Epidemiologic Notes and Reports Aedes albopictus
Introduction -- Texas
On August 2, 1985, the Harris County Mosquito Control District
in
Houston, Texas, discovered that Aedes albopictus, a mosquito of
Asian
origin, was established in Harris County (1); the identity of the
species was confirmed by the U.S. National Museum. In a
preliminary
survey, A. albopictus larvae were collected at 55.8% of 163 sites
inspected, suggesting the original introduction occurred some time
ago. The species was most prevalent on the east side of Harris
County, where the Houston Ship Channel, Ellington Field (U.S. Air
Force and National Aeronautics and Space Administration), Hobby
Airport, and Houston Intercontinental Airport are located.
The full distribution of A. albopictus in the Houston-Galveston
area is unknown because surveys were conducted only to the Harris
County line. It may extend to several adjoining counties.
Reported by RE Bartnett, Harris County Mosquito Control District,
BL
Davis, Environmental and Consumer Health Protection, Texas Dept of
Health; Div of Vector-Borne Viral Diseases, Center for Infectious
Diseases, CDC.
Editorial Note
Editorial Note:A. albopictus is a vector for dengue (2) and other
arboviral diseases of humans and is susceptible to a variety of
arboviruses in the laboratory (3). A. albopictus specimens have
been
collected or intercepted in the contiguous United States on three
previous occasions, but this is the first report that breeding
populations are established in this hemisphere. In a previous
report
identifying A. albopictus in Memphis, Tennessee (4), the source of
introduction was presumed to be cargo from international shipping.
However, the Memphis collection may have originated in Houston.
With
the discovery of an established focus of the mosquito in Texas, it
is
important to determine whether the species has spread to other
areas
and states.
In Asia, A. albopictus is primarily a woodland species that has
become adapted to the urban environment. It breeds in tree holes,
bamboo stumps, coconut husks, and other natural containers, as well
as
in tires and other discarded water-holding containers. It is not
as
strongly dependent on humans as A. aegypti, and it could colonize
tree
holes and other similar habitats in the southeastern United States.
Control of this species in such natural habitats would be
difficult.
Competition from A. aegypti and from native tree-hole Aedes species
may help retard the spread of A. albopictus (5,6). As in Hawaii
(7),
however, A. albopictus appears to have replaced A. aegypti. This
species has apparently been established in Hawaii for a long
period,
but Hawaii appears to be free of dengue infections.
In Asia, A. albopictus extends as far north as Beijing, China
(4),
and Sendai, Japan (8). This is the approximate latitude of
Philadelphia, Pennsylvania, and Denver, Colorado, well north of the
distribution of the other major dengue vector, A. aegypti.
Although
U.S. dengue epidemics have occurred principally in the Gulf Coast
states, a major A. aegypti-transmitted dengue epidemic occurred in
Philadelphia in the late 18th century (9), well north of the
present
distribution of A. aegypti.
The efficiency of the Houston A. albopictus population in
transmitting dengue is unknown. The susceptibility of native
populations of this species is known to vary from 8% to 46% (10).
In response to the introduction of A. albopictus, CDC has
notified
appropriate state, federal, and international agencies; has
modified
and intensified an ongoing surveillance program in the southeastern
United States to determine the current distribution of A.
albopictus;
and is preparing training materials on the biology and taxonomy of
the
species. Meetings are planned to involve CDC, state directors of
public health, and other key personnel in appropriate regional
areas
to develop surveillance and control strategies.
References
Sprenger D, Wuithiranyagool T. The discovery and distribution
of
Aedes albopictus (Skuse) in Harris County, Texas. J Am Mosq
Contr
Assoc (in press).
Russell PK, Gould DJ, Yuill TM, Nisalak Y, Winter PE. Recovery
of
dengue-4 viruses from mosquito vectors and patients during an
epidemic of dengue hemorrhagic fever. Am J Trop Med Hyg
1969;18:580-3.
Tesh RB. Experimental studies on the transovarial transmission
of
Kunjin and San Angelo viruses in mosquitoes. Am J Trop Med Hyg
1980;29:657-66.
Reiter P, Darsie RF Jr. Aedes albopictus in Memphis, Tennessee
(USA): an achievement of modern transportation? Mosq News
1984;44:396-9.
Gilotra SK, Rozeboom LE, Bhattacharya NC. Observations on
possible competitive displacement between populations of Aedes
aegypti Linnaeus and Aedes albopictus Skuse in Calcutta. Bull
WHO
1967;37:437-46.
Moore CG, Fisher BR. Competition in mosquitoes. Density and
species ratio effects on growth, mortality, fecundity, and
production of growth retardant. Ann Entomol Soc Am
1969;62:1325-31.
Usinger RL. Entomological phases of the recent dengue epidemic
in
Honolulu. Public Health Rep 1944;59:423-30.
Mori A, Wada Y. The seasonal abundance of Aedes albopictus in
Nagasaki. Trop Med 1978;20:29-37.
Anonymous. Dengue. Off Res Report Publ Response, National
Institute of Allergy and Infectious Diseases, National
Institutes
of Health, October 1977.
Gubler DJ, Rosen L. Variation among geographic strains of
Aedes
albopictus in susceptibility to infection with dengue viruses.
Am
J Trop Med Hyg 1976;25:318-25.
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