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.
Steve Baragona | EurekAlert!
Hot cars can hit deadly temperatures in as little as one hour
24.05.2018 | Arizona State University
3D images of cancer cells in the body: Medical physicists from Halle present new method
16.05.2018 | Martin-Luther-Universität Halle-Wittenberg
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
24.05.2018 | Ecology, The Environment and Conservation
24.05.2018 | Medical Engineering
24.05.2018 | Physics and Astronomy