Singapore MOH Reports Sharp Rise In COVID Cases

#18,068



Although COVID has been fairly subdued the past few months, new variants are continually emerging and our community immunity (from prior infection or vaccines) wanes over time. New waves are inevitable, and yesterday Singapore's MOH announced a week-over-week near doubling of cases. 

Their MOH released the following statement yesterday. 

UPDATE ON COVID-19 SITUATION

18TH MAY 2024

The Ministry of Health (MOH) is closely tracking the recent rise in COVID-19 infections in Singapore. While there is no indication that the circulating variants are more transmissible or cause more severe disease compared to previous variants, immunity in the population has likely waned over time. We urge the public to stay updated with COVID-19 vaccination to protect themselves against current and emerging virus strains, and exercise personal and social responsibility to minimise transmission.

2. The estimated number of COVID-19 cases in the week of 5 to 11 May 2024 rose to 25,900 cases, compared to 13,700 cases in the previous week. The average daily COVID-19 hospitalisations rose to about 250 from 181 the week before, while the average daily Intensive Care Unit (ICU) cases remained low at three cases compared to two cases in the previous week.

3. MOH is closely tracking the trajectory of this wave. To protect hospital bed capacity and as a precaution, public hospitals have been asked to reduce their non-urgent elective surgery cases, and move suitable patients to care facilities like Transitional Care Facilities or at home through Mobile Inpatient Care@Home.

4. Globally, JN.1 and its sub-lineages, including KP.1 and KP.2, remain the predominant COVID-19 variants. Locally, the combined proportion of KP.1 and KP.2 currently accounts for over two-thirds of COVID-19 cases in Singapore. As of 3 May 2024, the World Health Organization has classified KP.2 as a Variant Under Monitoring. There are currently no indications, globally or locally, that KP.1 and KP.2 are more transmissible or cause more severe disease than other circulating variants.

Vaccination continues to be recommended to protect against severe illness

5. Even as we live with COVID-19 as an endemic disease, we cannot afford to lower our guard. To date, about 80% of the local population have completed their initial or additional dose but have not received a dose within the last year. This indicates that immunity in the population is likely to have waned.

6. Since COVID-19 vaccination started in 2020/2021, the vaccines have consistently been proven to be safe and effective in protecting individuals from severe illness. Billions of COVID-19 vaccine doses have been administered globally and safety monitoring internationally has shown that the vaccine is safe. There have also been no long-term safety concerns with COVID-19 vaccination. Adverse effects from the vaccines, including the mRNA vaccines, have all been observed to occur shortly after vaccination.

7. Based on local data, keeping updated with vaccination (i.e. receiving an additional dose within the last year) has continued to be a key effective measure in preventing severe COVID-19 illness requiring hospitalisation or ICU admission. During the peak month of the previous JN.1 wave in December 2023, the incidence rate of COVID-19 hospitalisations and ICU admissions among seniors aged 60 years and above was 25% higher in those who had not kept their vaccination updated compared to those who had.

8. The effectiveness of COVID-19 vaccination has also been shown in a large number of previous studies and continues to be demonstrated in recent data. For example, between September 2023 and January 2024, the US Centers for Disease Control and Prevention observed that the updated COVID-19 vaccines reduced the risk of symptomatic COVID-19 by more than 50%, when comparing those who received an updated vaccine to those who did not.

9. The protection against COVID-19 outweighs the risk from COVID-19 vaccination, and we urge individuals to keep updated with their COVID-19 vaccination. Those who are at greatest risk of severe disease, including individuals aged 60 years and above, medically vulnerable individuals and residents of aged care facilities, are recommended to receive an additional dose of the COVID-19 vaccine for 2024, around one year (and not earlier than five months) after the last dose received. Next-of-kin of residents of aged care facilities (e.g. nursing homes) are reminded to provide consent (if necessary) in a timely manner, if they intend to enable the resident to receive an additional dose of the updated vaccine. In addition, all vaccinated individuals aged six months and above are encouraged to receive an additional dose of the COVID-19 vaccine for 2024 as well.

