Wednesday, October 05, 2022

HK CHP: A Cryptic Report of A 2nd H10N3 Case On the Mainland


Global tensions being what they are, and with the highly sensitive 20th National Congress of the Chinese Communist Party set for mid-October, in 2022 we've been getting considerably less information out of China on their `bird flu problem' than in recent years.

Reports, when we get them, are often delayed by weeks or even months, and are often lacking in detail (see  HK CHP Monitoring Human H5N6 Infection On The Mainland (Guangxi)).

Today, we've a cryptic mention (see above) of a 2nd H10N3 case in China in this week's Avian Influenza Report from Hong Kong's CHP; a simple line listing, with no other details offered, of a case with an onset date nearly 4 months ago. 

In June of 2021 (see CHINA NHC Reports 1st Human H10N3 Avian Flu Infection - Jiangsu Province) China's National Health Commission made a very brief announcement on the first known human infection with avian H10N3. In that case, notification occurred just over a month after the patient was admitted to the hospital (April 28th, 2021).

On June 10th, 2021 the WHO published their Risk Assessment On Human Avian H10N3 Infection In China:


The case is a 41-year-old male from Zhenjiang City, Jiangsu Province. He developed fever and nausea on 23 April 2021 and was admitted to the intensive care unit of a local hospital on 28 April 2021. The case is currently in a stable condition. The National Influenza Center of the Chinese Center for Disease Control and Prevention, a WHO Collaborating Centre for Reference and Research on Influenza, completed genetic sequencing and analysis of the specimen and confirmed the detection of an influenza A(H10N3) virus of avian origin.

The case had no clear history of exposure to poultry prior to illness onset, based on epidemiological investigation. No avian influenza A(H10N3) virus has been found in the local surroundings or poultry. Close contacts of the case have not shown any symptoms. Based on the local and national assessment, the case was considered to be an incidental infection from avian to human transmission, with a low likelihood of human-to-human transmission.

The first known human H10 infections were reported in 2004 (see Avian Influenza Virus A (H10N7) Circulating among Humans in Egypt) , followed in 2012 by a limited outbreak among workers at a chicken farm in Australia (see in EID Journal: Human Infection With H10N7 Avian Influenza).

Most of these avian flu infections were mild or asymptomatic, and self limiting. Often only producing conjunctivitis or mild flu-like symptoms.

But in late 2013 a new H10N8 virus emerged in Mainland China (see Lancet: Clinical & Epidemiological Characteristics Of A Fatal H10N8 Case) infecting three people, killing at least two.

While the number of reported H10 infected humans remains small - possibly due to a lack of surveillance and testing - in 2014's BMC: H10N8 Antibodies In Animal Workers – Guangdong Province, China, we saw evidence that people may have been infected with the H10N8 virus in China before the first case was recognized.

Today's announcement follows two recent reports of avian H3N8 infection on the Mainland (see here, and here) and the discovery of Novel Zoonotic Avian Influenza Virus A(H3N8) Virus in Chicken, Hong Kong, China.  

We've also seen roughly 50 H5N6 cases over the past year, and a small number of H9N2 infections.

Surveillance and testing is limited in China, and officials are often reluctant to report `bad news', meaning we are probably only seeing the tip of the iceberg.  

Hopefully we'll get more details on this latest case sooner rather than later. 

That Was The Flu Year That Was

OVER 300,000 US COVID Deaths In last 12 Months


In a normal, non-pandemic year, seasonal flu kills roughly as many Americans as does gun violence, or car accidents. In a bad year - such as we saw in 2017-2018, influenza can kill as many as both of those combined.

Since the emergence of COVID in early 2020, seasonal influenza has been greatly suppressed, although over the past 12 months we did see a relatively mild H3N2 flu season.  

For those who consider COVID nothing worse than the `flu', over the past 12 months roughly 300,000 Americans died from the coronavirus - more than 5 times more than would be expected from a severe flu season.

But I digress. 

