 |
|
Home -- ENSO Cycle -- ENSO Effects -- Mission -- Data -- Tools -- Site Map |
|
Introduction -- Local Links -- Web Links |
|
||||
Rift Valley Fever (RVF)
Introduction
During an El Niño season, the normal February-June rainy season of the Horn of Africa is extended, often resulting in excessive rainfall (TOVS rain data) (TRMM TMI rain data). The increased moisture permits explosive growth of plants (Pathfinder NDVI data). The plants are indicators of increased wetlands that support mosquitoes, one of the carriers of the RVF. The virus that causes RVF commonly attacks sheep and cattle and on occasion spreads to the local human population.
|
AVHRR SST Pathfinder |
TOVS HIRS2 Monthly MPE |
|
NDVI Map |
Rift Valley Fever Risk Map |
Disease Vector |
Between October 1997 and January 1998, heavy rains drenched eastern Kenya and southern Somalia. The resulting outbreak of RVF killed many cattle, causing food problems for the local farmers and villagers. RVF eventually spread to the local human population. In addition to transmission by mosquitoes, doctors believe that animals spread the virus to humans, and humans also infect other humans. WHO estimated that humans suffered some 89,000 cases, with an estimated total of 200-250 deaths. This was one of the largest outbreaks of RVF in recorded history.
Between August 2000 and January 2001, outbreak of RVF killed many people in Saudi Arabia and Yemen.
|
|
|
|
|
|---|---|---|---|
|
El Niño Conditions (May 1997 - April 1998) |
|||
|
January 1998 |
Kenya |
N.A. (as of Jan. 6) |
300 (as of Jan. 6) |
|
January 1998 |
Somalia |
13 (as of Jan. 6) |
N.A. (as of Jan. 6) |
|
La Niña Conditions (April 1998 - April 2001) |
|||
|
January 1999 |
South Africa |
3 (as ofFeb. 10) |
N.A. (as ofFeb. 10) |
|
September 2000 |
Saudi Arabia |
38 (as of Sept. 17) |
16 (as of Sept. 17) |
|
September 2000 |
Yemen |
134 (as of Sept. 29) |
31 (as of Sept. 29) |
Monitoring SST of the Indian Ocean (Pathfinder SST data) (TRMM TMI SST data) and vegetation (Pathfinder NDVI data) by Earth-observing satellites, scientists can provide warning for such large-scale outbreaks of RVF up to 6 months in advance. Retrospective studies have shown that when the water temperatures increase in both the Indian and Pacific Oceans, a viral outbreak follows in 2 to 5 months. Areas of greatest risk are determined by tracking vegetation changes.
Rift Valley Fever
Disclaimer: NASA offers these suggested sites for additional information regarding effects of El Niño and La Niña events. Web access is required to reach these sites. Link existence and contents are not under the control of the EOSDIS Science Operations Office.
Rift Valley Fever Web Sites
