Rift Valley Fever an emerging threat to livestock trade and food security in the Horn of Africa: A review P. Bonnet2, M. Tibbo1*, A. Workalemahu2, M. Gau1 1Action contre la Faim (ACF) – Ethiopia, PO Box 2357, Addis Ababa, Ethiopia 2International Livestock Research Institute (ILRI), CIRAD-EMVT, Livestock Policy Analysis Programme , PO Box 5689, Addis Ababa, Ethiopia 3Action contre la Faim (ACF), CIRAD-EMVT Ethiopia, PO Box 2357, Addis Ababa, Ethiopia Abstract Rift Valley Fever (RVF), an insect-borne viral zoonotic disease caused by a member of the Phlebovirus genus of the family Bunyaviridae, was first recognised in the Rift Valley of Kenya in the early 1930s. Since then, several epidemics of RVF have occurred in northern, southern and now eastern Africa becoming a continental problem. The epidemics that occurred in Egypt in 1977–78 and recent human and livestock cases in Yemen and Saudi Arabia (in September 2000) indicated the potential for the disease to spread to other inter-tropical regions of the world outside African continent. An embargo on livestock export by Gulf countries has brought in food insecurity in the East African countries due to indirect socio-economic mechanisms and impact of the ban on pastoralists household economy. Though food insecurity in the Horn of Africa is a longstanding problem, the recent bans imposed on eight countries, which are not yet recovered from the effects of recent droughts has further exacerbated the situation. Between September and December 2000, livestock export dropped by 92% in Somalia. According to FSAU/FEWS (2001), the estimated total loss of income at the Somali owner/producer level (including livestock originated from eastern Ethiopia), reached 20–30 millions of USD. This figure does not include the reduced government revenue from livestock trade taxes. In Somalia, about 80% of foreign exchange earned from livestock exports are used to import basic food items and other commodities. The effect of livestock export ban was further compounded due to the decrease in imported commodities. This review emphasises on epidemiology and risk of RVF, and the impact on the future of the livestock economy and pastoralists household economy in the Horn of Africa; underscores the consequence on food security; analyses the current situation in a region already with multifaceted crises viewed against international experience; and forward recommendations to the problem associated with RVF. Keywords: Rift Valley Fever; Epidemiology; Livestock Trade; Food Security; Economic impact; Policy implications; Recommendations; Horn of Africa; Early Warning System * Correspondence to: Dr. Markos Tibbo, ILRI, PO Box 5689, Addis Ababa, Ethiopia; E-mail: m.tibbo @cgiar.org 1 1. Introduction In the Horn of Africa, where 160 million people live, more than 40% (about 70 million) of the people suffer from chronic food insecurity (FAO, 2001). Drought, conflicts, poverty and population growth are some of the major underlying causes of food insecurity. Other natural disasters such as floods, locusts or contagious human and animal diseases, can predispose people to food insecurity. Among livestock diseases, the livestock export embargo due to Rift Valley Fever (RVF) has become one of the most important constraints to food security in the Horn countries in recent years. 1.1 The disease and its consequences RVF is a peracute or acute insect-borne disease of livestock and human beings caused by a member of the Phlebovirus genus of the family Bunyaviridae (Radostits et al., 1994). The first indication of development of an epidemic is frequently the abortion of sheep. Signs of the disease in animals tend to be non-specific, making it difficult to recognise individual cases of RVF. The simultaneous occurrence of numerous cases of abortion and disease in ruminants, together with disease of humans, following ecological and meteorological changes such as heavy and prolonged rainfall or in the presence of irrigation schemes, is characteristic of RVF. The disease generally leads to export bans (Embargo) due to its position in the OIE disease list A and international regulations or regional agreements on prerequisite conditions for livestock trade. Consequently, embargo on livestock export is hampering food security of livestock producers especially those households who relies on only livestock economy and therefore cannot generate cash from trade. Moreover, it affects the various scales of any nation macro and meso-economy when mainly relying on livestock production and trade (% of Gross Domestic Product) and additionally has negative effects on all commodity sectors linked to livestock sector. To lift any sanitary–caused ban it necessitates negotiating reopening of markets based on information on epidemiological status and risk assessment and it has high transaction costs. To recover markets rooms after a ban is lifted is a tough task for the whole livestock sector commodity chain. It is not the only disease where certification is asked for by importing countries and as noticed by Ostanello et al. (1999) necessary control of other diseases which are prevalent in the Africa Horn (like Brucellosis in Somalia in small ruminants) was quite common leading to chronic negotiation and technical problems for exporting. 