This fall and winter, if the recent flu season in Australia - and summer outbreaks in China and Vietnam - are any gauge, we may see a much more robust flu/COVID season.  But flu seasons are highly unpredictable, and can change course abruptly. 

Yesterday the CDC released a (belated) preliminary assessment of the 2021-2022 flu season, one that while mild, extended unusually well into the summer months. As we've discussed often (see Why Flu Fatality Numbers Are So Hard To Determine), the CDC can only make educated estimates on the burden of influenza.

But based on their analysis, the CDC estimates seasonal influenza over the 2021-2022 season caused 9 million illnesses, 4 million medical visits, 100,000 hospitalizations, and 5,000 deaths.

Some excerpts from the CDC's analysis follows (note: the 10K hospitalizations in the conclusion is a typo, and should read 100K)I'll return with a bit more after the break.  

Preliminary Estimated Influenza Illnesses, Medical visits, Hospitalizations, and Deaths in the United States – 2021-2022 influenza season

The overall burden of influenza (flu) for the 2021-2022 season was an estimated 9 million flu illnesses, 4 million flu-related medical visits, 100,000 flu-related hospitalizations, and 5,000 flu deaths (Table 1).

For the past several years, CDC has used a mathematical model to estimate the numbers of influenza illnesses, medical visits, hospitalizations, and deaths (1-4). The methods used to calculate the estimates have been described previously (1-2). CDC uses the estimates of the burden of flu in the population to inform policy and communications related to influenza prevention and control.

2021–2022 Burden Estimates

Since the emergence of SARS-CoV-2, influenza activity has been lower than observed before the pandemic. Compared with influenza seasons prior to pandemic, the 2021–2022 influenza season was mild and occurred in two waves, with a higher number of hospitalizations in the second wave. Influenza activity in the United States during the 2021–2022 season began to increase in November, declined in January 2022, increased again in March 2022 and remained elevated until mid-June 2022. The season was characterized by two distinct waves and predominately influenza A virus circulation. Overall, influenza A(H3N2) viruses were the most commonly detected influenza viruses this season. The 2021-22 season is described as having low severity**; however, the effect of influenza differed by age group and the severity of the season in some age groups was higher– hospitalization rates among older adults aged ≥65 years old were higher compared with other age groups (5).

CDC estimates that the burden of illness during the 2021–2022 season was low with an estimated 9 million people sick with flu, 4 million visits to a health care provider for flu, 100,000 hospitalizations for flu, and 5,000 flu deaths (Table 1). The number of cases of influenza-associated illness, medically attended illnesses, hospitalizations, and deaths were the lowest since the 2011-2012 season which was the first full season following the influenza A(H1N1)pdm09 pandemic (6). Adoption of mitigation measures intended to prevent the spread of COVID-19 may have also impacted the timing or severity of influenza activity during the 2021-2022 season.

CDC’s estimates of hospitalizations and mortality associated with the 2021–2022 influenza season show that despite the co-circulation of SARS-CoV-2 and other respiratory viruses, influenza viruses do still cause severe disease and death. Older adults accounted for 83% of deaths, which is similar to recent seasons before the COVID-19 pandemic. These findings continue to highlight the fact that older adults are particularly vulnerable to severe disease with influenza virus infection and that influenza prevention measures such as vaccination are important to reducing the impact of the seasonal epidemics on the population and healthcare system.

Deaths in children with laboratory-confirmed influenza virus infection have been a reportable disease in the United States since 2004; 39 deaths were reported for the 2021-22 season as of September 24, 2022. Although it is possible that reported deaths may under-estimate the true number of deaths for this age group, no deaths in children (aged <18 years) were observed through the Influenza Hospital Surveillance Network (FluSurv-NET) during the 2021-2022 influenza season. As a result, it was not possible to estimate deaths in this age group.


During the 2021-2022 influenza season, CDC estimates that influenza was associated with 9 million illnesses, 4 million medical visits, 10,000 hospitalizations, and 5,000 deaths. The influenza burden was similar to the burden observed during the 2011-2012 season.

