Killer Bugs for Halloween: Microbes and murder through the lens of Agatha Christie

October 30, 2026October 30, 2026 girlymicro General, Microbiology (Clinical), Science Communication, Writing Agatha Christie, anthrax;, book-review, books, detective novels, halloween, hercule poirot, microbiology, miss marple, murder mysteries, mystery, polio, rubella

I don’t think this is a surprise to any of the regular readers of this blog, but I adore Agatha Christie novels. Reading them has seen me through many a difficult period. They are a source of comfort, escape, and inspiration. I even wrote a previous blog about how there are parallels between solving her ‘who done its’ and my day job, as a hospital detective. What could be more Halloween than a little bit of murder, however, and so today I wanted to talk about how she uses microbes to kill in her books and why the science behind their use brings me so much joy.

Celebrating the Hospital Detectives: Why I describe Infection Prevention and Control as the detectives within our healthcare drama

When many people think of Agatha Christie murders, however, they think of her as the Queen of Poisons. They are even a number of books written about her experience as a apothecary’s assistant (pharmacy technician) during the Great War (First World War) and others breaking down her use of toxins. Most readers probably don’t necessarily think of her books having much to do with microbiology, even I hadn’t really made the link despite having listened to, read, and watched, all of her content multiple times.

I’ve been going through a difficult period at work, that combined with the hormonal chaos of the perimenopause, has led to a lot of being awake from 2 – 5am. In order to manage the anxiety I’ve been hitting the audiobooks pretty hard, and of course that has meant listening to a LOT of Christie. Imagine my surprise, therefore, that I finally clocked that although many of the deaths include death by poison, there also a few where the death featured is not by toxin, but by microbe! The excitement of this revelation probably didn’t help with the sleeping or resulting sleep deprivation, but it has inspired me to write this blog. So, not all bad then.

WARNING – THERE WILL BE SPOILERS AHEAD!

Who was Agatha Christie?

Dame Agatha Christie wrote 66 detective novels between 1916 and 1976. Her first novel, The Mysterious Affair at Styles, was written in 1916 and published in 1920. Her final work was published after her death in 1976 at the age of 85 and is one of my favourites, Sleeping Murder. Her work features so many wonderful characters, including detective characters that most people will have heard of, Hercule Poirot and Miss Jane Marple. There are many more however, including two of my favourites Tommy and Tuppence, and a girl who will forever hold a piece of my heart, Miss Ariadne Oliver, who is a novelist with some parallels to Christie herself.

Today we’re going to be talking about three main books, published over almost 30 years and featuring three different detective characters:

Cards on the Table, 2 November 1936, featuring Hercule Poirot (and my girl Ariadne Oliver)
Murder is Easy (originally Easy to Kill), 5 June 1939, featuring a one off appearance by Luke Fitzwilliam as the detective character
The Mirror Crack’d from Side to Side, 12 November 1962, featuring Miss Jane Marple

Cards on the Table

This book is based around a dinner party organised by Mr. Shaitana. He is an interesting chap, with an interest in collecting and also murder. He organises a dinner party with a pretty varied guest list, four detective or crime solving characters (Poirot, Oliver, Superintendent Battle, and Colonel Race), alongside four characters who may or may not have been involved with death under suspicious circumstances (Mrs. Lorrimer, Major John Despard, Dr. Geoffrey Roberts, Anne Meredith).

Shaitana is murdered after dinner, in plain sight, whilst sitting in an arm chair, as our suspects play bridge in the same room, and our detectives play bridge in another. The solving of the crime, in the most British way possible, comes down to an investigation of the Bridge hands played. On a side note as a Bridge player in my youth, albeit a very bad one, I kind of love this.

So where do the microbes come in? Not in the murder in the room, but the deaths by suspicious circumstances that one of suspects is trying to cover up.

The first murder by microbe is linked to an affair and the associated cover up, and the way it is done is pretty cool. One of our suspects has an affair with a married woman, and when he realises her husband has discovered what has happened by over hearing a conversation he takes a trip to the bathroom on the pretext of washing his hands. Whilst there he takes the opportunity to contaminate the bristles of a shaving brush with Bacillus anthracis spores, so that next time the gentleman shaves, and ideally has a few shaving cuts, the anthrax will be inoculated into the wounds.

