What is Histoplasmosis?

Histoplasmosis is a fungal infection resulting from inhalation of spores of the organism called Histoplasma Capsulatum. Individuals infected by the organism manifest symptoms such as mild influenza-like illness with fever, cough, headaches and muscle aches. These symptoms may manifest themselves in exposed individuals within 3 – 17 days after exposures. Chronic form of histoplasmosis can mimic tuberculosis. According to the National Eye Institute (NIE), histoplasmosis, if left untreated, can cause a serious eye disease called Ocular Histoplasmosis Syndrome (OHS), a leading cause of vision loss in America between the age groups of 20 – 40.


Spores of the organism are found in and around soils or structures where bird or bat droppings had accumulated. The organism already exists in the soil and uses bird droppings as a source of nutrient for its growth and development. The wings, feet and beaks of birds can be secondary means of spreading the organism to the roosting sites of large number of birds. Likely places for the organism to exist will be roof overhangs, pillars, beams, roof edges, vent holes, below the fascia board and abandoned buildings. Any activity that disturbs soil around the areas where large numbers of birds or bats have been roosting is a potential and likely exposure source.  


OSHA does not have specific regulation on histoplasmosis.  However, OSHA’s, General Duty clause requires employers to provide “a workplace free of recognized hazards that are likely to cause death or serious physical harm to the employees”.  While it may not be practical to decontaminate all sites contaminated with Histoplasma Capsulatum organism, the following work practices and personal protective equipment may be helpful:

  • Avoid areas that have bird or bat droppings. Persons with weakened immune systems are at greatest risk for severe infection. 
  • Recognize the symptoms: 
    • Fever 
    • Cough 
    • Fatigue
    • Chills
    • Headache
    • Chest pain
    • Body aches 
  • If possible, seal off points where bats and birds could enter your work area.
  • Wear a NIOSH-certified respirator. 
  • Wear single-use protective clothing and shoe coverings and dispose of them in sealed, heavy-duty plastic bags.
  • Carefully mist dusty material or piles of droppings with water before and during cleanup to keep the dust down. You can also saturate the excrement with a 2-5% hypochlorite solution, which is made from a concentration of 50% water and 50% household bleach. This will eliminate the possibility of workers becoming exposed to respiratory or skin irritants, as well as guarding against contracting Histoplasmosis.
  • Throw away the wetted material in secure containers or double, heavy-duty plastic bags. Truck-mounted vacuums are best for large amounts of droppings. 
  • Follow all rules for removing, transporting, and disposing of contaminated materials.
  • Personal protective equipment like–approved respirator, disposable coveralls and dust covers, are very important method of protection to our employees.

Juan’s Story

Juan was installing an air conditioning unit in an attic of an old home. He noticed bird or bat droppings on the floor and beams. In the middle of the project, he began coughing and having chills and a fever. He went to his doctor and described his working conditions. His doctor diagnosed histoplasmosis and treated him with an antifungal medication. The doctor told Juan that his discomfort might continue, because histoplasmosis can scar lung tissue.
  • Have you or someone you know worked on a project where bird or bat droppings were present? If so, what happened?
  • What could have been done to protect Juan?