticks [2]. Humans are infected by tick bites, or through exposure to blood or infected tissues from viremic animals, or infected persons [3]. Only 12% of infected people will develop symptoms. Acute CCHF in humans is character- ized by an onset of fever, tremors, myalgia, headaches, nausea and vomiting, abdominal pain and arthralgia. In severe cases, the disease is complicated by the appearance of bleeding from mucosal membranes (e.g., nose and vagina) and ecchymosis; lethality rates can reach 9–50% [4,5]. In contrast, CCHFV infection in wild and domestic mammals does not cause severe disease, in general, infected animals remain asymptomatic [6]; but they play an essential role in the amplification and spread of the virus [7,8]. Among these Pathogens 2021, 10, 769. https://doi.org/10.3390/pathogens10060769 https://www.mdpi.com/journal/pathogens