Is Dengue Fever on the Rise in the U.S.?
Dec. 23, 1999 (Atlanta) -- Dengue fever, a viral illness most often seen in
the tropics of Asia and Africa, is becoming a bigger threat here on U.S. soil.
Florida researchers report in the Dec. 24 issue of the CDC's Morbidity and
Mortality Weekly Report that incidence of dengue is higher than previously
reported in their state. Experts call for improved prevention, surveillance,
and reporting to prevent the spread of the virus to other parts of Florida and
to other states.
But some states seem to be having their own problems with dengue already. In
an unrelated report, the Texas state department of health has announced that a
girl who died earlier this month is the first casualty of a dengue outbreak
there that has infected 51 people this year -- the biggest outbreak there this
decade. It's thought the girl picked up the disease during a trip to
Dengue fever -- mainly transmitted via the Aedes aegypti mosquito --
is commonly referred to as "break-bone fever" due to pain so intense
that bones are often felt to be breaking. In addition to such pain, infection
with any of dengue's four types can lead to acute illness with joint pain,
headache, fever, rash, and hemorrhage. After infection with one type, the
antibodies that are produced usually protect the patient from future infections
related to that particular serotype. However, infection with a different type
puts the patient at risk for a more severe form of the illness, marked by
internal bleeding, called dengue hemorrhagic fever. Patients usually recover
from dengue within a few days, though related fatigue can last as long as a
month or two.
"In the last 10 years, a mean of 1.3 cases per year were reported in the
state [of Florida]," says lead author Julia Gill, PhD, MPH. "The number
of cases reported to the state was so low that I couldn't believe that that was
the true number of cases. ... I thought [by conducting this surveillance study]
we'd find a lot more cases." Gill is with the Florida Department of Health
in St. Petersburg.
This laboratory-based active surveillance study was implemented in Florida
for a year starting in April of 1997. Sixty-seven county health department
epidemiologists were mailed information explaining the program and requesting
participation; the dengue case definition, specimen requirements, and transport
instructions were provided. Departments were instructed to distribute enclosed
materials to clinics, hospital ERs, health departments, and infectious disease
physicians. Samples were tested, and those found to be in the acute phase of
the disease were sent to the CDC for further analysis.
In Florida, 83 suspected dengue cases were analyzed. Of these cases, recent
dengue infection was detected in 22%. Of the cases studied, all four dengue
types were identified. In 29% of the suspected cases, dengue was ruled out, and
in 49% of the cases, a diagnosis was indeterminable due to inadequate blood