Serological and molecular prevalence study of bluetongue virus in small domestic ruminants in Morocco

Daif, Soukaina; Berbri, Ikhlass El; Lhor, Youssef; Fihri, Ouafaa Fassi

doi:10.1038/s41598-022-24067-y

Cited by 7 publications

(3 citation statements)

References 55 publications

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“…BTV was detected in small ruminants in the same study regions during the same survey period [ 7 ], providing evidence of the active circulation of the virus and the impact of these Culicoides species in bluetongue outbreaks in Morocco. The diversity of BTV-vector Culicoides species in the Moroccan fauna poses a potential threat to livestock herds, reinforcing the importance of implementing effective management strategies and vector control programs.…”

Section: Discussionmentioning

confidence: 99%

First molecular evidence of potential Culicoides vectors implicated in bluetongue virus transmission in Morocco

Daif,

El Berbri,

Fassi Fihri

2024

Parasites Vectors

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Background Bluetongue is a non-contagious viral disease that affects both domestic and wild ruminants. It is transmitted primarily by small hematophagous Diptera belonging to the genus Culicoides (Diptera: Ceratopogonidae). The current study represents the first molecular investigation into the potential role of Culicoides imicola, Culicoides paolae, Culicoides newsteadi, Culicoides spp., and Culicoides circumscriptus as bluetongue virus (BTV) vectors in Morocco. Additionally, the study aimed to evaluate the vectorial activity of midges during the survey seasons. Methods Parous females of these species were captured from several regions of Morocco (6 out of 12) from 2018 to 2021 using Onderstepoort Veterinary Institute (OVI) traps. A total of 2003 parous female specimens were grouped into 55 batches. The midge body of each batch was dissected into three regions (head, thorax, and abdomen), and these regions were analyzed separately using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Results BTV RNA was detected in 45 out of the 55 batches tested, indicating a positivity rate of 81.8%. The RT-qPCR-positive pools of the studied Culicoides species exhibited high levels of BTV positivity in each body part (head, thorax, and abdomen), confirming the successful replication of the virus within midge bodies. The BTV circulation was substantial across all three survey seasons (spring, summer, and autumn). High infection rates, calculated using the minimum infection rate (MIR) and maximum likelihood estimation (MLE), were observed during the collection seasons, particularly in autumn and spring, and for all investigated Culicoides species, most notably for C. imicola and C. newsteadi. These increased infection rates underscore the significant risk of Culicoides transmitting the BTV in Morocco. Conclusions The detection of BTV positivity in Culicoides spp. (lacking wing spots that allow their differentiation according to morphological identification keys) suggested that other Culicoides species are competent for BTV transmission in Morocco. The study results indicated, for the first time at the molecular level, that C. imicola and C. newsteadi are the primary potential vectors of BTV in Morocco and that C. paolae and C. circumscriptus are strongly implicated in the propagation of bluetongue at the national level. Graphical Abstract

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Section: Discussionmentioning

confidence: 99%

First molecular evidence of potential Culicoides vectors implicated in bluetongue virus transmission in Morocco

Daif,

El Berbri,

Fassi Fihri

2024

Parasites Vectors

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“…The samples used in the study belonged to a subset of frozen sera and whole-blood samples collected during a Bluetongue surveillance study carried out between 2019 and 2021 in Morocco [28].…”

Section: Sample Selection and Serological Analysismentioning

confidence: 99%

Serological and Molecular Characterization of Small Ruminant Lentiviruses in Morocco

Colitti,

Daif,

Choukri

et al. 2024

Animals

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Recent studies that investigated the origins of SRLV strains offered new insights into their distribution among domestic ruminants. The aim of the study was to investigate SRLV circulation in Morocco. A total of 51 farms were selected in different geographical locations and tested by screening and genotyping ELISA. Whole blood was used for DNA extraction and nested gag PCR. The sample size allowed for an estimation of prevalence lower than 20% (CI 95%). Surprisingly, a large proportion of screening-positive samples were not correctly serotyped. Sanger and NGS amplicon sequencing approaches allowed us to obtain new sequences even from difficult-to-amplify samples. The serological data support the evidence of an intrinsic difficulty of SRLV to spread, likely due to management practices. The low rate of success by genotyping ELISA led us to suppose that divergent strains might have escaped from diagnostic tools, as partially confirmed by the evidence of an A subtype carrying a mismatch in serotyping epitope. The sequence analysis revealed the circulation of novel B and recombinant A/B subtypes. This study highlights the importance of monitoring viral sequences and their evolution to develop specific diagnostic tests, particularly in countries where control measures are in place.

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“…In Morocco, BTV-10, BTV-4, and BTV-6 were identified in 1956, 2004, and 2006, respectively. Subsequently, various outbreaks have been documented ( 10 ). In Algeria, outbreaks caused by BTV-2 were reported in 2000 ( 9 ), while BTV-1 was concurrently identified in 2006, 2008, 2009, and 2010 ( 11 ).…”

Section: Introductionmentioning

confidence: 99%

Estimation of the economic impact of a bluetongue serotype 4 outbreak in Tunisia

Ben Salem,

Ben Aicha,

Kalthoum

et al. 2024

Front. Vet. Sci.

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IntroductionSince 1999, Tunisia has experienced multiple occurrences of Bluetongue (BT) outbreaks, leading to numerous reported cases of infection and mortality in flocks. The re-emergence of the disease in 2020 caused substantial economic losses in cattle, attributed to the incursion of serotype BTV-4.MethodsTo evaluate the economic impact of the recent BT episode, we conducted a retrospective study on outbreaks that occurred in Tunisia between August and November 2020, focusing on the impact at the owner’s level and its effects on both small ruminants and cattle. A total of 234 ruminant farms (sheep, cattle, and mixed) were randomly selected across Tunisian governorates and included in the study to estimate both the direct and indirect costs of these outbreaks.ResultsTotal costs were calculated as the sum of losses and expenditures resulting from the BT outbreaks. At the animal level, total losses were estimated to range between 116.280 and 207.086 TND for one infected ewe (€33.721 and 60.055). For one lactating cow, costs varied between 2,590.724 and 3,171.107 TND (€751.310 and 919.621). In cattle, exposure to BTV led to a daily unit milk yield decrease of 12.50 to 14.66 L over an average period of 5 months. Diseased sheep experienced weight loss ranging between 4 and 10 kg during the BT outbreaks. The total mean cost of the 2020 BT outbreak in Tunisian investigated farms was estimated at 1,935 million TND (million €561.15) (range: 1,489 and 2,474 million TND; 431.81 and million €717.46). The most influential costs of the total BT outbreaks were the decrease in milk yield, mortality, and veterinary treatment.DiscussionThis study gives valuable insights on the economic impact of the incursion of a new serotype of BT in a naive population in Tunisia. Considering the substantial costs incurred, it is imperative that this disease receives increased attention from stakeholders, including animal owners, veterinary services, practitioners, and decision-makers.

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Serological and molecular prevalence study of bluetongue virus in small domestic ruminants in Morocco

Cited by 7 publications

References 55 publications

First molecular evidence of potential Culicoides vectors implicated in bluetongue virus transmission in Morocco

First molecular evidence of potential Culicoides vectors implicated in bluetongue virus transmission in Morocco

Serological and Molecular Characterization of Small Ruminant Lentiviruses in Morocco

Estimation of the economic impact of a bluetongue serotype 4 outbreak in Tunisia

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