Stepping up our vaccination efforts

10. The updated COVID-19 vaccines continue to be free for all eligible residents. Leveraging the trusted relationship between our family doctors and patients, Healthier SG enrolees can now receive their COVID-19 vaccination at about 250 participating Healthier SG clinics islandwide. Over the next few months, we will progressively expand the network of Healthier SG clinics offering COVID-19 vaccination to ensure its ready accessibility to the community. The public is advised to book their COVID-19 vaccination appointments via the Health Appointment System https://book.health.gov.sg/covid or call the clinics directly before making their way down.

Exercising personal and social responsibility

14. The public is urged to exercise personal and social responsibility. This includes maintaining good personal hygiene; reducing social interactions when feeling unwell; and wearing masks if medically vulnerable, in crowded areas, or when symptomatic. With the June holiday season approaching, those travelling overseas are reminded to be vigilant and to adopt relevant travel precautions. Please visit MOH’s Health Advisory for Travellers at www.moh.gov.sg/diseases-updates/travel-advisory for more information.

15. We also urge the public to reserve medical treatment at a hospital’s Emergency Department for serious or life-threatening emergencies, particularly if their symptoms are mild or if they have no medical vulnerabilities. This will preserve our hospital capacity for patients who need acute hospital care and allow those with severe illness to receive timely treatment.

EID Journal: Outbreak of Natural Severe Fever with Thrombocytopenia Syndrome Virus Infection in Farmed Minks, China

Credit ECDC  

#18,067

While it may seem like piling on after a litany of reports of HPAI H5N1 and SARS-CoV in farmed mink (see here, here, here, here, here, here, here and here), we've research letter today - published last week in the CDC's EID Journal - on the spread of Severe Fever With Thrombocytopenia Syndrome (SFTS) in farmed mink in China. 

Because fur farms can house thousands of animals in close quarters, the ability of diseases to spread rapidly and evolve is far greater than what might occur with other susceptible hosts - like companion animals (i.e. dog & cats) or Mustelids (ferrets, mink, weasels, etc.) in the wild.

While this risk may be greatest in mink, it also extends to other farmed animals (e.g. foxes, raccoon dogs, etc.), and is not limited to just HPAI H5 and coronaviruses (see here, here, and here).

Last summer, in PNAS: Mink Farming Poses Risks for Future Viral Pandemics, we looked at an excellent opinion piece penned by two well known virologists from the UK (Professor Wendy Barclay & Tom Peacock) on why fur farms - and mink farms in particular - are high risk venues for zoonotic diseases.

While considered as far less of a threat today than either COVID or avian flu, we've been following the spread of a tick borne Phlebovirus which causes SFTS for more than a dozen years. 

Also known as the Dabie bandavirus, SFTS is believed be carried and transmitted by the Asian Longhorned tick (along with Amblyomma testudinarium & Ixodes nipponensis).

The virus was first discovered in China in 2009, but has subsequently been found in Japan, South Korea and Vietnam - and in 2019 was detected for the first time in Taiwan.  The fatality rate in humans has ranged from single digits to > 30%, depending on the region. 

Although primarily spread ticks, there is evidence that the virus can also be transmitted from from animals-to-humans (see EID Journal Direct Transmission of SFTS from Domestic Cat to Veterinary Personnel), and from human-to-human (see Nosocomial person-to-person transmission of severe fever with thrombocytopenia syndrome) either through aerosols or close contact with infected body fluids.

Aerosol transmission of severe fever with thrombocytopenia syndrome virus during resuscitation

 

Nosocomial Outbreak of SFTS Among Healthcare Workers in a Single Hospital in Daegu, Korea.

Two months ago, we looked at a report from Japan's Institute for Infectious Diseases on that country's first confirmed case of Human-to-Human transmission of the virus; from an elderly patient to an attending doctor.

All of which brings us to the following EID report.  I've only posted some excerpts, so you'll want to follow the link for greater details.  I'll have a brief postscript after the break. 

Research Letter
Outbreak of Natural Severe Fever with Thrombocytopenia Syndrome Virus Infection in Farmed Minks, China

Ying Wang1, Mingfa Yang1, Hong Zhou, Chuansong Quan , and Hongtao Kang

Abstract

We isolated severe fever with thrombocytopenia syndrome virus (SFTSV) from farmed minks in China, providing evidence of natural SFTSV infection in farmed minks. Our findings support the potential role of farmed minks in maintaining SFTSV and are helpful for the development of public health interventions to reduce human infection.