So what would the anthrax do? The association with wounds is key, ideally a deeper cut, as there are 2 likely infectious outcomes from this. The most likely would be Cutaneous Anthrax, resulting in a surface lesion that gradually progresses to turn into a very characteristic, painless, coal-black necrotic eschar. The bacteria then release toxins that cause localised swelling. If the bacteria then enter the blood stream they then can lead to a 5% to 20% mortality rate if untreated, which of course they would be in 1936. Penicillin, which is the main treatment and fortunately the first antibiotic developed, didn’t become widely available until 1945/1946.

Even if penicillin was around it may not have helped if the bacteria entered the blood stream, as you would usually like to use either ciprofloxacin or doxycycline plus one or two additional active antibiotics like vancomycin, imipenem, or meropenem – none of which would be available for some time.

If the inoculation had been deeper, he may have developed Subcutaneous Anthrax, which could result in deep tissue infection and even anthrax meningitis. So the death of his target is not unexpected, especially given the consideration that the victim is likely to have multiple daily exposures every time they shaved.

Why is the shaving brush a clever idea? Well, firstly it’s an object that is likely to be used very regularly, and the spores will survive a very long time upon it. Secondly, not only will it be used often, the likelihood is that it will come into contact with broken skin sooner or later, increasing the chances that severe infection will occur. Third, the inoculation event will be temporarily distinct from the infection, with days to weeks separating the contamination of the brush and the presentation of the infection, making it very hard to trace back to an individual or time point. Finally, and probably most cleverly, these kinds of shaving brushes were often made of badger or boar bristles. During the Great War, however, there was a large scale cutaneous anthrax outbreak linked to shaving brushes that were made of untreated horsehair, some of which were mocked up to look like more expensive badger. This means even if someone identified the shaving brush as the cause, they would have reason to believe that it was an unintentional exposure and there would be even less likelihood of connecting it to our suspect.

Having succeeded once, like many murderers, our suspect decided to try again. The wife of his first victim, yes the one he was having an affair with, appears to become a little too much now her husband is no longer in the picture. He uses the cover of a routine typhoid injection (which had been available as required since the 1897) prior to a trip abroad to inject her with an infectious agent that resulted in her death. It doesn’t list what but if direct injection is an option, and no antibiotic exist, the world is your oyster in terms of bacterial choice.

This may feel a little far fetched, but the video below includes information about the way genetic evidence was collected to show that a doctor within the US injected his ex girlfriend with HIV under the cover of it being a vitamin B injection in order to infect her. Sometimes reality is even stranger than fiction.

Murder is Easy

This is one of my favourite Christie books, and I think it is one that is less known to many. It also has one of my favourite microbial deaths, this time of a main character. Under interrogation it would not be possible for me to deny that all these facts are connected. Luke Fitzwilliam, our detective character and a retired colonial police officer, meets Miss Lavinia Pinkerton on a train to London who is planning on visiting Scotland Yard. She confides in him that a serial killer is operating in her quiet English village, Wychwood-under-Ashe, and that the deaths have been disguised as ordinary accidents. She names a number of deaths that have already occurred (Amy Gibbs, Tommy Pierce, and Harry Carter) and says that the local doctor, Dr. John Humbleby, will be next. I do think this is why I don’t speak to strangers on trains.

Luke mostly thinks that Lavinia just has an over active imagination, until he sees in the newspaper the next day that Miss Pinkerton has been killed in a hit-and-run accident in London. As a result he travels to Wychwood-under-Ashe to investigate further.

He finds that the 3 deaths he’s been told about have occurred in a wide number of ways:

Amy Gibbs: Died after drinking hat paint swapped with her cough mixture bottle
Tommy Pierce: Pushed from a high windowsill (while cleaning) to his death
Harry Carter: Pushed off a footbridge into the river, where he drowned

Dr. Humbleby then dies under suspicious circumstances of sudden onset septicaemia (blood stream infection), but how does it happen? Although anthrax is cool, this method is even cooler. So let’s talk pus.

