US: July 4, 2008
NEW YORK (Reuters Health) - Several cases of respiratory illness that
occurred last year in northeastern Florida were brought on by exposure to a
so-called red tide caused by the toxic marine organism, Karenia brevis,
health officials conclude in a report released Thursday.
This harmful algal bloom organism is known to produce neurotoxins called "brevetoxins,"
which are responsible for neurotoxic shellfish poisonings and respiratory
illness.
According to the report, the detection of this red tide event "was unusual
because public health authorities were first alerted by a cluster of
reported symptoms of human respiratory illness among dredging workers rather
than by more common means (e.g., observation of dead fish or birds,
detection of contaminated seafood, or use of satellite imagery or routine
beach water sampling."
The illnesses, which involved 20 workers at a beach restoration worksite in
Fernandina Beach, were reported to the Nassau County Health Department on
September 25, 2007. The most common symptoms were coughing and throat
irritation followed by eye irritation, sneezing, and sniffling.
Many of the workers said that their symptoms came and went as they went to
and from work each day. None of the workers required medical care and all of
them were able to perform their jobs without impairment. After these cases
surfaced, public health agencies began receiving reports of similar illness
up to 200 miles south of Fernandina Beach.
Testing of water samples near the worksite and at other locations with
similar cases revealed the presence of K. brevis. Initial samples showed
medium levels of the organism, but testing in Jacksonville, which is 35
miles south of Fernandina Beach, showed high levels. However, after a major
storm hit on September 29, levels began to decline. By November 8, all test
samples were clear of the organism.
"During this red tide event, prompt investigation of a small cluster of
symptoms led to quick identification of the K. brevis bloom. This public
health vigilance enabled authorities to take immediate action to issue
advisories and otherwise alert the public to an illness of environmental
etiology," the report concludes.
SOURCE: Morbidity and Mortality Weekly Report, July 4, 2008.
REUTERS NEWS SERVICE
