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| Completed
Projects 1. Retrospective Cohort Study of Salmonella Typhi (1999-2000) A retrospective cohort study was
conducted to evaluate the affect of nalidixic acid-resistance on clinical
outcome among persons with typhoid fever. Medical records were abstracted
for all hospitalized S. Typhi cases with bloodstream or bone
marrow infection identified in the FoodNet catchment area from 1999
to 2002. Data from medical chart abstraction were linked to corresponding
laboratory test results and existing surveillance data. Medical chart
abstractions were successfully completed for all 20 (100%) eligible
cases in the California FoodNet site. Data have been pooled from 7
participating FoodNet sites for analysis. The CEIP contributed 35%
of the total eligible cases. Preliminary results, presented at the
2004 International Conference on Emerging Infectious Diseases, showed
that infection with nalidixic acid-resistant S. Typhi is
associated with poor clinical outcomes. A manuscript describing the
final analysis is currently under preparation. 2. Survey of Clinical Laboratory Practices for Campylobacter Isolation and Identification (2005-2006) The purpose of this project was to determine whether
the variation in incidence of laboratory-confirmed Campylobacter infection
by EIP site is associated with differences in laboratory techniques
for Campylobacter isolation at each site. A standardized questionnaire
was developed to collect detailed information from the lead microbiologists
at clinical laboratories regarding their routine practices to isolate
Campylobacter from stool specimens. The questionnaire includes routine
use of transport media, enrichment, or filtration, choice of selective
agar, and incubation duration and temperature, any of which could
affect isolation rates for Campylobacter and therefore affect laboratory-confirmed
incidence. Questionnaires were mailed in August 2005 and completed
surveys were collected until May 2006. A total of 26 (84%) of the
31 public health and private laboratories participating in FoodNet
Surveillance completed the questionnaires. Preliminary data of 499
enrolled laboratories in 10 FoodNet sites have been summarized and
presented at the International Conference on Emerging Infectious Diseases,
2006. The study showed that there were substantial differences in
methods such as routine culturing, length of incubation, and use of
transport media that might explain the variation in incidence rates
among the FN sites. The CEIP is participating in the final analysis
that utilizes statistical techniques to account for the different
caseload at each laboratory. 1. E. coli O157 Case-Control Study (1996-1997, 1999-2000) The CEIP conducted two population-based case-control
studies to explore risk factors for sporadic E. coli O157
infection in 1996-1997 and in 1999-2000. Cases were identified through
active surveillance for laboratory-confirmed E. coli O157.
Controls were matched to cases on age and telephone exchange and identified
through sequential digit dialing. For the first study, 196 cases and
372 controls were enrolled. The study identified eating a pink hamburger,
eating at a table-service restaurant, farm exposure, and cattle exposure
as significant risk factors. A total of 283 cases and 534 controls
were enrolled in the second risk factor study from 7 participating
FoodNet sites. The study found similar risk factors for sporadic E.
coli O157, including eating undercooked ground beef and exposure
to surface waters and farms. The CEIP lead a study with participation from 6
FoodNet sites to describe clinical features of illness with foodborne
pathogens among neonates and explore possible risk factors in the
first 7 days of life. Eleven (100%) of 11 eligible cases were enrolled
and medical charts abstracted by CEIP staff. The CEIP also lead the
analysis of data on the 54 total cases and presented findings at the
Infectious Disease Society of America Annual Meeting on October 2003.
