Since the eradication of smallpox in the
late 1970s, no other diseases have followed suit; the goal that has come
closest so far is eradication of polio. The development of vaccines in the
1950s led to cases of polio plummeting: whereas hundreds of thousands were
affected annually in the middle of last century, in 2012 around 250 people were
paralysed by the disease.
But the final stages of eradication are proving more
difficult than the early phases. The disease remains entrenched in three
countries—Afghanistan, Nigeria, and Pakistan—where social, political,
and logistical factors prevent effective vaccination campaigns and lead to
export of virus to countries that have previously been free of the disease.
As Haris Riaz and Anis Rehman reported
in
the journal last month, the global polio eradication programme suffered a
grave setback in December last year when seven vaccination workers were shot
dead by terrorists as they took part in a 3 day campaign to deliver vaccine in
Karachi and Peshawar. At the end of January, two more vaccine workers were
killed in a landmine explosion in the Kurrum tribal region. These two latest
casualties are not thought to have been directly targeted, but unwitting
victims of sectarian violence.
Such events are not only tragic
losses—people dedicating their time to a global health effort senselessly
killed—but also they leave children who would have received vaccine unprotected
and allow the virus to continue to circulate. The consequences of which can be
extremely far reaching: in January, poliovirus related to strains circulating
in Pakistan was detected in
sewage samples in Cairo, Egypt, more than 3000 km away (the last case of
polio in Egypt
was recorded in 2004). No new cases of polio have been recorded in Cairo, but health
authorities are surveying the impoverished districts of Al Salam and Al Haggana
where the virus was found for recent cases of paralysis, and vaccination
campaigns have been initiated.
In the middle of the 20th century,
children in developed countries of Europe and North
America would return to school at the end of the summer break and
look around to see empty chairs of classmates who had not returned because they
had been crippled or killed by polio. When the global polio eradication
initiative (GPEI) was launched in 1988, the disease was endemic in 125
countries and caused paralysis in around 350 000 people every year. Recent
events highlight how a threat that for many is thankfully a distant memory—or
for younger generations in some developed countries unknown—remains a real and
present danger.
The Bill & Melinda Gates
Foundation is one of the major contributors of financial aid to the polio
eradication effort, and speaking recently in London at the Richard Dimbleby lecture, Bill Gates reiterated his
commitment to wiping out the diseases, highlighting the new eradication target
of 2018. On January 23, the GPEI published a draft Polio Eradication and Endgame Strategic Plan (2013—18).
The plan has four main objectives and four milestones for eradication. The four
objectives are, detection and interruption of wild poliovirus, strengthening of
routine immunisation and withdrawal of the oral polio vaccine, containment and
certification (enabling some facilities to store poliovirus and outlining the
processes for certification of eradication), and legacy planning to ensure that
resources put aside for polio eradication are repurposed when the goal is
achieved. The milestones for the new strategic plan are for the last case of
wild polio by 2014, withdrawal of type 2 oral polio vaccine by 2015—16,
worldwide certification of polio eradication by the end of 2018, and cessation
of bivalent oral polio vaccination during 2019.
This is not the first deadline for
polio eradication. When the GPEI was set up, the planned date for eradication
was 2000. As the cases become fewer, the problems become knottier, and
hindrances to final eradication become ever more dependent on localized factors
and characteristics of the virus's remaining toeholds. As the saying goes, the
devil is in the detail.
The new plan encouragingly contains
intricate analyses of recent outbreaks in the three remaining countries,
reasons for programmatic declines, and reflection on the lessons learned from
success in India,
which has not recorded a case in more than 2 years. It is an excellent example
of how data, local knowledge, and experience can be synthesised to provide
clear goals and realistic targets. 2018 seems soon, but for some children it
will not be soon enough. And for the vaccination workers who have lost their
lives, eradication of polio within 5 years would be a tribute to their efforts.
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