Sunday, January 21, 2018

Russia As An Outlier in This Year's Flu Epidemic

Epi Week 2 - 2018


While the United States, Western Europe, and Asia are all dealing with a moderately severe-to-severe flu season, one usually hard-hit region of the world has so far gotten a pass this winter; Russia.

Russia - which often reports severe winter flu seasons even when the rest of the world has only mild or moderate flu - has yet to reach their epidemic threshold this winter - coming closest (under by 1.4%) in early December (week 51).

As we saw two weeks ago in Eurosurveillance: Changes In Timing Of Influenza Epidemics - WHO European Region 1996-2016, over the past 2 decades Russia's flu seasons have tended to peak earlier with each passing year.  
There is still time, however, for another late season flu surge in Russia.
While flu activity is up slightly this week over last, the latest surveillance report from the Russian Research Institute of Influenza, shows a remarkably mild flu season for January.  

Week 08.01.2018-14.01.2018

Influenza and ARI morbidity data

Epidemiological data show increase of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI & ARI morbidity level (51.4 per 10 000 of population) was lower than the new national baseline (calculated in country) for 2017-2018 season (72.6) by 29.2%.

ILI and ARI epidemic thresholds were exceeded in 12 of 61 cities collaborating with two WHO NICs in Russia.
Cumulative number of diagnosed influenza cases
Cumulative results of influenza laboratory diagnosis by different tests were submitted by 51 RBLs and two WHO NICs. According to these data as a result of 1668 patients investigation the overall proportion of respiratory samples positive for influenza was estimated as 2.8%, including 0.5% for influenza A(H1N1)pdm09 virus, 1.3% for influenza A(H3N2) virus, 0.06% for influenza type A virus and 0.9% for influenza type B virus. 



Influenza and ARI morbidity data.  Increased influenza and other ARI activity was registered during the week 02.2018 in traditional surveillance system in Russia. The nationwide ILI & ARI morbidity level (51.4 per 10 000 of population) was lower than the national baseline by 29.2%.

Etiology of ILI & ARI morbidity. The overall proportion of respiratory samples tested positive for influenza  was estimated as 2.8%, including 0.5% for influenza A(H1N1)pdm09 virus, 1.3% for influenza A(H3N2) virus, 0.06% for influenza A virus and 0.9% for influenza type B virus. Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 22.9% of investigated patients by IFA and 19.2% by PCR. 

Antigenic characterization. 7 influenza viruses were characterized antigenically including 5 influenza A(H3N2) strains and 2 influenza type B strains. All influenza A(H3N2) strains were related to influenza A/Hong Kong/4801/2014 virus. All influenza type B strains were belonged to Yamagata line and were like B/Phuket/3073/2013 reference virus.

Genetic characterizationOne influenza A(H3N2) virus was characterized in Saint-Petersburg NIC. Virus belonged to genetic subgroup 3C.2a1 and was like A/Bolzano/07/2016 reference virus. 4 influenza A(H3N2) strains from clinical samples were characterized in Saint-Petersburg NIC. Viruses belonged to genetic subgroup 3C.2a and were like A/Hong Kong/4801/2014 reference virus.

In sentinel surveillance system clinical samples from 87 SARI and ILI/ARI patients were investigated by rRT-PCR. 5 influenza cases were detected among SARI patients, including 1 influenza A(H1N1)pdm09 case, 3 influenza A(H3N2) cases and 1 influenza B case. Among ILI/ARI patients 5 influenza cases were detected, including 1 influenza A(H1N1)pdm09 case, 1 influenza A(H3N2) case and 3 influenza B cases.

This week's weekly (translated) summary from  Rospotrebnadzor reflects the low incidence of flu, along with high (46.6%) vaccination rate - a product of a massive campaign that began two years ago - for the current flu season.

