Teen Newsletter: August/September 2021 – Polio Eradication

Polio, or poliomyelitis, is a disabling and life-threatening disease caused by the poliovirus. The virus spreads from person to person and can infect a person’s spinal cord, causing paralysis.

Poliovirus is very contagious and spreads through person-to-person contact. It lives in an infected person’s throat and intestines. Poliovirus only infects people. It enters the body through the mouth and spreads through either contact with the feces (poop) of an infected person or droplets from a sneeze or cough of an infected person (less common). An infected person may spread the virus to others immediately before and up to 2 weeks after symptoms appear. The virus can live in an infected person’s feces for many weeks. It can contaminate food and water in unsanitary conditions. People who don’t have symptoms can still pass the virus to others and make them sick.

Most people who get infected with poliovirus (about 72 out of 100) will not have any visible symptoms. About 1 out of 4 people with poliovirus infection will have flu-like symptoms that may include sore throat, fever, tiredness, nausea, headache, and stomach pain. These symptoms usually last 2 to 5 days, then go away on their own.

A smaller proportion of people with poliovirus infection will develop other, more serious symptoms that affect the brain and spinal cord like paresthesia (feeling of pins and needles in the legs), meningitis (infection of the covering of the spinal cord and/or brain) which occurs in about 1 out of 25 people with poliovirus infection, or paralysis (either can’t move parts of the body or weakness in the arms, legs, or both) which occurs in about 1 out of 200 people with poliovirus infection. Between 2 and 10 out of 100 people who have paralysis from poliovirus infection die, because the virus affects the muscles that help them breathe.

Even children who seem to fully recover can develop new muscle pain, weakness, or paralysis as adults, 15 to 40 years later. This is called post-polio syndrome. Note that “poliomyelitis” (or “polio” for short) is defined as the paralytic disease. So only people with the paralytic infection are considered to have the disease.

There are two types of vaccine that can prevent polio:

• Inactivated poliovirus vaccine (IPV) given as an injection in the leg or arm, depending on the patient’s age. Only IPV has been used in the United States since 2000.
• Oral poliovirus vaccine (OPV) given by mouth as drops, is still used throughout much of the world.

Polio vaccine protects children by preparing their bodies to fight the poliovirus. Almost all children (99 children out of 100) who get all the recommended doses of the inactivated polio vaccine will be protected from polio.

CDC laboratories conduct testing for poliovirus, including culture, intratypic differentiation, genome sequencing, and serology.

The number of worldwide polio cases has fallen from an estimated 350,000 in 1988 to 176 in 2019—a decline of more than 99% in reported cases. Only two polio-endemic countries (nations that have never interrupted the transmission of wild poliovirus) remain—Afghanistan and Pakistan.

Did you know that due to a successful vaccination program, the United States has been polio-free since 1979? Poliovirus is still a threat in some countries, and travelers could once again spread poliovirus in the US.

Public health problems are diverse and can include infectious diseases, chronic diseases, emergencies, injuries, environmental health problems, as well as other health threats. Regardless of the topic, we take the same systematic, science-based approach to a public health problem by following four general steps.

1. Surveillance (What is the problem?)

In public health, we identify the problem by using surveillance systems to monitor health events and behaviors occurring among a population.

Overall, CDC is involved in several surveillance systems and groups that track polio:

• National Notifiable Diseases Surveillance System (NNDSS)

Poliovirus is a notifiable disease in the United States. Physicians must promptly notify the state health department of suspected cases, and laboratories must notify the state health department of all confirmed cases. State health departments use the NNDSS to report confirmed cases to CDC. NNDSS data is collected from states through several mechanisms, including the National Electronic Disease Surveillance System (NEDSS) Base System (NBS).

• Global Polio Eradication Initiative (GPEI)

CDC is a partner of GPEI, the global partnership with the goal to complete the eradication and containment of all wild, vaccine-related and Sabin polioviruses, so no child suffers from paralytic poliomyelitis ever again. One of GPEI’s four pillars of polio eradication is surveillance. They perform active surveillance for wild poliovirus through reporting and laboratory testing of all cases of acute flaccid paralysis among children less than fifteen years of age.

• Global Immunization Division (GID)

GID staff members work jointly with WHO and national Ministries of Health to plan and monitor polio surveillance and immunization activities in multiple countries worldwide.

• Stop Transmission of Polio (STOP)

STOP team members currently participate in 11-month assignments in 42 countries, providing support at the national and sub-national levels. In 2018 alone, the STOP program, in collaboration with WHO and UNICEF, has deployed 314 public health professionals to improve surveillance for acute flaccid paralysis (AFP, an early sign of possible polio), support planning and implementing polio SIAs (supplementary immunization activities), responding to polio outbreaks, and enhancing polio surveillance.

Polio surveillance is primarily conducted through acute flaccid paralysis (AFP) surveillance supplemented by environmental surveillance of sewage samples. One recent Morbidity and Mortality Weekly Report (MMWR) describes recent analysis of both of these surveillance types, and how data collection has been affected by COVID-19.

