Risk based serological survey of Rift Valley fever in Tunisia (2017–2018)

Sana Kalthoum,Catherine Cêtre-Sossah,Lilia Messadi,Soufien Sghaier,Pascal Hendrikx,Chédia Seghaier,Mohamed Naceur Baccar,Anissa Dhaouadi,Bassem Bel Haj Mohamed,Monia Lachtar,Aymen Mamlouk,Kaouther Guesmi,Raja Gharbi,Malek Zrelli,Cécile Squarzoni-Diaw,Jamel Cherni,Haikel Hajlaoui,Wiem Khalfaoui,Samia Mzoughi,Elena Arsevska

doi:10.1016/j.heliyon.2021.e07932

Abstract

Rift Valley fever (RVF) has been reported in the sub-Saharan region of Africa, Egypt and Arabian Peninsula - Yemen and Saudi Arabia, over the past 20 years and is a threat to both the animal and human populations in Tunisia. Tunisia is considered as a high-risk country for the introduction of RVF due to the informal movements of diseased animals already reported in the neighboring countries. The objective of this study was to assess the status of RVF in small ruminants and camels in Tunisia. A risk-based serological survey was conducted to evaluate the presence of RVF based on spatial qualitative risk analysis (SQRA). Samples were collected from small ruminants (sheep and goats) (n = 1,114), and camels (n = 173) samples, belonging to 18 breeders in 14 governorates between November 2017 and January 2018. Samples were tested using an RVF specific multispecies competitive ELISA. Out of the 1,287 samples tested for the presence of RVF IgG antibodies by ELISA, only one positive sample 0.07% (1/1 287) was detected but not confirmed with the virus neutralization test (VNT) used for confirmation. So far, no RVF outbreaks have been reported in Tunisia and our study confirmed the absence of RVF in livestock up to January 2018. Further investigations are needed to confirm the RVF-free status of Tunisia today.

Highlights

Rift Valley fever (RVF) is a mosquito-borne zoonosis that affects humans and domestic ruminants [1] caused by a virus of the Phlebovirus genus that belongs to the Phenuiviridae family
Of the 112 breeders of small ruminants included in the survey, 98.2% (110/112) were private farms and only two were public farms (Table 1)
The aim of this study was to investigate the circulation of RVF virus (RVFV) in small ruminant and camel populations in Tunisia using a risk-based sampling method, supported by a spatial qualitative risk analysis

Summary

Introduction

Rift Valley fever (RVF) is a mosquito-borne zoonosis that affects humans and domestic ruminants (camelids, cattle, goats, and sheep) [1] caused by a virus of the Phlebovirus genus that belongs to the Phenuiviridae family. The virus was identified for the first time in 1930 in the Rift Valley in Kenya [2, 3]. Humans are infected by the RVF virus (RVFV) through contact with the blood or organs of infected animals during slaughter, or when handling infected animals, or through the ingestion of contaminated meat and raw milk [4]. The RVFV has been isolated from at least 40 mosquito species belonging to eight genera (mainly Aedes spp. and Culex spp.) [6, 7] when feeding on viremic animals. Infected females of Aedes spp. are known to transmit the virus to their progeny, via desiccated eggs that are resistant to drought, maintaining the viral life cycle [8]

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