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Global Health 101: Control, Eradication, and Elimination, What’s the Difference?

“Peace,” taken by Perelman School of Medicine student Michael Chua during a health outreach trip with the Philippines’ Research Institute of Tropical Medicine.

Smallpox is the only disease in human history that has been completely wiped off the planet. But some recent global health news brings fresh hope that soon the world will see the end to some other scourges, such as polio, Guinea worm, and even HIV.

At Penn, our work spans the globe, from treating and preventing HIV in Botswana to conducting groundbreaking research to develop new treatments for malaria, we support education, research, and programs that can help end these and other diseases. But one of the first steps for anyone participating in our global medicine efforts is to understand the process and work behind ending these serious global health threats. As is often the case with infectious and parasitic diseases, the path to eradication is complex, starting with the terminology. To the average person, the words “control,” “eliminate,” and “eradicate” may seem synonymous, but when it comes to global health, the difference can be life and death. 

When public health experts talk about controlling a disease, they mean reducing the number of new infections, the number of people currently infected, and the number of people who become sick or die from a disease in local settings—such a town or small region. This is achieved through deliberate efforts including vaccines, medications, contact isolation, or other public health interventions.

“Malaria is a good example of a disease that can be controlled in local settings. You can't get rid of malaria entirely because the mosquito-borne parasites that transmit the disease can develop drug resistance. But you can control it through health care and prevention strategies such as aggressive mosquito control, bed nets, and anti-malaria medications,” said Stephen J. Gluckman, M.D., medical director of Penn Global Medicine.

Often, the first step toward disease elimination is disease control.

Elimination means stopping the transmission of a disease in a specific geographic area or country, but not worldwide. Elimination is a crucial step in the path toward eradication, requiring constant monitoring and interventions to keep serious diseases at bay.

Malaria is also a great example of disease control, as it no longer exists in North America or Europe, but still infects more than 214 million people around the world.

Great progress has also been made to eliminate polio, which is now endemic in only two countries: Afghanistan and Pakistan. With highly contagious diseases, such as polio, as long as the infection exists anywhere, its ability to spread means it remains a global threat. The polio virus can easily be imported into a polio-free country and can spread rapidly among unimmunized populations, making the polio vaccine crucial, especially for children.

Another example of a disease that is on the path to elimination and potentially eradication is pediatric HIV. During the past year, several countries, including Cuba, Thailand, and a handful of others have received official validation from the World Health Organization (WHO) that they have eliminated mother-to-child transmission of HIV—a key step to ending the entire AIDS epidemic.

However, the challenge with diseases such as HIV and polio is that ending these diseases also depends on populations getting a vaccine, adhering to medication regimens, and other behavioral changes.

“HIV is extremely vulnerable to these obstacles for many reasons, including the fact that a large number of people aren’t aware that they are infected. Fully stopping the virus’ spread requires significant changes in culture and behavior, which continues to be an ongoing barrier for many infectious diseases, not just HIV,” Gluckman said.

Disease eradication is the permanent reduction of a disease to zero cases through deliberate measures such as vaccines. Once a disease has been eradicated, intervention measures are no longer needed.

And soon, smallpox may have company on the eradication list.

As the Carter Center recently announced, cases of Guinea worm disease have fallen from more than 3 million cases annually in the 1980s, to a total of only two confirmed cases so far in 2016. Guinea worm disease is a parasitic infection that is contracted through contact with contaminated water. It has no cure, but thanks to water and sanitation efforts in endemic countries, the parasite itself is almost extinct, which means that we might see the very last Guinea worm infection in the near future.

“It’s important to note that some diseases, especially those that infect animals, such as influenza or rabies, may never be fully eradicated, but with the right education and interventions in place, we can help to ensure that people, especially those living in resource-limited settings, will soon see the end of some of the most serious public health threats the world has ever known,” said Gluckman.

To see some of our work in action, visit Penn’s Center for Global Health and check out winning photos from 2016 global health photo contest and learn more about our work to improve health around the world.

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