Showing posts with label WPV3. Show all posts
Showing posts with label WPV3. Show all posts

Thursday, October 31, 2019

POLIO ERADICATION--TWO STRAINS GONE, ONE TO GO

The three-decade-long campaign to eradicate polio--not long ago a worldwide scourge--passed an important milestone this month. The Global Polio Eradication Initiative (GPEI) announced the eradication of wild poliovirus type 3 (WPV3). Type 2 was declared eradicated in 2015. That leaves only one type of wild polivirus, WPV1, still in circulation.


 Somali child receiving an injection of inactivated poliovirus
Credit: PV2 Andrew W. McGalliard
Public Domain

That good news is augmented by the fact that WPV1 only exists in two countries, Afghanistan and Pakistan. This allows resources to be focused on those last two remaining reservoirs of the deadly virus.

However, the goal of finally eradicating polio remains elusive. There have been more cases of wild-virus-caused polio in those two countries (18 and 76 respectively) this year than in 2018. And, there have been a significant number of cases caused when the weakened virus used for oral inoculation mutates back to a disease-causing form. Although very rare, when millions of children are given the oral vaccine, mutation back to a virulent form is enough to keep the disease alive.

To address this problem, GPEI has now shifted into its Polio Endgame Strategy. This is a multifaceted campaign involving continued mass inoculations, rapid response teams to quickly contain and snuff out any flareups, and a shift from oral live attenuated immunization to inoculation by injection of completely inactivated virus. The endgame campaign is estimated to cost $4.2 billion and take four years. If it succeeds, humanity will have eliminated a second deadly disease (smallpox was the first) and no child will ever again be killed or paralyzed by polio.

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You can read an executive summary of the endgame strategy here.


Tuesday, May 02, 2017

QUICK UPDATE ON POLIO ERADICATION PROGRESS -- WE'RE SO CLOSE

Followers of this blog know that I'm fascinated by the international effort to eradicate polio. Wiping out this paralyzing, often deadly disease will be one of humankind's great accomplishments. The only other human disease that we've been able to eradicate is smallpox--the last spontaneous case was in 1977.

According to the Global Polio Eradication Initiative, the effort is incredibly close to success, with just 5 cases reported worldwide this year, to May 24 (vs. 16 this time last year). In the early 1950s, before the Salk and Sabin vaccines were introduced, 15,000 children died or were paralyzed by the poliovirus every year just in the United States, 500,000 worldwide.

It's taken decades of dedicated, sometimes dangerous work by scientists, international organizations, and on-the-ground health providers to reduce that number from 500,000 to 5. The goal now is to shrink it to zero.

It appears that the polio virus now survives in just a few locations--the 5 cases all occurred in Pakistan and Afghanistan, destabilized by war and refugees. In addition, all 5 cases were caused by Wild Polio Virus 1 (WPV1), meaning that the other two strains of wild polio virus, WPV 2 and 3, may already be eradicated.

Wild Polio Virus Type 3
Credit: Manuel Almagro Rivas/CreativeCommons

Massive vaccination programs of at-risk children and adults are continuing, and will need to to continue for some time even after there are no more documented cases.

We're so close . . .

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