Two outbreaks of occupationally acquired histoplasmosis: more than workers at risk.
OBJECTIVE
The objective of this study was to determine the etiology and risk factors for acute histoplasmosis in two outbreaks in Illinois among laborers at a landfill in 2001 and at a bridge reconstruction site in 2003.


METHODS
We performed environmental investigations during both outbreaks and also performed an analytic cohort study among bridge workers.


METHODS
Workers at the landfill during May 2001 and those at the bridge site during August 2003 participated in the study. At the landfill, workers moved topsoil from an area that previously housed a barn; at the bridge, workers observed bat guano on bridge beams.


METHODS
We defined a case by positive immunodiffusion serology, a > or = 4-fold titer rise in complement fixation between acute and convalescent sera, or positive urinary Histoplasma capsulatum (HC) antigen. Relative risks (RR) for disease among bridge workers were calculated using bivariate analysis.


RESULTS
Eight of 11 landfill workers (73%) and 6 of 12 bridge workers (50%) were laboratory-confirmed histoplasmosis cases. Three bridge workers had positive urinary HC antigen. At the bridge, seeing or having contact with bats [RR = 7.0; 95% confidence interval (CI), 1.1-43.0], jack-hammering (RR = 4.0; 95% CI, 1.2-13.3), and waste disposal (RR = 4.0; 95% CI, 1.2-13.3) were the most significant job-related risk factors for acquiring histoplasmosis.


CONCLUSIONS
Workers performing activities that aerosolized topsoil and dust were at increased risk for acquiring histoplasmosis. Relevance to professional and clinical practice: Employees should wear personal protective equipment and use dust-suppression techniques when working in areas potentially contaminated with bird or bat droppings. Urinary HC antigen testing was important in rapidly identifying disease in the 2003 outbreak.
Huhn
Gregory D
GD
Centers for Disease Control and Prevention, Atlanta, Georgia, USA. Gregory_Huhn@rush.edu
Austin
Connie
C
Carr
Mark
M
Heyer
Diana
D
Boudreau
Pam
P
Gilbert
Glynnis
G
Eimen
Terry
T
Lindsley
Mark D
MD
Cali
Salvatore
S
Conover
Craig S
CS
Dworkin
Mark S
MS
D000328:Adult; D000336:Aerosols; D000946:Antigens, Fungal / Q000032:analysis; D004196:Disease Outbreaks; D004391:Dust; D005160:Facility Design and Construction; D005260:Female; D006660:Histoplasmosis / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D007087:Illinois / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D009790:Occupations; D011482:Protective Devices; D012037:Refuse Disposal; D012307:Risk Factors; D012987:Soil
D000336:Aerosols; D000946:Antigens, Fungal; D004391:Dust; D012987:Soil