Severe fever with thrombocytopenia syndrome (SFTS) is an emerging disease caused by a novel tickborne bunyavirus, SFTS virus (SFTSV), which was first identified in China in 2009 (1). Outside of China, SFTS was subsequently reported in South Korea, Japan, Vietnam, Myanmar, and Pakistan and now poses a global health problem (2–6). SFTSV is an enveloped virus belonging to the genus Bandavirus, family Phenuiviridae, order Bunyavirales.

The virus has 3 single-stranded negative-sense RNA segments, large (L), medium (M), and small (S) (1). The Haemaphysalis longicornis tick is widely considered to be the primary transmission vector (7), but the natural animal hosts of SFTSV remain uncertain. Despite the high seroprevalence observed in various domestic animals in SFTSV-endemic regions, such as goats, cattle, dogs, pigs, chickens, and rodents, many of those animals do not show notable symptoms. Those infections were plausibly a result of SFTSV transmission from infected ticks (8).

We describe an outbreak of SFTS on a mink farm situated in Shandong, China. During late May through early July, 2022, >1,500 minks on this farm exhibited symptoms such as vomiting, diarrhea, and, in a small number, limb convulsions.

Most minks exhibiting clinical manifestations died of the disease (Figure 1, panel A). Clinical manifestations included loose stools, mesenteric lymph node enlargement, and hyperemia (Figure 1, panels B and C), consistent with typical enteritis symptoms. Treatment with multiple antibiotics was not effective, and mink enteritis virus infection was ruled out through testing with a colloidal gold immunochromatographic assay. Intestinal tissue samples from minks with diarrhea (n = 10) were collected and forwarded to the Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China, for testing.

(SNIP) 

Previous research has shown the presence of antibodies to the nucleoprotein of SFTSV in farmed minks and suggested that minks were infected with SFTSV in China (10). In this study, we successfully isolated and identified an SFTSV isolate, named SD01/China/2022, in farmed minks in China. 

The symptoms of farmed minks in this case were consistent with SFTS symptoms, such as gastrointestinal disorders and central nervous system manifestations, which proved the occurrence of natural SFTSV infection–related fatalities in this population. Our findings reveal the threat of SFTS to the fur animal–breeding industry.

Of note, phylogenetic analysis of the isolate indicated high homology with SFTSV strains in humans, suggesting that the viruses generally infected both humans and minks, further supporting the potential role of farm minks in maintaining SFTSV.

Farmed minks have potential for direct contact with humans and might serve as crucial amplifying hosts in the transmission of SFTSV. Further analysis of SFTSV infection in other captive fur animals, such as raccoon dogs and foxes, will be required to determine other key reservoirs for SFTSV. We recommend a focus on the registration of mink exposure for humans with SFTS-like illnesses, as well as increased measures to reduce SFTSV exposure risk.

Ms. Wang is a PhD candidate at Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China. Her primary research interests focus on the host–pathogen interactions of tickborne viruses. Dr. Yang is a research associate at Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China. His research interests focus on phylogeny, virology, and molecular epidemiology, especially for tickborne viruses.

Admittedly SFTS resides pretty far down our worry list, but over the past 3+ years we've seen a mutated COVID variant emerge and spillover into humans from mink, and last week we saw a risk analysis on a more transmissible mink-derived H5N1 virus, both illustrating the dangers inherent in fur farming. 

There is, however, a sizable gap between recognizing a problem and fixing it. 

We've long known of the dangers of live markets in Asia, and the bush meat trade in Africa, yet they both continue to thrive.  To be fair, we aren't exactly setting a great example with testing of dairy cattle (and other livestock) for H5N1 here in the United States. 

Hard decisions are, well . . . hard. 

But they are likely to be far less difficult than the ones that come with another pandemic. 

How Not To Swelter In Place

 #18,066

Two days ago a derecho with straight-line winds of greater than 100 mph struck metro Houston, Texas leaving 7 dead, and a million people without power.  Today, > 500,000 are reportedly still without power in Harris County, alone, and some may go weeks before power is restored. 

Between tornado outbreaks, derechos, and landfalling hurricanes we see this scenario repeated nearly every year; large regional power outages that can last days, weeks, or sometimes months. 

Invariably, we see deaths associated with extreme heat or cold, or from carbon monoxide poisoning from using generators, in the days or weeks that follow (see NEJM Mortality in Puerto Rico after Hurricane Maria).

