US flu activity continues slow fade as season lingers
Nearly all measures of seasonal flu circulation in the United States continued their slow decline last week, but they stayed above baseline levels, making the season officially longer than average, the Centers for Disease Control and Prevention (CDC) said today.
Thirteen weeks has been the average span of flu seasons over the past 13 years, and last week marked this season's 14th week, the CDC noted.
Outpatient medical visits for influenza-like illness (ILI) dropped to 3.0% of all visits last week, down from 3.2% the week before, but that level remained well above the national baseline of 2.0%, the CDC reported. Twelve states reported high ILI activity, one less than a week earlier.
Geographically widespread flu circulation was reported by 20 states, down sharply from 30 states the week before. The share of respiratory samples that tested positive for flu was down to 12.1% from 13.0% a week earlier, the CDC said.
The fraction of deaths attributed to pneumonia and flu was 7.4% last week, compared with 8.4% a week earlier, but it still hovered above the epidemic threshold of 7.2%.
The cumulative rate of flu-related hospitalizations continued to climb, reaching 51.7 per 100,000 population last week. For elderly people the hospitalization rate pushed further into record territory, reaching 258.0 per 100,000, far above the previous record of 183.0 in the 2012-13 season.
Six more flu-related deaths in children were reported, bringing the season total to 92, the CDC said. Three deaths were linked to influenza A/H3N2 viruses, one involved an influenza B virus, and the other two involved type A viruses that were not subtyped.
H3N2 viruses have been heavily dominant this season, but type B is staging a late-season surge, which is not unusual. Last week type B viruses accounted for 30.9% of specimens that were typed. For the season overall, only 6.9% of tested isolates have been type B.
Feb 27 CDC FluView summary
Feb 27 FluView report
Two elderly men latest H7N9 cases in China
Two more cases of H7N9 avian influenza have been diagnosed in China's Guangdong province, according to a press release yesterday from Hong Kong's Centre for Health Protection (CHP) and the machine translation of a report from the Ministry of Health and Family Planning Commission posted today by FluTrackers, an infectious disease news message board.
The first case-patient is a 78-year-old man from the city of Zhaoqing who was hospitalized in serious condition. No other details are provided.
The second is an 80-year-old man from the city of Shantou. He had preexisting medical disease including high blood pressure and heart failure and was hospitalized in critical condition.
These cases bring the total since 2013 to 616, according to a case listing maintained by FluTrackers. Guangdong province has seen more cases of H7N9 flu than any other, with Zhejiang province running a close second and 14 others reporting cases as well.
Feb 26 CHP press release
Feb 27 FluTrackers post
FluTrackers case listing
CDC says human risk from H5 outbreaks in birds is low
The CDC yesterday noted the recent detections of H5 highly pathogenic avian influenza (HPAI) in domestic and wild birds in western states but said the disease risk to people is low.
Since H5 was first detected in Washington state in December 2014, HPAI H5N2, H5N8, and a new H5N1 reassortant have been identified in California, Idaho, Oregon, Utah, Washington, and Nevada, the CDC said.
The agency added, however, "The risk to people from these HPAI H5 infections in U.S. birds and poultry is believed to be low at this time because these viruses do not normally infect humans easily, and even if a person is infected, the viruses do not spread easily to other people."
The CDC said it is coordinating efforts with state health departments to ensure that human health measures are in place "and is working with animal health colleagues to evaluate and minimize public health risk."
The agency concluded, "Because avian influenza A viruses have the potential to change and gain the ability to spread easily among people, monitoring for human infection and person-to-person transmission is extremely important for public health."
Feb 26 CDC statement
Evidence of H5N1 antibodies low in poultry workers: study
The level of antibodies to H5N1 avian flu in poultry workers in Bangladesh is low, according to a seroprevalence study today in Emerging Infectious Diseases.
Researchers from the CDC and Bangladesh analyzed blood samples from 404 Bangladeshi workers in live-poultry markets in which both hand washing after poultry handling and use of personal protective equipment were low. Nine of the workers (2%) were seropositive at baseline.
Of the 284 workers who completed the study and were seronegative at baseline, 6 (2%) seroconverted, for a rate of seven cases per 100 poultry worker–years. The team also determined that workers who frequently fed poultry, cleaned feces from pens, cleaned food or water containers, and did not wash hands after touching sick poultry had a 7.6 times higher risk of infection compared with workers who infrequently engaged in these behaviors.
The authors conclude, "The risk behaviors identified in our study may help public health officials explore interventions to interrupt poultry-to-human transmission of H5N1 virus and other avian influenza A viruses among the poultry workers."
Feb 27 Emerg Infect Dis study