Flu Scan for Oct 31, 2013

H7N9 and live-bird markets
H5N1 in Cambodia
H1N1 vaccine acceptance
Pandemic flu admissions in Canada

Study: H7N9 cases fell dramatically with poultry market closures

Closure of live-poultry markets (LPMs) in four Chinese cities in the spring of this year promptly cut H7N9 avian flu cases by more than 97%, according to a statistical analysis published today in The Lancet.

Chinese researchers analyzed information from a database created by the Chinese Center for Disease Control and Prevention on every lab-confirmed case of avian influenza A H7N9 reported by Jun 7 in Shanghai, Hangzhou, Huzhou, and Nanjing, where most human cases of infection had occurred.

They also obtained information from official sources on the 780 LPMs in those cities that were closed in early April and designed a statistical model to explain the patterns in incidence of cases reported in each city. They assumed a constant force of infection before LPM closure and a different constant force of infection after closure, they wrote.

They found that closure of LPMs reduced the average daily number of infections by 99% in Shanghai, 99% in Hangzhou, 97% in Huzhou, and 97% in Nanjing. Absolute humidity, the only common weather factor known to strongly affect flu transmission, did not explain the sudden drop in cases, they said.

The authors note in a Lancet press release that two new H7N9 cases this month in China are "of great concern" because they herald a renewed outbreak this winter; they recommend LPM closures in areas where the virus appears.

In a commentary in the same issue, experts from the Royal Veterinary College of London write, "Although LPM closure in specific circumstances can effectively interrupt human exposure to avian influenza A H7N9 virus, if applied alone this measure is unlikely to eliminate the zoonotic threat.

"The focus should move beyond detection of human cases and emergency response towards prevention at the infection source."
Oct 31 Lancet abstract
Oct 30 Lancet press release
Oct 31 Lancet commentary


Cambodia reports 22nd case of H5N1 this year

A 6-year-old girl has become the 22nd person in Cambodia this year to be infected with H5N1 avian flu, according to a joint press release from the country's Ministry of Health (MoH) and the World Health Organization (WHO) yesterday.

The youngster, from a commune in the Phnom Proek district of Battambang province, became ill Oct 14, was hospitalized Oct 19, and is in stable condition after treatment with oseltamivir. Chickens and ducks in the girl's neighborhood and in nearby villages had reportedly died recently, but it is not yet known whether she had direct exposure to ill or dead birds.

Health officials in Cambodia are identifying the child's close contacts as well as studying whether there are any epidemiologic links among the 22 patients infected this year. Animal health workers are investigating deaths in birds in the area.

A statement from Minister of Health Dr. Mam Bunheng points out the special danger of H5N1 to children in that they commonly care for, feed, and clean the cages of domestic poultry and often treat them as pets.

Parents are being urged through public health education campaigns to keep children away from sick or dead poultry, not allow them to play with chickens and ducks, and make sure they wash their hands with soap and water before eating and after contact with poultry.
Oct 30 Cambodian MoH/WHO press release


French surveys find pandemic-linked vaccine confidence drop

The arrival of the pandemic H1N1 (pH1N1) vaccine in France during the 2009 pandemic led to a shift toward unfavorable views, researchers reported today in Eurosurveillance.

They based their findings on three phone surveys conducted in 2000, 2005, and 2010. Negative attitudes about vaccinations climbed from 8.5% in 2000 to 9.6% in 2005, and to 38.2% in 2010. Of those who responded with unfavorable views in 2010, half said they were opposed to the pH1N1 vaccine.

The criticism was most pronounced in less educated people. The 2010 results saw a shift away from women being more likely to oppose vaccination, and opposition veering younger, away from seniors to those ages 50 to 64.

The researchers also found that the unfavorable opinions were linked to vaccination behaviors. Those with negative impressions were more likely to report that they had at least one child who had not been vaccinated against measles, mumps, and rubella. In the 2010 survey, seniors with negative attitudes were less likely to be vaccinated against seasonal flu.

Though the team said they couldn't pinpoint exactly when the unfavorable views started to increase, they noted that many respondents specifically mentioned the pH1N1 vaccine strengthens its link to the negative impressions. The negative comments seemed to peak as French health officials and the WHO criticized the French media for exaggerating the 2009 H1N1 threat, they added. Also, media reports in the summer aired controversy over large vaccine purchases by the French government.
Oct 31 Eurosurveill report


High pH1N1 hospitalization rates in Canadian First Nations populations

The risk of hospitalization for pneumonia and influenza (P&I) during the 2009 flu pandemic was disproportionately increased over baseline for residents of First Nations communities in British Columbia, Manitoba, and Ontario, say findings of a study yesterday in BMC Public Health.

The researchers compared the overall number of P&I hospitalizations during the April-June 2009 and October-November 2009 waves of pH1N1 in the provinces and compared them with the number in the same periods from 2004 to 2008 to determine pH1N1-attributable rates.

Overall admissions for P&I during the pandemic increased by about 10% in British Columbia and Manitoba and 33% in Ontario during the pandemic, but admissions among First Nations residents increased by an average of 45% in all three provinces.

The risk of pH1N1-attributable hospitalization for First Nations residents compared with the remainder of the population was elevated (rate ratio [RR] = 2.8 to 9.1). The baseline risk of P&I hospitalization for the First Nations population was also found to be elevated (RR = 1.5 to 2.1), suggesting that the risk may be elevated in general and not specific to pH1N1, say the authors.

Remoteness of First Nations communities was not an important risk factor, and outcomes were related to the care provided rather than to the location of communities, the authors said.
Oct 30 BMC Public Health abstract

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