vvEPA
                               United States
                               Environmental Protection
                               Agency
                               Health Effects Research
                               Laboratory
                               Cincinnati OH 45268
                               Research and Development
                               EPA-600/S1-81-053  Aug. 1981
Project Summary
                               Epidemiological Studies of
                               Otitis  Externa:  Report of  a
                               Prospective and of  a
                               Retrospective Study of  Otitis
                               Externa  Among  Swimmers
                               Rebecca L Calderon and Eric W. Mood
                                Two  epidemiological  studies of
                               otitis externa were conducted. One
                               was a prospective study conducted in
                               the summer of 1979 comparing boy
                               scouts at camp who swam in a fresh
                               water lake with boy scouts at another
                               camp who swam  in a  chlorinated
                               swimming  pool. The other was a
                               retrospective study conducted at Yale
                               University  during  the summer of
                               1980. In  the prospective  study 3
                               percent of the children reported ear
                               complaints in the week following
                               camp, but none had otitis externa
                               confirmed by  a  physician; the
                               retrospective study compared  29
                               cases with 29 controls  who were
                               matched by age and sex.
                                In the prospective study  a higher
                               relative humidity at the camp where
                               the boy scouts swam in a chlorinated
                               pool was  associated with a greater
                               degree of abnormal flora colonization
                               of the ear (Gram-negative bacteria and
                               S. aureus). In the retrospective study,
                               positive  association  was  demon-
                               strated with cases of otitis externa for
                               ambient  air temperatures,  water
                               temperature, less than 18  years of
                               age, being female, swimming, and
                               length of time spent swimming. There
                               was no association between cases of
                               otitis externa and water quality as
                               measured by fecal  coliforms,
                               enterococci and P. aeruginosa or
                               between abnormal flora colonization
                               of the ear with bacterial indices of
                               water quality.
                                This Project Summary was develop-
                               ed by EPA's Health Effects Research
                               Laboratory, Cincinnati, OH,  to an-
                               nounce key findings of the research
                               project that is fully documented in a
                               separate report of the same title (see
                               Project Report ordering information at
                               back).

                               Introduction
                                In  1921, the Committee on Swim-
                               ming Pools of the American Public
                               Health Association surveyed physicians
                               and health officers  to determine dis-
                               eases spread by bathing waters. Among
                               the major diseases listed was otitis
                               externa or, as it is more commonly
                               known, "swimmers ear." Otitis externa
                               is an inflammation  of  the outer ear
                               canal, characterized by pain, swelling,
                               drainage and occasionally fever.
                                As  part  of  the United  States
                               Environmental  Protection  Agency's
                               studies on recreation water quality and
                               indicators of water quality, a series of
                               studies were conducted to determine if
                               there was a direct relationship between
                               the.  incidence of otitis externa,

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swimming  and  the  quality of  the
recreational  water.   If  such  a
relationship did exist, what would be the
indicator of  choice and  what, if any,
should be the standard or guideline?
  The   first  of  these  studies,  a
prospective  study,   was   conducted
during  the  summer  of  1977,   and
involved swimming pools  and  fresh
water  ponds m the State of Rhode
Island.  Although  there  were  no
confirmed cases of otitis externa, ear
complaints  were  recorded  and there
appeared to be a slight correlation with
swimming,   abnormal   flora,   high
humidity and individuals less than 20
years of age.
  The second study conducted by the
government was based on the results of
the Rhode Island study and  was also a
prospective study. It was conducted in
the New Orleans area. The  third study
was a  retrospective  study and  was
carried  out  by the  Department of
Epidemiology and Public Health, School
of  Medicine,   Yale  University.   The
following summarizes the results of the
New Orleans study and the Yale Study.

The New Orleans Study
  In the summer of  1979, a second
study on otitis externa was undertaken.
The year prior to the study was spent
visiting various Boy Scout camps in the
southern United States to evaluate their
suitability for study. Sites for visitation
were evaluated by the following criteria:

  (1)   approximately  800   or   more
       campers enrolled  in the  camp
       during the summer;

  (2)   swimming  a  major  part of the
       camp's activities;

  (3)   swimming  in  a body  of water
       with  high densities  of P.  aeru-
       ginosa; and

  (4)   the water not contaminated by
       known sources of pollution.