On the situation on the incidence of influenza and acute respiratory viral infection and the course of immunization of the population in the Russian Federation


According to the WHO EURO in the European region recorded growth of influenza caused by influenza virus subtypes A (H3N2) and type B. +
At week 02 (08.01.2018-14.01.2018) in the Russian Federation there is a low incidence of influenza and SARS.
By the total population exceeding the weekly epidemic threshold incidence of SARS and influenza reported in 3 of the Russian Federation. Excess epidporoga the central city without exceeding epidporoga on the subject of the Russian Federation, recorded in 2 cities of Russian Federation.
Among children in age group of 0-2 years week thresholds of disease epidemic of SARS and influenza are exceeded in 5 Russian regions, among children in the age group 3-6 years - in 8 regions of Russia, among children in the age group 7-14 - in 6 regions of Russia, among people older than 15 years - in 3 of the Russian Federation.
Laboratory examined the reporting week, more than 3.3 thousand people in the 57 -. E cases of influenza A viruses are found in 32 - x - influenza B viruses
In the structure of positive findings parainfluenza viruses accounted for 16%, adenoviruses - 17%, RS viruses - 30%, other viruses are not influenza etiology - 35%. The proportion of influenza viruses in the structure of the positive findings was 10%.
Rospotrebnadzor continues to monitor the progress of immunization against influenza.
On 12/01/2018 at the expense of the federal budget vaccinated more than 17 million. Children (99.9% of the planned number) and more than 40.6 million. Adults (99.9%), in Vol. H. The more than 174 thousand. Pregnant women
From other sources vaccinated 8.1 million people, including through employer -. 6.6 million people..

Summary vaccinated more than 67.3 million. People (46.6% of the population).
The situation is under the control of Rospotrebnadzor.

All of which proves, once again, how fickle and unpredictable seasonal flu can be.

Saudi MOH: 3 New MERS Cases


Daily MERS-CoV reporting from the Saudi MOH continues to be a bit erratic, with updates sometimes posted belatedly, and the English language page occasionally missing reports that are posted on the Arabic page. 
Six days ago, in Saudi MOH Reports 1 New MERS Case & 3 Deaths, I reported on an update for January 13th that appeared on the Arabic list, but not on the English list. That data remains absent on the English language report.

Today the Arabic list shows 3 more MERS cases over three days (18th, 19th, 20th) while the English language list only shows 2 cases (18th & 20th).  It is possible this third case will be added to the English side in the next couple of days.
In any event, between the two lists we have 3 more cases, bringing January's reported total to 16 cases and 11 deaths.
The first case, reported yesterday, is of a 60 y.o. female in critical condition from Al Quryat, is dated the 18th,  and is listed as a primary case (no listed risk exposure).
The second case, dated the 20th on the English list - is dated the 19th on the Arabic list.  This one is a 58 y.o. male from Najran - also a primary case with no risk exposure - listed in stable condition.

The Arabic report for the 20th also appears to be a primary case from near Buraidah.  Since it is in graphic form, translation software won't decipher the details.

Although reports were slow during the month of December, we've seen an uptick in cases since the first of the year.  Of the 16 cases we are aware of in 2018, 3 have been linked to recent camel exposure, 12 are primary (community acquired), and 1 was a secondary HCW exposure.

Exactly how these community acquired cases arise remains a bit of a mystery, although sporadic community transmission from mildly ill or asymptomatic carriers is considered a possibility.
We saw a 2016 study (see EID Journal: Estimation of Severe MERS Cases in the Middle East, 2012–2016) suggesting that as much as 60% severe of Saudi MERS cases go undiagnosed. A 2013 study published in The Lancet Infectious Diseases, that estimated for every case identified, there are likely 5 to 10 that go undetected.
The last WHO EMRO MERS report was for the month of  November, while the last WHO GAR update on MERS was published on December 19th, but only current to December 8th.

Despite this recent uptick, and gaps in the data, the good news is we've seen no signs of any sustained or efficient transmission of the MERS virus outside of health care facilities.
That said, there have been some signs suggesting the MERS virus has gotten a little better at transmitting in the community (see Study: A Pandemic Risk Assessment Of MERS-CoV In Saudi Arabia).
So we keep watch on these reports for any signs that the status quo has changed.

Friday, January 19, 2018

CDC FluView Week #2 - Flu Still Rising


Although there were hopes expressed last week that influenza was beginning to plateau across the nation, today's FluView report shows another hefty increase in outpatient visits for ILI (Influenza-like Illness), and cumulative hospitalizations (all ages) have jumped by nearly 50% (22.7 to 31.5) since last week.

Last week the P&I mortality rate (which lags other data) was at the epidemic threshold of 7.0% for week 51, while this weeks report has it at 8.2% (see below) - well above the epidemic threshold of 7.1% for week 52.

P&I Mortality is a notoriously trailing indicator, and these numbers are subject to revision,  as severely ill patients may survive for days or weeks before succumbing and there are often delays in reporting adult flu deaths.

