a. Bird and bat excrement, commonly referred to as droppings, accumulates under trees near human habitations and on structures and machinery:
(1) Creating an environment favorable to the development of disease organisms harmful to humans and domestic animals.
(2) Causing corrosion.
(3) Creating objectionable odor and appearance.
(4) Impeding human activities.
b. This technical guide:
(1) Describes the potential health hazards associated with bird and bat droppings.
(2) Outlines procedures for the safe and effective management of bird and bat droppings.
(3) Is intended for use by persons interested in identifying and managing health hazards created by bird and bat droppings.
1-2. References
References are listed in appendix A.
1-3. Technical Assistance
a. You may obtain technical advice by telephone from the following divisions of the U.S. Army Center for Health Promotion and Preventive Medicine (CHPPM):
(1) DOD Pesticide Hotline, DSN 584-3773, commercial (410) 671-3773.
(2) Occupational and Environmental Medicine Division, DSN 584-2714.
(3) Industrial Hygiene Division, DSN 584-3118.
(4) Sanitation and Hygiene Branch, DSN 584-2488.
b. Direct requests for services through appropriate command channels of the requesting activity to:
Furnish an information copy to:
Return to Table of Contents
2-1. General
a. The high nutrient content of accumulated bird and bat
excrement provides an excellent growth medium for organisms of
potential human health concern. This guide primarily addresses the
prevention of two illnesses caused by those organisms: cryptococcosis
and histoplasmosis.
b. Cryptococcosis is usually associated with pigeon droppings at
elevated roost sites; histoplasmosis with bird and bat droppings on
soil under roosts. However, the infective stages of both organisms may
be found in any accumulation of dry droppings and associated organic
matter.
c. Personnel should also be aware of the possible dangers of
other disease organisms associated with bird and bat excrement,
discussed in para 2-2.
2-2. Disease Organisms Associated with Bird and Bat Droppings
a. Mycosis, a fungal infection resulting in disease, is usually
incurred by inhaling dusts, especially organic (decaying vegetation)
dusts and dusts enriched with bird or bat droppings, which contain
massive amounts of the disease organisms. These fungal organisms are
ubiquitous in the environment and exposure to them is impossible to
avoid. However, most humans are resistant to the amounts they
encounter during normal activities.
b. The risk of contracting certain of these fungal infections is
greatly increased by certain predisposing conditions such as an
immunocompromised state (e.g., HIV infection, immunosuppressing
medication, cancer, etc.), antibiotic therapy, surgical trauma, skin
injury, and chronic disease. (See also the National Center for Infectious
Diseases.)
c. The fungal disease organisms found in bird and bat droppings
are listed below, including the source of the organisms, the methods
of contraction, and the health effects.
(1) Cryptococcosis (Torulosis, European Blastomycosis).
(a) Source. Organic dusts, especially those contaminated
with pigeon or bat droppinqs, are the most important source of the
fungus, Cryptococcus neoformans, in the environment. C. neoformans
has been found in as many as 84 percent of samples taken from old
roosting sites. Up to 50-million colony forming units of C.
neoformans have been found per gram of pigeon droppings.
(b) Contraction. Cryptococcosis is acquired by inhaling
the yeast-like vegetative cells of the organism. These cells measure
1-3 microns in diameter and are easily airborne.
(c) Health Effects. Clinical manifestations of pulmonary
infection are not characteristic and may be absent. The infection may
disseminate to the central nervous system, resulting in cryptococcal
meningitis (inflammation of the membranes of the brain and spinal
cord), which is difficult to diagnose and fatal if not properly, and
promptly, treated.
(2) Histoplasmosis.
(a) Source. The causative agent of histoplasmosis,
Histoplasma capsulatum, a dimorphic fungus (mold), is found in soils
throughout the world. It flourishes by overwhelming other soil
organisms when high relative humidity and optimum temperatures are
present in soil that has been enriched by accumulated bird droppings
for 3 or more years. It has also been found in bird and bat droppings
not in contact with the soil. Once established in soil enriched by
bird or bat droppings, H. capsulatum is difficult to eliminate even
after the nutrient source is removed (Krzysik 1989).
(b) Contraction. Humans are infected by inhalation of the
spores of this fungus which can be carried by wind and dust.