Two campsites in the  New Orleans
Areas Boy Scout Council were chosen
using  the  above  criteria.  The  first,
Salmen  Reservation,  was   in  a
wilderness area around  a  man-made
lake.  Samples  taken during August
1978 showed that the lake  had  high
concentrations  of P.  aeruginosa. The
second,  Camp Salmen  was a  well
established  "conventional"  camp hav-
ing a chlorinated swimming pool. This
selection seemed to be ideal as it would
afford two types of recreational water,
two  levels  of P. aeruginosa and  two
comparable study groups to be analyzed
for the incidence of otitis externa.
  Samples   of  water   for  microbial
analyses were collected from both sites
(the  lake and swimming pool) during
camper  swimming  activities.  All
samples were examined for Escherichia
coli,  enterococci  and P.  aeruginosa.
Water  temperature,  air temperature
and  relative humidity were measured
daily. At  the time when the swimming
pool  water samples were collected, the
free residual chlorine levels and the pH
were determined.  All  campers  who
entered camp at noon on Sunday were
enrolled  in  the  study as part of their
medical check in. Each camperfilled out
a questionnaire concerning age, race,
and previous ear infection experience.
Upon leaving camp, all campers were
given postage paid cards to fill out  one
week after  leaving camp. These cards
asked if there were any ear problems
after leaving camp. Persons returning
cards marked "yes" were contacted by
telephone to determine if they  had
visited  a physician and if so, they were
queried about the physician's diagnosis
and treatment. Both right and left ears
of all campers  were  cultured during
their Sunday check in and on Saturday
when  they  checked   out.  Isolates
considered as normal flora were noted
as such (alpha-hemolytic streptococci,
corynebacteria,  and  non-S.  aureus
staphylococci). The results of the  ear
cultures  were  classified into  three
categories as follows:

  (1)  Normal flora  -  both  ears  had
       normal flora as described above
       or one ear had normal flora and
       the other showed no growth,

  (2)  No growth  - nothing was recov-
       ered from either ear,

  (3)  Abnormal flora - isolates cultur-
       ed from  one or both ears  that
       could not be classified as normal
       flora.

  A total of 444 subjects were cultured
during the three camp sessions at the
lake. There  was a significantly higher
number of Enterobacter. Acinetobacter
and  Bacillus   isolates  in  final  ear
cultures than initial ear cultures. There
were  no confirmed  cases of otitis
externa,  but  10  complaints of
subsequent earaches according to  mail
and  telephone  follow-up .were
ascertained.
  A total of 426 subjects were cultured
at the swimming pool camp. There were
significantly  more  Enterobacter,
Acinetobacter, P.  aeruginosa. Bacillus
and   other Pseudomonas  species
isolated in final ear cultures than in
initial ear cultures. No confirmed cases
of otitis externa were documented, but
there were 14 ear complaints according
to mail and telephone follow-up. At the
swimming  pool camp  there  was  a
higher frequency  of abnormal isolates
cultured than  at  the lake camp. This
difference  did  not  appear  to   be
associated with water temperature, air
temperature or water bacterial indices.
The relative humidity was significantly
higher at the swimming pool camp than
at the lake camp.

The  Yale Study
  The inability to collect information on
cases  of otitis externa in  the Rhode
Island and the New Orleans studies
prompted  a retrospective approach. A
third  study was  undertaken by Yale
University  using   participants  of  a
comprehensive health  care plan.  The
epidemiological design of  this  third
study consisted of examining persons
with  otitis  externa,   the  swimming
exposures  determined  and the water
quality assessed retrospectively. These
findings would be compared with data
collected from selected  controls.
  Two questionnaires were developed
for this study.  The first  was to be filled
out by the subject or subject's parent
concerning prior  swimming  episodes
and  prior ear infections. The second
was designed to  be filled  out by the
attending   health   professional. Basic
demographic  data  were obtained as
well as information concerning symp-
toms of otitis externa.
  The subjects were chosen from sub-
scribers to the Yale Health Plan, a health
maintenance  organization  whose
members  are primarily faculty,  staff,
employees and students of Yale Univer-
sity and their families. Only cases diag-
nosed clinically by a physician as being
otitis externa were  included. A control
group was selected from healthy indi-
viduals coming to the clinics for routine
physical examinations.  Controls  were
matched according to  age (± 2 years)
and sex.
  Cultures from right and left ears were
obtained separately from each control.'
The cultures were processed according

