Flu Scan for Sep 16, 2014

News brief

USDA says H3N1 viruses with human flu genes found in swine

The US Department of Agriculture (USDA) has found rare H3N1 influenza viruses in swine in two states in recent months, and two of the isolates carry genes from human seasonal flu viruses. The developments are grounds for serious concern about the potential spread of disease at fairs this fall, according to one animal health expert.

Christina M. Loiacono, DVM, PhD, of the USDA said "several" H3N1 isolates have been found in at least two states since last December. H3N1 viruses in swine are not unheard of but are rare, said Loiacono, who is associate coordinator of the National Animal Health Laboratory Network (NAHLM).

She said two of the isolates carry hemagglutinin (H) genes that come from contemporary human seasonal flu viruses "and are distinct from our current swine H3 viruses." Her report was posted today on ProMED-mail, the reporting service of the International Society for Infectious Diseases. It was originally sent to all NAHLN labs that work with swine flu viruses.

"Potential spread of H3N1 or H3N2 that carries the human-like H3 could have significant impact in swine herds due to poor herd immunity as well as potential public health ramifications," Loiacono wrote. "Preliminary findings by USDA-ARS [Agricultural Research Service] from testing of one of these H3N1 isolates with the human-like H3 gene in swine indicate the virus is fully virulent, causing typical influenza disease."

In the ProMED post, Tam Garland, DVM, PhD, of Texas A&M University's College of Veterinary Medicine, called Loiacono's notice "a serious alert." She is ProMED's moderator for animal diseases and zoonoses.

"It is especially concerning as we enter the autumn livestock show and fair season," Garland wrote. "Animals congregate at these gatherings, as do people. The opportunity for viral spread and viral assortment at these shows is quite large."

Noting that infected animals can spread disease before they look ill, she said swine owners who have sick animals or sick family members should keep them at home.
Sep 16 ProMED-mail post

First appearance of H5N6 in Laotian poultry

Low-pathogenic H5N6 avian flu, reported as a new strain in several outbreaks in Vietnam since August, has now appeared in Laos, says a report yesterday from the World Organization for Animal Health (OIE).

Two birds in a flock of 200 on a poultry farm in Viengsavang, Luangprabang, showed signs of clinical disease and died, for an apparent morbidity rate of 1% and an apparent case-mortality rate of 100%.

Testing by real-time polymerase chain reaction (PCR) at the National Animal Health Laboratory confirmed H5N6. The remaining birds in the flock were destroyed.

The report says active surveillance for avian flu was started in five Laotian provinces in July with support from the US Agency for International Development through the Food and Agriculture Organization of the United Nations.
Sep 15 OIE report
Most recent (Sep 4) CIDRAP News scan on Vietnamese outbreaks

Study: Preseason antibodies influence immunity to H3N2, flu B, not H1N1

Increased homologous hemagglutination-inhibiting (HI) antibody titers are significantly associated with protection against both H3N2 and type B but not H1N1 influenza in people whose influenza immunity has been shaped by prior natural infection rather than vaccination, according to a study today in the Journal of Infection. Resistance to H1N1 is influenced more by age, the authors found.

The researchers, from England, Australia, and Vietnam, carried out 3 consecutive years of surveillance for influenza-like illness (ILI) (ie, fever >38°C with cough or sore throat), in 940 individuals from 270 Vietnamese households (1,793 person-seasons) in which the residents had never received flu vaccine. The flu seasons covered, from 2007 to 2010, included recirculating flu strains, new antigenic variants, and H1N1 pandemic flu.

Nose and throat swabs and blood samples were collected at baseline and between each of the flu seasons in subjects with ILI. Paired blood samples spanning each season were available for at least 490 subjects.

Influenza was defined as either detection of flu RNA by reverse-transcriptase PCR in a swab sample or of seroconversion (ie, a four-fold or greater rise in HI titer, with a second titer of at least 40).

A significant linear effect of HI titer on the risk of H3N2 was apparent in season 2, as it was for influenza B Yamagata in seasons 1 and 2. No such effect was present for H1N1 in any of the three seasons. However, age was found to be independently associated with a decreasing risk of seasonal H1N1 infection in season 1 (P = 0.08) and season 2 (P < 0.0001), and with pandemic flu in season 3 (P < 0.0001).

