International Notes
Cave-Associated Histoplasmosis -- Costa Rica
An outbreak of histoplasmosis occurred among a group of
university
students who entered a cave in Santa Rosa National Park,
Guanacaste
Province, Costa Rica, on January 4, 1988. The cave was inhabited
by
about 500 bats, including three species of fruit bats (Glossophaga
soricina, Carollia perspicillata, and Carollia subrufra) and one
species of vampire bats (Desmodus rotundus). The cave consisted of
two
entrances to a single chamber 20 x 75 x 5 feet in size. Bat guano
covered the floor of the cave, and the ground was noted to be
exceptionally dry for the season.
Seventeen students (mean age, 24 years; range, 20-40 years)
entered the cave to observe the bats and photograph a small boa
constrictor feeding on them. The students were in the cave an
average
of 26 minutes (range, 3-90 minutes). Fifteen (88%) of the 17
students
became acutely ill within 9-24 days (mean, 14.4 days);* 12
remained
ill 14 days after onset of symptoms. One student, who did not
enter
the cave, did not become ill. Signs and symptoms among the 15 ill
persons included fever (93%), headache (87%), cough (80%), dyspnea
(80%), chest pain (73%); and myalgia (53%). Two patients were
hospitalized, but all recovered without antifungal treatment.
Chest x-rays were obtained for 12 of the 15 patients; 10 had
bilateral diffuse fluffy nodular parenchymal infiltrates. Late
acute-phase and early convalescent-phase serum specimens (3 and 5
weeks after exposure to the cave) and urine specimens (5 weeks
after
exposure) were obtained from all 15 patients. Twelve of the 15
patients had evidence of histoplasmosis by complement fixation
test,
immunodiffusion test, or urinary antigen detection test (1,2).
Reported by: JE Johnson, RN, BSN, JD Kabler, MD, Univ Health Svc,
Univ
of Wisconsin- Madison; MF Gourley, MD, DJ D'Alessio, MD, Univ of
Wisconsin-Madison Medical School; RW Dodge, MS, R Golubjatnikov,
PhD,
Wisconsin State Laboratory of Hygiene; JP Davis, MD, State
Epidemiologist, Wisconsin Dept of Health and Social Svcs. LJ
Wheat,
MD, Indiana Univ School of Medicine, Indianapolis. DH Janzen, PhD,
Univ of Pennsylvania, Philadelphia. Pan American Health
Organization.
Div of Field Svcs, Epidemiology Program Office; Immunology Br, Div
of
Mycotic Diseases, Center for Infectious Diseases; Respiratory
Diseases
Br, Div of Bacterial Diseases, Center for Infectious Diseases,
CDC.
Editorial Note: Histoplasmosis is caused by inhalation of spores
of
Histoplasma capsulatum from its natural soil habitat. Growth of H.
capsulatum requires moderate temperatures, high humidity, and a
source
of nitrates, often from decomposing feces of bats or birds. H.
capsulatum has been isolated from both bat caves and bird roosts,
and
human infection has been associated with exposure to both sources
(3).
This outbreak is typical of bat-cave-associated histoplasmosis
(4). The high attack rate (88%) could be explained by the
relatively
young age of the persons entering the cave or by exposure to a
large
inoculum of H. capsulatum spores. The extraordinarily dry ground
in
the cave also may have increased the dispersion of spores in the
cave.
H. capsulatum has been more readily isolated from caves under dry
conditions than after flooding (5).
Cave-acquired histoplasmosis differs in several respects from
histoplasmosis associated with bird roosts. Bats, unlike avian
species, may become infected with H. capsulatum (6). Therefore,
formaldehyde spraying, a useful control measure for
avian-associated
sources of histoplasmosis (7), may be ineffective in reducing the
risk
of infection in a bat cave because bats can recontaminate the
cave.
Furthermore, skin test surveys have shown that persons living near
contaminated caves have a lower prevalence of reactivity to
histoplasmin than spelunkers living in the same area (3). This
finding
suggests that H. capsulatum infection occurs only in persons who
enter
contaminated caves. In contrast, airborne dispersal of organisms
from
bird roosts can cause outbreaks involving at least several square
kilometers (8).
Much of Santa Rosa National Park consists of mature deciduous
dry
forest in the relatively dry climate of northwest Costa Rica.
During
the rainy season (June-November), a seasonal river usually floods
the
cave that was associated with this outbreak and washes out the bat
guano. However, flooding had not occurred because of
extraordinarily
low rainfall during this year's rainy season. Measured rainfall
since
1978 has averaged 160 cm per year, but only 50-70 cm were recorded
during 1987. The cave is accessible from a hiking trail and is
commonly included on tours of the park led by local field
biologists.
No illness was reported among groups from the same university who
entered the cave in January 1983 and January 1986. Officials of
Santa
Rosa National Park and field biologists in the area have been
notified
of the outbreak, and warning signs have been posted outside the
cave.
References
Kaufman L, Reiss E. Serodiagnosis of fungal diseases. In:
Lennette
EH, Balows A, Hausler WJ Jr, Shadomy HJ, eds. Manual of
clinical
microbiology. 4th ed. Washington, DC: American Society for
Microbiology, 1985:924-44.
Wheat LJ, Kohler RB, Tewari RP. Diagnosis of disseminated
histoplasmosis by detection of Histoplasma capsulatum antigen
in
serum and urine specimens. N Engl J Med 1986; 314:83-8.
Larsh HW. The epidemiology of histoplasmosis. In: Al-Doory Y,
ed.
The epidemiology of human mycotic diseases. Springfield,
Illinois:
Charles C Thomas, 1975:52-73.
Sacks JJ, Ajello L, Crockett LK. An outbreak and review of
cave-associated histoplasmosis capsulati. J Med Vet Mycol
1986;24:313-25.
DiSalvo AF, Bigler WJ, Ajello L, Johnson JE, Palmer J. Bat and
soil studies for sources of histoplasmosis in Florida. Public
Health Rep 1970;85:1063-9.
Emmons CW, Klite PD, Baer GM, Hill WB Jr. Isolation of
Histoplasma
capsulatum from bats in the United States. Am J Epidemiol
1966;84:103-9.
Centers for Disease Control. Histoplasmosis control:
decontamination of bird roosts, chicken houses, and other
point
sources. Atlanta: US Department of Health, Education, and
Welfare,
Public Health Service, 1979; HEW publication no. (CDC)80-8380.
DiSalvo AF, Johnson WM. Histoplasmosis in South Carolina:
support
for the microfocus concept. Am J Epidemiol 1979;109:480-92.
*A tour member who experienced any two of the following symptoms
within 30 days after returning to the United States was considered
to
have histoplasmosis: fever, headache, cough, dyspnea, or chest
pain.
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