Sadly, another 10 pediatric flu deaths are reported for week 2. While nationally reportable, these numbers likely only capture 1/2 to 1/3rd of the pediatric flu deaths each year, and we often see belated reporting in this category as well.

 This week's summary from a much longer, and far more detailed report:
2017-2018 Influenza Season Week 2 ending January 13, 2018

All data are preliminary and may change as more reports are received.

During week 2 (January 7-13, 2018), influenza activity increased in the United States.
  • Viral Surveillance: The most frequently identified influenza virus subtype reported by public health laboratories during week 2 was influenza A(H3). The percentage of respiratory specimens testing positive for influenza in clinical laboratories increased.
  • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was above the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
  • Influenza-associated Pediatric Deaths: Ten influenza-associated pediatric deaths were reported
  • Influenza-associated Hospitalizations: A cumulative rate of 31.5 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
  • Outpatient Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) was 6.3%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above region-specific baseline levels. New York City, Puerto Rico, and 32 states experienced high ILI activity; 9 states experienced moderate ILI activity; the District of Columbia and six states experienced low ILI activity; and three states experienced minimal ILI activity.
  • Geographic Spread of Influenza:The geographic spread of influenza in Puerto Rico and 49 states was reported as widespread; Guam reported regional activity; the District of Columbia and one state reported local activity; and the U.S. Virgin Islands reported sporadic activity.

There are reports from some parts of the country that the intensity of flu may be starting to wane.  Even so, there is like another 6 to 10 weeks of flu activity ahead, and the potential for seeing a `second wave' of influenza B or H1N1 later in the spring.

PNAS: Infectious Virus Exhaled In Breath Of Symptomatic Seasonal Flu Cases

Youtube Video (no sound)


Last weekend, in his Virology Down Under blog, Dr. Ian Mackay took a long look at the ways humans shed and spread influenza viruses (see Influenza virus transmission: with or without symptoms, you’re dropping Flu virus). It is an excellent review, well worth reading in its entirety,
Ian looked at both large droplet and fine aerosol transmission from coughing, sneezing and simply just breathing - along with fomite contamination - even from asymptomatic carriers
 While viral RNA had been detected simply from the exhalation of flu victims, Ian cautioned:
Viruses were not able to be grown in culture, or culture was not used in these studies and this is a limitation because we can’t say with certainty that viruses were breathed out during such studies could infect a susceptible person; we don’t know if the positive results mean infectious virus was present.
This is a topic I wrote about a couple of weeks ago myself, while reviewing a Journal of Infectious Disease study (see  J.I.D.: Asymptomatic Summertime Shedding Of Respiratory Viruses).
Well science marches on, and a new study published yesterday in the Journal PNAS (Proceedings of the National Academy of Science) provides additional evidence for, and gives considerable more weight to, the idea that flu carriers exhale substantial quantities of infectious influenza virus
Infectious virus in exhaled breath of symptomatic seasonal influenza cases from a college community

Jing Yana,b, Michael Granthama,1, Jovan Pantelica,2, P. Jacob Bueno de Mesquitaa, Barbara Alberta, Fengjie Liua,3, Sheryl Ehrmanb,4, Donald K. Miltona,5, EMIT Consortium6


Lack of human data on influenza virus aerosol shedding fuels debate over the importance of airborne transmission. We provide overwhelming evidence that humans generate infectious aerosols and quantitative data to improve mathematical models of transmission and public health interventions.
We show that sneezing is rare and not important for—and that coughing is not required for—influenza virus aerosolization. Our findings, that upper and lower airway infection are independent and that fine-particle exhaled aerosols reflect infection in the lung, opened a pathway for a deeper understanding of the human biology of influenza infection and transmission. Our observation of an association between repeated vaccination and increased viral aerosol generation demonstrated the power of our method, but needs confirmation.


Little is known about the amount and infectiousness of influenza virus shed into exhaled breath. This contributes to uncertainty about the importance of airborne influenza transmission. 

We screened 355 symptomatic volunteers with acute respiratory illness and report 142 cases with confirmed influenza infection who provided 218 paired nasopharyngeal (NP) and 30-minute breath samples (coarse >5-µm and fine ≤5-µm fractions) on days 1–3 after symptom onset. We assessed viral RNA copy number for all samples and cultured NP swabs and fine aerosols. 