As stated by the authors, "Our findings indicate that in this unvaccinated population, prior natural influenza H1N1 infections induced immunity against infection with new drifted and novel strains, which did not appear to be reliant on HI antibodies. . . . Non-HI antibodies could prevent HI antibody induction either by enhancing virus clearance or by competing for antigen. It will be important to confirm whether non-HI neutralizing antibodies account for the absence of a detectable protective effect of baseline H1N1 HI antibodies in our cohort."
Sep 16 J Infect abstract

News Scan for Sep 16, 2014

News brief

12 states and Canada report enterovirus D68 cases

The number of states reporting confirmed cases of enterovirus D68 (EV-D68) has doubled, to 12, the Centers for Disease Control and Prevention (CDC) reported today, and cases have been confirmed in Alberta as well.

EV-D68, a respiratory virus that was relatively rare until recently, has been sending children to hospital emergency departments with wheezing and breathing difficulty.

In today's update, the CDC said 130 cases have been confirmed in its own labs or in state health department labs, compared with 97 cases reported on Sep 12. The 12 states affected are Alabama, Colorado, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Missouri, New York, Oklahoma, and Pennsylvania. No deaths have been reported.

The CDC predicted that more states will report confirmed EV-D68 cases in coming weeks. Several states are investigating cluster of severe respiratory illnesses, and the testing is complex and slow, the agency said.

"As the backlog of specimens is processed, the number of states and confirmed cases will likely increase," the CDC said. "These increases will not necessarily reflect changes in real time, or mean that the situation is getting worse," though some of the increase will represent new cases.

Also, at least 18 EV-D68 cases have been confirmed in Alberta, including 10 in Calgary and 5 in Edmonton, according to a CBC News report yesterday. Alberta officials were unsure if it was the same strain as in the United States and were working with Canada's national lab to find out, the story said.

In a ProMED-mail post yesterday, Alberta health officials reported the confirmation of nine cases in children at Alberta Children's Hospital in Calgary. The cases involved children who were hospitalized for treatment of asthma or bronchiolitis between Sep 1 and 11, the report says. Their ages ranged from 22 months to 12 years. Two required intensive care, and four needed supplemental oxygen.
CDC information about states reporting cases
CDC EV-D68 page
Sep 15 CBC News story
Sep 16 ProMED post on Alberta cases

Saudi Arabia reports another MERS case

Saudi Arabia's Ministry of Health (MOH) today confirmed another serious MERS-CoV case, the fifth in that country in just over a week.

The case involves a 39-year-old non-Saudi man who lives in Riyadh and is in an intensive care unit (ICU), the agency said. He is not a healthcare worker but had pre-existing disease, the MOH said in its typically terse update. He reported no recent contact with animals.

Since Sep 8 the health ministry has confirmed five cases of MERS-CoV (Middle East respiratory syndrome coronavirus) scattered around the country. The other four cases also involved ICU hospitalizations.

The new case brings Saudi Arabia's MERS total to 731 cases, including 302 fatalities.
Sep 16 MOH update

Review: Half of drugs for kids' bacterial respiratory infections not needed

Acute respiratory tract infections (ARTIs) are caused by bacteria in 27.4% of cases yet are treated with antimicrobials in outpatient visits almost twice as often as expected, translating into an estimated 11.4 million prescriptions that may be unnecessary, according to a study yesterday in Pediatrics.

The authors conducted a meta-analysis of studies published between 2000 and 2011 of children under 18 years of age with acute otitis media (AOM), sinusitis, bronchitis, upper respiratory tract infection (URI), and pharyngitis to determine bacterial prevalence rates, as well as a retrospective cohort analysis of data from the 2000-2010 National Ambulatory Medical Care Survey (NAMCS) to study antimicrobial-prescribing rates for ARTI.

Bacterial prevalence in AOM cases, based on 12 studies that met inclusion criteria, was 64.7% (95% confidence interval [CI], 50.5% to 77.7%); in cases of Streptococcus pyogenes during pharyngitis, the rate was 20.2% (95% CI, 15.9% to 25.2%) based on 11 studies. No URI studies met inclusion criteria, and only one sinusitis study met critieria; bacterial prevalence in the latter study was 78%.

On the basis of the studies analyzed, the authors say the expected rate of antimicrobial prescriptions for ARTI overall would be 27.4% (95% CI, 26.5% to 28.3%). The actual prescribing rate in ARTI encounters during the NAMCS was 56.9% (95% CI, 50.8% to 63.1%), about twice the expected rate.

This translates to an estimated excess of 11.4 million prescriptions per year, say the authors. They point out that an estimated 31.7 million visits for ARTI in children result in prescriptions of antimicrobial agents.
Sep 15 Pediatrics abstract