Epidemiology of Shuni Virus in Horses in South Africa.

Thopisang P Motlou,June Williams,Marietjie Venter

doi:10.3390/v13050937

Abstract

The Orthobunyavirus genus, family Peribunyaviridae, contains several important emerging and re-emerging arboviruses of veterinary and medical importance. These viruses may cause mild febrile illness, to severe encephalitis, fetal deformity, abortion, hemorrhagic fever and death in humans and/or animals. Shuni virus (SHUV) is a zoonotic arbovirus thought to be transmitted by hematophagous arthropods. It was previously reported in a child in Nigeria in 1966 and horses in Southern Africa in the 1970s and again in 2009, and in humans with neurological signs in 2017. Here we investigated the epidemiology and phylogenetic relationship of SHUV strains detected in horses presenting with febrile and neurological signs in South Africa. In total, 24/1820 (1.3%) horses submitted to the zoonotic arbovirus surveillance program tested positive by real-time reverse transcription (RTPCR) between 2009 and 2019. Cases were detected in all provinces with most occurring in Gauteng (9/24, 37.5%). Neurological signs occurred in 21/24 (87.5%) with a fatality rate of 45.8%. Partial sequencing of the nucleocapsid gene clustered the identified strains with SHUV strains previously identified in South Africa (SA). Full genome sequencing of a neurological case detected in 2016 showed 97.8% similarity to the SHUV SA strain (SAE18/09) and 97.5% with the Nigerian strain and 97.1% to the 2014 Israeli strain. Our findings suggest that SHUV is circulating annually in SA and despite it being relatively rare, it causes severe neurological disease and death in horses.

Highlights

Accepted: 26 April 2021The Orthobunyavirus genus, family Peribunyaviridae belongs to the order Bunyavirales which consists mostly of vector-borne viral diseases transmitted by arthropods [1]
In this study we focused on the orthobunyavirus, Shuni virus (SHUV), a neglected reemerging zoonotic virus thought to be transmitted by hematophagous arthropods
This study aimed to describe the epidemiology of SHUV by investigating the temporal and geographical distribution of SHUV in horses with febrile and/or neurological infections in South Africa (SA) over a period of 10 years

Summary

Introduction

The Orthobunyavirus genus, family Peribunyaviridae belongs to the order Bunyavirales which consists mostly of vector-borne viral diseases transmitted by arthropods (e.g., mosquitoes, ticks, flies and midges) [1]. The viruses in this order produce illnesses ranging from acute febrile to hemorrhagic fevers, neuroinvasive diseases, abortions and birth defects [2,3]. The Peribunyaviridae family are negative sense single stranded RNA (ss-RNA) viruses with a segmented genome [4,5]. Genetic reassortment occurs naturally within these viruses due to the segmented genome leading to the emergence of new viruses in which the pathogenicity may be increased [8]. Viruses in the Orthobunyavirus genus are widely distributed in different continents [7,9] and include viruses of significant importance such as Akabane [6], Schmallenberg [10,11] and Oropouche viruses which have been reported to cause significant clinical diseases variability in humans and animals [12]

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