First Report of the Emergence of Peste des Petits Ruminants Lineage IV Virus in Senegal.

Peste des petits ruminants (PPR) is a highly contagious viral disease and one of the deadliest affecting wild goats, sheep, and small ruminants; however, goats are generally more sensitive. The causative agent is the Peste des Petits Ruminants virus (PPRV), which is a single-stranded RNA virus of negative polarity belonging to the Paramyxoviridae family. In February 2020, an active outbreak of PPR was reported in a herd of a transhumant farmer in the village of Gainth Pathé (department of Kounguel, Kaffrine region, Senegal). Of the ten swabs collected from the goats, eight returned a positive result through a quantitative real-time PCR. The sample that yielded the strongest signal from the quantitative real-time PCR was further analyzed with a conventional PCR amplification and direct amplicon sequencing. A phylogenetic analysis showed that the sequence of the PPR virus obtained belonged to lineage IV. These results confirm those found in the countries bordering Senegal and reinforce the hypothesis of the importance of animal mobility between these neighboring countries in the control of PPRV. In perspective, following the discovery of this lineage IV in Senegal, a study on its dispersion is underway throughout the national territory. The results that will emerge from this study, associated with detailed data on animal movements and epidemiological data, will provide appropriate and effective information to improve PPR surveillance and control strategies with a view to its eradication.

A Phylogeographic Analysis of Porcine Parvovirus 1 in Africa.

Porcine parvovirus 1 (PPV1) is recognized as a major cause of reproductive failure in pigs, leading to several clinical outcomes globally known as SMEDI. Despite being known since the late 1960s its circulation is still of relevance to swine producers. Additionally, the emergence of variants such as the virulent 27a strain, for which lower protection induced by vaccines has been demonstrated, is of increasing concern. Even though constant monitoring of PPV1 using molecular epidemiological approaches is of pivotal importance, viral sequence data are scarce especially in low-income countries. To fill this gap, a collection of 71 partial VP2 sequences originating from eight African countries (Burkina Faso, Côte d'Ivoire, Kenya, Mozambique, Namibia, Nigeria, Senegal, and Tanzania) during the period 2011-2021 were analyzed within the context of global PPV1 variability. The observed pattern largely reflected what has been observed in high-income regions, i.e., 27a-like strains were more frequently detected than less virulent NADL-8-like strains. A phylogeographic analysis supported this observation, highlighting that the African scenario has been largely shaped by multiple PPV1 importation events from other continents, especially Europe and Asia. The existence of such an international movement coupled with the circulation of potential vaccine-escape variants requires the careful evaluation of the control strategies to prevent new strain introduction and persistence.

Insight on Bluetongue virus transmission in small ruminants in Senegal.

Bluetongue (BT) is an infectious, arthropod-borne viral disease of domestic and wild ruminants. The disease causes animal mortality, production decrease and commercial limits for herds. Despite the active circulation of the disease in the world, few studies have been carried out in Senegal. The objective of this study was to assess the current prevalence of BT in small ruminants and the serotypes circulating in Senegal. A cross-sectional study was conducted in the fourteen regions of Senegal. After the sampling campaign, sera collected in sheep and goats herds were screened for the presence of Bluetongue virus (BTV) specific antibodies using c-Elisa. The whole blood of seropositive animals was further analyzed by RT-qPCR and positive samples were typed to identify BTV serotypes. Analysis of several risk factors such as age, sex and species of animals was performed using logistic regression. The overall seroprevalence of BTV in Senegal was 72.6% (95% CI: 70.3-74.9%) with 75.9% (95% CI: 72.2-79.5%) in goat and 70.6% (95% CI: 67.5-73.6%) in sheep. Female (prevalence=77.1%) and adult (prevalence=80%) animals showed the highest seropositivity to BTV compared respectively to male (55.7%, p=6.133e-09) and young (49.4%, p < 2.2e-16). The RT-qPCR results showed the presence of BT viral genome in 359 small ruminants. The results obtained from serological and genotyping studies showed an active spread of the Bluetongue virus in domestic ruminants and phylogenetic analysis showed that the BTV-2 is one of the circulating serotypes in Senegal. This study allows having baseline information for controlling Bluetongue in Senegal.

Assessing the Risk of Occurrence of Bluetongue in Senegal.

Bluetongue is a non-contagious viral disease affecting small ruminants and cattle that can cause severe economic losses in the livestock sector. The virus is transmitted by certain species of the genus Culicoides and consequently, understanding their distribution is essential to enable the identification of high-risk transmission areas. In this work we use bioclimatic and environmental variables to predict vector abundance, and estimate spatial variations in the basic reproductive ratio  R0. The resulting estimates were combined with livestock mobility and serological data to assess the risk of Bluetongue outbreaks in Senegal. The results show an increasing abundance of C. imicola, C. oxystoma, C. enderleini, and C. miombo from north to south. R0 < 1 for most areas of Senegal, whilst southern (Casamance) and southeastern (Kedougou and part of Tambacounda) agro-pastoral areas have the highest risk of outbreak (R0 = 2.7 and 2.9, respectively). The next higher risk areas are in the Senegal River Valley (R0 = 1.07), and the Atlantic coast zones. Seroprevalence rates, shown by cELISA, weren't positively correlated with outbreak probability. Future works should include follow-up studies of competent vector abundancies and serological surveys based on the results of the risk analysis conducted here to optimize the national epidemiological surveillance system.