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Exploring new tools against Rift Valley Fever (RVF) in the Horn of Africa and Middle East


30 April 2015 - RVF affects both ruminants and humans. It can be transmitted through several mosquito species and by contact with infectious animal material, e.g. body fluids and organs. The epidemiology of RVF is complex given its vector-borne nature. Infected mosquito eggs can survive for several years in dry conditions, until heavy rainfall and prolonged flooding cause them to hatch. This explains how the virus can remain present, but silent, in areas that thus should still be considered endemic. When infected animals introduce the virus into areas with vector presence, epizootics and associated human epidemics can occur in previously unaffected areas. The impact of RVF on local livelihoods (socio-economic) and trade (restrictions) can be high.

RVF is present in the larger part of sub-Saharan Africa, but occurs mostly in eastern and southern Africa, where sheep and cattle are raised. In 2000, the first RVF outbreaks outside Africa, in Saudi Arabia and Yemen, raised concerns that RVFV might extend to other regions.

RVF is recognised as a priority disease for the Middle East and Horn of Africa regions, largely because of the huge livestock trade (mostly cattle, small ruminants and camels) that takes place between the Greater Horn of Africa and the Gulf countries. Therefore, RVF has been integrated into the regions’ 5-year action plan for the GF-TADs (Global Framework for the progressive control of Transboundary Animal Diseases), which is a joint FAO/OIE initiative that combines the strengths of both organizations to achieve agreed common objectives.

The probability of a new RVF outbreak in the Horn of Africa is high, given that this is the 8th year after the last outbreaks (so animals have very low immunity against RVF) and the predictions of forecasting models for the coming months. Therefore, countries should remain alert and are encouraged to take mitigation measures.

In order to discuss preparedness, prevention and control of RVF, a conference was organized on 21-23 April under the auspices of GF-TADs in Djibouti, targeting around 70 animal health officials from 18 countries of the Horn of Africa and Middle East regions, along with national, regional and international stakeholders from public and private sectors, and from the medical and veterinary domains. This was the sixth of a number of meetings jointly or separately organized by FAO and OIE since 2007 to deal with a number of RVF-related issues.

The 3-day meeting consisted of a series of presentations divided into thematic sessions, two working group sessions and a visit of the Djibouti Quarantine Facilities. The main issues presented and discussed included:

  • The RVF situation in the different sub-regions and the coordination activities conducted by the different international organizations;
  • The main control options, particularly the issues related to vaccination. Despite the research on vaccines of greater safety, longer immunity and improved stability, there are no new vaccine candidates on the market, and the recommended Clone 13 vaccine is still not registered in the region;
  • Diagnostic tests for RVF, the role of Reference Laboratories, and updates on the development of new diagnostic tests. One major issue is the limited availability of commercial diagnostic serological tests;
  • The revised RVF OIE Code Chapters, which includes provisions for safe trade during inter-epizootic and epizootic periods;
  • Contingency and surveillance plans (for both animals and humans) in place and the identification of the main gaps;
  • The new One Health tool developed by the tripartite to facilitate reviews of competencies at the interface between Animal and Human Health Services;
  • The Decision Support Framework developed by the International Livestock Research Institute (ILRI) together with FAO, which has been updated to assist at risk countries to assess their preparedness level;
  • The RVF forecast for the coming months, showing that the risk will increase for the later part of this year and the region has to remain vigilant. The NASA Goddard Space Flight Center (GSFC) model has been used to monitor East Africa for years;
  • The OIE vaccine banks experience and how this could be used as a model for a regional RVF vaccine bank.

The meeting ended up with a set of recommendations, which will be available soon.

 

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