NASA Risk-map Successfully Predicts River Valley Fever Outbreak

Scientists at NASA have used satellites to draw a risk-map of areas that will be infected with River Valley Fever, and their predictions of the outbreak of RVF- River Valley Fever, have proved successful.

(Image copied from internationalspacemission.blogspot.com)

Do we need to worry about RVF?

No, and yes!.

No?

RVF is usually mild on people. Only a small percentage of us develop a much more severe form of the disease. They are affected with ocular (eye) disease (0.5-2% of patients), meningoencephalitis (less than 1%) or haemorrhagic fever (less than 1%). In all, less than one per cent of the RVF affected people die. WHO

If so, why 'Yes!' ?

Rift Valley fever mostly afflicts livestock- cattle, goats and sheep, resulting in a nearly 100 percent abortion rate in these animals. Its outbreaks periodically cause economic devastation in parts of Kenya, Somalia, Sudan and Zimbabwe. Bioterrorism experts warn that its introduction to the United States would cripple the North American beef industry. (-Science Daily). If USA feels that way, the we in India have more to worry.

Why India?

Rift Valley Fever Virus is endemic in areas that have heavy and sustained rainfall, and mosquitoes are there to do the dirty work for them. The virus is carried by mosquitoes and is transmitted to humans by mosquito bites or through contact with infected livestock. So we can guess the disaster RVF will bring to India if it ever gets here.

If NASA can prevent this RVF, ISRO can. But, what did NASA do?

Usually, ISRO does what NASA has done, right? No offence meant, just a dig.

It happened this way-

During an intense El Niño event in 1997, the largest known outbreak of Rift Valley fever spread across the Horn of Africa. About 90,000 people were infected with the virus.

A Science paper in 1999 described the link between RVF and the El Niño-Southern Oscillation (ENSO). ENSO is a cyclical, global phenomenon of sea surface temperature changes that can contribute to extreme climate events around the world. For some areas, the warm phase of ENSO brings drought, while in some areas like the Horn of Africa, ENSO leads to above-normal rainfall.

Excessive, sustained rainfall awakens the eggs of mosquitoes infected with Rift Valley fever that can remain dormant for up to 15 years in dried-out dambos—shallow wetlands common in the region. The link between the mosquito life cycle and vegetation growth had first been described in a 1987 Science paper by co-authors Kenneth Linthicum of the U.S. Department of Agriculture and Compton Tucker of NASA Goddard.

Given the threat posed by RVF after the 1997 outbreak, U.S. Department of Defense Global Emerging Infections Surveillance and Response System funded the formation of a working group in 1998 to see if predictions of an outbreak could be made operational.

How did NASA draw the RVF risk map?

Anyamba and colleagues at NASA set out to predict when conditions were ripe for excessive rainfall, and thus an outbreak. They started by examining satellite measurements of sea surface temperatures.

The greatest indicator of a potential outbreak is the measure of the mosquito habitat itself. The researchers used a satellite to measure the landscape's "greenness." Greener regions have more than the average amount of vegetation, which means more water and more potential habitat for infected mosquitoes.

The final product is the risk map for Rift Valley fever, showing areas of anomalous rainfall and vegetation growth over a three-month period. The forecast is updated and issued monthly as a means to guide ground-based mosquito and virus surveillance.

Does this work?

As early as September 2006, the monthly advisory from Anyamba and colleagues indicated an elevated risk of Rift Valley fever activity in East Africa. By November, Kenya's government had begun collaborating with non-governmental organizations to implement disease mitigation measures—restricting animal movement, distributing mosquito bed nets, informing the public, and enacting programs to control mosquitoes and vaccinate animals.

(All this information comes thanks to NASA)

The threat of Global Warming:

Professors Ernest A Gould of Oxford University, and Professor Stephen Higgs of University of Texas Medical Branch studied the effects of climate change on viruses that have been in the news during the last 10 years: West Nile, Chikungunya, Rift Valley Fever and Bluetongue.

They have concluded that during the past five decades there have been important changes in the way arbovirus diseases appear.

Since the movements and breeding of these arbovirus are greater in warm, damp areas, climate change, global warming, could lead to their migration to more places. -Fair Home

• Looks like there will be never an end to diseases, we conquer some for a while, but thanks to changes in population densities and distribution, thanks to change in climate and lifestyle- new diseases take control and strike out. But we are coping, that is what this NASA risk-map and its success shows, I feel.