In the 19th century, scarlet fever was a common killer in Europe. In 2016, nearly 20,000 cases were reported in the United Kingdom -- the biggest increase in 50 years.<br /><br />Scarlet fever is just one disease that many have forgotten but that is by no means gone, despite our best efforts to eliminate it.
In the 19th century, scarlet fever was a common killer in Europe. In 2016, nearly 20,000 cases were reported in the United Kingdom -- the biggest increase in 50 years.

Scarlet fever is just one disease that many have forgotten but that is by no means gone, despite our best efforts to eliminate it.
Badobadop/Wikipedia
Though it's often thought of as a medieval disease, the World Health Organization reports 1,000 to 3,000 global cases of plague every year. The US averages seven new human cases a year, <a href="index.php?page=&url=https%3A%2F%2Fwww.cdc.gov%2Fplague%2Fmaps%2Findex.html" target="_blank" target="_blank">mostly in the Southwest</a>. Pictured, a patient with gangrene and necrosis, caused by plague.<br />
Though it's often thought of as a medieval disease, the World Health Organization reports 1,000 to 3,000 global cases of plague every year. The US averages seven new human cases a year, mostly in the Southwest. Pictured, a patient with gangrene and necrosis, caused by plague.
CDC / Dr. Jack Poland
This 19-year-old girl in Neijiang, China, is being carried in a basket because she has rickets. Rickets is caused by a lack of vitamin D, which we get from sunlight. Experts believe rickets is making a comeback in developed countries because of the use of sunscreen and less time spent outdoors.
This 19-year-old girl in Neijiang, China, is being carried in a basket because she has rickets. Rickets is caused by a lack of vitamin D, which we get from sunlight. Experts believe rickets is making a comeback in developed countries because of the use of sunscreen and less time spent outdoors.
China Photos/Getty Images
Gout was once known as the "disease of kings" because of its links to excessive food and alcohol consumption. These days, unhealthy lifestyles are behind an increase in gout in developed countries.
Gout was once known as the "disease of kings" because of its links to excessive food and alcohol consumption. These days, unhealthy lifestyles are behind an increase in gout in developed countries.
The deadly disease diphtheria affects the nose and throat. Vaccinations mean it is now rare in developed countries, but in 2011, nearly 5,000 cases were reported to the WHO, with many more probably unreported.<br />
The deadly disease diphtheria affects the nose and throat. Vaccinations mean it is now rare in developed countries, but in 2011, nearly 5,000 cases were reported to the WHO, with many more probably unreported.
NOAH SEELAM/AFP/AFP/Getty Images
There were 216,000 global cases of leprosy, an ancient and disfiguring disease, in 2013.
There were 216,000 global cases of leprosy, an ancient and disfiguring disease, in 2013.
CHANDAN KHANNA/AFP/Getty Images
Although there is a pertussis vaccine, there were an <a href="index.php?page=&url=http%3A%2F%2Fwww.who.int%2Fimmunization%2Ftopics%2Fpertussis%2Fen%2F" target="_blank" target="_blank">estimated 16 million global cases</a> of whooping cough in 2008, killing about 195,000 children.
Although there is a pertussis vaccine, there were an estimated 16 million global cases of whooping cough in 2008, killing about 195,000 children.
James Gathany/CDC
In April 2015, the Americas became the first region to eliminate rubella; the <a href="index.php?page=&url=https%3A%2F%2Fwww.cdc.gov%2Frubella%2Fabout%2Fin-the-us.html" target="_blank" target="_blank">Centers for Disease Control and Prevention says</a> there are fewer than 10 cases each year.<strong> </strong>But globally, about <a href="index.php?page=&url=https%3A%2F%2Fmeaslesrubellainitiative.org%2Fresources%2Fadvocacy-tools%2F2017-fact-sheet%2F" target="_blank" target="_blank">110,000 babies</a> are born with <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2016%2F09%2F08%2Fhealth%2Frubella-house-zika-babies-future%2Findex.html">congenital rubella syndrome</a> every year.
In April 2015, the Americas became the first region to eliminate rubella; the Centers for Disease Control and Prevention says there are fewer than 10 cases each year. But globally, about 110,000 babies are born with congenital rubella syndrome every year.
CDC.gov
TB, or tuberculosis, is one of the top 10 killers in the world, according to the WHO. In 2016, 10.4 million people around the globe contracted tuberculosis, and more than 1.7 million died. Ninety-five percent of those <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2017%2F03%2F24%2Fhealth%2Ftuberculosis-cambodia-tb-day-photos%2Findex.html">deaths were in developing countries</a>.
TB, or tuberculosis, is one of the top 10 killers in the world, according to the WHO. In 2016, 10.4 million people around the globe contracted tuberculosis, and more than 1.7 million died. Ninety-five percent of those deaths were in developing countries.
Spencer Platt/Getty Images/File
Vaccination programs mean polio is on the verge of extinction -- but there are still cases in Afghanistan and Pakistan.
Vaccination programs mean polio is on the verge of extinction -- but there are still cases in Afghanistan and Pakistan.
Courtesy UNICEF