Dive even deeper into polio surveillance by checking out the MMWR Polio Reports.

For ease of explaining and understanding the public health approach for this public health problem (polio), let’s focus on a 2013-2015 Middle Eastern Polio outbreak, when the World Health Organization (WHO) and CDC surveillance system known as the Early Warning Alert and Response Network (EWARN) first detected AFP cases in Syria. The lab tests identified 36 cases in Syria first, followed by confirming two more polio cases in Iraq.

2. Risk Factor Identification (What is the cause?)

After we’ve identified the problem, the next question is, “What is the cause of the problem?” For example, are there factors that might make certain populations more susceptible to disease, such as something in the environment or certain behaviors that people are practicing?

Countries and regions experiencing active conflict, chronic insecurity, and large-scale displacement of persons are particularly vulnerable to outbreaks because of the disruption of health care and immunization services. The outbreak occurred 2 years after the onset of the Syrian civil war, resulted in 38 cases, and was the first time wild poliovirus as detected in Syria in approximately a decade.

Regional conflicts had prevented children from getting routine vaccinations, which put them at the highest risk for polio infection. The conflicts had forced people from their homes and into unsafe areas, challenging vaccination efforts. Other children at high risk for infection included those in remote, difficult-to-reach areas and in districts with low vaccination coverage. Routine vaccination coverage in the region was high before the war, which limited the number of children who were susceptible to the poliovirus and the size of the outbreak. The children who were most vulnerable to the disease were those born during the Syrian conflict.

3. Intervention Evaluation (What works?)

Once we’ve identified the risk factors related to the problem, we ask, “what intervention works to address the problem?” We look at what has worked in the past in addressing this same problem and if a proposed intervention makes sense with our affected population.

After the polio cases were lab confirmed, Commander Derek Ehrhardt, BSN, MPH, MSN—CDC’s Global Immunization Division epidemiologist and Team Lead for the Eastern Mediterranean Region in the Polio Eradication Branch—immediately left for Geneva, Switzerland to work with other Global Polio Eradication Initiative (GPEI) partners: World Health Organization (WHO), UNICEF, Rotary Foundation, the Bill and Melinda Gates Foundation, and UNHCR, as well as eight ministries of health, which included Syria, Iraq, Jordan, Lebanon, Egypt, Iran, Palestine, and Turkey.

Ehrhardt worked closely with Mike Ryan, MD, WHO’s interagency team lead for GPEI technical experts. The interagency team traveled to the affected areas to collect and analyze information that Ehrhardt, Ryan, and other GPEI leads used to create a coordinated strategic response plan, considering each country’s unique culture.

“We needed a plan to reach the kids to vaccinate them against polio. We came up with a strategic response that involved three phases,” says Ehrhardt. Now it was up to CDC and the other GPEI partners, and the eight Middle Eastern Countries affected—Syria, Iraq, Jordan, Lebanon, Egypt, Iran, Palestine, and Turkey—to prevent polio from crossing borders and infecting polio-free countries.

4. Implementation (How did we do it?)

In the last step, we ask, “How can we implement the intervention? Given the resources we have and what we know about the affected population, will this work?”

The interagency team created a 3-phase response plan, tailored to the specific challenges of the region during the conflict, to prevent additional polio spread and stop the outbreak.

The three phases they used were:

• Implementing numerous immunization campaigns in Syria and Iraq to vaccinate children against the poliovirus from October 2013 to April 2014
• Targeting intervention for high-risk groups for supplemental immunization activities (SIAs) to vaccinate those who had missed routine immunizations from May 2014 to January 2015.
• Strengthening routine immunization systems and conducting additional vaccination campaigns to catch up children who had missed some of their routine vaccines from February to October 2015 to increase polio immunity in the region.

To reach the many children who needed vaccinations, the response set up immunization sites at healthcare clinics, border crossings, and displaced person camps, as well as sent vaccinators house to house in some locations. Mobile vaccination teams also traveled to remote regions.

The response provided CDC and its global partners with insight and best-practice strategies for areas at high risk for disease outbreaks. Quick detection followed by a rapid response stopped the outbreak within six months by vaccinating about 27 million children, many of whom were in unsafe and difficult-to-access areas of conflict. Countries suffering active conflict continue to be at high risk for polio and other diseases, mainly because it is difficult to vaccinate displaced people who are in politically unstable areas.

As you can see, using The Public Health Approach helps public health professionals identify a problem, find out what is causing it, and determine what solutions/interventions work.

This month’s Out of the CDC Museum Collection features an object in the historic collection that serves as a reminder of the importance of eradicating polio. Pictured here is a pediatric iron lung. Iron lungs are ventilators used to help polio patients who experienced upper body paralysis breathe. This iron lung has been in the CDC Museum historic collection since 2010 when it was donated to the collection by Jack Kovalski. Mr. Kovalski is a polio survivor and works to restore iron lungs so they can be used to teach about the importance of vaccinations. Read about a polio survivor’s experience using an iron lung and watch this video on how the iron lung works.