We recovered infectious virus from 52 (39%) of the fine aerosols and 150 (89%) of the NP swabs with valid cultures. The geometric mean RNA copy numbers were 3.8 × 104/30-minutes fine-, 1.2 × 104/30-minutes coarse-aerosol sample, and 8.2 × 108 per NP swab. Fine- and coarse-aerosol viral RNA were positively associated with body mass index and number of coughs and negatively associated with increasing days since symptom onset in adjusted models.
Fine-aerosol viral RNA was also positively associated with having influenza vaccination for both the current and prior season. NP swab viral RNA was positively associated with upper respiratory symptoms and negatively associated with age but was not significantly associated with fine- or coarse-aerosol viral RNA or their predictors. Sneezing was rare, and sneezing and coughing were not necessary for infectious aerosol generation. Our observations suggest that influenza infection in the upper and lower airways are compartmentalized and independent.
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 The full, open access study can be read here, and it contains  a number of gems. 
  • Men shed influenza viruses in greater quantity than women through fine aerosols.
  • But women cough more frequently
  • Most surprisingly, they observed `6.3 (95% CI 1.9–21.5) times more aerosol shedding among cases with vaccination in the current and previous season compared with having no vaccination in those two seasons.'
This is the first detection of a possible vaccination connection and must be verified by additional studies, and then perhaps a reason can be attached.

In addition to releasing a short video, the University of Maryland School of Public Health published the following press release (see excerpt below) on this new study.  You'll also find a pretty good picture of the Gesundheit II machine they used in their study on their site.

Flu may be spread just by breathing, new study shows; coughing and sneezing not required

January 18, 2018
It is easier to spread the influenza virus (flu) than previously thought, according to a new University of Maryland-led study released today. People commonly believe that they can catch the flu by exposure to droplets from an infected person’s coughs or sneezes or by touching contaminated surfaces. But, new information about flu transmission reveals that we may pass the flu to others just by breathing.


“We found that flu cases contaminated the air around them with infectious virus just by breathing, without coughing or sneezing,” explained Dr. Donald Milton, M.D., MPH, professor of environmental health in the University of Maryland School of Public Health and lead researcher of this study. “People with flu generate infectious aerosols (tiny droplets that stay suspended in the air for a long time) even when they are not coughing, and especially during the first days of illness. So when someone is coming down with influenza, they should go home and not remain in the workplace and infect others.”

Researchers from the University of Maryland, San Jose State University, Missouri Western State University and University of California, Berkeley contributed to this study funded by the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health.

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All of these tests were conducted on symptomatic, flu positive cases and illustrate why it is important to stay home when you are sick, even if you aren't coughing or sneezing up a storm.
What may be a `mild flu' for you could easily be deadly for someone else.
As we've discussed previously, people can spread influenza during the 24 hours before symptoms appear - or may have such minor symptoms as to not realize they are ill - (see PLoS One: Influenza Viral Shedding & Asymptomatic Infections).

While asymptomatic spread still provides a loophole for the virus to spread, this study lends  additional support to the idea of having and wearing simple surgical masks when you are home with the flu and are around other family members - even if you aren't coughing or sneezing. 

But most of all, this study shows us just how easily influenza can spread in the community, even from someone who doesn't appear all that sick.

Thursday, January 18, 2018

Eurosurveillance Review: Association Between Acute Flaccid Myelitis (AFM) & Enterovirus D68 (EV-D68)

AFM Surveillance United States 2014-2017  - Credit CDC


Acute flaccid myelitis (AFM) is a rare polio-like illness that affects a person’s nervous system - specifically the spinal cord - and is characterized by sudden weakness in one or more arms or legs, along with loss of muscle tone and decreased or absent reflexes.

AFM is a subset of conditions that fall under a broader `umbrella' of syndromes called Acute Flaccid paralysis (AFP), which may include myelitis, peripheral neuropathy, myopathy, Guillain-Barré syndrome (GBS), toxic neuropathy, and other muscle disorders.

While the exact causes of Acute flaccid myelitis aren't fully understood, it has been linked to a number of viral infections, including West Nile Virus, Adenoviruses, and a number of (polio and non-polio) enteroviruses, including EV-71 and more recently, EV-D68
A nationwide outbreak of EV-D68 was linked to a concurrent spike in AFP cases across the United States in the fall of 2014, and while a pretty strong circumstantial case has been made over the past couple of years (see EID Journal Enterovirus D68 Infection in Children with Acute Flaccid Myelitis, Colorado, USA, 2014), no definitive causal link to EV-D68 has been established.
Since then we've seen a number of EV-D68 outbreaks around the world (see here, here & here) where a concurrent spike in AFM cases have also been reported. 
Today the ECDC's Eurosurveillance Journal has a review of the literature, and an examination of the available evidence using the Bradford Hill criteria, that attempts to establish a potential link between EVD68 infection and AFM.

