I.'s statement on Polio Infections in
USA & Southeast Asia
Polio infections in Minnesota, USA
14 October 2005 -
Four Children from an Amish community in central Minnesota, USA, have
been infected with a vaccine-derived poliovirus, the state's health
department announced in a 13 October press release.
2 November 2005 Update: Since most children throughout Minnesota are immunized, there is little possibility that the strain identified in the four children will spread outside the Amish community. None of the five children is suffering paralysis from polio. Their infection is most likely explained by the fact that most Amish parents typically decline immunization of their children. The virus responsible for the infections appears to be a weakened variant of the strain used in the oral polio vaccine. Naturally occurring polio, which is caused by the wild form of the poliovirus, has been successfully eradicated from the United States and the entire Western Hemisphere.
State and federal health officials
in the United States are working in concert to ensure that the public
is fully protected from the infections. In addition, the Rotary Club
of Long Prairie, which is in the community where the polio infections
have occurred, has received a PolioPlus grant to support local polio
South Asia optimistic about ending
polio as tens of millions immunized
In all three countries, especially India, government officials and representatives of the Global Polio Eradication Initiative are optimistic that they are close to halting the spread of the poliovirus. "We are faced with the best case ever for the interruption of polio in India," says Deepak Kapur, chair of the India National PolioPlus Committee. "From what we can tell, India could be free of polio by the end of this year."
Kapur says that the oral polio vaccine was administered to children first at centrally located centers and then house-to-house in the least accessible neighborhoods. "The main target was to reach 100 percent of the children in Bihar and Uttar Pradesh," he says. Bihar and Uttar Pradesh states carry the bulk of polio cases reported so far this year, with 12 and 18 children, respectively, infected. Only three cases have occurred elsewhere: Delhi, Jharkand, and Uttaranchal.
"But even this is an artificial [description]," says Kapur. "Delhi is right next door to Uttar Pradesh, and before they were created into new states, Uttaranchal and Jharkhand were part of Uttar Pradesh and Bihar. People are related across state borders and they move freely. So, in reality, polio now occurs in only two clusters. That becomes clear when you look at a polio surveillance map." In Uttar Pradesh, the polio cases are mostly confined to five administrative districts, Kapur explains.
That would be thanks to a heightened awareness of the stakes among governments of infected states and a redirection of resources where they are most needed. For example, in the most recent subnational campaigns, state officials and civil servants were closely involved with mobilization and immunization activities, alongside religious and civic leaders. "We [the India National PolioPlus Committee] are putting 90 percent of our resources toward polio immunization activities in Bihar and Uttar Pradesh," say Kapur. "One big initiative is to have polio mobilizers - essentially volunteers, both Rotarians and others - go into communities where there is still significant resistance to immunization."
Fortunately, the nature of resistance to polio has been changing, according to Kapur. For a long time, many parents who opposed having their children immunized were reacting mostly to fears created by rumors that the oral polio vaccine would cause sterility. "Now, the resistance is from repeated immunizations," he explains. "It is more passive. Now, [reluctant parents] would say: 'No, our kids have already received several rounds of the vaccine. Why are you giving them more drops?'"
According to Kapur, in the past, resistant parents were simply ignorant of the benefits of polio immunization. If parents understand that the vaccine isn't harmful, he says, then it's easier to persuade them to bring a child for follow-up drops of the oral polio vaccine. "But delivery [of vaccine] is still a big problem, especially in Bihar, which is a poor state," says Kapur. "Still, where we have reached, surveillance medical officers are confident that we have achieved near-universal, considerable coverage. Only about 6 percent of children are not yet reached during immunizations."
The CDC issued a public health dispatch online in the MMWR (Morbidity and Mortality Weekly Report, Vol. 54) on 14 October 2005 regarding the five Minnesota children who were infected with vaccine-derived poliovirus. The following questions and answers are based on that CDC dispatch.
It has been widely reported in the press that none of the five children showed any symptoms of paralytic polio. How did the fact a child was infected by the poliovirus type 1 become known? The first child, who was never vaccinated against polio for religious reasons, was admitted to a hospital for pneumonia, and later to three other hospitals for recurrent infections. Health officials found the poliovirus while investigating the cause of the child's illness. Eventually, the child was diagnosed with severe combined immunodeficiency (SCID).
What kind of poliovirus is it? The poliovirus has been identified as a Sabin oral polio vaccine-derived poliovirus (VDPV).
Is this poliovirus different from the one that has caused cases of paralytic polio in countries such as Nigeria, India, and Yemen? Yes, most polio cases in the world are caused by wild (naturally occurring) poliovirus. The first objective of the Global Polio Eradication Initiative is to stop polio caused by wild poliovirus. After eradication is achieved, it is planned that oral polio vaccine (OPV) use will stop entirely, eliminating vaccine-derived poliovirus cases soon thereafter.
How did a child who was never vaccinated acquire the poliovirus? This mystery has not yet been solved. Facts show that three unvaccinated siblings in another household in the Central Minnesota Amish community have been found to have the same VDPV type 1. None of these children have been ill and are not immunocompromised. A fifth child from a family not related to the others has also been found with the poliovirus. Public health officials are investigating not only the families of the poliovirus-infected children but also members of their community. The hospitals involved are being investigated along with their healthcare workers and staff members to determine the source of the VDPV.
Why is it such a mystery? Couldn't the poliovirus come from another child who was vaccinated in the U.S.? No. As stated earlier, the genetic evidence identifies that the poliovirus is Sabin vaccine derived, and the U.S. has not used the Sabin oral polio vaccine (OPV) since January 2000. It is thought that the source of the poliovirus is a person who received the OPV in another country. The last outbreak of paralytic polio in the U.S., which occurred in 1979, was traced back to the Netherlands through unvaccinated Amish persons in Canada.
In addition to tracking the source of the poliovirus, what are public health officials doing? The families and community members of the Amish children and the healthcare workers who may have been exposed who are at ongoing risk or whose immunization status is uncertain are being offered the inactivated polio vaccine (IPV).
What is Rotary doing? Based on discussions with members of the Rotary Club of Long Prairie, which is in the community where the polio infections have occurred, a PolioPlus grant is being provided to the club to support local polio immunization efforts.
Don't the majority of parents vaccinate their children? Yes. For example, Minnesota reports that 93 percent of its children aged 19-35 months are vaccinated and so are 98 percent of its school-aged children.
Who should be worried about this recent discovery in Minnesota? The vast majority of the population has nothing to worry about because they have been vaccinated. However, individuals who are unvaccinated or have incomplete polio vaccinations are at risk for developing polio when exposed to VDPV-infected persons. That said, we all should be worried when polio cases are reported anywhere in the world and should support the ongoing efforts to vaccinate the world's children.
What is the lesson learned by this experience? There are three important lessons to be learned: First, it is important to vaccinate all children for polio; second, all countries live under a continued threat as long as polio transmission continues in any country; and finally, this experience reminds us of the importance of rapidly completing global polio eradication.
Learn more about Rotary's role in the worldwide polio eradication effort.
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