Polio in Minnesota, 2005

Summary of current polio situation in Minnesota. Also included are answers to questions about polio.

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On this page:
I heard there is polio in Minnesota, is this true?
Is this finding unusual?
What is vaccine-derived poliovirus?
I didn’t think we had polio in the United States. How did this child become infected?
What is polio?
What are the symptoms of polio?
What health problems does polio cause?
How is polio diagnosed?
Who gets polio?
Is there a vaccine for polio?
How is polio spread?
When and for how long is a person able to spread polio?
What can be done to prevent the spread of polio?

I heard there is polio in Minnesota, is this true?

You may have heard media reports of polio in Minnesota and wondered what this means, here are the facts:

• In August, stool samples from a Minnesota infant were found to contain oral polio vaccine virus, a strain of poliovirus. This infant does not have polio disease and does not have any symptoms.
• Through more testing it was found that the poliovirus the infant was infected with was initially contained in live-attenuated oral polio vaccine, which has not been used in the U.S. since 2000.
• Following a community investigation three children from the same family unrelated to the infant were found to be infected with poliovirus.
• An additional fifth child, from a family unrelated to the other children, also tested positive for poliovirus.
• Like the infant, none of these children have symptoms of polio.
• All five of these children were not vaccinated for polio.
• The Minnesota Department of Health along with county health departments in Minnesota, as well as health departments in other states and Canada, continue to monitor the situation.

Is this finding unusual?

Yes, this finding is unusual because this is the first case of a vaccine-derived poliovirus in the U.S. since polio vaccination was changed from oral vaccine to an injection (shot) vaccine in 2000. This finding is also important because it means the poliovirus is circulating in the community, and could cause polio disease in persons exposed and not immune to polio.

What is vaccine-derived poliovirus?

Vaccine-derived poliovirus (VDPV) is a strain from the Sabin type 1 strain used in the oral polio vaccine. Oral vaccine is still used in some parts of the world, but has not been used in the United States since 2000. Although this VDPV has not been associated with paralytic disease, based on previous experience with VDPVs, the virus is considered to have potential both for wider transmission and for causing paralytic disease. VDPVs have caused outbreaks of poliomyelitis in several countries. VDPVs in highly immunized populations are rare.

I didn’t think we had polio in the United States. How did this child become infected?

That is correct. Polio was considered eliminated from the U.S. in 1979 because transmission of the disease no longer occurred in the U.S. However, polio still exists in some developing countries. The use of live oral polio vaccine was phased out in the U.S. between 1997-2000 and is no longer used in this country. Inactivated (injectable) polio vaccine, which does not contain live virus, is currently used in the U.S.

This infant was infected through exposure to someone who was shedding vaccine-related poliovirus. We do not know who that person is and though MDH is conducting a thorough investigation, we may never know. However, it is unlikely that the person who exposed this infant to vaccine-derived poliovirus was the original oral polio vaccine recipient since this vaccine has not been used in the U.S. since 2000 and people with healthy immune systems do not usually shed poliovirus for more than a few weeks. It is possible that this vaccine-derived poliovirus strain infected a number of other people before being spread to this infant.

What is polio?

Polio (poliomyelitis) is caused by a virus that lives in the intestinal tract and sometimes in the throat.

What are the symptoms of polio?

Symptoms of polio include fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs. Up to 95 percent of all persons infected with polio will have no symptoms.

What health problems does polio cause?

Most people recover from polio without any problems. However, approximately 4 to 8 percent of those with polio develop health problems such as meningitis and less than 1 percent develop permanent paralysis.

How is polio diagnosed?

Polio can only be diagnosed with laboratory testing. Taking samples from the stool or throat are common ways to test for polio.

Who gets polio?

Anyone who has not been vaccinated can get the disease. Because there are people throughout the world and in the United States that are not vaccinated, it is possible that infected travelers can carry polio to unvaccinated people.

Is there a vaccine for polio?

Yes. The inactivated polio vaccine, or IPV, is very effective.

• Children usually receive three doses of IPV vaccine at 2, 4, and 6 months of age.
• Booster doses are given again at 4 to 6 years of age.
• In the United States, polio vaccination is generally unnecessary for person 18 years of age or older.
• In the case of travel to areas where polio disease exists, adults should receive a booster dose.
• In the case of an outbreak in a local area, previously vaccinated persons involved in the outbreak should receive a dose of polio vaccine. If they have never been vaccinated, a three-dose series of polio vaccine is recommended.

How is polio spread?

The poliovirus is found in the stool and throat. It is spread through contact with the stool of an infected person (for instance, by changing diapers). Poliovirus must be swallowed to cause infection. This can happen when hands that are contaminated with stool are put in the mouth.

The period between exposure to the virus and onset of illness is usually 6 to 20 days, but can range from 3 to 35 days.

When and for how long is a person able to spread polio?

A person with polio can spread the virus to others 7 to 10 days before and after the illness appears, but the virus can be found in the stool from 3 to 6 weeks.

What can be done to prevent the spread of polio?

Vaccination is the best way to prevent the spread of polio. Widespread immunization against polio is critical to controlling the spread of the disease and preventing disability. In addition everyone should:

• Avoid close contact with others who are ill
• Stay at home if ill
• Wash hands with soap and water after toileting, changing diapers, and before preparing food and eating. If soap and water are not available, use an alcohol-based hand rub.
  

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