As a Floridian, I've gone through this more than a few times, and even when it isn't life-threatening, going without electricity for days - particularly during the summer - can be miserable.

With Hurricane season starting in a couple of weeks, and the fact that severe weather, earthquakes, and even solar storms can happen at any time, now seems like a good time to review some preparedness options for when the grid goes down. 

Generators are an obvious solution, but they are expensive, loud, emit deadly fumes, and consume fuel at a voracious rate. Keeping enough gas on hand to run more than a day or two is impractical for many, and getting more fuel when the power is off can be nearly impossible. 

Those with tens of thousands of dollars to spend can have a whole-house Solar system - one capable of running freezers, refrigerators, and air conditioners - when the grid goes down.

But on far less of a budget during my last hurricane outage (2022) I had lights, fans, radios, phone and iPad charging capability, and even a mini-DVD player for my entertainment.  

Believe me, under those conditions, having fans was as luxury. 

I detailed my previous solar power system upgrade 3 years ago, in My New (And Improved) Solar Battery Project (for CPAP).

It relied upon a pair of 40 watt solar panels I bought in the early 1990s, and a couple of small (35 amp/hr) lead acid batteries. The panels still work, but are approaching the end of their life, and lead-acid batteries - while cheap - are heavy, have a short (2-4 year life), and can only be discharged about 50% without damage. 

Since they are still serviceable, I haven't replaced them, but a little over a year ago I augmented them with a third (50 amp/hr) LiFePo battery (light, long lasting, and able to discharge > 80%), and a new 100 watt solar panel. 

This new single battery/panel will charge faster, and deliver more power, than the two other batteries combined.  And I did it for roughly $300. 

I'm not going to give a step-by-step tutorial on how to build a system, since there are scores of videos on YouTube that can do that. Instead, I'm going to give an overview of my system, and why I've made the choices I've made. 

If you are at all handy, and comfortable working with 12 volt DC systems, you should be able to cobble together your own system.

Disclaimer: lead acid batteries can offgas Hydrogen, which can be explosive, and should be kept in a ventilated are. A dead short across the terminals of a 12 volt battery can cause a fire or explosion. Reversing the polarity of your connections can fry components. If you are unsure of how to safely deal with batteries or DC voltage, have someone who knows how assist you.

Admittedly, for many people the best solution may be dropping $500-$1000 on a solar generator (really, a battery-inverter), and $150-$400 on a matching solar panel.  Its a plug-and-play solution that can be set up by just about anyone, and they certainly are far more aesthetically pleasing than a home brew setup. 

But if something breaks, you usually have to send it back to the factory for repairs. That turnaround time might be weeks. No matter how good the warranty, it's of limited comfort when the power is already out.  

A home brew system, by its very nature, makes it possible for you to repair it yourself. Except for the cables, a typical system has between 3 and 5 components; Solar panel, Solar Charge Controller, and battery.  For more versatility you can add a 12v/5v USB outlet, and (if desired) a 110v inverter.

For systems of this size, 110v inverters have limited value.  They drain a battery very quickly, and while I have a couple (100 watt & 400 watt), I honestly have a hard time thinking of where I would use them. Charging a laptop, perhaps.

While many of my electrical needs are now met using USB batteries, and small solar panels (see Some Simple Off-The-Shelf Solar Solutions For Power Outages), they won't run my CPAP, larger fans, or a DVD player. 

Still, this may be adequate for a lot of people.  The advantage is, everything is plug and play, relatively inexpensive, will fit into a duffel bag, and you can start small and add components at your own pace.  

As for my new system, it looks like this:

The solar panel is about 18" wide & 39" long.  The battery, LiFePo solar charge controller, and output devices all fit into a plastic crate, and weigh about 12 lbs. It provides dual 12V Car Cigarette Lighter Sockets (for CPAP, or Inverter), 2 USB outlets, and the ability to expand.

Major Parts list: 

• ECO-WORTHY 12V 50Ah Trolling Motor LiFePO4   $160
• 100 Watt 12 v Monocrystalline Solar Panel                     $70
• Solar Charge Controller 10A, Bateria 12V/24V              $18
• 12V 3A LiFePO4 Battery Charger                                   $20
• Misc cabling and connectors                                            $20

So, what did my (roughly) $300 upgrade add?

