Flu maintains strong grip on US
Influenza seems reluctant to release its grip on the United States, as most measures of flu activity showed little change last week, according to today's update from the Centers for Disease Control and Prevention (CDC).
The agency said 4.4% of outpatient visits to healthcare providers last week were related to flu-like illness (ILI), compared with 4.5% the week before. The number of states with geographically widespread flu activity stayed the same at 44. However, 29 states reported high ILI activity, up from 23 states a week earlier.
There was little change in the proportion of respiratory samples that tested positive for flu: 19.9% of 23,339 specimens, versus 19.5% of 26,205 the previous week.
The share of deaths attributed to flu and pneumonia was 9.1% last week, which was down slightly from 9.2% a week earlier but well above the epidemic threshold of 7.1%.
Flu-related deaths in children dropped to 5 last week, from 11 the week before. Four of the deaths were linked to influenza A/H3N2 infections, the overwhelmingly dominant strain this season, the CDC said. The other death involved a type A virus that was not subtyped.
The cumulative estimate of hospitalizations reached 40.5 per 100,000 population, up from 36.3 the week before. The CDC noted that this number is ahead of the 27.4 per 100,000 in the same week of 2013, during the last H3N2-dominated season.
The CDC also revealed that a novel flu infection was reported in Minnesota. The state reported an infection with an H1N1 variant (H1N1v) virus in a person who had been exposed to pigs before the illness. The patient has recovered, and no further transmission has been observed, the agency said.
Jan 30 FluView report
Jan 30 FluView summary
In other developments, the European Centre for Disease Prevention and Control (ECDC) said in a risk assessment this week that most European countries are likely to see medium or high levels of flu circulation the rest of this season.
Children up to the age of 4 have been the hardest-hit group so far, the agency said. "We face an influenza season that could be more severe and exert bigger pressure on health care systems than in the last few years," ECDC Director Marc Sprenger, MD, PhD, said in a press release.
As in the United States, H3N2 viruses are dominant in almost all countries, and most of them differ from the H3N2 strain in the vaccine, the ECDC said. The mismatch has been blamed for low flu vaccine effectiveness in the United States and Canada so far this season.
Jan 28 ECDC risk assessment
Jan 28 ECDC press release
Infection confirmed in husband of Canada's first H7N9 patient
Canadian officials confirmed that the husband of a British Columbia woman infected with H7N9 avian flu tested positive for the virus, making him the country's second H7N9 case-patient, according to a Canadian Press story yesterday.
The man and his wife returned to Canada from China on Jan 12, and both became ill several days after their return. Although the man did not seek treatment for his illness, he was tested after his wife was diagnosed with H7N9 avian flu. The National Microbiology Laboratory in Winnipeg, Man., confirmed last night that the man had been infected with H7N9.
Both people have recovered without complications, and Canadian health officials do not expect any of their contacts to become ill.
Jan 29 Canadian Press story
Jan 27 CIDRAP News scan on potential second case
Jan 26 CIDRAP News story on woman's case