NEWS SCAN: H5N1 in South Korea, yellow fever vaccine, polio in Congo Republic, monkeys as malaria reservoir

Apr 8, 2011

H5N1 hits South Korean poultry farm
After only a 2-week respite, South Korean officials today confirmed another outbreak of highly pathogenic H5N1 avian flu in poultry, according to the country's Yonhap News Agency. Tests confirmed H5N1 in 13,200 birds at an egg-laying farm in Yeongcheon, 344 kilometers southeast of Seoul, according to the National Veterinary Research and Quarantine Service (NVRQS). The farm was placed under quarantine Apr 6 after about 130 chickens died suddenly, and all of the farm's birds will be culled to prevent spread of the disease. The last avian flu outbreak in South Korean birds was confirmed Mar 24. The new outbreak is the country's 52nd since the disease resurged late last year, the story quotes the NVRQS as reporting. Officials have culled more than 6.27 million birds in six provinces across the country since then.
Apr 8 Yonhap News story

Inactivated yellow fever vaccine shows promise
A phase 1 trial of an inactivated yellow fever vaccine in adults found that it produced a good immune response with a better safety profile than the current live-virus vaccine, researchers reported yesterday in the New England Journal of Medicine. Though the current vaccine is effective, it can produce serious side effects, including viscerotropic disease. The trial involves an inactivated, adjuvanted cell-culture vaccine made by Xcellerex, based in Marlborough, Mass. In the trial that included 60 healthy adults, researchers compared two doses of the vaccine containing either 0.48 micrograms (mcg) or 4.8 mcg of antigen with a placebo. Volunteers received the vaccine doses 21 days apart, and investigators measured neutralizing antibodies at baseline and on days 21, 31, and 42. They saw an antibody response in all subjects who received the larger dose and in 88% of those who got the smaller dose. Adverse events were higher in the vaccine groups, which included mild pain, tenderness, and itching at the injection site. The researchers said ongoing studies are under way to assess the duration of protection, and they predicted that the regulatory pathway to licensure may be complex, because some measures of protection might be somewhat inferior to the current vaccine. However, they said the better side-effect profile might offset lower antibody titers.
Apr 7 N Engl J Med abstract

Polio outbreak in Republic of Congo reached 387 cases
A polio outbreak that began last fall in the Republic of the Congo—the first there in 10 years—led to 387 confirmed cases and at least 190 deaths, the World Health Organization (WHO) reported today. The epidemic appeared "nearly controlled" by Mar 15, as the latest case onset was reported on Jan 22, the WHO said in its Weekly Epidemiological Record. The beginning of the outbreak was traced back to September 2010, though the first case of polio due to wild poliovirus type 1 (WPV1) was not confirmed until November. By Mar 15, 560 cases of acute flaccid paralysis with onset between Sep 20, 2010, and Feb 27, 2011, had been identified. The virus was confirmed in 70 of 106 cases for which adequate stool specimens were available for testing; a national polio expert committee confirmed another 317 cases, including 190 fatal ones, because of their geographic and temporal connection to the outbreak. Factors that contributed to the outbreak included low polio vaccination coverage in young adults, a long period with no WPV1 transmission, crowding, water shortages, and poor sanitation, the report says. It also says four rounds of immunizations targeting the whole population have been conducted in response to the outbreak.
Apr 8 WHO report

Monkeys found to be reservoir for emerging malaria strain in SE Asia
An emerging strain of malaria parasite is harbored by monkeys and can spread to humans, according to a study in PLoS Pathogens. Malaysian and UK researchers studied Plasmodium knowlesi, a malaria parasite that had been thought to be restricted to macaques in Southeast Asia but is now recognized as a significant cause of human disease in the region. Unlike with the more common and similarly appearing P malariae, P knowlesi infection can cause death, according to the authors. The team discovered five Plasmodium species in 108 wild macaques, including P malariae and "an extremely high prevalence" of P knowlesi and another species (P inui). Evolutionary analysis indicated that P knowlesi existed in the macaques before human settlement in Southeast Asia and underwent a recent population expansion. "Our findings strongly indicate," said lead author Balbir Singh in a press release, "that P knowlesi is a zoonosis in this area, that is to say it is passed by mosquitoes from infected monkeys to humans, with monkeys acting as a reservoir host." The study authors conclude, "We consider that the current increase in the human population, coupled with ecological changes due to deforestation, could result in a switch to humans as the preferred host for this pathogenic Plasmodium species."
Apr 7 PLoS Pathog study
Apr 7 press release on the study

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