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 to standard laboratory procedures by
 the Yale Health Plan medical laboratory.
   Data were collected noting the loca-
 tions  where  cases and  controls had
 been swimming during the prior seven
 days.  If the sites were accessible for
 collecting  a  water sample,  samples
 were  obtained for analyses  within 48
 hours of the subjects visit to the clinic.
 At each site the air temperature, water
 temperature,  relative humidity and pH
 of the water were measured  and re-
 c6rded. All sites were analyzed for fecal
 coliforms,  enterococci  and P.  aerugi-
 nosa.   Swimming pools  were   also
 analyzed by total  plate counts and for
 staphylococci.
   During the nine-week study period
 from July 7th to September 6th, data on
 29 cases and 29 matched controls were
 collected.  All cases  came  from  the
 Adolescent and Pediatric Clinic with an
 age range of 4 to 17 years. Twenty-one
 of the cases were female compared to
 seven males  Similar to the findings of
 the Rhode Island study, the frequency of
 cases  correlated  positively  with  the
 average weekly temperature. There was
 no association with relative humidity.
   The proportion  of swimmers among
 diagnosed  cases was  significantly
 higher than the proportion of swimmers
 among controls. When comparing only
 swimmers,  the  average  time  spent
 swimming  during a  one-week period
 was significantly higher incasesthan in
 controls. As  to the quality of water,
 there  were no  significant differences
 between cases and controls concerning
 fecal coliforms,  enterococci,  P. aerugi-
 nosa,  Staphylococcus  or total  plate
 counts. The range of organisms isolated
 was greater in cases than in controls,
 and,  with  the exception of  Pseudo-
 monas stutzeri, there  were no Gram
 negative isolates from controls. The
 distribution of Gram positive  isolates
 was similar for both cases and controls.

 Conclusions
   1. Otitis  externa appears to  be  a
     disease  associated primarily with
     people under  18 years  of  age.
     Otitis externa in adults does occur,
     but was not found in these studies.

   2. Hot and humid air appears to be
     associated with otitis externa. This
     association may be indirect rather
     than direct. Hot and humid air may
     affect a person's swimming habits
I     during  such periods of extreme
     weather.
3. Swimming   appears  to  be
   associated with otitis externa but,
   more  importantly, seems to be
   associated  with the  amount  of
   time spent actually swimming.

4. Otitis  externa does not appear to
   be  associated  with   bacterial
   indicators of recreational water
   quality,  such as fecal  coliforms,
   enterococci, or P. aeruginosa. This
   suggests that  bacterial  indices
   involving these organisms as mea-
   sures  of recreational water quality
   may be of little use in evaluating
   the potential  risk  of  acquiring
   otitis externa in swimmers bathing
   in these waters.

5  While P. aeruginosa may be the
   most commonly isolated organism
   from cases of otitis externa, the
   role of other organisms  as etio-
   logical  agents,  Acinetobacter,
   Klebsiella,  Enterobacter and
   Staphylococcus.  should  not  be
   excluded when  studying  otitis
   externa.
Rebecca L Calderon and Eric W. Mood are with the Department of Epidemiology
  and Public Health, Yale. University School of Medicine, New Haven, CT06517.
Theadore H. Ericksen is the EPA Project Officer (see below).
The complete report, entitled "Epidemiological Studies of Otitis Externa: Report
  of a Prospective and of a Retrospective Study  of Otitis Externa Among
  Swimmers," (Order No. PB8J-226 136; Cost: $6.50, subject to change/ will be
  available only from:
        National Technical Information Service
        5285 Port Royal Road
        Springfield, VA 22161
        Telephone: 703-487-4650
The EPA Project'Officer can be contacted at:
        Health Effects Research Laboratory
        U.S. Environmental Protection Agency
        Cincinnati. OH 45268
    : US GOVERNMENT PRINTING OFFICE 1961 -757-012/7288

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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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