By: Karen Coates on March 09, 2016 (Along the Laos/Vietnam Border) — A polio outbreak has Lao health officials on high alert and determined to vaccinate thousands of children nationwide, as well as adults in high-risk areas. This comes 15 years after the country was declared free of the disease. It began in September with the death of an 8-year-old boy who was first paralyzed then killed by a rare form of polio derived from an oral vaccine. According to the World Health Organization, 10 cases have been identified as of late February. Meanwhile, I spent several days camping in a mountaintop village near the Lao/Vietnam border, defecating on a scrub-covered hillside along with dozens of other people, plus chickens, cows and pigs. The only outhouse around was broken, the entry blocked with a generator. The great outdoors served as everyone’s toilet. This is typical in many remote villages across the developing world. And this has everything to do with polio, an infectious disease that, like so many others, is spread through feces. Worldwide, polio cases have decreased by 99 percent since a massive campaign to stop the disease began in 1988. Polio remains endemic in only two countries—Afghanistan and Pakistan. But these recent cases in Laos and several other countries are putting health experts on edge. As the World Health Organization notes, “As long as a single child remains infected, children in all countries are at risk of contracting polio.” All of this raises a few key points about public health, and about polio in particular. First, vaccination is not a cure-all, especially when portions of a population are not immunized. In fact, vaccination can contribute to an outbreak if a community’s overall immunization rates are low—as happened with polio in Laos. Here’s how that works: Many countries use an oral form of the polio vaccine (OPV), which contains a weakened form of the virus. This triggers the body’s immune system. The immunized child produces antibodies in the blood to prevent the virus from attacking the nervous system in the event of infection. The child also produces an immune response in the intestines (where the virus multiplies) that inhibits person-to-person transmission. But there’s a downside: the vaccine-virus replicates in the intestines and is excreted in the child’s feces. If a child who has been given OPV lives in an unsanitary area where others have not been immunized, the virus can circulate and spread to others in the community. The lower a population’s immunity rate, the longer the virus can circulate and the greater its chances of mutating into a form of paralytic polio. This is rare. But it happens when the conditions are right. Countries like the United States use an injected form of the vaccine (IPV), which contains a killed strain of poliovirus that cannot cause this rare form of circulating vaccine-derived polio. But IPV is more expensive, plus it requires sterilized injection equipment as well as health workers trained to administer the vaccine. Since October, Lao health officials have stepped up their vaccination programs, adding a dose of IPV to the routine OPV immunizations given to children in an effort to further boost immunity. © UNICEF/NYHQ2012-2154/LeMoyneGuinea-Bissau, 2012 — A girl closes a pit latrine in a small village between Gabú and Bafatá Regions which had just been declared open-defecation free But the outbreak in Laos demonstrates one more thing: While vaccines are absolutely necessary to eradicating polio worldwide, toilets also play a crucial role in ending this and stopping other infectious diseases. That’s why so many international organizations and governments spend enormous efforts on ending open defecation, the only option for 1 billion people worldwide. The lack of adequate sanitation costs developing countries $260 billion a year in healthcare, lost productivity and more. Consider this: a single gram of feces can contain 1,000 parasite cysts, 1 million bacteria and 10 million viruses. The body can be its own critical form of protection. Think, for example, about how the polio vaccine works. It causes the body’s immune system to develop its own mechanisms for protection through antibodies. That immune response is what keeps a person healthy. The job of a vaccine is to boost a child’s immune system so it can protect that child later in life. This is a good principle to remember on a broad scale. Vaccines are critical—but so is the rest of a person’s health. Children who are malnourished, anemic, weak or otherwise compromised suffer greater rates of infectious disease and increased risks of dying. This is an area that needs further study. But clearly there is an undeniable cycle of poverty, malnutrition and disease that puts many of the world’s poorest children at greatest risk. Ultimately, it takes a combination of vaccines, toilets, clean water, fresh air, nutritious foods and education to build strong bodies that go on to live long and healthy lives.