(c) Health Effects. Most infections produce no symptoms
or only a mild influenza-like illness. However, pneumonia, blindness,
and even death from a chronic infection are possible.
(3) Psittacosis (Ornithosis, Parrot Fever).
(a) Source. A rickettsial-like organism, Chlamydia
psittaci, causes psittacosis. Approximately 150 cases are reported
annually in the United States.
(b) Contraction. This disease is contracted by inhaling
C. psittaci which is found in feathers and droppinqs from infected
birds. Since the organism becomes less infectious with time, active
roosts are of greatest concern. While the disease most often occurs
in bird handlers, persons cleaning up bird excrement could contract
the disease as well.
(c) Health Effects. Psittacosis is characterized by
fever, headaches, and muscle pain, with or without obvious
respiratory symptoms. Untreated cases, especially in older patients,
can progress to pneumonia and/or generalized toxemia resulting in
death.
(4) Other Fungal Diseases. Paracoccidioidomycosis is a
serious mycosis among workers in contact with the soil in tropical
and sub-tropical regions from Mexico to Brazil. Although little is
known about it at present, it is probably acquired by inhaling soil
or fungus laden dust. Other fungal diseases found in soil and/or
decaying organic matter--such as aspergillosis, coccidioidomycosis,
blastomycosis, and sporotrichosis--are less likely to cause disease
in humans.
d. Unlike the diseases listed above, rabies (a rhabdovirus) is
not a fungal disease. However, rabid bats may be encountered during
cleanup operations.
(1) Source. Rabies is contracted when the virus-laden
saliva of an infected animal is introduced into the body by a bite or
scratch (very rarely through mucous membranes or a fresh break in the
skin). Airborne rabies infection has been demonstrated only in one
cave in Texas where millions of bats had roosted for many years.
(2) Contraction. The danger of rabies infection by
inhalation is slight, but the danger from handling bats is much
greater, especially since infected bats may be present during a
cleanup operation. Cleanup personnel should be cautioned to handle
bats only with nets and gloves.
(3) Health Effects. The onset of rabies often begins with a
sense of apprehension, headache, fever, malaise and indefinite
sensory changes. The disease progresses to paralysis, throat muscle
spasms when attempting to swallow (causing fear of water or
hydrophobia), delirium and convulsions. Death is often from
respiratory paralysis. Rabies can be prevented by vaccination during
the disease's incubation period. Once symptoms appear, however,
death is almost always inevitable.
Return to Table of Contents
3-1. Case Studies
As an example of the health threat of mycotic organisms inhabiting bird
and bat droppings, four documented cases of human infection are
presented here.
a. Cryptococcosis in a Farm Mechanic. A farm mechanic worked on
machinery in a grain-drying building where live pigeons were present.
The mechanic developed cryptococcal meningitis and was hospitalized for
8 weeks. The pigeon droppings from the grain-drying building were
found to have 24.4 x lO6 colony-forming units per gram. Eventually he
recovered fully.
b. Cryptococcosis Misdiagnosis. Failure to diagnose
cryptococcosis can result in fatalities. A 46-year-old man developed a
chronic neurologic syndrome after dismantling a steeple. He was
treated for tuberculous meningitis and the symptoms went into remission
(as they may do for a disseminated infection). One year later he was
hospitalized with chronic inflammation of the brain and diagnosed as
having cryptococcal meningitis. Treatment at that time with
amphotericin B and flucytosine was unsuccessful.
c. Histoplasmosis Outbreak at an Arkansas Courthouse. Pigeon
droppings had accumulated to a depth of one foot on the catwalk around
an Arkansas courthouse tower. Cleanup workers shoveled the dry
droppings off the catwalk, allowing them to fall four stories to the
ground. Air conditioners picked up the falling spore-laden dust and
distributed it within the building. Of the 84 employees inside, 52
percent developed fever, cough, chest pain, myalgia, and/or laboratory
evidence of histoplasmosis. Twenty-four other cases of histoplasmosis
occurred among construction workers and people who visited the
courthouse during the cleanup; one individual contracted the disease
after visiting for only 10 minutes. Of those exposed who escaped
illness, 87.5 percent had been previously infected. However, five
people with evidence of previous infection did become ill. It is
probable that their previous infection afforded only partial immunity.
d. Histoplasmosis Outbreak Due to Disturbing a Bird Roost. The
potential for histoplasmosis to disseminate downwind is clearly
illustrated by an outbreak that occurred in Iowa when the dry soil
under a starling roost was bulldozed. People up to one mile away
contracted histoplasmosis and the bulldozer operator died after a
7-week illness.
