- ATLANTA (Reuters) - At least
one of three deaths in New York City originally blamed on St. Louis encephalitis
was confirmed as being caused by a bird virus previously unseen in the
Western Hemisphere, federal health officials said on Sunday. Researchers
are reviewing three deaths and 15 illnesses that occurred in New York during
the past month after the discovery in dead birds last week of a virus usually
seen only in Africa and Asia.
- "DNA sequencing on brain tissue from one of the
case patients of this outbreak determined that it was West Nile virus in
the sample," Barbara Reynolds, a spokeswoman for the Centres for Disease
Control and Prevention (CDC), said on Sunday.
- The CDC said the virus, called the West Nile-like virus,
is closely related to St. Louis encephalitis. The two viruses are difficult
to tell apart with commonly used tests.
- "CDC is continuing to look and retest some of our
serology samples from patients in this outbreak to determine whether in
fact they also have been infected with West Nile-like virus," she
- Reynolds said researchers were working to identify the
exact virus strain to determine if it had been reported elsewhere.
- "We're going to be doing further testing to determine
what subtype this is of West Nile and see if it's one that we recognise
from other places in the world or if this is a new variant," she said.
- New York City health officials began mosquito control
measures, including the spraying of insecticide, in an effort to control
the mosquitoes that spread encephalitis.
- Duane Gubler, director of the CDC's Division of Vector-Borne
Infectious Diseases, said there was "considerable potential"
for the West Nile-like virus, never before reported in the Western Hemisphere,
to spread to Central and South America as birds migrate.
- The West Nile-like virus and the St. Louis encephalitis
virus are both transmitted through the bite of a mosquito that has become
infected by feeding on an infected bird. Neither virus is transmitted directly
from person to person or from birds to people.
- West Nile-like Virus in the United States
- CDC, in collaboration with the New York City and New
York State departments of health, has isolated and identified a West Nile-like
virus from birds that died in New York City and were submitted for testing
by the Bronx Zoo.
- West Nile virus is an arbovirus closely related to St.
Louis encephalitis virus, but generally causes a milder disease in humans.
Both viruses are transmitted through the bite of a mosquito that becomes
infected with the virus by feeding on an infected bird. Like St. Louis
encephalitis, West Nile virus is not transmitted from person to person
or from birds to persons. West Nile virus never before has been recognized
in the United States or any other area of the Western Hemisphere.
- Since late August, New York City has been experiencing
an outbreak of arboviral (mosquito-borne) encephalitis. Previously, diagnostic
tests on serum from human cases in this outbreak were reported as consistent
with St. Louis encephalitis virus infection. At present, the relationship
between this isolation of West Nile-like virus from birds in New York City
and the outbreak of encephalitis among persons in New York City remains
uncertain and further laboratory testing is underway. The CDC is testing
these and additional human specimens for the possibility of West Nile-like
- CDC and city and state health departments emphasize that
current mosquito control efforts by individuals and communities are appropriate
because the same mosquito species transmit both viruses. Individuals should
continue to do the following to reduce their contact with mosquitoes:
- When outdoors, wear clothing that covers the skin such
as long sleeve shirts and pants; spray clothing and exposed skin with insect
repellant. Curb outside activity at dawn, dusk and during the evening.
Communities should continue to do the following:
- Raise public awareness about the outbreak, control measures,
and personal protection. Continue current efforts of mosquito control.
CDC further recommends that communities in the area should consider mosquito
spraying if they have not yet done so.