We conducted a population-based case-control study
of shigellosis in adults in San Francisco, California during the period
19981999. Cases of Shigella infection were identified through
laboratory-based active surveillance conducted by the CEIP. Seventy-six
case patients were matched by sex with 146 control subjects. Exposure
data were collected on established risk factors, sexual practices,
and HIV infection status. From the multivariable analysis, for men,
shigellosis was associated with sex with men (odds ratio [OR], 8.24;
95% confidence interval [CI], 2.7025.2), HIV infection (OR, 8.17;
95% CI, 2.7124.6), direct oral-anal contact (OR, 7.50; 95% CI, 1.7432.3),
and foreign travel (OR, 20.0; 95% CI, 5.2676.3), with population-attributable
fractions of 0.72, 0.42, 0.31, and 0.18, respectively. For women,
shigellosis was associated only with foreign travel (OR, 21.0; 95%
CI, 2.52899), with a population-attributable fraction of 0.37. Among
men who have sex with men, shigellosis is predominantly a sexually
transmitted disease, with direct oral-anal contact conferring the
highest risk and HIV infection likely contributing to increased host
susceptibility. Due to the large number of Yersinia enterocolitica
cases in California and their diverse racial/ethnic distribution,
the CEIP interviewed Y. enterocolitica cases with a hypothesis-generating
questionnaire from 1998 to 2000. Fifty-nine cases were successfully
interviewed. In addition, 22 Y. enterocolitica isolates were
submitted to the MDL for sero- and bio-typing. Seventeen (77%) of
the isolates were serotype O:3, suggesting the involvement of pork
products. Results from this project may be used to inform future studies
of Y. enterocolitica in California, particularly among communities
of color. This study investigates risk factors for sporadic
infection with Cryptosporidium among immunocompetent persons
during 1999-2001. Over the 2-year period of data collection, 282 laboratory-confirmed
cases and 490 age-matched controls were enrolled, including 26 cases
and 62 controls in California. Analysis of the pooled data for all
FoodNet sites identified international travel as a significant risk
factor. Other risk factors included contact with cattle, contact with
children age 2-11 years with diarrhea, and freshwater swimming. A
separate analysis of the data collected through California FoodNet
showed that international travel was the primary risk factor for the
urban population in the San Francisco Bay Area. 6. Physicians Survey - 2000 Randomly selected physicians practicing in the CEIP
catchment area were mailed questionnaires to investigate the role
of physicians as food-safety educators. The CEIP received 106 completed
questionnaires. Of the 1100 enrolled physicians in all FoodNet sites,
only 331 (30%) of the respondents reported providing food-safety information
to their patients. The goal of this case-control study was to identify
dietary and behavioral risk factors for listeriosis. Controls were
identified by clinicians and were matched based on underlying medical
condition and broad age groups. The study started in California with
specimen collection date March 15, 2000, and ended with specimen collection
date March 15, 2003. During the study period, 169 cases were enrolled,
including 24 cases from California. In addition, 376 controls, including
50 controls from California, were successfully enrolled. Multivariate
analysis of study data showed that eating melons and eating hummus
were independently associated with infection with Listeria.
The goals of this study were to identify behavioral,
dietary, and medical risk factors for infection of infants under 365
days old with Salmonella or Campylobacter, and to
describe the epidemiologic and medical characteristics of infants
with these infections. From May 1, 2002 to April 30, 2004, 442 salmonellosis
cases, 123 campylobacteriosis cases, and 928 controls were interviewed
and enrolled in the study. The CEIP contributed substantially to the
projects ability to explore infant illness in Asian communities by
contributing 58% of all Asian Salmonella cases, 64% of all
Asian Campylobacter cases, and 63% of all Asian controls.
9. Case-Control Study of Salmonella Newport (2002-2003) The CEIP and FoodNet partners implemented the first
multi-state investigation of S. Newport infections in the
United States to identify behavioral, dietary, and medical risk factors
associated with S. Newport. From 2002 through 2003, 215 laboratory-confirmed
S. Newport cases and 1154 healthy controls were enrolled
in the study. Our study found substantial evidence of the role of
the U.S. food supply in the transmission of multidrug-resistant (MDR)
S. Newport. Eating uncooked ground beef (OR, 7.8 [95% confidence
interval {CI}, 1.444]) and runny scrambled eggs or omelets prepared
in the home (OR, 4.9 [95% CI, 1.319]) were associated with illness
with MDR S. Newport. Use of antimicrobial agents prior to
illness was also an important risk factor (odds ratio [OR], 5.0 [95%
CI, 1.616]). Recommendations included food-safety educational efforts
regarding thorough cooking of ground beef and poultry products and
education of physicians regarding prudent use of antimicrobial therapy.
10. Propective Viral Study (2002-2003) The goal of this project was to better describe
the role of caliciviruses (specifically norovirus) in foodborne disease
and the associated epidemiologic and clinical profiles. A contracted
medical courier facilitated the delivery and pickup of self-contained
stool specimen collection kits directly to case-patients in outbreak
settings for timely and proper specimen collection. During October
2002 to June 2003, the stool collection kits were deployed in 21 (72%)
of 29 outbreaks reported to the CEIP. Norovirus was confirmed by PCR
in 13 (57%) of these outbreaks. Data from this study were pooled with
data from two other FoodNet sites and results were published in Clinical
Infectious Diseases. The study showed that delivery of kits to and
from patients could substantially reduce the number of outbreaks with
an unknown etiology. |