Elimination and Engineering Controls

Excluding bats or birds from a building

Work-related histoplasmosis often involves disruption of bird or bat droppings.1 The best way to prevent exposure to Histoplasma is to prevent bird or bat droppings from accumulating in the first place.

Moving bats from an occupied roost

To move bats away from an occupied roost in a building:23

• Identify and seal entry and exit points, even the smallest holes.A
• Install and maintain lights in the roosting area, forcing bats to seek another daytime roosting site.
• Construct bat houses near former roosts.B

Ultrasonic devices and chemical repellents are not effective for eliminating bats from a roosting area.4

Excluding birds

To exclude birds from a building:5

• Identify and seal entry and exit points.
• Consider visual deterrents (balloons, flags, lights, and replicas of hawks and owls) and noises.C
• Use nontoxic, chemical bird repellents like liquids, aerosols, and nondrying films.D
• Use mechanical anti-roosting systems consisting of angled and porcupine wires made of stainless steel.E

Controlling dust generation

Upon discovering a roosting site, make plans to restrict the area and determine the extent of contamination. When deciding about removing accumulations, consider factors like:

• The amount and location of the material.
• The structural integrity or soundness of the building or structure.
• Weather conditions.
• Whether people are nearby.

Methods

If the material has to go, there are ways to eliminate or reduce dust generation to lower risk of infection.

Avoid shoveling or sweeping dry, dusty material. Instead, carefully spray it to reduce the amount of aerosolized material (or material dispersed or spread into the air).6 Adding a surfactant to the water might reduce further the amount of aerosolized material.F Once the material is wetted, it can be collected in a secure container for immediate disposal.

An alternative method is to use an industrial vacuum cleaner with a high-efficiency filter to collect potentially contaminated material. Truck-mounted or trailer-mounted vacuum systems are recommended for areas with large accumulations of bat or bird manure. See the personal protective equipment page for workers involved in these activities.

What to do next

In most cases, environmental sampling to confirm Histoplasma is no longer present after removal of droppings is unnecessary. However, visually inspect the cleaned area to ensure no residual dust or debris remains. After this, a removal activity may be considered finished.

Disinfecting potentially contaminated material

Disinfectants have occasionally been used to treat contaminated soil and accumulations of bat droppings. However, this occurred when removal was not practical or as a precaution before a removal process was started. However, there are no Environmental Protection Agency-approved products registered specifically as soil disinfectants or as being effective against Histoplasma. In past histoplasmosis outbreak settings, formaldehyde was used to decontaminate material contaminated with Histoplasma.789 This is not recommended because formaldehyde can cause a variety of health problems.10

Disposing of waste

Any material removed from a work site that might be contaminated with Histoplasma should be disposed of properly and safely. It should not be moved to another area where it could still be a health hazard.

State and local requirements for the removal, transportation, and disposal of potentially contaminated material should be followed. Some state or local landfill regulations define material contaminated with Histoplasma to be infectious waste. In that case, incineration or another disposal method may also be required. If disposing in a landfill, arrangements should be made with a landfill operator.

Controlling dust during construction

Even in the absence of large accumulations of bat and bird droppings, Histoplasma spores can be aerosolized during construction, excavation, or demolition. Once airborne, spores can be carried easily by wind currents over long distances. These spores could infect people outside of the work site. Regardless of location, take precautions to prevent dust in the air from active and inactive bird or bat roosts.11

In regions where Histoplasma is common, use water sprays or other dust suppression techniques should be used to reduce aerosolized dust during construction, excavation, or demolition.12 During windy periods or other times when typical dust suppression techniques are ineffective, earthmoving activities should be interrupted.

All earthmoving equipment (bulldozers, trucks, and front-end loaders) should have enclosed cabs with air-conditioning and HEPA filtration (if available) to protect their operators. Air filters on air-conditioners should be inspected on a regular schedule and cleaned or replaced as needed. During filter cleaning or replacement of exceptionally dusty air filters, maintenance workers should wear respiratory protection if there is a potential for the dust to be aerosolized. Truck beds carrying dirt or debris from a work site should be covered, and all trucks should pass through a wash station before leaving the site. When at a dump site, a truck operator should ensure that people in the vicinity will not be exposed to aerosolized dust while the truck is emptied.