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Dr. Angela Rasmussen Profile picture
Dr. Angela Rasmussen
@angie_rasmussen
Virologist. PI @VIDOInterVac. Adj Prof @USask BMI. P2 @covarr_net. Jeopardy! loser. "Disreputable vaccine cheerleader." 🇺🇸in🇨🇦. she/her
70 subscribers
Dec 19 • 19 tweets • 5 min read
For months now, the CDC has described H5N1 as “mild” compared to prior H5N1 viruses. I disagree—the virus alone doesn’t determine pathogenicity.

I hypothesize that the 2 most critical determinants of H5N1 severity are the host (it’s always the host 🥰) & the route of infection. The severely ill Louisiana case was infected by contact with backyard birds. In birds, influenza is gastrointestinal as well as respiratory, so contact with a lot of bird shit can cause a person to become infected.
Dec 18 • 30 tweets • 7 min read
My replies are perpetually full of anti-vaxxers these days telling me about polio vaccines.

Not shockingly, most of what they are saying is wrong. Luckily, I trained with @profvrr & he taught me a few things about poliovirus.

So let’s discuss the king of the Picornaviridae👇🏻 Image Let me start off by saying that while poliomyelitis is a terrible disease & I am anti-polio, I fucking LOVE working with poliovirus. It routinely grows to titers of 10e9 in HeLa cells & makes the clearest, most beautiful plaques even in BactoAgar that every other virus hates
Nov 17 • 14 tweets • 3 min read
Highly recommend going to Bluesky to read this thread about some of the mutations found in the H5N1 virus from the patient in BC.

If you wonder what this means for pandemic risk, the answer is a very complex but unsatisfying “we don’t know”. Host adaptation is complicated. In terms of basic technical requirements, H5N1 cannot become a pandemic virus without adapting to its host. For humans, that means adapting to different receptors, body temperature, host cell types, tissue organization, etc etc. Big changes from the avian host it’s adapted to.
Nov 11 • 23 tweets • 5 min read
Thanks to the first Canada acquired H5N1 case, there’s an uptick in “bird flu pandemic imminent” and “omg it’s gone H2H!” posts. Those are not accurate.

However, given the situation in the US, I have some real concerns about this that grow progressively more grave. First let’s get this out of the way: while a case has never occurred locally in Canada, there have been many human cases of H5N1 during this panzootic (since 2021).

It’s probably direct spillover from a bird or other animal, not human to human transmission.
Oct 24 • 6 tweets • 2 min read
Finally, we have H5N1 serology data from Missouri. 🙏🏻 @CDCgov.

Both the MO patient and their household contact were positive for antibodies against H5N1 in 1/3 tests. This is not definitive per WHO criteria (2 tests positive) but does suggest infection.

cnn.com/2024/10/24/hea… Testing positive on just 1/3 tests may suggest that these patients had a transient infection. Weak seropositivity can indicate low titers of antibodies, consistent with an immune response to low levels of virus replication.
Oct 20 • 4 tweets • 2 min read
When you move quickly to assess the origins of an outbreak, you can learn a lot about how it emerged just by analyzing the viral genomes.

In the case of the Marburg virus outbreak in Rwanda, it was a single zoonotic spillover from an unknown host.

Really excellent work here. A question I have concerns the animal host. Was it R. aegyptiacus (known Marburg reservoir) or something else?

Because this “limited mutation rate” is interesting. Ebola (also a filovirus) appears to persist without replicating much as seen in outbreaks in survivors.
Oct 10 • 21 tweets • 6 min read
Have you ever wondered how Ebola virus manages to induce such a catastrophically lethal host response?

I have. So @mhamdi_zeineb & I joined Satoko Yamaoka & Hideki Ebihara to get some answers about mechanisms of pathogenesis.

