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An end to polio?

Burnet Institute

24 October, 2016

Professor Michael Toole AM is a Deputy Director of Burnet Institute and a member of the Independent Monitoring Board of the Global Polio Eradication Initiative.

We are on the cusp of a polio-free world, with a deadline set by the Polio Oversight Board to interrupt wild poliovirus (WPV) in 2016, but while progress has been made, eradication remains tantalisingly out of reach.

In 2015, there were 74 cases of WPV in Afghanistan and Pakistan, believed to be the only two countries still seeing the virus. But in 2016, Nigeria saw three new cases, the first in almost three years in that country. There have been 26 cases of WPV reported globally in 2016 compared with 41 this time last year.

The Global Polio Eradication Initiative (GPEI) was launched in 1988, when approximately 350,000 children were paralysed by polio every year, and initial progress towards the goal was rapid. While deadlines for world eradication have been missed in 2000, 2012 and 2015, significant milestones have been met: elimination in India, and no WPV in the Americas since 1993.

WPV infects mostly children and can cause severe paralysis or death. It is transmitted via the faecal-oral route, and therefore thrives in environments where sanitation is poor.

The most common polio vaccine worldwide is the trivalent oral polio vaccine (OPV), which contains three types of live, weakened vaccine-viruses. In most countries, three or four vaccine doses can protect a child from infection. But, in areas with poor sanitation and hygiene, children may need 10 or more doses, because other viruses in their gut hamper effective immune response. Also after a child is vaccinated, some of the vaccine-virus may be genetically altered during replication upon excretion; in rare cases this can begin circulating and is subsequently termed a vaccine-derived poliovirus.

With the year 2016 heading towards a close, challenges to eradication need to be overcome before world health bodies meet their goal.

Insecurity is the first, with armed conflict a major constraint to accessing children for vaccination in endemic countries of Afghanistan, Pakistan and Nigeria. In Northeast Nigeria, the militant Boko Haram group disrupted vaccination campaigns, but temporary ‘health camps’ were established offering a range of health services in addition to the polio vaccine. Since the three cases reported in Nigeria this year, the GPEI has mounted an emergency vaccination campaign in the Northeast and in adjacent Lake Chad basin countries of Chad, Cameroon and Niger.

Visiting Afghanistan on behalf of the IMB, I witnessed several innovative efforts to overcome security barriers, such as market day vaccination and women’s polio activist groups.

Another challenge is vaccination fatigue, where parents see their children have 15 or more vaccinations, and also outright bans by military groups such as Al Shabaab in Somalia, and the Taliban in Pakistan. A third challenge is vaccine-derived polio which can sometimes circulate and cause paralysis in populations with low immunity.

Progress will be made with high quality campaigns that achieve the greatest possible vaccination coverage, with combined use of OPV and inactivated polio vaccine. Environmental surveillance needs to be expanded throughout outbreak countries, and these countries also need high level political commitment.

While eradication of this terrible disease is clearly for the global public good, we cannot presume that support will be universal. If we are to succeed in eradicating the second human disease in history during 2016, an unprecedented global endeavour will be required, involving parents, vaccinators, community and religious leaders, state, province and national governments, political leaders, international technical agencies, and the world’s major aid donors.

This talk is edited from a piece published in BMC Medicine.

World Polio Day

Rotary International established World Polio Day to commemorate the birth of Jonas Salk, who led the first team to develop a vaccine against poliomyelitis. Use of this inactivated poliovirus vaccine and subsequent widespread use of the oral poliovirus, developed by Albert Sabin, led to the establishment of the Global Polio Eradication Initiative (GPEI) in 1988. The GPEI has reduced polio worldwide by 99 per cent.

Countries

Contact Details

For more information in relation to this news article, please contact:

Professor Michael Toole AM

Epidemiologist, Technical Advisor Know-C19 Hub

Telephone

+61392822216

Email

mike.toole@burnet.edu.au

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