Polio is considered one of the worst crippling diseases to affect children; yet is also one of the largest success stories. While medical efforts have largely wiped out the disease, it still manages to resurface every summer.
Recently, cases of polio were reported in the Democratic Republic of the Congo (DRC) in Africa. The outbreak first began in June 2017, and despite government efforts to contain it, has spread to a few other provinces. The World Health Organization (WHO) has warned that there is a risk of the outbreak spreading beyond DRC, especially since some areas are close to the border with Uganda.
Afghanistan and Pakistan are still in the midst of a polio outbreak, although the numbers have gone down significantly. What is polio and why is it reappearing after we thought we had wiped out the virus?
What is Polio?
Polio (also known as Poliomyelitis) is a viral disease caused by the poliovirus and normally affects young children. Symptoms of polio include fever, fatigue, headache, vomiting, stiffness in the neck, and painful limbs. In a small percentage of children, the virus affects the body's nervous system and can cause a gradual weakening of the leg muscles and loss of movement. Less than 1-2% of those who contract the virus become paralyzed.
The polio virus lives in the throat and intestines of an infected person and is transmitted due to contact with an individual's feces. Polio can also be transmitted by contaminated food or water, and very occasionally through coughing and sneezing.
By the 1950s, the U.S was seeing nearly 25,000 to 50,000 cases of polio each year. Several scientists were working hard to contain the polio epidemic. One of them was Dr. Jonas Salk who developed an inactivated polio vaccine, containing a dead polio virus. Dr. Salk’s vaccine was made publicly available in 1955, and thanks to his medical breakthrough, hundreds of thousands of children were saved from paralysis or even death.
Later, Dr. Albert Sabin developed a live vaccine that contains a live or weakened poliovirus. This vaccine was made publicly available in 1961, and is given orally (referred to as OPV or Oral Polio Vaccine). The live vaccine has not been used in the United States (U.S.) since 2000. The reasons the oral vaccine are used more often in poorer countries is because it’s about three times cheaper than the inactivated one.
Who Is Polio Re-appearing?
Wild-polio virus (a type of polio found in the wild) usually resurfaces during the rainy months. However, the outbreak of polio in the DRC is caused by a rare genetic mutation of the weakened virus that is given for the oral polio vaccine. This new type of polio is referred to as vaccine-derived poliovirus type 2 (VDPV). When an individual contracts VDPV, they can easily spread polio to others in their villages who haven’t been vaccinated against polio. The sanitation in many areas is poor, so the virus can spread easily into food and water supplies.
In Pakistan and Afghanistan, groups like the Taliban have outlawed vaccinations, and as such, it is extremely difficult to vaccinate children in those areas. In some areas, health organizations have mobilized women in certain communities to vaccinate children. These women are well-known and trusted by the society, which makes families less wary of vaccinating their children.
While efforts to eradicate polio have reduced the disease by 99.9 percent, there is still concern over these occasional cases and outbreaks. Scientists are working around the clock to try and produce a vaccination that won’t cause VDPV. Until then, the OPV is the only readily accessible vaccination in many poor countries.
Sources: BBC, Guardian, CNN, VOX, polioeradication.org, WHO, CDC