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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., QRA methodology, Risk mapping, Survey, Tunisia, Rift valley fever, Small ruminants, Camels

International audience; The World Organisation for Animal Health advocates the zoning approach for the surveillance and monitoring of foot and mouth disease (FMD), a highly contagious animal disease. Our purpose is to implement the zoning approach in Tunisia by identifying existing natural and artificial barriers to the movement of live animals. A Geographic Information System (GIS)-based MultiCriteria Evaluation approach was developed. Eight national and international experts were asked to identify the barriers and prioritize them, characterized by a percentage weight between 0 and 100. These barriers were mapped and combined, taking into account their relative importance, to create a friction map that makes it possible to visualize areas where animal movements are restricted. Uncertainty analysis was performed to assess the robustness of the model. The results showed that the selected barriers were in order of decreasing importance: maritime borders with a weight of 33.5%, rivers (13.8%), slopes equal to or greater than 10% (13.8%), wetlands (13.3%), forests (7.7%), land borders (7.7%), railway networks (5%) and main roads (4.9%). The Cap Bon zone is the only favourable zoning area for the control of FMD in Tunisia. A regional approach resulting from this work could be a major asset in identifying regions suitable for zoning in North Africa.

Rift Valley fever (RVF) is a mosquito-borne disease mostly affecting wild and domestic ruminants. It is widespread in Africa, with spillovers in the Arab Peninsula and the southwestern Indian Ocean. Although RVF has been circulating in West Africa for more than 30 years, its epidemiology is still not clearly understood. In 2013, an RVF outbreak hit Senegal in new areas that weren’t ever affected before. To assess the extent of the spread of RVF virus, a national serological survey was implemented in young small ruminants (6–18 months old), between November 2014 and January 2015 (after the rainy season) in 139 villages. Additionally, the drivers of this spread were identified. For this purpose, we used a beta-binomial (BB) logistic regression model. An Integrated Nested Laplace Approximation (INLA) approach was used to fit the spatial model. Lower cumulative rainfall, and higher accessibility were both associated with a higher RVFV seroprevalence. The spatial patterns of fitted RVFV seroprevalence pointed densely populated areas of western Senegal as being at higher risk of RVFV infection in small ruminants than rural or southeastern areas. Thus, because slaughtering infected animals and processing their fresh meat is an important RVFV transmission route for humans, more human populations might have been exposed to RVFV during the 2013–2014 outbreak than in previous outbreaks in Senegal.

This article presents a participative and iterative qualitative risk assessment framework that can be used to evaluate the spatial variation of the risk of infectious animal disease introduction and spread on a national scale. The framework was developed through regional training action workshops and field activities. The active involvement of national animal health services enabled the identification, collection and hierarchization of risk factors. Quantitative data were collected in the field, and expert knowledge was integrated to adjust the available data at regional level. Experts categorized and combined the risk factors into ordinal levels of risk per epidemiological unit to ease implementation of risk-based surveillance in the field. The framework was used to perform a qualitative assessment of the risk of introduction and spread of foot-and-mouth disease (FMD) in Tunisia as part of a series of workshops held between 2015 and 2018. The experts in attendance combined risk factors such as epidemiological status, transboundary movements, proximity to the borders and accessibility to assess the risk of FMD outbreaks in Tunisia. Out of the 2,075 Tunisian imadas, 23 were at a very high risk of FMD introduction, mainly at the borders; and 59 were at a very high risk of FMD spread. To validate the model, the results were compared to the FMD outbreaks notified by Tunisia during the 2014 FMD epizootic. Using a spatial Poisson model, a significant alignment between the very high and high-risk categories of spread and the occurrence of FMD outbreaks was shown. The relative risk of FMD occurrence was thus 3.2 higher for imadas in the very high and high spread risk categories than for imadas in the low and negligible spread risk categories. Our results show that the qualitative risk assessment framework can be a useful decision support tool for risk-based disease surveillance and control, in particular in scarce-data environments.

A Rift Valley fever (RVF) outbreak occurred in Madagascar from January to May 2008. The objectives of this study were (1) to assess the current and past circulation of RVF virus (RVFV) in livestock in Madagascar and (2) to evaluate the extent and magnitude of the 2008 RVF outbreak in livestock. The results of a country-wide serosurvey conducted in August 2008 on small and large ruminants are reported here. The study included 3437 cattle and 989 small ruminants (227 sheep and 762 goats) sampled in 30 of the 111 Malagasy districts, selected to be representative of the different ecozones and livestock density areas. Sera of animals were tested for the detection of immunoglobulins M (IgM) and G (IgG) against RVFV using commercial enzyme-linked immunosorbent assays kits. Recent infections (presence of IgM against RVFV) were detected in only 9 cattle (0.3% [0.1-0.4]) and 33 small ruminant (3.3% [2.2-4.5]) samples. Past infections (presence of IgG and absence of IgM against RVFV) were detected in 887 cattle (25.8% [24.3-27.3]) and 244 small ruminant (24.7% [22.0-27.4]) samples. Past infections were detected in all sampled sites. All ecozones were affected. In the southern and northwestern areas, the prevalence of cattle showing evidence of past infection with RVFV increased with the age of the animals. Our results suggest that there has been country-wide circulation of RVFV in 2008 in Madagascar, including in parts of the country where no clinical illness, either in animals or in humans, was reported. The data also suggest that the southern and northwestern areas may be endemic for RVFV, and that the virus may spread when ecological conditions are favorable for its amplification.