Return to Table of Contents
4-1. Assessment and Decontamination of Bird and Bat Droppings
a. Risk Assessment.
(1) Cryptococcus neoformans is primarily found in pigeon
droppings and less often in soil and organic debris. The risk of
contracting cryptococcosis is not related to the age of the excrement.
(2) Histoplasma capsulatum usually develops only at bird
roosts that have existed for 3 years or more. It is uncommon at pigeon
roosts. Although H. capsulatum grows well in excrement-enriched soil,
it cannot form spores under the acidic conditions of fresh droppings.
An active bird roost may only produce a few spores. However, when the
droppings have dried and/or been leached by rain, massive amounts of
spores can be released, especially if the soil is disturbed under dusty
conditions. Once established, H. capsulatum will remain in the soil
under a roost for many years after the birds have abandoned it.
b. Sampling for Disease Organisms. Sampling is not recommended
due to the difficulty, time, and expense involved. Laboratory
processing of samples may require up to 8 weeks, test procedures are
not totally reliable (the disease organisms may be present but not
detected), and interpretation of the results is difficult. Sampling is
generally not necessary if the cleanup precautions outlined in this
guide are followed.
c. Decontamination.
(1) Cryptococcus neoformans is sensitive to alkali. Areas of
suspected contamination can be treated with an alkaline wash consisting
of 500 grams of hydrated lime and 18 grams of sodium hydroxide per 12
liters of water. Commercial disinfectant products of similar
alkalinity may also be used.
(2) Decontamination of droppings and associated soil for
control of Histoplasma capsulatum is not recommended. Decontamina-
tion with formalin presents a health hazard and no other effective
material is available. Decontaminated soil is subject to reinfestation
as long as the nutrients that enabled the fungus to establish itself
are still available. Information on decontamination with formalin is
included in Appendix C for those situations, such as construction
sites, where extensive and/or prolonged soil disturbance with attendant
exposure risks may occur.
4-2. Cleanup and Removal of Bird and Bat Droppings
Cryptococcosis and histoplasmosis infections typically occur by
inhaling the pathogenic spores through the nose and mouth. Therefore,
bird droppings are most dangerous when they are dry and subject to
becoming airborne as a fine dust, particularly when disturbed by
sweeping or scraping. Although germicides could be applied to
accumulated droppings prior to cleanup, their effectiveness is not
proven. Safe cleanup is based on protection from spore inhalation and
minimization of spore dispersal. If at all possible, coordinate
cleaning efforts with the installation of a modern birdproofing system.
Assume that a health hazard is present whenever bird and bat droppings
are disturbed and observe the following precautions:
a. Protection of Workers from Infective Organisms.
(1) Preliminary Consultation. Prior to disturbing accumulated
droppings, inform the occupational medicine physician of the proposed
activity and consult with an industrial hygienist for advice on
personal safety measures such as protective clothing and the proper
selection, use, and fitting of respirators.
(2) Breathing Protection. When working with accumulated
droppings, wear a NIOSH-approved full face respirator with high
efficiency particulate air (HEPA) filters capable of excluding
particles of 0.3 micron size or a supplied air respirator with full
face piece. Dust and particle masks will not provide adequate
protection and are not approved for this use.
(3) Protective Clothing. Wear disposable coveralls, gloves,
boots, and hats to protect personal clothing from contamination with
infective organisms. Seal the glove/sleeve and boot/leg interfaces
with duct tape before entering the worksite. Before leaving the work
site, vacuum the protective coveralls, boots, and gloves using a HEPA
vacuum, then walk to an excrement free area, remove the protective
clothing, and place it in plastic bags prior to removing respiratory
protection. Treat disposable clothing believed to be contaminated with
disease agents as an infectious waste.
(a) Nondisposable work clothing and respirators should be
removed, placed in a plastic bag, and sealed. These items must be
disinfected in the bag before final cleaning and reuse. Workers must
not wear their own personal street clothing under the disposable
coveralls.
