On August 12, 2002, the Stephenson County Health Department (SCHD)
notified the Illinois Department of Public Health Rockford Regional
Division of Environmental Health of reports of illness among family
members from four families who stayed at a hotel in Freeport August
9 through 11, 2002. Thirty-one of 36 individuals reported high
fever, headache, and muscle aches. Based on preliminary findings,
exposure to the swimming pool, spa, and the swimming pool/spa
enclosure were found to be common among the ill guests. The hotel
voluntarily closed the swimming and spa facilities pending further
investigation by SCHD, the Department’s regional environmental
health staff and the Rapid Response Team.
On August 14, 2002, Department staff initiated an environmental
investigation of the hotel. Several 100 ml water samples were
taken, including spa filter backwash water taken prior to superchlorination.
Further samples taken included spa water, pool water, and water
from the drinking fountain. Samples were submitted to the Illinois
Department of Agriculture and to the Centers for Disease Control
and Prevention (CDC) to be analyzed for the presence of Legionella
Daily log records for spa water bromine and pH levels and approximate
number of bathers were reviewed for August 9 - 11. Bromine levels
were 3.5 and pH levels were between 7.4 - 7.5. The approximate
number of spa bathers was estimated to be 95 – 115 persons.
The spa was superchlorinated during this inspection to approximately
50 ppm of chlorine and recirculated. The spa filter was backwashed.
The spa was drained, thoroughly cleaned, and then refilled prior
to reopening, August 14. On August 26, 2002, resamples of the
spa filter backwash water were obtained and cultured.
The Department was notified on August 30, 2002 by the Illinois
Department of Agriculture that the initial
samples taken of the spa filter backwash water on August 14,
2002 were positive for Legionella dumoffii. Samples submitted
to the CDC were positive for L. micdadei and L. maceachernii.
On September 3, 2002, the hotel was advised that the results of
the resampled cultures were again positive for Legionella dumoffii
and the spa was voluntarily closed pending additional disinfection
procedures. Superchlorination was performed and duplicate resamples
were obtained on September 25, 2002 and sent to the Illinois Department
of Agriculture. These duplicate resamples tested negative for
Legionella species. Hotel Guest Investigation The Rapid Response
Team developed a questionnaire for active case ascertainment for
a retrospective cohort study of hotel guests and visitors who
stayed at the hotel from August 9, the first date of hotel stay
for index cases, through August 15, the date of completion of
the initial environmental survey.
A case was defined as:
Any guest of the hotel who stayed or visited the hotel (or employee
who worked at the hotel) from August 8 until the 15, 2002, who
reported any of the following symptoms within two weeks of hotel
stay: fever or headache with muscle aches.
The total number of guests during the study period was 380 from
23 states, Canada and Belgium. Public health officials from the
states and Canada (officials from Belgium could not be contacted)
were recruited via conference calls to administer the questionnaire
to hotel guests within their jurisdiction by telephone or mail.
SCHD administered the questionnaire to hotel employees. A differential
diagnosis information sheet was distributed to public health officials
and disseminated to care providers in communities who treated
ill hotel guests. The information sheet provided instructions
for performing diagnostic lab tests including nasopharyngeal swabs
for adenovirus, influenza, coxsackie virus, and parainfluenza
virus, sputum cultures, Legionella urinary antigen tests, and
serology assays for acute and convalescent sera for Legionella.