• With 40-45 amps available from the LiFePo battery I can run my CPAP for 5 (8 hour) nights without recharging.  Or, I can watch 35-40 hours of DVDs, or run a large 12 volt fan for 40+ hours. I can also use it to recharge smaller USB battery banks, run 12 volt lights, radios, etc. 

• With a 100 watt Solar panel, I can probably average 5+ amps an hour charging, for 4 to 7 hours a day.  On on good day, I could probably recharge the battery from being 80% discharged. 

My two older 35 amp batteries, and solar panels together probably add another 30 to 40 available amp/hrs per day.  All three solar panels, and batteries, weigh in at about 100 lbs, and will fit in the trunk of my car if I have to bug out again. 

I've also invested $10 into a lead-acid trickle wall charger (110 v) and a $20 3 amp LiFePo wall charger (110 v), so I can keep batteries fully charged when the power is on, without having to deploy the solar panels. 

Having this solar gear won't guarantee I'll come away unscathed from the next hurricane, or natural disaster.  But, along with having a propane camp stove and heater, a decent first aid kit, 60 gallons of water stored, a well stocked pantry, and a disaster buddy . . .  it should certainly improve my odds. 

CDC Announces Plans For IRAT Assessment of Texas H5N1 Virus

USDA :  51 Cattle Outbreaks Across 9 States
 

#18,066

A dozen years ago the CDC developed the IRAT (Influenza Risk Assessment Tool) to evaluate the risks of novel flu viruses with zoonotic potential.  In 2012, the list was pretty short:

But 2013-2014 was a major turning point in the evolution of avian (and to a lesser extent, other) flu viruses.  H7N9 appeared in China, along with H5N6, H10N8, H9N2 G1, along with several swine & canine viruses. 

By the end of 2016, the number of viruses on the list had tripled (n=12).

The CDC is quick to point out their Influenza Risk Assessment Tool (IRAT) is not meant to be predictive.  As stated in their FAQ:

Can the IRAT predict a future pandemic?

No. The IRAT is an evaluative tool, not a predictive tool. Flu is unpredictable, as are future pandemics.

But the IRAT can help planners decide which viruses pose the greatest risks, so they can prioritize their efforts and investments.  Today, there are 24 novel influenza A viruses on the IRAT list, with the most recent addition (July 2023) being the 2022 mink-derived H5N1 virus from Spain. 

The IRAT process scores a virus based on 10 parameters (see above).  In this case, the latest IRAT was published roughly 7 months after the outbreak in mink. 

While that assessment increased a number of its risk factors over earlier H5N1 viruses, a few days ago - in Nature Dispatch: Risk Assessment On HPAI H5N1 From Mink - we saw new evidence of limited airborne transmission via ferrets, which may require additional scrutiny. 

Of the 24 novel flu viruses on the CDC's IRAT list, 9 are H5 viruses (4 H5N1, 2 H5N8, 2 H5N6, and 1 H5N2), far and away the most represented HA type.  H7 viruses (H7N9, H7N7, H7N8) come in second, appearing 6 times.  

But in terms of likelihood of emergence, two swine viruses currently top the list: 

Those rankings could change, as last night in A(H5N1) Bird Flu Response Update May 17, 2024, the CDC announced plans to conduct an IRAT assessment on the (A/Texas/37/2024) H5N1 virus, a process that could take several months.  

They wrote:

Beginning the process of conducting a pandemic risk assessment on the virus from the human infection in Texas (A/Texas/37/2024) using the Influenza Risk Assessment Tool (IRAT). The IRAT is an evaluation tool developed by CDC and external flu experts that assesses the potential pandemic risk posed by novel influenza A viruses. The IRAT uses 10 risk elements to measure the potential of an influenza virus to emerge to cause a pandemic as well as the potential public health impact that a pandemic caused by that virus would have.

An IRAT is a multi-step process that can take months to complete. (More on IRAT below.) The current assessment of the risk level to the general public, which is based on available epidemiologic and laboratory data, remains low.

In addition, the CDC listed some of the steps they are taking to deal with the outbreak of H5N1 in dairy cattle, and potential additional spillovers into humans.   I'll have a postscript after the break. 