** Some parameters for evaluation influenza season severity were updated staring in 2021-22. More information is available.

          (Continue . . . )

Yesterday the CDC announced their 2022-2023 Flu Vaccination Campaign Kickoff amid concerns that fewer Americans will roll up their sleeves for the flu vaccine this fall.  An NFID (National Foundation For Infectious Diseases) poll, released this week, suggest that only 49% of U.S. adults plan to get the flu shot this year. 

Following a mild flu season in 2021-2022, NFID survey shows only 49% of US adults plan to get a flu vaccine this season

Contact: Diana Olson,, 301-656-0003 x140

Bethesda, MD (October 4, 2022)—With a potentially severe respiratory season ahead, about half of all US adults remain vulnerable to influenza (flu), according to new data released today by the National Foundation for Infectious Diseases (NFID). The new NFID survey of US adults found that only 49% plan to get a flu vaccine during the 2022-2023 flu season. Leading health experts from NFID and the Centers for Disease Control and Prevention (CDC) are urging everyone age 6 months and older to get vaccinated against flu now, amid concerns of a potentially severe season in the US.

Between pandemic and COVID booster fatigue, coming off an exceedingly mild flu year, and several years of lackluster flu vaccine effectiveness (VE) particularly against H3N2 (see here, here, and here), it is easy to understand why some people may be inclined to skip this year's shot. 

Despite these disincentives, I've already gotten my shot this year, and encourage others to do so as well. 

First, a mild flu season last year doesn't guarantee a repeat this year, and no one is sure what a severe flu/COVID season will look like.  Some studies suggest co-infection produces more severe illness, while others do not. 

This year, we are also on heightened alert for human infection with novel swine variant and avian influenza viruses.  While the seasonal flu shot isn't designed to protect against either of these novel viruses, bad things can happen when an individual is infected with a seasonal and novel virus at the same time. 

A novel/seasonal flu reassortment is not a new concern, nor is this scenario limited to H5N1, or a swine variant virus. Anytime two different flu viruses inhabit the same host (human, avian, porcine, etc.) at the same time, the potential for seeing a reassortant virus exists (see MMWR: Seasonal H3N2 & H1N1pdm09 Reassortant Infection — Idaho, 2019).

Most reassortments end up as evolutionary failures, but every once in a while a genetic winner emerges. And given the events of the past couple of years, there is no sense aiding and abetting these viral contenders. 

Admittedly, the seasonal flu shot isn't as effective as we'd like, but most years it provides moderate protection against infection, and for those over 65, there are more effective high-dose and adjuvanted vaccines available.  

Even when the flu shot doesn't prevent infection, there is growing evidence it can reduce the severity of one's illness, and reduce your odds of having a heart attack or stroke (see Study Suggests Flu Vaccine May Lower Stroke Risk in Elderly ICU Patients).

While the current flu vaccine is far from perfect, and can’t promise 100% protection, it – along with practicing good flu hygiene (washing hands, covering coughs and/or wearing a mask & staying home if sick) – remains your best strategy for avoiding the flu and staying healthy this winter. 

COCA Call Tomorrow (Oct 6th): Situational Update for Clinicians About Severe Monkeypox Virus Infections


A week ago, while this blog was offline due to Hurricane Ian, the CDC released a HAN Advisory (see below) detailing severe presentations of Monkeypox infection among immunocompromised individuals.

Health Alert Network (HAN) No. 475 – Severe Manifestations of Monkeypox among People who are Immunocompromised Due to HIV or Other Conditions 09/29/2022 2:15 PM

Tomorrow (Oct 6th) the CDC will hold a follow up COCA Call for clinicians (details below) where presenters from the CDC and various medical institutions will provide their experiences treating severe monkeypox infection, and review the latest treatment and prevention information. 

These 1-hour presentations are usually technical in nature, and are of greatest interest to clinicians and healthcare providers, but also may be of interest to others.

 If you are unable to attend the live presentation, these (and past) webinars are always archived and available for later viewing at this LINK.   

