Rift Valley fever in Niger
On 30 August 2016, WHO received reports about unexplained deaths among humans, along with death and abortion in livestock in the North Western parts of Niger, and the areas bordering Mali.
From 2 August to 22 September 2016, 64 human cases including 23 deaths have been reported in Tchintabaraden health district in Tahoua region. The area is mainly populated by nomadic stockbreeders.
Most of the cases are male (62.5%), and work as farmers or animal breeders. In the affected area, an epizootic outbreak is also reported among livestock during the same time duration, including deaths and abortions among cattle and small ruminants.
As of 16 September 2016, 6 of the 13 human specimens tested at Institute Pasteur (IP), Dakar were positive for Rift Valley Fever (RVF). Among the 6 animal specimens tested, 3 were positive for RVF. Sequencing and further laboratory testing is ongoing. Genetic sequence data is required to confirm or refute the endogenous origin of the outbreak. Moreover, laboratory support for Niger is being considered.
Public health response
On 31 August, a multisectoral national rapid response team, including members from the Ministry of Health, veterinary services and Centre de Recherche Médicale et Sanitaire (CERMES), and World Health Organization, was deployed for field investigation. Ministries of Health and Agriculture/Livestock have developed a national response plan.
The WHO Country Office continues to provide technical and financial support for surveillance, outbreak investigation, technical guidelines regarding case definition, case management, shipment of samples and risk communication.
FAO, OIE, and WHO are coordinating on animal and human health and providing additional support to Niger for the outbreak response WHO is working with partners in the Global Outbreak Alert and Response Network (GOARN) to coordinate international support for the response. IFRC, and Unicef are supporting outbreak response.
The NGO ALIMA and the Nigerian NGO BEFEN are providing support for case management and social mobilisation on the ground.
Currently, in conjunction with the Ministry of Public Health, an entomological survey is being prepared for urgent implementation with WHO technical and financial support. This is to identify potential vectors for RVF in the region and it is considered to be in the definition of vector control activities.
Currently, some of the main challenges include under-detection of human cases. The risk that only severe cases are being detected and reported cannot be ruled out. There is no national local capacity to test the specimens. For laboratory confirmation for RVF, the samples are being shipped to WHO regional collaborating centres. Moreover, to ascertain the extent of this outbreak, the involvement of the national livestock department is required.
WHO risk assessment
Based on the available information, the event risk assessment is ongoing. The risk of further spread of outbreak within Niger and internationally (especially to neighbouring countries and those on the transhumance and migration routes) cannot be ruled out.
Nomadic stockbreeders from Niger and neighbouring countries have just participated in the Cure Salée festival, a major annual mass gathering event from 23 to 25 September. During this festival, herds are brought to graze on the salty pastures ahead of the dry season. Around 2 million cattle and even more small ruminants were expected to be part of the event.
At the end of the rainy season, as per known migration patterns, the nomadic human population along with their herds will progressively move to other Southern Sub Saharan countries and irrigation systems along the Niger river where pastures may still be available. In conjunction with the ongoing outbreak, the high density of animals in the area and the transhumance pattern significantly increases the risk of international spread. The security situation in the Sahel is unstable and also needs to be taken into consideration.