NEWS SCAN: Cambodia's mystery disease, community-onset MRSA, UN food standards, polio battle, malaria prevention

Jul 5, 2012

WHO helping probe Cambodia's mysterious fatal illness
The World Health Organization (WHO) announced yesterday it is helping to investigate an undiagnosed respiratory illness that has struck 62 Cambodian children since April and killed 61 of them. Most of the children were from southern Cambodia and were treated in a children's hospital in Phnom Penh, the WHO said. The disease causes a high fever, followed by respiratory and/or neurologic problems and rapid deterioration of respiratory function. Nima Asgari, a WHO physician and public health specialist, said the disease does not appear to be influenza and does not seem to have spread to other hospital patients or to medical staff who treated the patients, according to a Wall Street Journal story published today. Asgari said investigators are testing for a host of potential pathogens in the lab and collecting data in the field. The story noted that a Cambodian mother and child died of H5N1 avian flu in February.
Jul4 WHO statement
Jul 5 Wall Street Journal story

Large study finds signs of decline in community-onset MRSA infections
An analysis of 6 years' worth of data from patients in the US military healthcare system suggests that community-onset methicillin-resistant Staphylococcus aureus (MRSA) infections may be decreasing. Writing in the Journal of the American Medical Association (JAMA), the authors note that a decline in hospital-onset MRSA cases has already been observed but that recent rates of community-onset MRSA have been less clear. Using military healthcare data for the period of 2005 through 2010, they identified S aureus blood infections and skin and soft-tissue infections (SSTIs) and classified them as either methicillin-susceptible (MSSA) or MRSA and as either hospital-onset or community-onset. They counted 2,643 blood infections and 80,281 SSTIs among the 9.2 million people covered by the system. Annual incidence rates for community-onset MRSA bacteremia decreased significantly from 1.7 per 100,000 person-years in 2005 to 1.2 per 100,000 person-years in 2010. The researchers found no significant overall trend in the annual rates of community-onset MRSA SSTIs, but the proportion of community-onset SSTIs due to MRSA peaked at 62% in 2006 before decreasing annually to 52% in 2010, a significant trend. For hospital-onset MRSA bacteremia, incidence rates decreased from 0.7 per 100,000 person-years in 2005 to 0.4 per 100,000 person-years in 2010, also a significant drop. Despite the improvements, the burden of S aureus infections in the military health system remains substantial, the authors comment.
Jul 4 JAMA report
Jul 3 JAMA press release

UN lists new standards to limit food contamination
The United Nations' food standards agency yesterday released new standards designed to limit aflatoxin contamination in dried fruits, bacteria in sliced melons, and viruses in seafood, among other hazards. The standards were announced by the Codex Alimentarius Commission, which is run jointly by the UN Food and Agriculture Organization and the WHO. For aflatoxins, which are produced by molds and can be found in dried fruits, nuts, and spices, the commission set a limit of 10 milligrams per kilogram for dried figs. The panel advised that pre-cut melons should be wrapped and refrigerated as soon as possible and distributed at a temperature of 4ºC or lower. In addition, the commission recommended measures to prevent contamination of seafood, especially mollusks, with viruses such as norovirus. The group said the main risk factor is the biological contamination of the waters in which mollusks grow. In other steps, the commission set a new limit for melamine in liquid infant formula and called for nutrition labeling on all foods.
Jul 4 WHO statement

Study links polio rise in Afghanistan, Pakistan to ebbing vaccine coverage
Decreases in polio vaccination coverage in parts of Pakistan and southern Afghanistan, two of the three remaining polio-endemic countries, have led to an increasein cases despite eradication efforts and more-effective polio vaccines, says a study published online yesterday in The Lancet. The researchers, from Imperial College London and the World Health Organization (WHO), did a matched case-control analysis of data from national surveillance programs in Afghanistan and Pakistan to study the effect of immunization campaigns and the effectiveness of the three polio vaccines available. The database included 46,977 children 0 through 14 years old with acute flaccid paralysis from 2001 through 2011. The team found that the serotype 1 monovalent vaccine and the serotype 1/3 bivalent vaccine had comparable effectiveness and were both superior to the trivalent vaccine. They report that the number of polio cases increased from 40 in Pakistan and 31 in Afghanistan in 2006 to 198 and 80 in 2011, respectively. The increase is occurring primarily in regions where vaccination coverage and population immunity are decreasing, including Balochistan and the Federally Administered Tribal Areas in Pakistan and parts of southern Afghanistan where security concerns continue. Kath O'Reilly, lead author, says in a press release, "The best vaccine in the world will not work unless it reaches the children it's intended to protect. So it's vitally important that vaccine coverage is considerably improved in 2012 through better campaigns and routine programmes if we're to finally eradicate polio globally."
Jul 4 Lancet study
Jul 3 Imperial College London press release

Study finds high effectiveness for indoor spraying to prevent malaria
Indoor insecticide spraying has reduced malaria infections in malaria-endemic communities by 62%, according to a meta-analysis published online Jul 3 in the American Journal of Tropical Medicine and Hygiene (AJTMH). The researchers examined 13 studies published between 2000 and 2010 on the effect of indoor residual spraying (IRS) on malaria transmission, primarily in Africa. Because the effectiveness of IRS in the studies varied considerably, as did study design and other factors, the authors performed a meta-regression analysis using 45 observations and deduced the following: IRS is most effective in areas with a high initial prevalence of malarial disease, where both Plasmodium falciparum and Plasmodium vivax parasites are a threat, when several rounds of spraying are conducted, and where DDT rather than pyrethroids or other insecticides is used. The use of DDT is controversial and has been banned in many countries, the authors acknowledge, but it may be worth consideration in areas of intense malaria transmission.
Jul 3 AJTMH IRS study
In another study from AJTMH, researchers found that P falciparum in Africa does not appear to be developing resistance to the artemisinins, as the parasite has done in at least one area in Southeast Asia. The therapeutic efficacy of the artemisinin derivative artesunate used as monotherapy in Mali was evaluated in a prospective trial of 100 children with uncomplicated malaria in 2010-11 and compared with efficacy in a 2002-04 clinical trial, when the agent was initially used in Africa. No significant differences were found between the two trials in the percentage of patients who cleared their infection completely within 24 hours. The lack of evidence of resistance after several years of the agent's use in Africa is a welcome finding, says an accompanying editorial, because of the high rate of malaria transmission and disease burden there and the expanded use of the artemisinins.
Jul 3 AJTMH P falciparum–resistance study
Accompanying editorial
Jul 3 EurekAlert press release on above two studies

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