Geographic distribution of endemic fungal infections among older persons, United States.
Article Type: Letter to the editor
Subject: Mycoses (Distribution)
Mycoses (Demographic aspects)
Aged (Health aspects)
Authors: Haselow, Dirk
Saccente, Mike
Vyas, Keyur
Bariola, Ryan
Safi, Haytham
Bradsher, Robert
Smith, Nate
Phillips, James
Baddley, John W.
Xie, Fenglong
Curtis, Jeffrey R.
Pub Date: 02/01/2012
Publication: Name: Emerging Infectious Diseases Publisher: U.S. National Center for Infectious Diseases Audience: Academic; Professional Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2012 U.S. National Center for Infectious Diseases ISSN: 1080-6040
Issue: Date: Feb, 2012 Source Volume: 18 Source Issue: 2
Topic: Event Code: 690 Goods & services distribution Advertising Code: 59 Channels of Distribution Computer Subject: Company distribution practices
Geographic: Geographic Scope: United States Geographic Code: 1USA United States
Accession Number: 281175435
Full Text: To the Editor: We read with interest the article by Baddley et al. (1) and appreciate their efforts to characterize incidence rates of mycoses. We agree that histoplasmosis, blastomycosis, and coccidioidomycosis are differential diagnoses for patients with consistent symptoms but who reside outside mycosis-endemic areas.

However, we believe that the methods of Baddley et al. probably do not determine the true incidence of these mycoses in sparsely populated states such asArkansas. Their estimates contrast markedly with surveillance data from the Arkansas Department of Health (Table) and with our clinical experience as infectious disease physicians. We characterize Arkansas as a state in which histoplasmosis and blastomycosis incidence is high and coccidioidomycosis incidence is low; however, Baddley et al. indicate that in Arkansas, incidence of blastomycosis is relatively low and incidence of coccidioidomycosis is high.

To investigate whether this finding might be associated with their small 5% sample of Medicare beneficiaries, we used data from the Arkansas census to determine that in 2008 the population of adults [greater than or equal to] 65 years of age was [approximately equal to] 407,014, and during 1999-2008, there were -3,840,896 person-years for persons in this age group. A 5% sample would account for -192,045 person-years. Using their rate ranges (7.8412.3 cases/100,000 person-years for histoplasmosis, 3.97-6.71 for coccidioidomycosis, and 0.39-0.86 for blastomycosis), we calculated the approximate numbers of cases in their sample: 15-23 histoplasmosis cases, 7-12 coccidioidomycosis cases, and only 1 blastomycosis case. Compared with rates from surveillance averaged over the 10 years, the midpoints of the Baddley et al. estimates are -6-fold higher for histoplasmosis, -60-fold higher for coccidioidomycosis, and -0.4-fold lower for blastomycosis. Only their estimate for blastomycosis incidence falls within the 10-year 95% CIs from surveillance data. We believe that the small cell sizes require that the rate estimates of Baddley et al. be interpreted with care, especially with respect to less populous states.

Dirk Haselow, Mike Saccente, Keyur Vyas, Ryan Bariola, Haytham Safi, Robert Bradsher, Nate Smith, and James Phillips

Author affiliations: Arkansas Department of Health, Little Rock, Arkansas, USA (D. Haselow, H. Safi, N. Smith, J. Phillips); and University of Arkansas for Medical Sciences, Little Rock (D. Haselow, M. Saccente, K. Vyas, R. Bariola, R. Bradsher, N. Smith)

DOI: http://dx.doi.org/10.3201/eid1802.111537

Reference

(1.) Baddley JW, Winthrop KL, Patkar NM, Delzell E, Beukelman T, Xie F, et al. Geographic distribution of endemic fungal infections among older persons, United States. Emerg Infect Dis. 2011;17:1664-9.

Address for correspondence: Dirk Haselow, Arkansas Department of Health, Communicable Disease and Immunizations, 4815 W Markham St, Little Rock, AR 72205, USA; email: dirk. haselow@arkansas.gov

In Response: We thank Haselow et al. (1) for their careful review of our article (2). They raise the relevant concern about potential instability of incidence rates from our data because of small cell sizes. We agree that use of administrative data has major limitations. As such, our intent was not to compare infection incidences of individual states; but rather, our intent was to focus on geographic distribution of endemic mycoses and whether infections occurred in nonmycosis-endemic areas.

Specifically, for blastomycosis, our study showed incidence in Arkansas to be 0.8 (0.12-5.8) cases per 100,000 person-years, comparable to the rate provided by Haselow et al. of 1.1 case per 100,000 person-years (1). For coccidioidomycosis, our study found the rate to be much higher than that calculated from the Arkansas surveillance data. Potential reasons for this discrepancy might be lack of case capture with surveillance data, because mandatory reporting for coccidioidomycosis is not required in Arkansas, or misclassification of incident cases in the administrative data. Finally, for histoplasmosis, the incidence rate calculated from administrative data was much higher than that reported by Haselow et al. By using administrative data, we identified a large number (15) of cases and doubt that rate instability is present. We agree that surveillance that uses administrative data has inherent limitations, which require that care be taken when interpreting epidemiologic measures, especially when sample sizes are small.

John W. Baddley, Fenglong Xie, and Jeffrey R. Curtis

Author affiliation: University of Alabama at Birmingham, Birmingham, Alabama, USA

DOI: http://dx.doi.org/10.3201/eid1802.111617

References

(1.) Haselow D, Saccente M, Vyas K, Bariola R, Safi H, Bradsher R, et al. Geographic distribution of endemic fungal infections among older persons, United States [letter]. Emerg Infect Dis. 2012;18:360-1. http://dx.doi.org/10.3201/eid1802.111537

(2.) Baddley JW, Winthrop KL, Patkar NM, Delzell E, Beukelman T, Xie F, et al. Geographic distribution of endemic fungal infections among older persons, United States. Emerg Infect Dis. 2011;17:1664-9. http://dx.doi.org/10.3201/eid1709.101987

Address for correspondence: John W. Baddley, Division of Infectious Diseases, Department of Medicine, University of Alabama at Birmingham, 229 Tinsley Harrison Tower, 1900 University Blvd, Birmingham, AL 35294-0006, USA: email: jbaddley@uab.edu
Table. Reported cases of fungal diseases in Arkansas, by year *

                              No. cases/no. cases in persons
                          [greater than or equal to] 65 y of age

Disease                 1999      2000      2001      2002      2003

Blastomycosis,          20/5      15/3      20/9      15/3      19/6
n = 166/43

Coccidioidomycosis,      2/0        0         0         0         0
n = 3/0

Histoplasmosis,         15/3      13/3      23/6      22/2      16/4
n = 372/65

                              No. cases/no. cases in persons
                          [greater than or equal to] 65 y of age

Disease                 2004      2005      2006      2007      2008

Blastomycosis,          17/4      16/6      13/3      15/1      16/3
n = 166/43

Coccidioidomycosis,      1/0        0         0         0         0
n = 3/0

Histoplasmosis,         42/9      51/9      66/4      78/13     46/12
n = 372/65

                              Incidence rate
                           (95% CI) ([dagger])

Disease                   Overall         Persons
                                       [greater than
                                       or equal to]
                                           65 y

Blastomycosis,         4.3 (2.9-5.7)    1.1 (0-2.3)
n = 166/43

Coccidioidomycosis,    0.08 (0-0.4)          0
n = 3/0

Histoplasmosis,         9.6 (0-20)      1.7 (0-3.5)
n = 372/65

* Data from Arkansas Department of Health.

([dagger]) No. cases/100,000 person-years, 1999-2008.
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