Tuberculin, also known as purified protein derivative, is a combination of proteins that are used in the diagnosis of tuberculosis. This use is referred to as the tuberculin skin test and is recommended only for those at high risk. Reliable administration of the skin test requires large amounts of training, supervision, and practice. Injection is done into the skin. After 48 to 72 hours, if there is more than a five to ten millimeter area of swelling, the test is considered positive.
Common side effects include redness, itchiness, and pain at the site of injection. Allergic reactions may occasionally occur. The test may be falsely positive in those who have been previously vaccinated with BCG or have been infected by other types of mycobacteria. The test may be falsely negative within ten weeks of infection, in those less than six months old, and in those who have been infected for many years. Use is safe in pregnancy.
Tuberculin was discovered in 1890 by Robert Koch. Koch, best known for his work on the etiology of tuberculosis (TB), laid down various rigorous guidelines that aided the establishment between a pathogen and the specific disease that followed that were later named Koch's postulates. Although he initially believed it would cure tuberculosis, this was later disproved. Tuberculin is made from an extract of Mycobacterium tuberculosis.
It is on the World Health Organization's List of Essential Medicines.
Medical uses
The test used in the United States at present is referred to as the Mantoux test. An alternative test called the Heaf test was used in the United Kingdom until 2005, although the UK now uses the Mantoux test in line with the rest of the world. Both of these tests use the tuberculin derivative PPD (purified protein derivative).
History
Hope for a cure
Tuberculin was invented by German scientist and physician Robert Koch in 1890. The original tuberculin was a glycerine extract of the tubercle bacilli and was developed as a remedy for tuberculosis. This was originally considered a cure for tuberculosis, given to patients in subcutaneous doses of a brownish, transparent liquid that was gathered through cultured filtrates. However, the treatment did not result in the anticipated reduction of deaths.
When the tuberculin treatment was first given to patients in 1890, a febrile reaction that lasted between four and five hours was recorded in most patients. The symptoms of these reactions included a fever that was accompanied by vomiting, rigors, or other forms of constitutional symptoms. After these symptoms became recurring in patients, Koch had noted how increasing dosages of the treatment over time resulted in quicker and more effective healing in the mild cases of tuberculosis, along with the more serious cases where progression was slower, yet still progressive.
British efforts to set up "dispensaries" for the examination, diagnosis and treatment of poor citizens achieved better results, as the protocol of the Edinburgh System encompassed treatment of the homes and all contacts of the patients with TB. As an example, Dr Hilda Clark's dispensary at Street, Somerset was especially noted for its efficacious treatment of the less severe cases.
Clemens von Pirquet, an Austrian physician, discovered that patients who had previously received injections of horse serum or smallpox vaccine had quicker, more severe reactions to a second injection, and he coined the word allergy to describe this hypersensitivity reaction. Soon after, he discovered that the same type of reaction took place in those infected with tuberculosis. His observations led to the development of the tuberculin skin test. Individuals with active tuberculosis were usually tuberculin positive, but many of those with disseminated and rapidly progressive disease were negative. This led to the widespread but erroneous belief that tuberculin reactivity is an indicator of immunity to tuberculosis.
Effectiveness proclaimed
In Koch's time, close to one in seven Germans died of tuberculosis. For that reason, the public reacted euphorically to the discovery of the pathogen since it sparked hope for a cure. Until that time, the only effective remedy for an infectious disease was quinine, which was used to treat malaria.
At the Tenth International Medical Congress held in 1890 in Berlin, Koch unexpectedly introduced a cure for tuberculosis, which he called tuberculin. He did not reveal its composition, which was not unusual as it was not then customary to patent medicine, Phenazone being the only exception. The public trusted the famous physician and reacted enthusiastically. Koch was awarded the Grand Cross of the Order of the Red Eagle.