SPOILER ALERT: it's VP40
biorxiv.org/content/10.110… Ebola pathogenesis is brutal and super complex. When people hear Ebola hemorrhagic fever (now Ebola virus disease or EVD), they shouldn't think Ebola kills cells and causes bleeding. They should instead think Ebola causes a massive, uncontrolled systemic inflammatory response.
Oct 3 • 15 tweets • 5 min read
Every time there’s a Marburg or Ebola virus outbreak, my feed instantly fills with filovirus fear porn.

It’s airborne! Deadliest virus ever! OMG IT’S IN EUROPE! Pandemic imminent!

These takes are at best wrong & at worst anti-scientific and racist.

Here are some facts.


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Image You may have heard two travelers, including a medical student who had contact with patients in Rwanda while wearing PPE, got sick on a train in Hamburg.

You may not have heard that they both tested negative for MARV but are staying in quarantine anyway.

ndr.de/nachrichten/ha…
Sep 22 • 4 tweets • 1 min read
When competent scientists disagree with the conclusions of a peer-reviewed paper in a top-tier journal, they present evidence to show why it’s wrong.

When incompetent scientists have no evidence, they harass journal editors so severely that they abandon the public discussion. Abuse is not acceptable and there should be consequences for academics who relentlessly target journal editors or other professionals for simply doing their jobs. Targeted harassment should never be excused because the harassers are unable to falsify a hypothesis they dislike.
Sep 19 • 28 tweets • 8 min read
Two years ago, we demonstrated that the SARS-CoV-2 pandemic likely began at the Huanan Market via zoonosis resulting from the wildlife trade.

Many unanswered questions remained about the animals themselves.

Some answers, out today in @CellCellPress.

cell.com/cell/fulltext/… First let's get this out of the way:

We did not find an infected animal. We cannot identify an individual infected animal with environmental samples. To do that, we need a sample taken directly from an infected animal. As far as we know, no such samples were ever collected.
Sep 18 • 31 tweets • 7 min read
I’m pessimistic about the Pandemic Accord. Here’s a little story about why. In March 2023, I was invited to a Canadian Pandemic Accord stakeholder meeting in Ottawa.

I had just co-authored a report on environmental data that showed genetic proof of wildlife at Huanan Market. There were round table exercises in which we were asked to address the components of the Pandemic Accord zero draft that we felt were most important.

The report we had just released raised so many relevant issues to pandemic response:
Sep 7 • 15 tweets • 4 min read
There are critical outstanding questions about the MO bird flu case that need to be addressed now (and why reporting delays are unacceptable). They concern its pandemic potential.

Where did this virus come from?
How was the infection acquired?
Is human transmission occurring? Where did the virus come from?

Viruses don’t materialize out of thin air. They only come from infected hosts, so we need to think about how the patient could be exposed to said hosts. No contact with animals reported, but indirect contact or exposure could still occur.
Sep 7 • 7 tweets • 2 min read
This is being presented like it’s a triumph for flu surveillance, but I don’t think I would brag that the CDC and Missouri DHSS have known it was H5Nx for at least a week, probably longer, and waited to disclose this publicly until a Friday night.

cdc.gov/media/releases… The patient was hospitalized on August 22nd and they only disclosed that it’s H5 with no known animal contact (meaning it could be human transmission) on September 6th? They also haven’t sequenced it or subtyped for neuraminidase yet.

health.mo.gov/news/news-item…
Aug 2 • 28 tweets • 8 min read
Yesterday I shared this piece by me & 40 colleagues on the harms of the “lab leak” hypothesis inflicts on science & scientists.

I’m not finished talking about it. The origins “debate” has consumed my life for >4 years & I want to talk personally about the damage it has caused. First I’ll review what the commentary says because I know not everyone will read it. People are busy & @JVirology is not always going to publish thrilling page-turners for non-virologists. But here’s the link if you do want to read—it’s pretty accessible:

journals.asm.org/doi/10.1128/jv…
Jul 31 • 7 tweets • 2 min read
There's a big problem with the way the US is responding to the H5N1 cattle outbreak.

Samples are not being tested in a timely manner (months later) and then these results are not being disclosed in a timely manner (again, months later) either.