CDC A(H5N1) Bird Flu Response Update May 17, 2024

          (excerpts) 

May 17, 2024 – CDC continues to respond to the public health challenge posed by a multistate outbreak of avian influenza A(H5N1) virus, or “A(H5N1) virus,” in dairy cows and other animals in the United States. CDC is working in collaboration with the U.S. Department of Agriculture (USDA), the Food and Drug Administration (FDA), state public health and animal health officials, and other partners using a One Health approach. USDA is now reporting that 51 dairy cattle herds in nine U.S. states have confirmed cases of A(H5N1) virus infections in cattle. There have been no additional human cases detected since the one recent case from Texas was reported on April 1, 2024. [1][2] 

Among other activities previously reported in past spotlights and still ongoing, recent highlights of CDC’s response to this outbreak of influenza A(H5N1) virus in dairy cattle and other animals include:

• Continuing to support states that are monitoring people with exposure to cows, birds, or other domestic or wild animals infected, or potentially infected, with avian influenza A(H5N1) viruses. To date, more than 300 people have been monitored as a result of their exposure to infected or potentially infected animals, and at least 37 people who have developed flu-like symptoms have been tested as part of this targeted, situation-specific testing. All except the one case in Texas have tested negative. Testing of exposed people who develop symptoms is at the state or local level, and CDC conducts confirmatory testing as needed.
• Working on a plan for enhanced, nationwide summer monitoring to help ensure that even rare cases of A(H5N1) virus infection in the community would be detected. This plan includes increasing the number of influenza virus specimens that are tested and then subtyped in public health laboratories, which can detect A(H5N1). Nationally, since March 24, 2024, almost 11,000 specimens have been tested for influenza in public health laboratories as part of this surveillance stream. While influenza testing typically declines over the summer, this approach would maintain an increased level of testing. More information on this will be forthcoming.

(Snip)

• Continuing to monitor flu surveillance data, especially in areas where A(H5N1) viruses have been detected in dairy cattle or other animals, for any unusual trends including in flu-like illness, conjunctivitis, or influenza virus activity.

• CDC posted influenza A wastewater surveillance data for this first time this week. Wastewater surveillance complements other existing human flu surveillance systems to monitor trends in influenza viruses. Current wastewater monitoring methods detect influenza A viruses but do not distinguish the subtype or source of the influenza A virus (whether it is from humans or animals). Reported levels of influenza A virus from each site are compared against levels reported by the same site during the prior flu season. When influenza A levels in wastewater are high (at the 80th percentile or higher), that triggers follow up by CDC, including outreach to the relevant jurisdiction to determine the source of the signal and intensive surveillance review. The data are presented in the format of an interactive map and updated weekly.
• Overall, for the most recent week of data, CDC flu surveillance systems show no indicators of unusual flu activity in people, including avian influenza A(H5N1) viruses.

The CDC continues to urge people to be proactive in reducing their risks. 

CDC Recommendations

• People should avoid close, long, or unprotected exposures to sick or dead animals, including wild birds, poultry, other domesticated birds, and other wild or domesticated animals (including cows).
• People should also avoid unprotected exposures to animal poop, bedding (litter), unpasteurized (“raw)” milk, or materials that have been touched by, or close to, birds or other animals with suspected or confirmed A(H5N1) virus.
• CDC has interim recommendations for prevention, monitoring, and public health investigations of A(H5N1) virus infections in people. CDC also has updated recommendations for worker protection and use of personal protective equipment (PPE). Following these recommendations is central to reducing a person’s risk and containing the overall public health risk.

In addition to limiting interactions between infected animals and people, containing the outbreak among animals also is important, which underscores the urgency of the work being done by USDA and animal health and industry partners.

         (Continue . . . )

Whether H5N1 will spark a pandemic is anyone's guess - and while it seems unlikely - it could fizzle and recede as it has done in the past.   

Trying to predict what a flu virus will - or won't - do, is a mug's game. 

But another pandemic will come, and our tepid and uncoordinated response to today's threat gives little indication that we'll be ready when that inevitably happens. 

There is still time to correct that.  

But the clock is ticking . . . 

CDC Updated Influenza A in Wastewater Report

Week Ending 5/11/24

#18,065

Earlier this week the CDC unveiled their Influenza A wastewater surveillance program, which receives reports from 674 facilities across the nation, although we've been seeing data from about 1/3rd of those stations over the first 3 weeks. 

This sudden interest in wastewater surveillance has been driven by the recent detection of avian H5N1 in American dairy cattle, and concerns there might be uncaptured spillovers into humans.

