Histoplasmosis skin test is a procedure to check if you have been exposed to the histoplasma capsulatum fungus. This fungus causes histoplasmosis infection. Histoplasmosis is an infection that usually affects the lungs and varies in severity and symptoms. If this infection affects other parts of the body it is referred to as disseminated histoplasmosis.
This is an air-borne infection. If soil or dust containing the histoplasmosis fungus is disturbed, then this fungus spores get into the air. Any person in the vicinity can then contract this infection by breathing in the spores. This disease, however, does not spread from one person to another.
Quite often, this infection does not have any symptoms. Even when the symptoms occur, they are varied. The lung infection caused because of histoplasmosis could be mild or acute. In case of acute or chronic infection, you will experience tiredness, chest pains, dry cough and fever. Usually, the chronic infection occurs in people who already have an existing lung disease and in such cases, this infection stays for months and can cause lung scarring.
As for disseminated histoplasmosis, the symptoms will depend upon the body organ that has been affected. There could be sores in the gastrointestinal tract or liver and the spleen can also enlarge. Disseminated histoplasmosis can in certain cases, also be fatal.
Symptoms, if any, of this infection usually occur in a week to a fortnight after exposure to the histoplasmosis function.
There are various methods of diagnosing this infection. The doctor can order a laboratory culture or conduct a blood test. There is another method, particularly when a doctor wants to investigate an outbreak of this infection and that is through a histoplasmosis skin test.
The lab technician or person administering the test will clean a particular area of your skin—usually it is the forearm. An allergen is then injected into the skin. The area that was injected is then checked after 24 and 48 hours to see if there is any reaction. There are rare occasions, when it could take as long as 72 hours before a reaction appears on the skin.
There is no specific preparation required for this test, and the risks involved are also almost negligible.. The allergen is only intended to bring about a reaction in case of a histoplasmosis infection. Therefore, you needn’t worry about any side-effects.
If there is no reaction or inflammation at the injection site within 48 hours, it indicates that the test is normal and that you do not have any infection. However, if there is a reaction or inflammation at the site, it implies that you have been exposed to Histoplasma capsulatum fungus. Do note though, that there are rare instances when the skin test can cause a positive result in further histoplasmosis antibody tests.
Since, the skin test only checks if the patient has been exposed to the fungus, it not used too often these days. Doctors prefer conducting a urine or blood tests to diagnose this condition.