Up to 48 per 100,000 (1:2100) of individuals tested positive for the mutation of DM1 in New York, although not all of these individuals would have become symptomatic. Again in New York, premutations for DM1 were found in 191 per 100,000 (1:525). DM2 prevalence is not known, but genetic studies estimate it to be as high as 1:1830. DM affects males and females approximately equally. About 30,000 people in the United States are affected. In most populations, DM1 appears to be more common than DM2. However, recent studies suggest that type 2 may be as common as type 1 among people in Germany and Finland.DM1 is the most common form of myotonic muscular dystrophy diagnosed in children, with a prevalence ranging from 1 per 100,000 in Japan to 3–15 per 100,000 in Europe. The prevalence may be as high as 1 in 500 in regions such as Quebec, possibly due to the founder effect. The incidence of congenital myotonic dystrophy is thought to be about 1:20,000. History
Myotonic dystrophy was first described by a German physician, Hans Gustav Wilhelm Steinert, who first published a series of 6 cases of the condition in 1909. Isolated case reports of myotonia had been published previously, including reports by Frederick Eustace Batten and Hans Curschmann, and type 1 myotonic dystrophy is therefore sometimes known as Curschmann-Batten-Steinert syndrome. The underlying cause of type 1 myotonic dystrophy was determined in 1992.
Evidence indicates that CYD-TDV is partially effective in preventing infection, but may lead to a higher risk of severe disease in those who have not been previously infected and then do go on to contract the disease. It is not clear why the vaccinated seronegative population have more serious adverse outcomes. A plausible hypothesis is the phenomenon of antibody-dependent enhancement (ADE). American virologist Scott Halstead was one of the first researchers to identify the ADE phenomenon. Dr. Halstead and his colleague Dr. Phillip Russell proposed that the vaccine only be used after antibody testing, to rule out prior dengue exposure and avoid vaccination of sero-negative individuals.Common side effects include headache, pain at the site of injection, and general muscle pains. Severe side effects may include anaphylaxis. Use is not recommended in people with poor immune function. Safety of use during pregnancy is unclear. Dengvaxia is a weakened but live vaccine and works by triggering an immune response against four types of dengue virus.Dengvaxia became commercially available in 2016 in 11 countries: Mexico, the Philippines, Indonesia, Brazil, El Salvador, Costa Rica, Paraguay, Guatemala, Peru, Thailand, and Singapore. In 2019 it was approved for medical use in the United States. It is on the World Health Organizations List of Essential Medicines. In Indonesia it costs about US$207 for the recommended three doses as of 2016.In 2017, the manufacturer recommended that the vaccine only be used in people who have previously had a dengue infection, as outcomes may be worsened in those who have not been previously infected.