Dr Humbleby dies as a result of our killer accidentally-on purpose injuring him with scissors whilst he visits their home. When dressing the injured hand our killer uses a bandage that they have deliberately contaminated with pus discharging from the ear of an infected cat, named Wonky Pooh.

Pus is not just fluid; it is a dense mixture of dead white blood cells, cellular debris, and often billions of microorganisms, frequently from different species, combined in one sample. The act of introducing pus (even a small amount) has an infection rate of close to 100% (although obviously no trials on this) as it will overwhelm local tissue defenses, frequently leading to localised tissue damage, and delayed healing. As we are talking about the pre-antibiotic era here, systemic infection (i.e. infection impacting blood or organs) is very likely to occur as the local wound infection cannot be treated. It means our killer has a very high chance of fulfilling their deadly objective. I personally love a pus sample as they are such great specimens to work with…I don’t know what that says about me.

The Mirror Crack’d From Side to Side

Although I have only found three deaths directly linked to microbes, Agatha Christie didn’t just use microbes for murder, she also used them as the motivation for murder.

There is no avoiding spoiling this one I’m afraid, so skip this section if you don’t want to know the core of the plot

The story starts out with film star Marina Gregg and her husband, film producer Jason Rudd, moving into Gossington Hall (the same Hall that features in the Body in the Library) in the village home of Miss Jane Marple, St Mary Mead. The stylish couple host the local village fête where a deadly encounter occurs.

One of the local villagers, Heather Badcock, meets Marina and as part of their discussion talks about how many years before in Barbados she had left her sick bed in order to get an autograph from her. Heather later dies of poisoning at the same event. Miss Jane Marple is not well and so is at home and misses both the conversation and the death, but when more people start to die she decides to investigate and find the reason behind Heather’s death.

As she speaks to people she gets many different explanations as to the reason that Heather was sick when she went to collect the autograph, everything from Chickenpox to Flu. Miss Marple works as an infection detective as the causative organism is what the entire motive hangs on. Eventually, she manages to get an accurate recounting of the conversation from the Vicar, who tell her that Heather says she had German Measles. This fits with what others have said, in that she covered her face with powder in order to hide her rash.

First, let’s talk about what German Measles is, as it is not actually a name in common scientific use, and hasn’t been the approved name since 1881. The virus in question is rubella, but when the presentation was originally discovered it was known as German Measles because it was first described as being distinct from measles by German physicians. Prior to this presentation recognition, rubella was considered to be a variant of either measles or scarlet fever. In 1740, the German physician and chemist Friedrich Hoffmann recognised that it was, in fact, a separate infection. The name rubella was given by surgeon Henry Veale in 1866, meaning little red, as a way to more accurately describe the rash and was widely adopted in 1881.

Why does it matter that Miss Marple identified rubella as the cause? In healthy adults rubella presents as a rash with small flat spots and a high temperature, with or without joint pain and cold like symptoms. You are infectious for ~1 week before the rash starts and 1 week afterwards. Infection is usually mild and self resolves in a week to 10 days. So why would this conversation with Marina result in Heather’s death?

Well, it turns out that Marina had been desperate to have children, so desperate she had adopted. She finally found herself pregnant, but in a way she had never understood, she discovered she had caught rubella when she was 4 months pregnant. As a result, her child was born with a severe congenital learning disability and was placed in a special care facility from birth. Marina suffered a nervous breakdown and became reliant on medication as a result. When Heather approaches her, for the first time ever Marina knows precisely where she was infected and by whom.

Far from being a mild disease in pregnant women, infection, especially early in pregnancy can have devastating consequences for the foetus. For this reason in the 1970s the rubella vaccination programme was introduced. I remember all the girls in my class being walked into a room separate from the boys when I was in primary school to get vaccinated. The aim of this selective program was specifically to target pre-pubertal schoolgirls and non-immune women of childbearing age in order to protect future pregnancies from the risk of Congenital Rubella Syndrome (CRS).