1.2 Transmission Many species of mosquito biologically transmit RVF virus and non-vector transmission of the virus in livestock is also possible mechanically. Enzootic status of the disease due to persistence of the virus by transovarian transmission in a zoophilic Aedine mosquitoes that oviposit at edge of standing water which explicit the sustainable infection from a year to another has been described (Davies and Nunn, 1998; Fontenille, 1998). Transmission to humans occurs via mosquito bites, inhalation of aerosols, slaughtering and necropsy procedures on infected animals. Milk consumption from infected animals is known to be an important transmission route to human beings especially in pastoral communities where milk is a major component of the diet. Introduction of the virus to long distant countries such as Egypt (1977/78) and Iraq (July 2001) might be due to the arrivals of viraemic people, infected livestock, contact of humans 2 slaughtering or handling tissues, transport of infected mosquitoes by plane and wind-borne movement of mosquitoes (EMPRESS/FAO, 1998; ProMED, 2001). 1.3. Historical background in Africa RVF appeared to be limited to Africa. It was recognised first in the Rift Valley of Kenya at the turn of 20th century (clinical signs of the disease was first observed in Kenya in 1913 Naivasha Lake, Rift Valley on ovine) but the agent was not isolated until 1931. In 1987, the disease was reported for the first time in Western Africa (OIE, 2000). Most epidemics have occurred in eastern and southern Africa and, until 1977, the furthest north that the disease was known to have occurred was the Sudan. Up to 1973 the disease was considered as a normal animal disease and not a human threat but during 1977 and 1978, a major epidemic occurred in the Nile delta and valley in Egypt leading to 18 000 human clinical cases out of which 600 died. A severe epidemic affected the Senegal River basin in Mauritania and Senegal in 1987 (EMPRES/FAO, 1998) with the result of 1000 clinical cases out of which about 100 died. All have had major public health impact and have changed the perception of the disease to a pure zoonotic one and with regard to its spreading capacity. The epidemics in Egypt in the 1977 (WHO, 1982) and 1993 (EMPRES/FAO, 1998) as first to pass the Saharan border have signalled that the potential exists for spread to other regions of the world outside the African continent. It was predicted in 1982 that next to Egypt, Middle East receptive areas would most likely be affected by RVF epizootic (WHO, 1982). An outbreak in Kenya, Somalia, and Tanzania during 1997 to 1998 involved an estimated 89,000 human cases. During the same period, there were rumours and hypothesis that the epidemic cases had been in Afar and Somali region in Ethiopia. In September 2000, RVF was reported for the first time outside Africa reaching Middle East (ProMED BBC, 2000) and having lead to death of 16 human beings. According to the report of 25th September 2000, RVF virus has killed 10,768 sheep, cows and camels in Jizan (a town in Saudi Arabia near border to Yemen) and as many as 16,212 sheep have aborted and 153,000 animals were treated against the disease. As of 26 October 2000, the Ministry of Health of Saudi Arabia reported 443 human cases of RVF with 88 deaths. In Yemen, 97 people have died and 1,797 animals have perished (ProMED, 2000). The area covered is indicated on Maps 1 and 2 (Source: OIE FAO Internet site, 2001). An internet report of BBC on 25 September 2000 showed that following an outbreak of RVF in mid-September six Gulf states banned livestock imports from eight East African countries and Nigeria to prevent the spread of the viral disease, which has drown the attention of the affected countries. An assessment by FSAU (Food Security Assessment Unit) has warned that the ban to result a serious food insecurity in the Horn of Africa (Flash, Issue 6-30 November, 2000). Very recently (July 2001), unconfirmed cases of RVF have been reported in Iraq (ProMED, 30 July 2001), which resulted an embargo on livestock import, by Saudi Arabia from Iraq. In general, the disease has shown its potential of spreading to other neighbouring countries of Southern Europe. This review emphasises on the risk of RVF on the future livestock economy and consequent food security in the Horn of Africa and analyses the current situation in severely suffering regions. Mechanisms and concepts of food security and insecurity and how the current ban affects food security of the agro-pastoralists and pastoralists are discussed and recommendations are forwarded based on international experience and local context.