Situational Update for Clinicians about Severe Monkeypox Virus Infections


This COCA Call supports and expands on the Centers for Disease Control (CDC) Health Alert Network (HAN) Health Advisory released on September 29, 2022, about people experiencing severe manifestations of monkeypox and medical countermeasures available to treat people who have monkeypox.
  1. The HAN Health Advisory informs healthcare providers that Severe manifestations of monkeypox have been observed in the United States in the current outbreak.
  2. People who are immunocompromised due to HIV or other conditions are at higher risk for severe manifestations of monkeypox than people who are immunocompetent.
  3. Because people with HIV-associated immunocompromise are at risk for severe manifestations of monkeypox, the HIV status of all sexually active adults and adolescents with suspected or confirmed monkeypox should be determined.
  4. There are diagnostic and clinical management strategies that may help address severe manifestations of monkeypox.
During this COCA Call, presenters from CDC, the Los Angeles County Department of Public Health, and Emory University will share an update about people with monkeypox who have severe manifestations of the disease. Presenters will also describe the clinical courses of two patients with monkeypox, review interventions to prevent and treat monkeypox with antiviral therapy, discuss updated information about the risk of monkeypox transmission, and provide new guidance on selecting a site on the body when administering the vaccine intradermally.


Agam Rao, MD, FIDSA
CAPT, U.S. Public Health Service
Subject Matter Expert, Vaccine Task Force and Clinical Task Force
2022 Multinational Monkeypox Response
Centers for Disease Control and Prevention

Caroline Schrodt, MD, MSPH
LCDR, U.S. Public Health Service
Lead, Clinical Escalations Team
2022 Multinational Monkeypox Response
Centers for Disease Control and Prevention

Jemma Alarcón, MD, MPH
Los Angeles County Department of Public Health
Epidemic Intelligence Service Officer
2022 Multinational Monkeypox Response
Centers for Disease Control and Prevention

Alexandra Dretler, MD
Adjunct Professor
Infectious Diseases
Emory University

Call Materials

Please check back later.

Call Details

Thursday, October 6, 2022,
2:00 PM – 3:00 PM ET

Webinar Link:

Webinar ID: 161 725 6559

Passcode: 319509

US: +1 669 254 5252 or +1 646 828 7666 or +1 669 216 1590 or +1 551 285 1373

International numbers

One-tap mobile:
US: +16692545252,,1617256559#,,,,*319509# or +16468287666,,1617256559#,,,,*319509#

Tuesday, October 04, 2022

Post-Disaster Sequelae

430K Customers Still Without Power


The common denominator across nearly all natural (and many man-made) disasters is that the power - and by extension water, internet, banking, cell service and other essentials - will go out. Often for hours, days, or even weeks. 

While I got very lucky and ended up on the northern fringe of Hurricane Ian - and my power was restored in less than 48 hours - hundreds of thousands of my fellow Floridians to my south are now in their 6th day of darkness. 

Although remarkable progress is being made in the restoration of power, many may be without electrical service for weeks, possibly months. 

Making matters worse, hundreds of communities in 25 Florida counties who are lucky enough to have running water, are under boil water notices. A task made doubly difficult when the power is out.  For many, sanitary sewers are backed up or offline as well. 

Living under these conditions is hard, dirty, tedious and sometimes even dangerous. 

Many have lost their businesses or source of employment. And for those whose homes are damaged, and are in a queue of thousands of others waiting for insurance adjusters, settlements and repairs, it can be demoralizing as well. 

We tent to regard the first 24 hours of a hurricane's impact as being the most dramatic and newsworthy, but the real impact comes in the days, weeks, and months that follow. 

The loss in terms of mortality, morbidity and permanent disability, PTSD, homes and belongings, businesses, jobs and life savings, and continuity of a community are never fully tallied or appreciated.

We've looked at some of these after effects in the past.

There are always the usual post-disaster accidents; drownings, carbon monoxide poisoning from using charcoal or generators indoors. Falls from roofs or ladders from clearing debris, or chain saw accidents. And even skin infections and food poisoning from contaminated waters (see After The Storm Passes). 