(b) If the disposable coveralls or other protective clothing
are torn, the worker(s) must shower prior to putting on their street
clothes. It is recommended that workers shower and thoroughly wash
their hair at the end of their shift.
b. Application of Water. Although droppings are usually easier to
clean up when they are dry and crusted, saturating them with water
prior to removal is recommended to prevent the debris and any pathogens
from becoming airborne. This should be done with a low-velocity mist
spray. Using high pressure and/or a concentrated stream, such as from
a hose nozzle, may scatter the droppings before they can be adequately
wetted. However, hosing may be used for removing small amounts of
recently deposited droppings from sidewalks and pavement. A portable,
hand pressurized sprayer is satisfactory for applying limited amounts
of water.
c. Nonmetallic Tools. On historic structures, use only
nonmetallic tools (such as plastic spatulas and brushes with natural
fiber or nylon bristles) to remove droppings. Do not use tools that
can easily damage building surfaces, such as coarse wire brushes.
d. Public Protection. Do not perform bird excrement removal on
public buildings during normal working hours. If possible, schedule
the removal for weekends or other periods of minimum building use.
Protect interior air by closing all heating and cooling system air
intakes during the cleanup (shut down the entire system if possible).
Unless droppings are inside the building itself, perform all work
from the outside of the building. Provide barricades and signage to
keep the public clear of the work site during all operations.
e. Disposal.
(1) Double bag the droppings and associated soil in 3 mil or
thicker plastic bags, close the bags securely, and transport them
directly to a landfill to be buried. If the droppings have been
proven to contain Cryptococcus neoformans and/or Histoplasma
capsulatum they may be incinerated. Do not place the bags in a
dumpster or leave at a collection point for later pickup as they
could be torn during handling and release their potentially
infectious contents. Wear protective clothing and equipment when
collecting the bird and bat droppings for final disposal.
(2) You may clean up small amounts of fresh droppings by
scraping or hosing with water.
Return to Table of Contents
5-1. Selection of Disease-Resistant Individuals
Contact your Occupational Medicine Physician for assistance in
selecting personnel for cleanup and/or decontamination of bird and
bat excrement. They should be screened for general health status,
conditions that may predispose them to infection by fungi (see para
2-2.b), and resistance to histoplasmosis.
a. Currently, there are no screening tests for available for
determining immunity to Cryptococcus neoformans.
b. Most persons who come in contact with Histoplasma capsulatum
for the first time will become infected. Personnel who have had
histoplasmosis and have recovered are less likely to contract this
disease again. Therefore, such individuals, if available, should be
selected for the job. Skin testing for histoplasmosis is recommended
for screening, with positive tests indicating active immunity in
healthy workers. Histoplasmin antigen is available for skin testing
and provides reliable identification of individuals who have had past
infection. Blood serology titers are less sensitive than skin
testing and should not be used as a screening tool.
c. The best technique to prevent infection with Cryptococcus
neoformans or Histoplasma capsulatum is to provide proper respiratory
protection to exposed workers and to properly handle the droppings as
described in this guide.
5-2. Selection of Healthy Individuals
a. Perform preplacement evaluation on all individuals who are
selected for bird and bat excrement cleanup work crews to determine
if they have increased susceptibility. A medical history and
physical exam should be performed with attention to cancer, steroid
therapy, immunodeficiencies, pulmonary disease, diabetes mellitus,
and other immunocompromising states.
b. Select workers who are physically and psychologically able to
perform their work while wearing the prescribed respiratory
protection. As a minimum, preplacement respiratory examinations
should include the determination of the forced expiratory volume in
one second (FEV1) and forced vital capacity (FVC) (TB MED 502, para
2-10).
1. Allejo, Libero and Robert J. Weeks. 1983. "Soil decontamination
and other control measures." In DeSalvo, Arthur F., ed. Occupational
Mycosis. Lea and Febiger, Philadelphia, PA. pp. 229-238.
2. Benenson, Abram S., ed. 1990. Control of communicable diseases
in man. 15th edition. American Public Health Assoc., Washington,
DC. 532 pp.
3. Coene, R. F. 1981. "Formaldehyde: Evidence of carcinogenicity."
National Institute for Occupational Safety and Health, Current
Intelligence Bulletin 34, U.S. Department of Health and Human
Services. 15 pp.
