SURVEILLANCE AND ECOLOGY OF MOSQUITO, BITING AND FILTH BREEDING INSECTS
Location: Mosquito and Fly Research Unit
Title: POTENTIAL FOR RIFT VALLEY FEVER ACTIVITY ON THE ARABIAN PENINSULA: DETECTION OF SUITABLE ECO-CLIMATIC CONDITIONS
| Anyamba, A. - NASA/GODDARD SPACE FLIGHT |
| Chretien, J. - DOD, SILVER SPRING, MD |
| Formenty, P. - WORLD HLTH ORG./SWITZERLA |
| Small, J. - NASA/GODDARD SPACE FLIGHT |
| Tucker, C. - NASA/GODDARD SPACE FLIGHT |
| Malone, J. - DOD, SILVER SPRING, MD |
| El Bushra, H. - WORLD HEALTH ORG./EGYPT |
| Martin, V. - FOOD & AGRIC. ORG./ITALY |
Submitted to: Emerging Infectious Diseases
Publication Type: Abstract Only
Publication Acceptance Date: March 19, 2006
Publication Date: April 28, 2006
Citation: Linthicum, K., Anyamba, A., Chretien, J., Formenty, P.B., Small, J., Tucker, C.J., Malone, J.L., El Bushra, H., Martin, V. 2006. Potential for Rift Valley Fever activity on the Arabian Peninsula: detection of suitable eco-climatic conditions [abstract]. International Conference on Emerging Infectious Diseases, March 19-22, 2006, Atlanta, Georgia.
Background: Rift Valley fever (RVF) virus causes severe disease, abortion, and death in domestic animals in Africa and Arabia. Humans are infected by mosquitoes, which maintain epizootic transmission, or through exposure to infected animal tissue. Although human disease may be mild, sometimes patients may develop severe retinitis, meningoencephalitis, or hemorrhagic fever syndromes. In Africa, epizootics and associated human epidemics usually follow heavy rainfall. RVF was first confirmed outside of Africa in September 2000 in Saudi Arabia and Yemen following elevated rainfall levels in nearby highlands which flooded the coastal areas, providing ideal environments for mosquito populations similar to those found in RVF endemic regions of East Africa.
Methods: To provide early warning of conditions favorable for RVF epidemics, the National Aeronautic and Space Administration (NASA) and the Department of Defense Global Emerging Infections Surveillance and Response System (DoD-GEIS) monitor satellite-derived normalized difference vegetation index (NDVI), which reflects recent rainfall and other ecological and climatic factors.
Results: NDVI anomalies in the highlands east of affected areas during the 2000 outbreak show similar spatial pattern (though of lower magnitude) to recent anomalies in those areas, which show above normal NDVI (+20-60%) in the Sarawat Mountains, from just northeast of Djeddah, Saudi Arabia southwestwards beyond Jizan and into Hodeidah governorate, Yemen, during May and June, 2005. Satellite-derived rainfall estimates show widespread rainfall occurred over most of western Saudi Arabia and Yemen from mid-April to mid-June 2005, and accounts for the high magnitude and spatial pattern of observed NDVI anomalies in May and June 2005.
Conclusions: Since RVF virus can be maintained in mosquito eggs for extended periods and be transmitted under favorable conditions, the high magnitude of NDVI and rainfall patterns described above should prompt heightened veterinary and human surveillance for RVF in coastal Arabia and mass vaccination of susceptible animals if indicated based on surveillance.