But there are some other post-disaster impacts that have only recently become well acknowledged. 

In March of 2009, in a study led by Dr. Anand Irimpen (Associate Professor of clinical medicine at Tulane), it was disclosed that residents of New Orleans saw a 300% increase in heart attacks in the first 2 years after hurricane Katrina.

A follow up, published in 2014 (see Tulane University: Post-Katrina Heart Attack Rates - Revisited), once again found the impact of Katrina on cardiac health remained pronounced.

In the wake of Hurricane Katrina, a study funded by the National Institute of Mental Health, which surveyed 1,043 survivors,  found:

  • More than 11% were diagnosed with a serious mental illness following the storm. This compares to just over 6% before the hurricane.
  • 9.9% had mild-moderate mental illness, compared to 9.7% before Katrina.
  • They estimated  200,000 people facing serious mental problems, such as PTSS (Post Traumatic Stress Syndrome) and depression, in the three states most affected.

In 2014, in Post-Disaster Stress Cardiomyopathy: A Broken-Hearted Malady, we looked at a rare condition known as Takotsubo cardiomyopathy – or stress induced cardiomyopathy which is often linked to extreme grief or stress, as might be experienced following a disaster.

Also known as broken heart syndrome, this acute ballooning of the heart ventricles is a well-recognized cause of acute heart failure and dangerous cardiac arrhythmia's. 

While often hidden from view, the psychological impact of a disaster can be enormous and ongoing. In 2011, in Post Disaster Stress & Suicide Rates, we looked at the impacts of disaster-related PTSD (Post Traumatic Stress Disorder). 

Living as I do in hurricane country, I've made it a point to have a disaster plan, a disaster buddy, a bug-out destination, and the things I would need to survive without electricity, running water, open grocery stores or pharmacies for a week or longer: 

  • A battery operated NWS Emergency Radio to find out what was going on, and to get vital instructions from emergency officials
  • A decent first-aid kit, so that you can treat injuries
  • Enough non-perishable food and water on hand to feed and hydrate your family (including pets) for the duration
  • A way to provide light when the grid is down.
  • A way to cook safely without electricity
  • A way to purify or filter water
  • A way to handle basic sanitation and waste disposal. 
  • A way to stay cool (fans) or warm when the power is out.
  • A small supply of cash to use in case credit/debit machines are not working
  • An emergency plan, including meeting places, emergency out-of-state contact numbers, a disaster buddy, and in case you must evacuate, a bug-out bag
  • Spare supply of essential prescription medicines that you or your family may need
  • A way to entertain yourself, or your kids, during a prolonged blackout

I do this not only for my physical health and comfort, but for my mental health as well. I sleep better at night knowing I'm prepared for the worst, and if it happens, I'll be less stressed and less challenged than had I not prepared. 

I'm not as young, or as physically able, as I used to be.  I realize that conditions I might have tolerated when I was 30 are a lot harder to deal with, now that I'm nearing 70.

You don't have to live in Hurricane country to battered by a natural disaster. Earthquakes, floods, tornadoes, tsunami's, blizzards, volcanic eruptions, and even solar storms can strike with little or no warning.  

Preparedness is cheap insurance.  A good place to get started is READY.GOV

 For more on dealing with the trauma of a disaster, the CDC has a website geared to post-disaster stress.

Coping with a Disaster or Traumatic Event

The outbreak of coronavirus disease 2019 (COVID-19), may be stressful for people and communities.

Learn more about coping during COVID-19.

During and after a disaster, it is natural to experience different and strong emotions. Coping with these feelings and getting help when you need it will help you, your family, and your community recover from a disaster. Connect with family, friends, and others in your community. Take care of yourself and each other, and know when and how to seek help.

People with preexisting mental health conditions should continue with their treatment plans during an emergency and monitor for any new symptoms. Additional information can be found at the Substance Abuse and Mental Health Services Administration (SAMHSA) website.

Explore the resources below to learn how to cope and take care of yourself and each other during an emergency. 

