"For your information, I am sending you the message below which we are distributing through our EMPRES and RADISCON networks to alert our contacts in Eastern Africa/the Horn and the Arabian Peninsula. It summarizes most of the information we have from your postings augmented by that from other sources in Kenya. However, the situation is obviously evolving, and new facets are being revealed, continuously. This message refers to the current human and animal disease epidemic in Kenya and Somalia of which many of you will be aware. It serves as an EARLY WARNING MESSAGE from EMPRES and RADISCON. The human and animal disease situation in North and North East Kenya/Southern Somalia is alarming; some 500 people are reported to have died in Kenya and Somalia while mortalities in animals is estimated to be in the thousands. These figures are largely guesses and are, almost certainly, underestimates as the whole area is even more difficult to access than normal. Investigations are severely hampered by continuing heavy rainfall and flooding. Rift Valley fever (RVF) has been identified as the main cause of the human epidemic by the WHO Collaborating Centre in South Africa and is undoubtedly a significant component of the animal epidemic; abortions in small ruminants are now being reported. However, some of the disease signs reported are not consistent with this disease in animals. Anthrax is suspected to be involved, as would be expected from the predisposing factors in the epidemic, and there is strong clinical evidence of bluetongue disease affecting small ruminants and even, possibly, an antelope species (Gerenuk) in Kenya. The conditions of human and livestock movements away from flooded areas and concentration on higher land would also be expected to favour the transmission of other disease agents including foot-and-mouth disease, contagious bovine pleuropneumonia, contagious caprine pleuropneumonia and morbillivirus infections (rinderpest and peste des petits ruminants), if present. Of domesticated livestock, goats appear to be most severely affected at present, followed by sheep, camels and cattle. It might be some time before the situation in animals, and aetiological components of the disease complex, are clarified. RVF, which affects humans and can cause very serious economic losses in animals, especially small ruminants, is transmitted by mosquitoes and, when weather conditions of high rainfall and flooding are favourable for breeding of the vectors, outbreaks may reach serious dimensions and cause extensive epidemics. The virus was originally recognised in Southern Africa but is now endemic in much of sub-Saharan Africa. In the last two decades West Africa has experienced epidemics. It has spread into Egypt and clearly has the potential to spread to other regions. An excellent description of the disease can be found in the relevant chapter of Coetzer JAW, Thomson GR and Tustin RC (1994) Infectious Diseases of Livestock with Special Reference to Southern Africa. Cape Town: Oxford University Press. Rift Valley fever virus is a member of the Phlebovirus genus of the family Bunyaviridae transmitted by mosquitoes. It is a disease of mainly ruminant animals and humans. Classically it causes abortions of pregnant animals and a high mortality rate in young animals, primarily small ruminants. In humans it causes a severe influenza-like disease with occasional more serious haemorrhagic disease, encephalitis, mortality and retinal damage noticeable in survivors. Recent epidemics have shown higher than normal pathogenicity in humans and mortality in livestock of all ages and this appears to be the case in East Africa at present. Often the first signs of an epidemic developing are abortions in small ruminants and these may not be recognised as RVF until much later. Humans can also be infected by contact with blood or body fluids from infected animals which may occur during slaughtering of animals or handling of aborted foetuses and animal tissues. Meteorological and remote sensing data (Cold Cloud Duration [CCD] - = a measure of rainfall; and Normalized Difference Vegetation Images [NDVI] - a measure of vegetation density) indicate that large areas of the Horn of Africa have experienced unseasonal and abnormally high rainfall recently (which is continuing at present); suitable conditions exist for high multiplication of mosquito vectors. Without wishing to be pessimistic or alarmist, the risk exists that the RVF epidemic could expand considerably from its present relatively restricted focus in Kenya and Somalia. The movement of viraemic livestock could spread infection into new areas. The presence of disease in man and his animals, and fear of its consequences, might itself precipitate further movements of pastoralists and their livestock (together with any epidemic diseases they are harbouring) into other areas. It is also conceivable that the disease might even cross the Red Sea and affect livestock in the Arabian Peninsula, for the first time on record, if conditions exist there for mosquito reproduction. Hence this message is to put our RADISCON National Liaison Officers ON THE ALERT. We strongly advise the recipients of this message to be extremely vigilant for any condition which could be suggestive of RVF (and indeed other disease epidemics), especially if abnormal rainfall has created conditions for the multiplication of mosquitoes. We advise you to monitor the weather conditions and collaborate with your colleagues from the medical services. This is not Kenya's or Somalia's problem alone; the situation has the makings of a major international emergency and demands the highest vigilance in disease surveillance with diligent attention to emergency preparedness in all countries at risk. PLEASE REPORT ANY SUSPICIONS THROUGH THE NETWORK WITHOUT DELAY. The situation may change rapidly and we will keep you informed of any significant developments. We stand ready to assist in any way possible."--Peter Roeder <Peter.Roeder@fao.org>