These surveillance reports only detect influenza A levels, and do not tell us what subtype, or the likely source.  

But this time of year, we would expect community flu levels to be declining.  

As you can see by the following comparison chart of the past 3 weeks, the number of stations reporting above average rates of influenza have increased week-over-week.  

This despite slightly fewer stations (n=218)  submitting data in this latest report.  

Much of this week's increase is centered in northern California, going from 2 to 5 sites. Again, it isn't clear what might be driving this increase. 

But we will definitely be watching this situation closely over the weeks ahead. 

EID Journal: Antibodies to Influenza A(H5N1) Virus in Hunting Dogs Retrieving Wild Fowl, Washington, USA

Credit Wikipedia

#18,064

One of the problems with trying to draw conclusions about the threat posed by HPAI H5 clade 2.3.4.4b is that there are multiple subtypes (H5N1, H5N5, H5N6, etc.) - and scores of genotypes - circulating concurrently around the globe. 

The H5 virus infecting cattle in America is related to - but is genetically distinct from - the H5 viruses infecting sea lions in Chile, farmed mink in Spain, raccoons in Nova Scotia, or cats in Poland.

Complicating matters, these viruses continue to evolve slowly via antigenic drift, and generate new genotypes through antigenic shift (reassortment).  HPAI H5 is a continually moving target, meaning past performance does not guarantee future results. 

Most of this viral evolution occurs outside of our view, either in remote regions of the world, or in hosts that are difficult to sample.  Even in more accessible regions, many countries are either ill-equipped - or unwilling - to conduct extensive testing. 

Fortunately, the vast majority of these evolutionary changes will do little to enhance the virus, and many will actually prove a detriment.  Most of these viral GOF experiments will fail to thrive, and wither away into obscurity. 

None of this is to diminish the importance of studies that can only look at a small slice of HPAI H5  conducted over a brief moment in time, but it is important we realize their limitations.  

A seroprevalence study of cattle in the United States six short months ago would have likely reassured us that cattle were not susceptible to H5N1.  Things change. 

With that in mind we have the following study, published this week in the CDC's EID journal that finds low - but significant - number of hunting dogs with antibodies to H5N1 tested over a 2 month period in 2023.  

The authors make it abundantly clear, that this study applies to `subclade 2.3.4.4b H5N1 HPIAV strains that circulated in North America during 2022–2023'.

Due to its length, I've only posted some excerpts (reformatted for better readability).  Follow the link to read it in its entirety.  I'll have a brief postscript after the break. 

Antibodies to Influenza A(H5N1) Virus in Hunting Dogs Retrieving Wild Fowl, Washington, USA

Justin D. Brown , Adam Black, Katherine H. Haman, Diego G. Diel, Vickie E. Ramirez, Rachel S. Ziejka, Hannah T. Fenelon, Peter M. Rabinowitz, Lila Stevens, Rebecca Poulson, and David E. Stallknecht

Abstract

We detected antibodies to H5 and N1 subtype influenza A viruses in 4/194 (2%) dogs from Washington, USA, that hunted or engaged in hunt tests and training with wild birds. Historical data provided by dog owners showed seropositive dogs had high levels of exposure to waterfowl.

(SNIP)

Despite the prolonged global epizootic of HPIAV H5N1, reported infections in dogs have been rare.

• During an HPIAV H5N1 outbreak in Thailand, a fatal canine infection in 2004 associated with a dog eating a duck carcass was reported (1).
•  A follow-up serosurvey of outwardly healthy stray dogs in Thailand detected HPIAV H5N1 antibodies in 25.4% (160/629) of sampled dogs (2).
•  During April 2023, another fatal HPIAV H5N1 infection was identified in Ontario, Canada, in a dog that developed severe respiratory and systemic signs shortly after chewing on a dead wild goose (3).
•  In experiments, beagles were susceptible to HPIAV H5N1 infections, during which some infected dogs excreted high concentrations of virus through the respiratory tract and experienced severe disease (4).
•  In contrast, previous studies in beagles reported susceptibility to HPIAV H5N1 infection that manifested with moderate to no clinical signs (5,6).

Existing field and experimental data collectively suggest dogs are susceptible to HPIAV H5N1 infection but clinical outcomes vary. However, infection appears to be restricted to dogs with high virus exposure. To investigate this further, we tested for antibodies to influenza A(H5N1) virus in bird hunting dogs, a category of dogs at high risk for contact with HPIAV H5N1–infected wild birds, and compared serologic results to reported hunting or training activities.