Taking Care of Your Emotional Health

Helping Children Cope

Planning Resources for State and Local Governments

Response Resources for Leaders

Responders: Tips for Taking Care of Yourself

A small reminder that in the wake of a disaster not all wounds bleed, not all fractures show up on an X-ray, and that the best treatment doesn't always come from inside your first aid kit. 

Study: Influenza A (H6N6) Viruses Isolated from Chickens Replicate in Mice and Human lungs Without Prior Adaptation


When we talk about avian flu viruses with zoonotic (or even pandemic) potential, the various incarnations of H5N1 first come to mind, followed perhaps by China's H7N9 virus. Between them they have caused thousands of infections and hundreds of deaths during the 21st century, but reports of both have declined sharply in recent years. 

H5N6, also from China, continues to worry researchers, with 80 cases reported on the Mainland since 2014 (see map below) and a high fatality rate (40%-50%).   

LPAI H9N2 has caused roughly 100 known infections (and undoubtedly many more undiagnosed), primarily is Asia, but generally produces mild to moderate illness.  To that we can add sporadic human infections by H10Nx and H7N4 viruses in China, H7N2 (infecting cats and humans in NYC), and this year, China reported the first two known infections by avian H3N8 (see IJID: A Review Of The Pandemic Potential Of Avian H3N8). 

There are a lot of novel avian flu viruses with zoonotic potential (that, along with swine variant viruses), could spark the next global health crisis. 

Including H6 viruses, which don't get a lot of attention, but are common in both wild birds globally and in domesticated poultry in China, and have demonstrated the ability to jump species (to humans, to pigs, and to dogs) as well.  Some past blogs include:

But since H6 viruses only rarely produce clinical illness in poultry, and are not legally reportable to the OIE (now WOAH), we are only rarely aware of their presence, or of the potential threat they may pose. 

Two years ago, in Nature: Evolution & Pathogenicity of H6 Avian Influenza Viruses, Southern China 2011-2017we looked at study on the evolution of H6 viruses in China, and their growing adaptation to mammalian physiology.

Today we have another study published in the Journal of Virus Eradication, which warns that H6N6 viruses continue to evolve, and are becoming better adapted to human physiology, and that their threat to human health may be increasing.

This is a lengthy, and quite detailed, open-access report and I've only posted some highlights. Follow the link to read it in its entirety.  I'll have a brief postscript when you return. 

Influenza A (H6N6) viruses isolated from chickens replicate in mice and human lungs without prior adaptation

Weijuan Zhong Lingxi Gao Xijing Wang Shanggui Su  Yugui Lin  Kai Huang Siyu Zhou Xiaohui Fan Zengfeng Zhang 


The H6H6 subtype avian influenza virus (AIV) is currently prevalent in wild birds and poultry. Its host range has gradually expanded to mammals, such as swines. Some strains have even acquired the ability to bind to human-like SAα-2,6 Gal receptors, thus increasing the risk of animal to human transmission. To investigate whether the H6N6 AIV can overcome interspecies barriers from poultry to mammals and even to humans, we have assessed the molecular characteristics, receptor-binding preference, replication in mice and human lungs of three chicken-originated H6N6 strains. 

Among these, the A/CK/Zhangzhou/346/2014 (ZZ346) virus with the P186T, H156R, and S263G mutations of the hemagglutinin molecule showed the ability to bind to avian-like SAα-2,3 Gal and human-like SAα-2,6 Gal receptors. Moreover, H6N6 viruses, especially the ZZ346 strain, could replicate and infect mice and human lungs. Our study showed the H6N6 virus binding to both avian-like and human-like receptors, confirming its ability to cross the species barrier to infect mice and human lungs without prior adaptation. This study emphasizes the importance of continuous and intense monitoring of the H6N6 evolution in terrestrial birds.



