May 9, 2011
WHO: Global flu activity pausing between seasons
Influenza activity is back to baseline or preseason levels across temperate parts of the Northern Hemisphere and has not yet started to increase in the temperate Southern Hemisphere, the World Health Organization (WHO) said in its latest flu update. In northern countries, one exception to the downward trend in flu indicators occurred in Mexico, where the proportion of respiratory specimens testing positive for flu increased from 9% to 14%. The increase involved mainly 2009 H1N1 viruses, following a recent outbreak of that strain in Chihuahua state. In Europe, northern China, and Japan, most or all of the few respiratory specimens that tested positive were influenza B. Flu activity also was generally low in tropical regions, though Ghana and Kenya reported ongoing transmission of 2009 H1N1 and type B viruses.
May 6 WHO flu update
Experts advocate flu vaccination for pregnant women in developing world
In a lengthy review in Vaccine, researchers assert that flu vaccination in pregnant women is "an important and potentially cost-effective approach" for protecting both pregnant women and young infants in low- and middle-income countries. The authors, from the nonprofit global health group PATH and the University of Washington, examine the evidence for and feasibility of vaccinating pregnant women in the developing world. They note that flu vaccine is not widely used in pregnant women worldwide, despite its recommendation by the WHO and many governments. They also note that recent prospective, controlled studies in Bangladesh and the United States showed that flu vaccination in pregnant women can reduce confirmed flu cases in their newborn babies. Even in the least developed countries, about 70% of women receive prenatal care, offering an opportunity to vaccinate them, the report says. "While further clinical effectiveness, operational, and cost-effectiveness studies may be necessary to convince decision-makers of the benefit of incorporating TIV [trivalent inactivated vaccine] into routine prenatal care within particular countries, maternal TIV vaccination is not an investigational concept, and it does not require further scientific evaluation in all settings before deployment," the authors state.
May 6 Vaccine report
Brazil reaches half of target population with flu vaccine
Brazil has administered flu vaccine to more than 12 million people, half of those targeted, according to Prensa Latina, Cuba's official state news agency. The 24 million targeted in the nationwide campaign, which began Apr 25 and is slated to end this week, represent 80% of at-risk Brazilians, according to the story. At-risk groups include people over 60, pregnant women, indigenous populations, children aged 7 months to 2 years, and health workers. Vaccine is available at 65,000 medical facilities in a country of about 200 million people.
Researchers say pandemic modeling tool recognizes conditions in tropics
US researchers have released an open-source mathematical model for pandemic influenza that they say treats the seasonality of flu in the tropics in more detail than other models. The model, described in PLoS One, predicts the spread of pandemic flu among and within 321 major cities, on the basis of transmissibility, the point of origin, and the time of year of emergence. The researchers also used the model to examine the effectiveness of vaccination strategies, assuming it takes 6 months to make and distribute vaccine. Regarding the 2009 H1N1 pandemic, the model predicts that the vaccine would have reduced attack rates considerably if it had been widely available starting Oct 1, 2009, as originally predicted. But with the vaccine's late arrival, it reduced the attack rate only from 23% to 20%, according to the model. The tool also suggests that for pandemics starting in the spring in the Northern Hemisphere, vaccination would have little effect in the temperate Southern Hemisphere. The authors say their model is simple enough to run easily on a laptop computer, making it more accessible to public health officials. They are from the Fred Hutchinson Cancer Research Center and the University of Washington, both in Seattle.
May 6 PLoS One report
Recirculating air during car trip with sick passenger may increase risk of flu
Driving slowly for 90 minutes in a car with a person who has the flu while recirculating the vehicle's air may lead to a high risk of contracting the disease, according to a modeling study published today. However, driving faster and not recirculating the air dropped the risk dramatically. Australian researchers studied a 1998 Mazda 21 and a 2005 Volkswagen Golf at speeds of 25, 50, and 100 kilometers per hour (16, 31, and 62 mph) for 90 minutes. They used a variation of the Wells-Riley mathematical model to estimate infection risk, which assumed that an ill passenger would emit infectious droplets at a constant rate and that air would mix uniformly. They tested air circulation at three car speeds and at low, medium, and high ventilation rates (fan speeds). At the low-ventilation rate, air was recirculated, but for medium- and high-ventilation rates it was not. At low ventilation, infection risk in the older car reached 68%, 49%, and 31% at slowest to fastest car speeds, respectively. For the newer car the rates were 99.9%, 99.7%, and 98%, respectively. At high ventilation, risk in the older car dropped to 21%, 19%, and 16%, respectively, and in the newer car to 17% at all speeds. At medium ventilation, risk in the older car ranged from 35% down to 20%, and in the newer car from 30% to 24%.
May 9 Epidemiol Infect abstract
Report: PCR, cooperation key to identifying non-O157 E coli
Researchers from the US Centers for Disease Control and Prevention and New York's state health department summarized two outbreaks of non-O157 Shiga toxin–producing Escherichia coli (STEC) and reported that proper diagnostic testing and coordinated efforts by health and lab professionals were keys to quick identification. They report on an outbreak involving 213 people who drank unpasteurized apple cider from a local orchard. Of 27 who tested STEC-positive, 26 (96%) were confirmed as having O111 STEC with an identical pulsed-field gel electrophoresis (PFGE) pattern. The other outbreak involved 54 total cases of bloody diarrhea in prison inmates, 18 of whom had cultures of O45 STEC that were indistinguishable on PFGE. The authors conclude that polymerase chain reaction (PCR) testing that targets Shiga toxin genes is an effective way to identify non-O157 STEC but is not widely used by clinical diagnostic labs. A recent outbreak of O111 STEC linked to a raw beef dish recently sickened more than 70 and killed 4 in Japan.
May 5 Epidemiol Infect abstract
May 6 Wall Street Journal blog post on Japanese outbreak