Eradication Bill Brieger | 24 Nov 2012 05:35 pm
The Tail End of Eradication, an Elusive Goal
We are nowhere near eradicating malaria with hundreds of thousands of cases annually throughout the world. It reappears in Greece, and in subclinical form stymies surveillance efforts in the Solomon Islands. But eventually we will close in on this parasite. What can we learn from eradication efforts of another scourge, polio?
Recently the Express Tribune published an article that provided some shock not only in Pakistan, where the issue was detected, but throughout the polio eradication community. “The Prime Minister’s polio cell, the World Health Organisation (WHO), and the United Nations Children’s Fund (UNICEF) confirmed … a newly-found strain of the polio virus.”
The technical reason for the new stain was explained by the international health agencies: cVDPV cases that cause type 2 poliovirus mutate and attain a form that can cause paralysis after passing through multiple children in environments with substandard sanitation. Fortunately polio associated with vaccines is extremely rare, but a more damning administrative explanation of why this may have happened in Pakistan is “poor routine immunization coverage” that enabled these mutations to occur.
Administrative problems include poor scheduling of the current immunization round during a sacred religious period resulted in four districts not participating, but on top of this was a more pressing problem, “the global shortage of the oral polio vaccines especially as anti-polio campaigns are increasing .” This calls into question the upcoming second round of immunization in December. The problem is persistent since it was reported earlier this year that, “Polio coverage (in Pakistan) remained sub-optimal during the past year in Islamabad, as revealed by an independent evaluation report on the post-polio campaign conducted by the World Health Organization.”
Four endemic countries remain as seen in the graph, and Pakistan’s performance to date is actually better than some of the others, but the situation is volatile, as is the civil/political situation in the remaining affected countries. Interestingly, another eradication-targeted disease, Guinea Worm, was down to 1058 cases in 2011 and remains in only 4 countries, but this is 17 years after the initial date set for its eradication.
Polio and Guinea Worm offer malaria some lessons for the present in countries approaching pre-elimination now and those who will hopefully join them over the next decade (if global funding levels are maintained). One lessons is that surveillance is an active part of current polio eradication efforts, otherwise these reports on progress and its challenges would not be published. But the key lesson is that regardless of the effectiveness of the technical intervention (e.g. a vaccine), deployment of the technical intervention is subject to human, administrative, managerial and social complications.
Polio focuses on a vaccine; malaria has treatment medicines, preventive medicines, insecticide sprays, treated bednets, diagnostic tests, and maybe also one day an effective vaccine. It is not too early to plan on how to coordinate all this into achieving effective disease elimination, nationally, regionally and globally.