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Who Is At Risk For Histoplasmosis?

What is Histoplasmosis?

Histoplasmosis is also known by other terms like ”cave disease”, ”Darling’s disease”, ”Ohio Valley disease”, ”reticuloendotheliosis”, ”spelunker’s lung” and ”caver’s disease”. It is a disease which is caused due to Histoplasma capsulatum fungus. This fungus is a species of dimorphism fungi. Histoplasmosis is known for causing morbidity and mortality worldwide. It is famous all over the world except for Antarctica. It is mostly concentrated in endemic regions like Central and South America. It is also found in North American regions like Ohio and Mississippi river valleys. Some parts of China, Southeast Asia, the Indian subcontinent, Australia and Africa are also affected by this fungus.

Histoplasmosis primarily affects the lungs. Therefore, Histoplasmosis is fundamentally a pulmonary disease. Inhaling spores causes infection, which involves the lungs. The term Histoplasmosis was initially described by an American physician, Samuel Darling in the year 1905. He reported the disseminated form of the disease in a lethal case from Martinique. Darling reported the organism as a protozoan (the small living thing with only one cell). However, in the year 1912, da Rocha Lima described the organism’s similarity to a yeast. After almost 20 years later, growth on artificial medium revealed that the organism was mold at room temperature and yeast at 37 degree Celsius. Histoplasma capsulatum exists in the form of mold in the environment and forms a white tan colony Sabouraud dextrose agar at 25 to 30 degree Celsius. It is reported that every year, hundreds and thousands of individuals in the United States and Central America are infected with Histoplasma capsulatum fungus.

Histoplasmosis may be broadly classified into 4 types:

  1. Primary pulmonary Histoplasmosis,
  2. Progressive disseminated histoplasmosis,
  3. Primary cutaneous Histoplasmosis
  4. African Histoplasmosis.

Anyone found with acute febrile respiratory illness and has travelled to an area where Histoplasmosis is endemic may suffer from Histoplasmosis. Around 90% of people are asymptomatic. It is estimated that around 250,000 people are affected by Histoplasmosis every year in the United States.

Who Is At Risk For Histoplasmosis?

Who at Risk for Histoplasmosis?

In some patients who have a weak immune system, Histoplasmosis may become a long term issue or further spread to other body parts. Around 10% to 20% of progressive, disseminated cases involve the central nervous system. Due to weak immunity, Histoplasmosis is much more common among patients with AIDS. People taking medications like corticosteroids or TNF inhibitors (consuming these drugs may weaken individuals immune system) are prone to get affected by Histoplasmosis easily.

Histoplasmosis may even affect infants and adults around 55 years and even more. People who work with soil or earth materials are at an increased risk of getting affected by Histoplasmosis. This includes farmers, landscapers, construction workers, archaeologists, and geologists.

Patients of emphysema (lung disease) are also likely to get affected by Histoplasmosis. The fungus, Histoplasma capsulatum is found in soil, generally linked with decaying bat guano or bird droppings. Histoplasmosis is non-communicable. Rarely though, the infection can spread if the infected organ is transplanted. Often questions are asked whether people already affected by Histoplasmosis can be once again affected by the disease. It is plausible for a once affected person to be affected by Histoplasmosis once again, but this time the body’s immune system is much more alert and provides some protection to make the infection less severe. People who have a weak immune system, Histoplasmosis may remain unrecognized inside the body for months and years altogether, and can suddenly show some symptoms later.

Causes of Histoplasmosis

The main cause of Histoplasmosis is the fungus, Histoplasma capsulatum. This fungus is cognate with bird or bat droppings in the environment, especially in caves. If a person inhales the fungal spores, they develop an illness similar to pneumonia. It is not that everyone who inhales this spore might be affected by the illness. The spores may become airborne in demolition projects in areas that contain bat or bird droppings. These airborne spores travel almost hundreds of feet.

Sign and Symptoms of Histoplasmosis

Nearly all Histoplasmosis infections are resolved by themselves. Different types of Histoplasmosis exist. The patient suffering from the mildest form may show no signs or symptoms of Histoplasmosis. Severe type can be life-threatening. If at all any signs and symptoms occur, they usually appear 3 to 17 days after exposure. Acute Histoplasmosis may show the following symptoms may be fever, chills, headache, muscle ache, dry cough, chest pain, shortness of breath, loss of appetite and fatigue.

If there is too much, then it may result in respiratory failure leading to life threats. The normal symptoms of persistent Histoplasmosis Include hard cough, breath shortness and feeling dizzy including losing weight. Patients suffering from disseminated Histoplasmosis may show symptoms including bleeding in gastrointestinal area, low blood pressure, failure in respiratory organs, cough for pain in chest, further leading to the bone marrow failure. It is very important to consult your doctor if a person thinks he might be suffering from Histoplasmosis. If left unattended, Histoplasmosis could spread or cause scarring inside the lungs. Scarring may put pressure on the individual’s blood vessels, heart esophagus, and lymph nodes.

Diagnosis of Histoplasmosis

The signs and symptoms of Histoplasmosis may not be enough for a physician to identify it. The diagnosis rests upon the immune system’s response to the fungus. These are some of the available lab tests for the diagnosis of histoplasmosis. Body fluids and tissue culture and urine test are done to identify the fungus. Some blood tests are run to measure the response of antibody to Histoplasma and samples of infected tissue are taken so that they can be examined under a microscope. People suffering from acute Histoplasmosis normally undergo a chest x-ray. Calcification of lymph nodes around bronchi may provide corroboration to physicians of prior healed infections. CT scan is found useful for identification of the areas where disseminated Histoplasmosis is spread in the individual’s body.

Complications of Histoplasmosis

Many serious complications are caused due to Histoplasmosis. For infants, older adults, and people with a weak immune system, the complications are proved to be life-threatening. Complications may include acute respiratory distress syndrome (ARDS). Lungs can be damaged to the point that the air sacs may begin to fill with fluid when a patient is suffering from Histoplasmosis. This can deprive the oxygen level in the blood. Secondly, Histoplasmosis may also be problematic to heart. When the fluid in the pericarditis increases, it can interfere with the heart’s ability to pump blood systematically. Thirdly, Histoplasmosis caused complications in individual’s adrenal sufficiency. It can harm one’s adrenal gland, which produces hormones that give instructions effectively to every organ and tissue present in one’s body. Lastly, Histoplasmosis can cause Meningitis. It is an infection and inflammation of membranes surrounding individual’s brain and spinal cord.

Prevention of Histoplasmosis

Though it is difficult to prevent Histoplasmosis yet certain measures can be taken. Some are the following ways to reduce the risk of infections; avoid exposure to the fungus by avoiding projects such as cave exploring and raising birds like pigeons or chickens. Before digging soil or working in areas that help the fungus to grow, spray it thoroughly with water as it prevents spores from being released into the air. Wear a mask while working in these areas.


Therefore, to summarize Histoplasmosis is a disease caused due to Histoplasma capsulatum fungus. It mostly affects people who live in the endemic areas and people who work with soil, pigeons, and chickens. It may affect the extreme ages that are infants and adults above the age of 55 years. Though this disease is known worldwide yet the people living in the United States are majorly affected by it. People with HIV and AIDS are more likely to get affected with Histoplasmosis than any other normal individual. One should immediately consult the doctor as and when they see any of the signs and symptoms of Histoplasmosis.


Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 17, 2019

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