Histoplasmosis Fungal Infection
What is histoplasmosis?
Histoplasmosis is a particularly nasty fungal lung infection - especially in the acute stages - caused by histoplasma capsulatum . People catch the infection when they breath in the spores.
There are several different strains of the infection. However, many people who have the fungi in their lungs often experience no symptoms at all. This is due to the fact that there are several forms of this infection.
In addition, histoplasmosis is also known by other localised names such as:
- Cave or caver's disease
- Darling's disease
- Ohio valley disease
- Spelunker's lung
The disease became known in 1906 by Samuel Darling who observed the fungi in human tissue cells. The first actual diagnosis was made in 1936 by Katherine Dodd and Edna Tompkins. The fungi is now found worldwide, although most cases are still found in Equatorial regions and is endemic to a few areas in North America. In fact this fungal infection is one of the most common now diagnosed in the USA.
According to an article in 'Scientific America', over half the people who live in the USA's endemic regions will have inhaled histoplasmosis spores by the age of 20. In healthy individuals this usually causes no problems or symptoms. If there are signs of the infection then most people pass it off without the need for medical intervention. However, where even healthy people are exposed to a more intense concentration of the fungi - for example working with soil, or exposed to concentrated accumulations of bat or bird droppings - the infection has the potential to become much more severe. In these individuals pneumonia can develop requiring hospital admission, but they usually recover.
People who already have comprised immune systems - for example organ transplant patients, AIDS patients - who contract the fungi infection could develop serious problems ending in death.
Types and symptoms of histoplasmosis
There are three main forms of histoplasmosis summarised below:
- Acute pulmonary histoplasmosis. This strain of the infection may develop symptoms, but just as often there are no signs of the illness.
- Chronic pulmonary histoplasmois - the symptoms of this form usually involve the lungs. More rarely, the eyes can also be affected.
- Progressive disseminated histoplasmosis. This is the most serious form of the infection. In addition, there are various sub-types affecting different areas of the body.
Symptoms of histoplasmosis
The symptoms of this infection can vary depending on the severity of the case and as stated previously, sometimes there are no symptoms at all. Below are the signs that may be found with the acute illness and are usually mild.
Acute histoplasmosis symptoms:
- Fever and chills
- Dry cough and chest pain, shortness of breath
- Joint/muscle pain and stiffness
- Flu like tiredness/malaise and headache
- In some people a rash may also develop on the lower half of the legs. This is called erythema nodosum
Other people who are more vulnerable and may develop the more severe forms of this infection are:
- People with a lung condition already present such as emphysema. These people are at risk of developing a chronic form of histoplasmosis
- The Elderly
- Young children
- People who have suppressed immune systems
As well as the above symptoms serious infections also give rise to:
- Severe joint and muscle pain.
- The risk of developing pericarditis . Pericarditis is inflammation around the heart.
- Serious lung infections that may cause the person in some cases to bring up blood - very similar to tuberculosis.
People who have immune system suppression and infants may go onto develop the most severe form of the infection called 'disseminated histoplasmosis '. This would cause many of the body's organs to be affected such as:
- Adrenal glands
- Central nervous system
Histoplasmosis can in fact affect any area of the body and if left untreated would be fatal.
Test your knowledge
view quiz statistics
Treatment and precautions for histoplasmosis
Most cases of this infection will actually clear up itself due to the body's immune system. However, as stated previously there are some situations and some categories of people who may well develop a more severe form. Tests can be carried out to determine if a person is carrying the fungal infection. This can be verified through a few tests such as:
- Blood tests and in some cases biopsy is taken from an infected site
- Bronchoscopy is carried out usually with people who have a severe form
- Full blood count is usually only needed with disseminated histoplasmosis
- Chest x-rays could show that pneumonia is present. Sputum samples can also be taken but they can show up negative even if the person has the infection.
- In very severe cases the urine of the person may be tested as well.
Treatment is basically with drug therapy. Medications such as itraconazole and amphotericin B. In addition, medication may also be given to relieve the symptoms of the illness.
- People who live in areas where the fungus is found can't really prevent the spores from being breathed in. However, as previously stated for most healthy people this is not a health risk.
- One of the main precautions is to avoid areas with high concentrations of bird and bat droppings where the fungus is known to be present. For example people who have chicken coops and similar could be at higher risk. In addition, people who have chest complaints or weakened immune systems should be particularly careful in these areas.
- People at risk should also avoid areas with high dust levels such as building/construction sites in areas where the fungus is known to be endemic.
- People who explore caves on a frequent basis should also be aware that the fungus could be present in some areas.
- In locations where the fungus is known to inhabit, be self aware about the organism, the danger areas and the signs and symptoms.
Histoplasmosis can be a formidable infection to have, especially for people who are already coping with another illness. However, if people keep vigilant and seek medical advice if they have any concerns, the this dangerous fungus can be kept under control.