The First Filling of Merowe Dam: A Potentially Important Risk of Amplification of the Rift Valley Fever Virus Disease in Sudan

Dams: Negative impacts Lifespan The base line conditions, before construction. The experience of comparable eco- settings is more reliable basis for forecast (WHO, 1998).

The Virus: It has a broad-spectrum of host range that includes humans, sheep, cattle, buffalo, camels and goats but sheep and cattle were primarily targeted. The Vector and host animals: There are three main means of transmission of RVFV: transcutaneous transmission, aerosol transmission, and by mosquito or other insect bite. Aedes vexans, Ae. ochraceus, and Ae. dalzieli mosquitoes, as well as other mosquitoes and blood sucking insects, such as sand fly Phelobotomus duboscqui. Ae.cumminsii, Ae. circumluteolus, and Ae.micintoshi were reported to be vectors for the disease, but their role of transmitting the virus is not yet known.

Small ruminants and bovines are among the most sensitive domestic species to host animals for the virus.

Epidemiology : (RVFV) is a serious zoonosis. It can adapt itself easily to ecological changes and to being transported, and transmitted by a wide variety of mosquitoes causing livestock and human deaths.

Geographical distribution: Epizootics first concerned regions at high altitude (South Africa, 1951, Zimbabwe and Nigeria, 1958, Chad and Cameron, 1967) before getting over the Saharan barrier and affecting river valleys (Sudan, 1973, Egypt, 1977, Mauritania, 1987)

Experiences There is a significant relationship between the heavy rainfall and outbreaks of the virus. The 1987 epidemic in the Senegal River Valley of Mauritania near the Diama and Manantali Dams Where, the filling up of dams then favours the proliferation of mosquitoes and the concentration of men. The conjunction of these two factors probably originated the recent epidemics of Rift Valley Fever in Egypt after the first filling of Aswan Dam in 1977.

Expectations: (the experience of comparable eco-settings is more reliable basis for forecast) The first filling of Merowe Dam is expected to catalyze the spread of RVF virus.

Reasons: /or factors fan the flames for an outbreak after the first filling of the Merowe Dam) The Dam is associated with three agricultural schemes; Presence of pastoralists with their small herds who constitute a significant fraction of the Manasir tribe inhabit the desert regions close to the Nile valley. The location of these schemes New bridges were built Marowe-Karima and Karima –Dongola Road. Thus the virus could have been transported to the area through infected people or insects or even their eggs especially it is capable of being transported and there was no tracing for both animal and human movement in Sudan during the recent outbreak.

The predication of an outbreak of RVFV It is sound (Saharan barrier) It is useful for policy makers since it provides a means for preventing, control or mitigating the consequences of the disease. And also because repeated prophylactic vaccination of susceptible livestock during the long-inter epidemic periods that the RVF takes, is very expense

Precaution measures: Why should be taken following the filling up of Merowe Dam? (1) There was an outbreak in the country during October- December 2007 where it was accompanied by human deaths and affected the economy and livestock business; (2) “Conditions which precipitate an epidemic of RVF are also predisposing to occurrence of other major diseases epidemics which can occur simultaneously”; and (3)The virus being transported by wind, there is a risk of spreading of the virus again to Egypt.

Measures: Advance preparations to implement wide area vector control measures can be an effective means of combating vector-borne diseases. Starting a vaccination programme for the herd is of vital importance.

Recommendations: 1/ Interdisciplinary co-operation among professionals, is especially needed to perform risk assessment and to address the system-based, physical and ecological impact of Merowe Dam in Sudan; 2/ As well forecasting changes in weather in Sudan is necessary for predicting new outbreaks

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