The authors found that analysis based on the Bradford Hill criteria suggested good evidence for EV-D68 being a cause of AFM.  Today's review is a lengthy, detailed one, which most of my readers will want to read it in its entirety.

The link and a few small excerpts follow:
The association between acute flaccid myelitis (AFM) and Enterovirus D68 (EV-D68) – what is the evidence for causation?  

Amalie Dyda1, Sacha Stelzer-Braid2,3, Dillon Adam1, Abrar A Chughtai1, C Raina MacIntyre1,4
Historically, the incidence of EV-D68 has been low, with sporadic cases and small clusters of mild illness reported. Whether this represents under-ascertainment or true low incidence in the past is unclear, but active EV surveillance studies in several countries including Germany in 2013-14, Hong Kong in 2014, France in 2014 and China in 2011-15 suggest that EV-D68 was a rare cause of clinical infection in the past [18-21]. Since 2014, the number of reported infections and clusters has increased. In addition, severe complications including AFM have been reported since 2014 [3]. Several clusters of AFM in recent years were associated with EV-D68 and a large outbreak of EV-D68 in 2014 in the US was associated with severe respiratory illness.

Our application of the Bradford Hill criteria suggested good evidence for EV-D68 being a cause of AFM. While EVs in general are neurotropic, AFM has never previously been associated with EV-D68. It could be that incidence of EV-D68 was genuinely been much lower in the past, so that rare complications of infection have not been apparent. An analogous example is the association between Zika virus and microcephaly which was only recognised during a large-scale epidemic in Brazil in 2015 [62,63]. However, retrospective analysis of a large outbreak of Zika virus in French Polynesia two years earlier showed the same association with microcephaly but was not recognised at the time [64]. In addition, clades A, B and B1 of EV-D68 were highly neurovirulent in animal studies, with specific tropism for motor neurons [47]. It appears that these strains which evolved after the year 2000 are capable of causing AFM, as demonstrated in a mouse model, while the original Fermon and Rhyne strains do not cause AFM [47].

There is a need for phylogeographic epidemiology to ascertain temporal and geographic changes in the virus and whether such changes could explain why AFM is newly associated with the virus. Genetic changes in the virus which have rendered it more neuropathic could explain the association, and several clades have been shown to be highly neurovirulent. Phylogenetic studies have demonstrated that strains isolated in recent outbreaks are very divergent from the original Fermon strain isolated in 1962 [15]. Clades B1 and B2 caused the 2014 outbreak [30] and clade B3 caused an outbreak of severe EV-D68 infection in the Netherlands in 2016 [17]. Strains in clade B1 have mutations in structural and non-structural proteins, which could play a role in the reported neurovirulence of these strains [12], and all EV-D68-infections in human AFM cases were attributed to clade B. However, mouse studies showed that multiple clades (A, B and B1) cause paralysis [47]. The observation that clade B1 was associated with AFM in 2014 may be due to the much higher incidence of clade B1 infection in 2014. More research is needed to study biological gradient and to quantify measures of association between EV-D68 and AFM.

Given that the association of AFM with EV-D68 is recent, there is a strong case for systematic and enhanced EV surveillance, which will enable investigation of epidemiological data for measures of association. While past studies and EV surveillance showed that EV-D68 was a rare cause of EV infection, there has been a change in disease epidemiology since 2014, including a rise in the incidence of clade B infections. The lack of association between AFM cases and EV-D68 in the US in 2015 and 2016 [11] does not detract from our analysis, as AFM is a clinical syndrome with multiple possible aetiologies. More recent AFM cases could be due to a different aetiology, as other EVs continue to cause AFM, or could reflect the difficulty in isolating the virus from tissue and CSF. The Bradford Hill criteria are a tested and systematic method for evaluating causality and could be applied to other EVs.
In summary, the application of the Bradford Hill criteria suggests that EV-D68 causes AFM. AFM has not previously been associated with EV-D68, and a mouse model shows that the original Fermon strain does not cause AFM, whereas the 2014 outbreak strain does [47]. It appears that the incidence of this infection and the clade-specific epidemiology have changed. Phylogeographic epidemiology will further our understanding of the temporal and spatial spread of increasingly neurovirulent clades and improve risk analysis. Further investigation into this relationship is important because of the severity of AFM, ongoing outbreaks of AFM and because there is currently no treatment for AFM related to EV-D68, and no vaccine to prevent infection [24,65].
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Hong Kong Flu Express: Influenza B Ramps Up


