Hypertension overview and Definition

Histoplasmosis is type of lung infection. It is caused by fungal spores by inhaling Histoplasma capsulatum. These spores are found in the soil and in the dropping of bats and birds.  It is common among the immunocompromised peoples and might result in the severe complications.

This is also called as the Cave disease. The infection can cause a lung disease similar to pneumonia. In certain cases the infection spreads throughout the body known as disseminated disease. It is more common  in the immunocompromised individuals such as HIV/AIDS and those receiving the cancer treatments such as the cancer therapy such as chemotherapy and target therapy. The most of the organs affected includes liver, spleen, brain, joints, eyes and bone marrow. The disease does not spread from human to other humans and hence it is not contagious.


The fungus grows in soil and in the material which is contaminated with bird or bat dropping . the fungus has been found in poultry house litter, caves , areas harboring bats and bird roosts  particularly those of starlings. The fungus is thermally dimorphic in the environment and it grows as a brownish mycelium and at body temperature at 37 degree in humans it morphs into the yeast. Histoplasmosis is not spread to others but it is contracted by inhalation of the spores from disturbed soil. The inoculum is represented principally by microconidia. These are inhaled and reach the alveoli. In the alveoli, macrophages ingest these microconidia. They survive inside the phagosome. As the fungus is thermally dimorphic, these microconidia are transformed into yeast.

They grow and multiply inside the phagosome. The macrophages travel in lymphatic circulation and can spread the disease to different organs. Within the phagosome, the fungus has an absolute requirement for thiamine. Cell mediated immunity for histoplasmosis develops within 2 weeks.

Within the phagosome, the fungus has an absolute requirement for thiamine Cell-mediated immunity for histoplasmosis develops within 2 weeks. If the patient has strong cellular immunity, macrophages, epithelial cells, and lymphocytes surround the organisms and contain them, and eventually calcify. In immunocompromised individuals, the organisms disseminate to different organs such as bone, spleen, liver, adrenal glands, and mucocutaneous membranes, resulting in progressive disseminated histoplasmosis. Chronic lung disease can manifest.

Clinical signs & symptoms

  1. The patients with the pulmonary histoplasmosis and have no symptoms or only mild symptoms. The most common symptoms include are:
  • Chest pain
  • Chills
  • Cough
  • Fever
  • Joint pain and stiffness
  • Muscle aches and stiffness
  • Rash (usually small sores on the lower legs)
  • Shortness of breath
  • Acute pulmonary histoplasmosis can be a serious illness in the very young, older people, and people with a weakened immune system, including those who:
  • Have HIV/AIDS
  • Have had bone marrow or solid organ transplants
  • Take medicines that suppress their immune system
  • Symptoms in these people may include:
  • Inflammation around the heart is called pericarditis
  • Serious lung infections
  • Severe joint pain

Differential Diagnosis

Tests include:

  • Antibody tests for histoplasmosis
  • Biopsy of infection site
  • Bronchoscopy(usually only done if symptoms are severe or you have an abnormal immune system)
  • Complete blood count (CBC) with differential
  • Chest x ray (might show a lung infection or pneumonia)
  • Sputum culture (this test often does not show the fungus, even if you are infected)
  • Urine test for Histoplasma capsulatum antigen
  • Chest Xray:
  • The chest x ray predicts any abnormal area in the lungs
  • Computed tomography:
  • It reveals the slice of the lung. It uses both the combination of x ray and computer aided device.
  • It helps to analyse the size, shape and position of any lung tumour and also it helps in the detection of enlarged lymph nodes.
  • It also looks for any masses in the adrenal gland, liver, brain and other organs.
  •  CT guided needle Biopsy:
  • CT scan might be used to guide a biopsy needle into this  area to get the tissue for lung structure.
  • MRI scan:
  • It uses the soft tissue image of the organ. It uses the both the magnet and radiowaves.
  • It reveals abnormality in the lung tissue and lymph node enlargement.


The histoplasmosis shows good prognosis. If the histoplasmosis involves lung then the mortality rate is 50%. If the histoplasmosis starts to spread then the mortality rate is increased.


  • Avoid exposure:

Avoid projects and activities that might expose you to the fungus, such as cave exploring and raising birds, such as pigeons or chickens.

  • Spray contaminated surfaces:

Before you dig soil or work in an area that could harbour the fungus that causes histoplasmosis, soak it with water. This can help prevent spores from being released into the air. Spraying chicken coops and barns before cleaning them also can reduce your risk.

  • Wear a respirator mask:

 Consult the National Institute for Occupational Safety and Health to determine which type of mask will provide protection for your level of exposure.