4. Dean, Andrew G., Joseph H. Bates, Callie Sorrels, William
Germany, Libero Ajello, Leo Kaufman, Charles McGrew, and Augusta
Fitts. 1978. "An outbreak of histoplasmosis at an Arkansas
courthouse, with five cases of probable reinfection." Am. J.
Epidemiol. 108(1):36-46.
5. Fiennes, R. 1978. Zoonosis and the Origins and Ecology of Human
Disease. Academic Press, London.
6. General Services Administration. GSA Custodial Management
Handbook, PBS P 5810.2B.
7. Gordon, Morris A. 1983. "Cryptococcosis." In DeSalvo, Arthur
F., ed. Occupational Mycosis. Lea and Febiger, Philadelphia, PA.
pp. 1-11.
8. Hammerman, K.J., K.E. Powell and F.E. Tosh. 1974. "The incidence
of hospitalized cases of systemic mycotic infections." Sabouraudia,
12:33-45.
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Robert M. Timm, ed. Prevention and Control of Wildlife Damage.
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11. Hubbert, William, William McCulloch, and Paul Schnurrenberger,
eds. 1975. Diseases Transmitted from Animals to Man, 6th edition.
Thomas, Springfield.
12. Krzysik, Anthony J. 1989. "Birds in Human Modified
Environments and Bird Damage Control: Social, Economic, and Health
Implications." USACERL Technical Report N-90/03. pp. 39-42;100-101.
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F., ed. Occupational Mycosis. Lea and Febiger, Philadelphia. pp. 29-
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14. Lewis, Warren C. 1985. "Histoplasmosis can cause blindness."
National Speleological Society News. Nov 1985:351.
15. Lucid, Vincent J. and Roy S. Slack. 1980. Handbook on Bird
Management and Control. Dir. Environ. Planning. Air Force
Engineering Serv. Cent. Tyndall Air Force Base, Florida 32402.
16. National Institute for Occupational Safety and Health (NIOSH).
1990. NIOSH Pocket Guide to Chemical Hazards. National Institute
for Occupational Safety and Health, U.S. Department of Health and
Human Services. (NIOSH) Publication No. 90-117.
17. Occupational Safety and Health Administration. 1991. Code of
Federal Regulations, Title 29-Labor, Part 1910.1048 Formaldehyde.
U.S. Govern. Print. Off., Washington DC.
18. Pappagianis, Demosthenes. 1983. "Coccidioidomycosis (San
Joaquin or valley fever)." In DeSalvo, Arthur F., ed. Occupational
Mycosis. Lea and Febiger, Philadelphia, PA. pp. 13-28.
19. Tosh, Fred E., Irene L. Dato, Donn J. D'Alessio, Artone A.
Medenos, Stanley L. Hendricks, and Tom D.Y. Chin. 1966. "The second
of two epidemics of histoplasmosis resulting from work on the same
starling roost." Am. Rev. Respir. Dis. 94:4O6-413.
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1970. "Relationship of starling-blackbird roosts and epidemic
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21. Weeks, Robert J., and Fred E. Tosh. undated. "Histoplasmosis
control: Decontamination of bird roosts, chicken houses and other
point sources." Brochure 00-3021. U.S. Public Health Service,
Center for Disease Control, Atlanta. 10 pp.
22. White, Paul 0., Leo Kaufman, Robert J. Weeks, Mack D. Jones,
James A. Hotz. 1982. "Cryptococcal Meningitis: A case report and
epidemiology study." J. Med. Assoc. Georgia, 71:539-542.
23. Office of the Surgeon General. 1982. "Respiratory Protection
Program." Technical Bulletin MED 502.
CHAPTER 2
DISEASE ORGANISMS COMMONLY FOUND IN BIRD AND BAT
EXCREMENT
CHAPTER 3
REPRESENTATIVE CASES OF CRYPTOCOCCOSIS AND
HISTOPLASMOSIS
CHAPTER 4
REPRESENTATIVE CASES OF CRYPTOCOCCOSIS AND
HISTOPLASMOSIS
CHAPTER 5
SELECTION OF PERSONNEL FOR DECONTAMINATION AND
CLEANUP
APPENDIX A
REFERENCES
APPENDIX B