Joint #FAO / #WHO / #WOAH Rapid #Risk #Assessment of Rift Valley fever (#RVF) in #Senegal and #Mauritania: Implications for Public Health and Animal Health (Oct. 24 '25)

 

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Risk statement

This risk assessment is based on the current epidemiological and epizootic situation of Rift Valley fever (RVF) in Senegal and Mauritania, from 20 September through 8 October 2025.

The risk assessment was conducted separately for each country. However, the findings indicate that the level of risk is the same for both countries across all levels, for both human and animal health.  

During this period, Senegal reported 119 confirmed human RVF cases, including 16 deaths, resulting in a case fatality rate (CFR) of 13.4%. Cases were recorded across eight health districts in three regions of Senegal, with the majority in Saint-Louis Region with 110 cases (92%) followed by Louga (four cases) and Matam (one case). 

The affected districts in Saint-Louis Region: Podor, Richard-Toll, Dagana, and Saint-Louis are located along the northern border with Mauritania along the Senegal River.  

The most affected age groups were 15- 35 years, accounting for 69 cases (58%), and 35-60 years with 34 cases (29%), with 77 % of cases occurring in males. 

Hemorrhagic symptoms were reported in 22 cases (18%) of which 13 resulted in death.  

Animal infections resulting in abortions and livestock mortality were also reported. 

On 23 September, 1122 blood samples and four abortion samples were collected from small ruminant herds in villages where human cases were reported. 

Of these, 36 samples tested positive across six herds. 

By 30 September, a total of 27 confirmed animal cases, two deaths have been reported to the World Organisation for Animal Health (WOAH) through the World Animal Health Information System (WAHIS). 

As of that date, five animal outbreaks have been confirmed in Saint-Louis Region, with four additional outbreaks expected to be included in a forthcoming follow-up report currently in draft.  

RVF is endemic in Senegal, with previous outbreaks affecting both humans and animals. 

The last confirmed human case before this outbreak occurred in January 2025 in Touba, located in the Diourbel region, while the last recorded human case in Saint-Louis region occurred in 2022.   

Between 27 September and 5 October 2025, Mauritania reported 17 confirmed human RVF cases, including eight deaths, resulting in a CFR of 47%. 

Cases were recorded across seven districts in five regions (wilayas), three of which have international borders: Assaba which borders Mali to the south, Brakna and Trarza both bordering Senegal along the Senegal River. 

Of 66 samples tested, the positivity rate was 25.7%.  

Multiple active outbreaks in animals have also been reported. According to the Ministry of Animal Resources of Mauritania, as of 6 October, 17 outbreaks across eight regions, with 86 out of 307 samples testing positive. 

The first animal cases, involving goats and camels, were reported in August 2025. A total of 39 clinical animal cases (including 16 deaths in two dromedaries and 14 goats) were reported in Aioun, Hodh-Gharbi region and Timbedra, Hodh-Charghi region, both are located in southeastern Mauritania near the Mali border, and in Maghta Lahjar, Brakna region, in central Mauritania.  

In Brakna region alone, 233 animal cases and 55 deaths have been reported to WOAH by 3 October 2025. 

Affected animals include sheep, goats, camels and cattle.  

RVF is endemic in Mauritania. The last major outbreak occurred in 2022, with 47 confirmed human cases, including 23 deaths (CFR 49%), mostly among animal breeders in nine of 15 regions. 

The virus also affected animals such as cattle, camels, and small ruminants, with sample positivity rates of around 24% tested during that outbreak period.  

The current outbreak in Senegal and Mauritania is unusual in both its magnitude and severity. It involves multiple districts in border regions, particularly along the Senegal River, increasing the risk of cross-border transmission between Senegal and Mauritania. 

In Mauritania, the outbreak also extends to eastern regions bordering Mali, raising concerns about potential regional spread beyond the Senegal River basin.  

A notably high proportion of severe and haemorrhagic cases has been reported. In Senegal, 18% of confirmed human cases presented with haemorrhagic symptoms, with 13 cases resulting in death.  

The situation is particularly concerning in Mauritania, where the CFR has reached 47%, reflecting both the severity of illness and potential gaps in early detection and clinical management. 

Further information is needed to better understand the factors contributing to this high fatality rate. 

Possible contributing factors include delayed access to adequate care, shortage of essential medical products and supplies and underreporting of mild cases, which may result in disproportionate detection of severe cases. However, additional factors should also be investigated.  

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Source: World Health Organization, https://www.who.int/publications/m/item/joint-fao-who-woah-rapid-risk-assessment-of-rift-valley-fever-(rvf)-in-senegal-and-mauritania--implications-for-public-health-and-animal-health

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