The H6N6 subtype AIV is widely prevalent in poultry, and its host range has expanded to mammals. Undoubtedly, it has become an endemic disease of domestic fowl and animals. Here, three chicken-originated H6N6 subtypes of AIV were of multiple reassortment viruses, with gene segments derived from the Gr(SNIP)oup-II (ST2853-like) of Eurasian lineages. Terrestrial birds may be an intermediate host in the cross-species transmission of the influenza virus from birds to humans.35,36 At the same time, molecular epidemiological investigations have shown that the H6N6 subtype AIV is prevalent in terrestrial chickens.14 Therefore, the H6H6 virus in chickens may acquire the potential to infect humans.

The switch of the receptor-binding preference from the avian-like SAα-2,3 Gal to the human-like SAα-2,6 Gal receptor is a key factor in AIV crossing interspecies barriers and efficiently transmitting to humans. The receptor-binding domains in the head of the influenza virus HA can specifically recognize and bind to the avian-like SAα-2,3 Gal and/or human-like SAα-2,6 Gal receptors; yet, the molecular mechanism of receptor-binding preference switch in different avian influenza virus subtypes needs to be further elucidated. The H5N1 HA with the N224K/Q226L mutations has a key role in switching the receptor-binding preference from the avian-like SAα-2,3 Gal to the human-like SAα-2,6 Gal receptor.37 The HA with the Q226L and G186V mutations in the H7N9 virus could result in virus binding to the human-like receptors, and the H6N6 HA with the S137 N, E190V, and G228S mutations is essential in the process of acquiring the ability to recognize human-like virus receptors.38, 39, 40


The first case of human infection with the H6N1 avian influenza virus was reported on May 20, 2013, in Taiwan.5 The emergence of human cases infected with H6N1 shows the unpredictability of influenza virus transmission and the potential threat from novel viruses. Some studies have reported that the influenza virus responsible for a pandemic is generated by avian-human (or-swine) influenza A virus reassortments,43 but the AIV involved in the reassortment is not necessarily a highly pathogenic one. Moreover, mild symptoms caused by low pathogenic viruses can be easily overlooked, increasing the chances of virus spread, adaptive mutation, and reassortment. Currently, prevention and control of the influenza pandemic are mainly focusing on the H5N1 and H7N9 subtypes which cause severe human disease and deaths. However, due to the unpredictability and gaps in knowledge about influenza, we cannot predict which subtype of the influenza A virus will cause the next pandemic.

Although the H6N6 virus has low pathogenicity, it is widely prevalent in poultry. It has repeatedly infected swines, with the potential to evolve into a novel influenza virus infecting human beings. Therefore, this study has confirmed that some chicken-originated H6N6 viruses might acquire the ability to recognize and bind to human-like receptors, thus increasing risk to humans. Our study emphasizes the importance of continuous and intensive monitoring of these viruses evolution to prevent transmission to humans.

          (Continue . . . )

While avian H6 viruses don't get a lot of press, and aren't represented on the CDC's IRAT (Influenza Risk Assessment Tool) list of novel flu viruses with pandemic potential - they continue to reassort, evolve, and spillover into non-avian species - making them very much worthy of our attention. 

Monday, October 03, 2022

Denmark's SSI Issues Warning On Legionella in Hot Water Systems


Legionella Bacteria - Photo Credit CDC PHIL


While not a scientific law like Boyle's law or Torricelli's law, the Law of Unintended Consequences can be pretty much counted on turn up anytime you think some new idea will `fix things'.

One famous example was the introduction of South American Cane Toads to Australia in 1935 to control a pesky sugar cane beetle, which backfired when these poisonous, and highly promiscuous, invasive amphibians began to crowd out or kill other native species.  

With Europe facing an unprecedented energy crisis this winter, there are now calls for Europeans to begin conserving energy in every way possible (see Euronews Energy crisis: Europeans 'must lower thermostats to prepare for Russia turning off gas supplies). Today Denmark's SSI (Statens Serum Institut) has issued a warning on a potential adverse health risk from lowering the thermostats on hot water systems; Legionella. 

First a little background. 

