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Eradication Bill Brieger | 05 Jul 2010 07:37 am

Eradication campaigns – past and present

The World Health Organization reminds us that …

2010 marks the 30th anniversary of the eradication of smallpox. Smallpox was officially declared eradicated in 1980 and is the first disease to have been fought on a global scale. This extraordinary achievement was accomplished through the collaboration of countries around the world.

A key point to keep in mind is that the final battle was fought in Africa and Asia where health systems were often weak.  The organizers adapted to this reality and in the end adopted a case containment strategy.  This entailed a move away from the resource intensive mass vaccination campaigns to focused vaccination within a radius of a detected case. Containment required a good surveillance system, but was helped by the easy recognition of the distinctive signs of a ‘case.’

gwcounter.jpgTwo other diseases are now on the verge of eradication, guinea worm and polio. WHO reports on guinea worm that, “There were only 3190 confirmed cases in 2009 compared with 25217 cases in 2006 and almost 3.5 million cases in 1986.”

So far in 2010 there are less than 600 reported cases. Guinea-worm disease is now endemic in only four countries in Africa: Ethiopia, Ghana, Mali and Sudan. The guinea worm effort also drew valuable lessons from the case containment strategy of smallpox.

At WHO’s Media Center, Veronica Riemer reports that …

Polio eradication is at a critical juncture. Only four countries in the world remain polio-endemic: Afghanistan, India, Nigeria and Pakistan. In Nigeria, case numbers have collapsed by more than 99% in the past year, from 312 cases to just three in 2010. In India, for the first time, the remaining endemic states of Uttar Pradesh and Bihar have not reported any wild poliovirus type 1 cases concurrently for more than six months. That’s the good news. The bad news is that Tajikistan, which had been polio-free since 1996, was reinfected with poliovirus from northern India in 2010. By mid June more than 200 children were paralysed.

casemap-201006-sm.gifSo far this year there have been 456 cases of wild polio virus detected; 1604 were counted in 2009. There still are a few cases being reported this year in Chad, Nigeria, Mauritania, Niger and Mali among 15 affected countries.

What can malaria elimination proponents learn from these experiences? At present malaria programs are generally at a mass intervention scale-up phase, though some places, notably in southern Africa, are getting close to elimination.

It is in these pre-elimination countries that we will begin to learn whether surveillance and containment activities used in other eradication efforts can be successful. Malaria does not have the relatively unmistakable signs of the smallpox rash, the emergent guinea worm or acute flaccid paralysis that makes surveillance and detection relatively easier for the other three diseases. Malaria is known to be confused by both community members and clinical staff for other febrile illnesses.

What we do share is that conflict or post-conflict countries are among the hot spots of the remaining cases of polio and guinea worm – as is also the case of malaria, and these areas have health systems challenges that make both mass intervention and focused surveillance systems difficult to operate.

We also worry as the number of cases wind down for polio and guinea worm that attention may wane and new cases spring up.  Guinea worm for example, has been lumped under the rubric of ‘neglected tropical diseases,’ which hopefully will not be a recipe for further neglect.

Unexpected outbreaks gave occurred with both guinea worm and polio because of human movement alone (the pond-bound cyclops that serve as intermediate host of guinea worm can be dealt with using temephos). With malaria both humans and vectors/mosquitoes are on the move.

This leads to another major difference. smallpox and polio have been attacked with one major tool – vaccines. Guinea worm could be solved with provision of safe water supplies or at least by filtering pond water through a piece of cloth. Malaria requires medicines and nets and sprays.

We have our work cut out for us. we can draw hope from the successes of other eradication campaigns, but also take lessons that the job requires perseverance until the last case is detected and controlled.

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