Dog owners completed a questionnaire providing details about their dogs’ retrieving activities, canine influenza virus (CIV) vaccination status, and clinical history. Methods used in this research were approved by the Institutional Animal Care and Use Committee at Penn State University (#202302394).

During March–June 2023 in Washington, USA, we collected blood samples from 194 dogs identified by owners as having engaged in bird hunting or bird hunt tests and training over the previous 12 months (Figure). Waterfowl hunting season in Washington extends from mid-October through February; consequently, we collected samples 1–4 months after season closure. We collected blood from the jugular vein, immediately centrifuged it, and stored it at 4ºC in the field, then stored serum at –20°C until testing was performed.

(SNIP)

We used conservative positive threshold titers: H5 HI, >1:32; H5 VN, >1:20; and N1 ELLA, >1:80. We considered samples H5 seropositive if positive for H5 using HI assay or VN and N1 seropositive if positive for N1 using ELLA. We also tested all bELISA-positive serum samples for antibodies to H3N2 and H3N8 CIV by HI assay (positive threshold ≥1:8) (9). We calculated seroprevalence using R (10).

Most dogs retrieved waterfowl (86%), and many (69%) retrieved both waterfowl and upland game birds (Appendix Tables 1, 2). Dogs most commonly contacted dabbling ducks (81% of dogs), which are notable reservoirs for HPIAV H5N1. Dogs also frequently contacted birds from other categories considered high risk for HPIAV H5N1, including geese (32% of dogs) and diving ducks (23% of dogs) (Appendix Table 3). Most dogs had retrieved or trained multiple times during the previous 12 months; 38% were reported to have been in the field during ≥15 hunts and 78% reported to have trained with live or dead birds ≥15 times (Appendix Table 2). Reportedly 11% of dogs retrieved dead or clinically ill waterfowl that showed no evidence of having been shot or hunted.

(SNIP)

Over the previous 12 months, all 4 H5- and N1-seropositive dogs reportedly had hunted waterfowl extensively in areas affected by H5N1 HPIAV outbreaks in wild waterfowl. Three H5- and N1-seropositive dogs reportedly had retrieved waterfowl that were either dead or had neurologic symptoms but that showed no evidence of having been shot or hunted.

Two H5- and N1-seropositive dogs were from households that owned multiple hunting dogs included in this study; 1 seropositive dog was 1 of 2 dogs included in the study and the other was 1 of 3. None of the other tested dogs from those multidog households were seropositive for IAV. 

Conclusions

We detected antibodies to H5 and N1 only in hunting dogs with high levels of bird hunting and waterfowl retrieval. Although that finding suggests transmission of HPIAV H5N1 from waterfowl to dogs can occur, low seroprevalence, lack of reported disease in seropositive dogs, and lack of evidence for dog-to-dog transmission among dogs sharing households collectively indicate that the subclade 2.3.4.4b H5N1 HPIAV strains that circulated in North America during 2022–2023 were poorly adapted to dogs.

Those results suggest that effective risk communication with hunting dog owners could be an inexpensive and effective strategy to reduce the potential for spillover to dogs, and monitoring hunting dogs for IAV could be a useful addition to existing surveillance efforts.

Dr. Brown is an assistant teaching professor in the Department of Veterinary and Biomedical Sciences in the College of Agricultural Sciences at Pennsylvania State University. His research focuses on defining the impacts of infectious diseases on wildlife populations.

Last month, in Microorganisms: Case Report On Symptomatic H5N1 Infection In A Dog - Poland, 2023, we looked at a much different case report, with the authors writing:

The case described in our report confirms that on rare occasions the A/H5N1 virus can also induce a natural severe respiratory disease in dogs. While in some of them the infection remains asymptomatic, capable of shedding the virus [35], others exhibit mild symptoms such as transient fever [34], or even fatal disease [20].

 The authors also note:

In Poland, as in most European countries, dogs presenting with respiratory symptoms are not routinely tested for influenza.

Different country, different time, different genotype . . .  different outcome. 

While this is likely an outlier, the more I write about novel flu viruses, the less inclined I am to make blanket assumptions about what a given strain can - or can't - do.