Hong Kong, which saw a relatively mild winter flu season last year - followed by an unusually severe H3N2 summer flu (see chart above) - entered back into their 2018 winter flu epidemic a little over a week ago, this time with influenza B leading the charge. 
Although Influenza B is generally regarded as being less severe than Influenza A, it can still exact a heavy toll, particularly on small children and the elderly. 
Today the HK CHP released their week 2 Flu Express report, and it shows increasing flu activity.  During week 2 and the first 4 days of week 3 (January 7th - 18th), Hong Kong has seen 24 flu deaths, including 1 pediatric fatality.

Flu Express is a weekly report produced by the Respiratory Disease Office of the Centre for Health Protection. It monitors and summarizes the latest local and global influenza activities.

Local Situation of Influenza Activity (as of Jan 17, 2018)
Reporting period: Jan 7 – 13, 2018 (Week 2)

  • The latest surveillance data showed that the local influenza activity continued to increase. Currently the predominating virus is influenza B.
  • Influenza can cause serious illnesses in high-risk individuals and even healthy persons. Given that seasonal influenza vaccines are safe and effective, all persons aged 6 months or above except those with known contraindications are recommended to receive influenza vaccine to protect themselves against seasonal influenza and its complications, as well as related hospitalisations and deaths.
  • Apart from adopting personal, hand and environmental hygiene practices against respiratory illnesses, those members of the public who have not received influenza vaccine are urged to get vaccinated as soon as possible for personal protection.
  • The Vaccination Subsidy Scheme (VSS) and the Government Vaccination Programme (GVP) for the 2017/18 season have been launched on Oct 18 and Oct 25, 2017 respectively. The VSS continues to provide subsidised vaccination to children aged 6 months to under 12 years, elderly aged 65 years or above, pregnant women, persons with intellectual disabilities and recipients of Disability Allowance. Eligible groups for free vaccination are the same as those of 2016/17 under the GVP. For more details, please refer to the webpage
Since the start of the 2017/18 winter influenza season in week 2, 41 adult cases of ICU admission/death with laboratory confirmation of influenza were recorded, in which 23 of them were fatal (as of January 17). Among them, 34 patients had infection with influenza B, 5 patients with influenza A(H1N1)pdm09, one patient with influenza A(H3N2) and one patient with influenza A pending subtype.
In week 2 and the first 4 days of week 3 (Jan 14 to 17), there were three cases of severe paediatric influenza-associated complication/death, in which one of them was fatal.               

Global Situation of Influenza Activity
  • In Mainland China (week ending Jan 7, 2018), the influenza activity in both southern and northern provinces was at the seasonal level for winter influenza season, and was still on an increasing trend. In southern provinces, the proportion of ILI cases in emergency and outpatient departments reported by sentinel hospitals was 6.0%, higher than that reported in the previous week (5.5%) and that in the corresponding period in 2014-2016 (3.0%, 3.2%, 3.3%). In northern provinces, that proportion was 5.8%, higher than that reported in the previous week (5.5%) and that in the corresponding period in 2014-2016 (4.1%, 2.9%, 3.8%). The proportion of influenza detections in the week ending January 7, 2018 was 44.8%. The most common influenza virus detected currently was influenza B.
  • In Macau (week ending Jan 6, 2018), the proportions of ILI cases in emergency departments among both adults and children increased. The proportion of influenza detections was 32.2%, an marked increase from 17.0% in the previous week.
  • Taiwan (week ending Jan 13, 2018) was at influenza season. In the week ending January 13, the proportion of ILI cases in emergency department was 13.18% which was above the threshold of 11.4%. The predominating virus was influenza B.
  • In Japan (week ending Jan 7, 2018), the influenza season has started in late November 2017. The average number of reported ILI cases per sentinel site slightly decreased to 16.31 in the week ending January 7, 2018, which was higher than the baseline level of 1.00. The most frequently identified influenza virus type in the past five weeks was influenza A(H1N1)pdm09, followed by influenza B and A(H3N2).
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