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Letter
Shigellosis and Cryptosporidiosis, Baltimore, Maryland
David M. Hartley,* Karl C.
Klontz,†‡ Patricia Ryan,§ and J. Glenn Morris Jr*
*University of Maryland
School of Medicine, Baltimore, Maryland, USA; †The George Washington University
School of Public Health and Health Services, Washington, DC, USA; ‡US Food and
Drug Administration, College Park, Maryland, USA; and §Maryland Department of
Health and Mental Hygiene, Baltimore, Maryland, USA
Suggested citation for this
article
To the Editor: Floret et al. argue convincingly that natural disasters, including severe
floods and windstorms, tend not to result in epidemics of infectious disease (1).
This conclusion is consistent with the lack of epidemics of shigellosis and
cryptosporidiosis after hurricane rains in Baltimore, Maryland.
Shigellosis and
cryptosporidiosis are associated with waterborne and foodborne transmission (2,3).
We examined Baltimore shigellosis and cryptosporidiosis incidence to assess
whether disease risk was related to temperature or rainfall from January 1,
1998, to December 31, 2004. Maryland FoodNet supplied case data; population
estimates were acquired from the Maryland Department of Planning State Data
Center; and meteorologic data for Baltimore Washington International airport (≈10 miles from the city center) were obtained
from the National Atmospheric and Oceanic Administration (4).
During the study
period, 38 cases of cryptosporidiosis and 943 cases of shigellosis were
reported in Baltimore. Temperature was strongly seasonal; precipitation was
not. A dry period during 1999 was observed. No seasonal cryptosporidiosis
patterns were identifiable. Two outbreaks of shigellosis occurred; in 2000 (≈50 cases) and 2002–2004 (≈870 cases). Sporadic cases of shigellosis were
not seasonal.
Two hurricanes
resulted in heavy rainfall in Baltimore during the study period (5).
Hurricane Floyd inundated the city with rain on September 16, 1999, and on September
19, 2003, Hurricane Isabel produced heavy rains and storm surge in Baltimore (which is located near the northern end of Chesapeake Bay). Approximately 4
other named tropical storms or depressions directly affected Baltimore rainfall
during the study. However, collectively, none of these events had
distinguishable signatures in the incidence of shigellosis or cryptosporidiosis
in this urban environment.
The
institutional review boards of the University of Maryland School of Medicine,
The George Washington University Medical Center, and the Maryland Department of
Health and Mental Hygiene approved this study. Dr Hartley is supported by a
National Institutes of Health Career Development Award (K25 AI-58956).
References
- Floret N, Viel JF, Mauny F, Hoen B, Piarroux R. Negligible
risk for epidemics after geophysical disasters. Emerg Infect Dis.
2006;12:543–8.
- Centers for Disease Control and Prevention. FoodNet
surveillance report for 2002. May 2004. [cited 2006 Apr 6]. Available from http://www.cdc.gov/foodnet/reports.htm
- Naumova EN, Christodouleas J, Hunter PR, Syed
Q. Effect of precipitation on seasonal variability in cryptosporidiosis recorded
by the north west England surveillance system in 1990–1999. J Water Health.
2005;3:185–96.
- National Oceanic and Atmospheric Administration. Federal
climate complex global surface summary of day data. Version 6. National Oceanic
and Atmospheric Administration National Climatic Data Center. [cited 2006 Feb
18]. Available from ftp://ftp.ncdc.noaa.gov/pub/data/globalsod/readme.txt
- National Oceanic and Atmospheric Adminstration. Hurricane
history. [cited 2006 Apr 6]. Available from http://www.nhc.noaa.gov/HAW2/english/history.shtml
Suggested citation
for this article:
Hartley DM, Klontz KC, Ryan P, Morris JG Jr. Shigellosis and
cryptosporidiosis, Baltimore, Maryland [letter]. Emerg Infect Dis [serial on
the Internet]. 2006 Jul [date cited]. Available from
http://www.cdc.gov/ncidod/EID/vol12no07/06-0449.htm
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