|
Polio Outbreak From Oral Vaccine Identified -- And
Controlled -- In China
Main Category: Immune System / Vaccines News
Article Date: 18 Aug 2006 - 0:00 PST
A 2004 outbreak of polio in China traced back to live attenuated
oral polio vaccine (OPV), which is widely used in global eradication
efforts, highlights the small but significant risk to eradication
posed by the use of OPV at suboptimal rates of coverage. The study,
reported in the Sept. 1 issue of The Journal of Infectious Diseases,
and now available online, describes the first outbreak of poliomyelitis
in China in more than a decade and the first in that country caused
by vaccine-derived virus.
This marks the fifth outbreak of vaccine-derived poliomyelitis
reported in the world since 2000, the year in which China was certified
free of wild-type poliovirus.
The study was conducted in 2004 by Jingjin Yu, MD, and colleagues
in Beijing and elsewhere, involving virus isolated from an outbreak
in Guizhou province in rural China. Reported national immunization
coverage in China is close to 90 percent, but children in the affected
area of Guizhou, the poorest province in China, had much lower rates
of immunization at the time of the study: only 72 percent of one-
to three-year-olds had received at least three doses of the oral
vaccine.
The investigators identified six children (three cases and three
contacts) in two small towns who had had acute and residual polio-like
paralysis and from whom the same type of vaccine-derived poliovirus
(type 1) was isolated. A seventh child with paralysis was negative
for type 1 virus, but it was found in a close contact of that child.
None of the children had been immunized against polio.
Based on the virus strain's known rates of mutation, the finding
indicated that the isolates had been circulating for less than a
year. This is in contrast to past experience with vaccine-derived
strains, which have tended to persist for several years--suggesting
how quickly this strain can revert to a paralytic and transmissible
form.
Once the outbreak was identified, a province-wide immunization
campaign was mounted targeting all children under age 5, with reported
coverage of more than 90 percent. To date, the outbreak strain has
not been found in any child with polio-like paralysis in the province
or elsewhere in China.
In an accompanying editorial, Walter Dowdle, PhD, of the Task Force
for Child Survival and Development and Olen Kew, PhD, of the Centers
for Disease Control and Prevention, suggest that the China outbreak
indicates that vaccine-derived poliovirus can emerge within pockets
of lower OPV coverage in countries with overall high levels of immunization
and disease surveillance, and that the virus can be contained if
identified quickly. They also emphasize the importance of paying
close attention to regions that have historically acted as reservoirs
of polio, despite the fact that such remote communities as Guizhou
were long thought to be unlikely sites for the re-emergence of the
virus after eradication because of a lower frequency of exposure.
According to Dowdle and Kew, important questions about the use
of oral polio vaccine arise from this outbreak. In 2003, the World
Health Organization recommended discontinuing the use of live virus
vaccine after the eradication of the disease and containment of
poliovirus stocks. But the cost of switching entirely to inactivated
polio vaccine would present financial challenges to poor nations,
as the cost of the inactivated preparation is estimated at $2.00
to $3.00 per dose, in contrast to 3 cents per dose for the live
attenuated oral vaccine. As Yu and colleagues point out, immunization
policies will have to be carefully considered in light of both medical
and financial concerns.
###
Founded in 1904, The Journal of Infectious Diseases is the premier
publication in the Western Hemisphere for original research on the
pathogenesis, diagnosis, and treatment of infectious diseases; on
the microbes that cause them; and on disorders of host immune mechanisms.
Articles in JID include research results from microbiology, immunology,
epidemiology, and related disciplines. JID is published under the
auspices of the Infectious Diseases Society of America (IDSA). Based
in Alexandria, Va., IDSA is a professional society representing
about 8,000 physicians and scientists who specialize in infectious
diseases. For more information, visit http://www.idsociety.org/.
Contact: Steve Baragona
Infectious Diseases Society of America
Condoms urged in prisons to curb AIDS in blacks
Last Updated: 2006-11-16 16:30:13 -0400
(Reuters Health)
By Will Dunham
WASHINGTON - U.S. prisons should make condoms
available to inmates and test for HIV as part of a broader effort
to curb the spread of AIDS among blacks, who have been hit disproportionately
hard by the incurable disease, experts urged on Thursday.
The National Minority AIDS Council advocacy group, backed by U.S.
black lawmakers and medical leaders, issued a series of recommendations
aimed at U.S. policymakers to slow the epidemic among blacks, who
are 10 times more likely than whites to have AIDS.
"In 2006, AIDS in America is a black disease," said Phill Wilson,
executive director of the Black AIDS Institute in Los Angeles.
With U.S. black men seven times more likely than whites and three
times more likely than Latinos to be imprisoned, the council's report
said incarceration has become "one of the most important drivers
of HIV infection among African-Americans."
More than half of new U.S. HIV infections are in blacks, according
to the Centers for Disease Control and Prevention.
While blacks make up 13 percent of the U.S. population, more than
40 percent of U.S. prisoners are black. The AIDS rate among prisoners
is three times the rate in the general public.
HIV, the virus that causes AIDS, most often is spread through sexual
contact or by sharing needles used to inject drugs.
Behaviors such as having unprotected homosexual sex and injecting
drugs raise HIV infection risk in prisons and the problem is compounded
when black men are infected in prison and then transmit the virus
to others after their release, the report stated.
The report urged prisons and jails to make available condoms, along
with HIV prevention education programs.
The report said condoms are banned or unavailable in 95 percent
of U.S. prisons. It said state prisons in Mississippi and Vermont
make condoms available, as do county jails in New York City, Philadelphia,
Washington, D.C., San Francisco and Los Angeles.
'DOES INDEED OCCUR'
"HIV transmission does indeed occur in prison," said the report's
author, Robert Fullilove, professor of clinical sociomedical sciences
at Columbia University in New York.
"We certainly need to have each of the prison systems think more
thoroughly about the impact that failure to provide condoms can
have if there's significant (HIV) transmission within the walls
of their facilities," Fullilove added.
The report stated, "Nonprofit organizations, government and public
health agencies must be allowed to discuss the relationship between
substance abuse and HIV risk and to distribute condoms in prison
facilities."
The report also urged prisons to provide voluntary, routine HIV
testing of inmates upon entry and release.
It also recommended that governments expand substance abuse prevention
programs, drug treatment services and clean needle exchange programs
to cut HIV infections caused by injection drug use.
Other recommendations included: expanding HIV prevention education
programs, combating discrimination against homosexual and bisexual
blacks and supporting more affordable housing to promote stable
black communities.
CDC estimates that about 1.1 million Americans are infected with
HIV, with blacks making up 47 percent of them.
HIV attacks the immune system and renders the body vulnerable to
numerous life-threatening infections and cancers. About 40 percent
of the roughly half million Americans who have died of AIDS were
black.
The report cited several factors to account for AIDS hitting U.S.
blacks hardest, including less access to medical insurance, distrust
of the medical establishment and greater homelessness, drug use
and levels of incarceration.
Copyright © 2006 Reuters Limited. All rights
reserved. Republication or redistribution of Reuters content, including
by framing or similar means, is expressly prohibited without the
prior written consent of Reuters. Reuters shall not be liable for
any errors or delays in the content, or for any actions taken in
reliance thereon. Reuters and the Reuters sphere logo are registered
trademarks and trademarks of the Reuters group of companies around
the world.
|