This outbreak is not containable. A central principle of outbreak response and containment is to identify cases so they can be isolated. From there, contact tracing and quarantine measures need to be applied with the goal of eliminating further onward transmission (to cows, as well as spillover to humans).
Jun 16 • 10 tweets • 3 min read
In spring 2020, Craig described NY Presbyterian Hospital to me as “the fucking apocalypse.”

By July, the same sentient pancake stack bragging about his spaceships told me that even though an even bigger surge was hitting sunbelt states, the epi data was “bs” & PCR is fake. Because I, a virologist with 2 masters & a PhD, ~20 yrs experience with emerging viruses, & whose life at the time was like the forced reeducation scene in Clockwork Orange except with COVID data, was less skillful at interpreting basic epi data than a rich dude with opinions.


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Jun 4 • 20 tweets • 5 min read
People asking why this is factually incorrect…I’m at a conference today so am pressed for time but I’ll quickly address each of the 5 “key points.”

Bottom line: You can dress up unsupported horseshit in as much polished data viz as you want, but it still stinks. Yes the virus emerged in Wuhan & the WIV is there & studies SARS-related CoVs, but that’s where the truth ends.

Shi Zhengli’s lab does great work on SARSr-CoVs, but they aren’t the only lab in the world doing so. They aren’t even the only lab in China doing this work. Image
May 23 • 8 tweets • 3 min read
This is great news, as more testing is urgently needed, but there are some caveats.

Wastewater data can be difficult to interpret. It can be especially difficult to identify the source and won’t catch anything not connected to municipal sewage systems (many farms are not). Because there is no data indicating widespread human infection, spikes of H5 in wastewater could indicate dumping of infected milk, birds or other animals defecating into sewersheds, etc. Unlike other environmental samples, the host can be very difficult to identify.
May 3 • 22 tweets • 7 min read
Out now on @virological_org: preliminary report on the genomic epidemiology of H5N1 sequences in cattle. This complements the preprint @USDA put out yesterday.

There was a lot of data to work with, so it's split in two parts 👇🏼

virological.org/t/preliminary-…
virological.org/t/preliminary-… Some key findings from this preliminary analysis:

1. There was a reassortment event shortly before the cattle outbreak.

Only segmented viruses like influenza can reassort. If 2 viruses infect the same host, they can shuffle their genome segments like 2 decks of cards
Apr 24 • 20 tweets • 4 min read
Very important to note here that qPCR positives are not the same as "virus particles." It's much easier to detect viral RNA by qPCR than it is to detect infectious virus or intact virus particles (as the article correctly notes).

This finding does have some big implications: 1. This suggests there are undetected herds shedding virus into the milk supply. Viral RNA does not materialize out of thin air—it is the product of a current or very recent viral infection.

No virus replicating in cows, no viral RNA in milk.

No viral RNA, no PCR positives.
Apr 5 • 12 tweets • 5 min read
Here is the article linked above and what it actually says: “The Texas Animal Health Commission said in an email that sick cats tested positive for the virus.”

cidrap.umn.edu/avian-influenz…
“The Texas Animal Health Commission said in an e-Mail that it has received lab confirmation of HPAI in three cats.” Last I checked, 3 is 37 fewer than 40. There may be more cats affected but I did not find a single credible report of more than these 3 cats (for now). Also to be clear there is no evidence that it is “spreading rapidly” in mammals & sequence data suggests transmission from birds.

cidrap.umn.edu/avian-influenz…
“She said sequences from the dairy cows nest with those from wild bird samples collected from Texas about the same time. However, the goat samples from Minnesota are most similar to a pheasant sequence from Colorado. Moncla said none of the PB2 sequences have known adaptive markers, and the similarity of internal genes from wild bird and cattle sequences suggest direct transmission from wild birds.” The human case did have 1 PB2 mutation that suggested mammalian adaptation—likely adaptation to the human who got it. Cat H5N1 armageddon is not yet upon us.