Flu Scan for Jul 29, 2014

Mild H7N9 cases in kids
;
H10N8 in China
;
Global flu update

Study: Children could be 'silent' H7N9 spreaders

An analysis of seven children infected with H7N9 avian influenza during the outbreak's second wave in China found that the illnesses were mild, a phenomenon that could contribute to spread of the virus. Researchers from China's Guangdong province published their findings today in an early online edition of the Pediatric Infectious Disease Journal.

They looked at seven children whose illnesses were identified in Guangdong province as of Feb 10, 2014. Ages ranged from 2 to 17, and four of the patients were boys. Three illnesses were detected during sentinel surveillance, three during contact tracing, and one during border-crossing screening. The patients were from five cities in Guangdong province, with illness onsets that ranged from Oct 29, 2013, to Jan 31.

All of the children had mild fever, with other symptoms varying, the most common ones being throat congestion and rhinorrhea. Three had upper respiratory infections but none had pneumonia. Six were hospitalized, and none of the children required intensive care. One child never visited a clinic or hospital.

Six of the kids had a history of poultry exposure, four of them at their homes. Environmental testing in the wake of the infection detections yielded positive samples in three cases.

Family links were found for four of the children, two of whom had parents with H7N9 infections. Two of the children were cousins, but their parents tested negative for the virus.

Mild infections occurring in highly contaminated environments may contribute to underestimation of H7N9 infections in children, posing challenges for surveillance, because they may continue to spread the disease, making the epidemic more difficult to control, the authors wrote. They added that more vigilance for H7N9 in youngsters and their close contacts is needed, along with more thorough disinfection of poultry markets to curb the source of infection.
Jul 29 Pediatr Infect Dis J abstract

 

Human H10N8 in China linked with live poultry markets

The human cases of H10N8 avian flu that occurred in China in 2013 could have derived from strains circulating at live poultry markets (LPMs), according to a study yesterday in Emerging Infectious Diseases.

H10N8 was the infectious agent in birds in Chinese outbreaks in 2007 and 2012. The first known human H10N8 case occurred in December 2013 in a 73-year-old woman in Nanchang, Jiangxi province, who had visited an LPM 4 days before symptom onset. Two other human cases followed.

In January the authors collected 226 pairs of cloacal and oropharyngeal specimens from apparently healthy poultry from several LPMs in Nanchang, including the ones visited by the case-patients. Genetic analysis showed H10N8 in two of the pairs that closely matched isolates from the index patient in 2013.

The authors write, "Exposure to infected and/or virus-carrying poultry or to contaminated environments in LPMs and the emergence of mammal-adapted and drug-resistant viruses puts humans at high risk for infection with novel influenza viruses." They urge strict biosecurity measures for bird transport as well as proper disposal of diseased and dead birds and closure of LPMs when necessary.
Jul 28 Emerg Infect Dis study

 

Flu season starting in some Southern Hemisphere countries

After a slow start, flu activity in the Southern Hemisphere is on the rise, with different patterns in different regions, the World Health Organization (WHO) said yesterday in its latest global flu update.

The flu season in Australia and New Zealand seems to have started, with the 2009 H1N1 virus as the most commonly detected strain. South Africa reported an uptick in flu activity, but with H3N2 as the dominant strain. In South America's temperate zone, flu activity also increased, but most respiratory samples were positive for respiratory syncytial virus (RSV); the dominant strain so far in countries such as Chile and Paraguay has been H3N2.

Elsewhere flu activity was low or at interseasonal levels, with a few exceptions. In southern China, rates were slightly higher with increasing numbers of H3N2 detections. In Africa, Cameroon and Kenya reported rises in flu activity, mainly H3N2 for the former and 2009 H1N1 for the latter.

In related developments, the European Centre for Disease Prevention and Control (ECDC) today posted its latest analysis of circulating flu strains that have been detected since the end of December. It said samples have shown influenza A and B viruses at a ratio of 20:1, with H3N2 and 2009 H1N1 at similar levels.

Recently circulating 2009 H1N1 and H3N2 viruses are similar to vaccine viruses.

For influenza B, two clades of the Yamagata lineage are circulating, with the most recent samples being mainly clade 3, represented by B/Wisconsin/1/2010. However, the recommended vaccine component for 2013-14 was, and for 2014-15 is, clade 2, represented by B/Massachusetts/02/2012.

The ECDC's analysis of two Victoria lineage influenza B viruses in June found that neither was recognized well by the vaccine virus A/Brisbane/60/2008, which was recommended for the additional B strain in the quadrivalent vaccines for the past and upcoming flu seasons.
Jun 28 WHO global flu update
Jun 29 ECDC flu strain update

 

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