Legionella bacteria thrives in warm water, such as is commonly found in air-conditioning cooling towers, hot tubs, hot water systems, and even ornamental water fountains. When water is sprayed into the air the bacteria can become aerosolized and inhaled. 

Those who are susceptible (often smokers, the elderly and the immunocompromised, etc.) can develop serious – even life threatening – pneumonia.

We know Legionella to be a major cause of infectious pneumonia, and that it sometimes sparks large outbreaks of illness. According to the CDC between 8,000 and 18,000 Americans are hospitalized with Legionnaire's Disease each year, although the actual number of infected is likely higher.

The CDC's website Controlling Legionella in Potable Water Systems recommends (among many other actions):

  • Store hot water at temperatures above 140°F (60°C) and ensure hot water in circulation does not fall below 120°F (49°C). Recirculate hot water continuously, if possible.
  • Store and circulate cold water at temperatures below the favorable range for Legionella (77–113°F, 25–45°C); Legionella may grow at temperatures as low as 68°F (20°C).
All of which brings us to the following warning, issued by Denmark's SSI, on the risks of turning down the temperature of hot water systems.
Energy conservation can cause growth of Legionella in hot water systems

The Danes must be careful that their attempts to save energy and money do not lead to the growth of Legionella here during the current energy crisis. Statens Serum Institut warns against lowering the temperature too much.
Last edited on October 3, 2022

Due to the current energy crisis, the authorities have various proposals for, and requirements for, saving on energy. Among other things, you can lower the temperature in hot water systems, and you can use less hot water by e.g. taking shorter baths, washing your hands in cold water and installing water-limiting measures, e.g. energy-saving showers.

However, both parts can contribute to increased growth of Legionella pneumophila in the water systems with a risk of infection and disease. It is therefore important that Danes think carefully before saving on energy.
Hot water systems can cause severe pneumonia

Most of our hot water systems contain Legionella pneumophila . The bacterium can cause a serious pneumonia called Legionnaires' disease. Infection occurs by inhaling atomized water that is contaminated with the bacteria, e.g. while showering.

"The disease particularly affects elderly and debilitated people and causes up to 300 hospitalizations per year, but the bacterium is presumably the cause of far more mild cases of the disease, also in younger people. Since the bacteria are common in our hot water systems, it is important to limit their growth. This happens at home primarily by ensuring that cold water is no more than 20 °C and that hot water is at least 50 °C, as the bacteria cannot grow at these temperatures and begin to die at 50 °C," says Søren Anker Uldum , who is head of department at the Statens Serum Institut.

Rinse through with very hot water

It is therefore important to continue to maintain at least 50 °C throughout the hot water system. The temperature must be reached at all tapping points after no more than 30 seconds. rinse and in the return water (before hot water tank or heat exchanger). In most cases, this can be achieved by heating the hot water to 55 °C in the hot water tank.

With reduced consumption of hot water, the water has longer residence times in the pipes and can have temperatures in the bacteria's growth area for a longer period of time, so there must be a certain consumption of hot water.

Taps, such as faucets and showers that are rarely used, should be flushed with hot water at a minimum of 50 °C for a few minutes at least once a week.

When showering (which may well be short), it is also a good idea that at least once a week you first set the mixer tap to maximum temperature and let the water run (to the drain) until it is as hot as it can be before setting it to bath water temperature (approx. 36 °C).

This advice applies especially if there are vulnerable people in the household or institution, such as the elderly or people with chronic illness or a weakened immune system.

See also for savings advice on the Danish Energy Agency's website

Temperature leaving hot water tank/heat exchanger - generally min. 55 °C.
Temperature at tap point and in return water – min. 50 °C after < 30 sec.
Taps (taps and showers) should be flushed through at least once a week with water ≥ 50 °C
The above is especially important if there are vulnerable people in the household.

Lest anyone think that a home shower is an unlikely place to contract Legionella, we've seen this durable bacteria turn up in surprising places, including automobile windshield wiper fluid (see EID Journal: Vehicle Windshield Wiper Fluid As Potential Source Of Sporadic Legionnaires' Disease).