You may have noticed, however, that the virus infects all individuals, and so by only vaccinating those physiologically capable of bearing children the transmission chain is not interrupted, only the consequences of infection. For this reason the vaccine, within the UK, was extended to everyone in 1988 in order to support better transmission control.

Global vaccine introduction was driven by an outbreak across Europe and the US between 1962 – 1965 that impacted over 12.5 million people in the US alone, and resulted in 11,000 miscarriages and stillbirths. The Mirror Cracked came out in 1962, and so the audience would have been very sensitive to the plot lines within, especially as there was no way to protect pregnancies at the time. Heather deciding to ignore her symptoms and deliberately risk exposing others would have been a particularly heinous act, I image, and there is a powerful quote associated with it as the end of the book:

Heather Badcock meant no harm. She never did mean harm, but there is no doubt that people like Heather Badcock (and like my old friend Alison Wilde), are capable of doing a lot of harm because they lack – not kindness, they have kindness – but any real consideration for the way their actions may affect other people. She thought always of what an action meant to her, never sparing a thought to what it might mean to somebody else.
Agatha Christie, The Mirror Crack’d From Side to Side

I feel that is a strong reflection on some of the more modern behaviours that we see in response to infectious disease, especially post pandemic, and the way vaccine related behaviours are starting to impact wider society. Not only are vaccines beneficial to individuals, but they protect the wider community, not all of whom can get vaccinated. By protecting ourselves we protect others, an option that wasn’t available for Marina, but is available to all of us.

The every present impact of infectious disease

Infectious diseases were part of every day life for most of the time that Christie was writing, and for most of it responding with antibiotics was also not an option. In The Mirror Crack’d, Doctor Haydock says he has to continue his rounds as he has 8 cases of German Measles, Whooping Cough, and Scarlet Fever that he needs to see. Numbers that would be shocking today in a small English village, two thirds of which are now vaccine preventable, and the other readily treated with antibiotics. I think because we don’t see the negative consequences of these types of infection in our every day life, outside of healthcare, we don’t realise how fortunate we are to live in an age where we have such options.

As well as being background, some infectious diseases, especially polio, even provided an alibi…as well as a setting up scenarios for becoming a target for murder in her books.

Christie wrote books at the height of the global polio epidemics and the resulting disease is used as a realistic backdrop to shape the characters’ temperaments, physical mobility, or alibis. Polio is a virus that causes everything from asymptomatic infections to life-threatening paralysis, and nowadays is another vaccine preventable infection.

Before modern ventilators became available, patients who experienced muscle weakness due to polio infection were sometimes managed within iron lung machines, that were used to mechanically assist or if needed take over the work of breathing for a patient who has lost control of their respiratory muscles. Having seen historic examples of these when I worked at Boston Children’s Hospital, I can testify to how terrifying they must have been if your child ended up in one.

Within the book, the Crooked House, which came out in 1949, one the main characters is a boy of 16 who is recovering from a mild case of polio. He has a lot of residual stiffness that causes his grandfather to pull him out of school and provide him with a private tutor instead. He becomes isolated by being at home, and the presence of the tutor is also a big driver in the plot after his grandfather is found dead. Polio, therefore, drives a number of the circumstances that result in the subsequent deaths.

Another book that some people may be less familiar with is called Ordeal by Innocence that was published in 1958. The matriarch of the Argyle family is found murdered and one of her adopted children is found guilty, is sent to jail, and subsequently dies.

Dr. Arthur Calgary is a geophysicist who returns from a two year expedition to the antarctic. He sees coverage of the case and realises he is the alibi for the son Jacko who was convicted, but he could not testify as he was away. He turns up to inform the family of the son’s innocence and sets in motion a series of events that reveal the real killer, but also results in many more deaths.

It also causes Philip Durrant, who is married to one of the other Argyle children, to begin his own investigation. Philip has recently contracted a case of severe polio that has left him paralysed and confined to a wheelchair. He hates being dependent and commences his own investigation as a way of asserting his independence. It may not end well for him.

Finally, and I’ve saved one of the best for last. I’m talking about The Pale Horse released in 1961. Some people don’t love this one, but I have to tell you I find it brilliant and clever, and so atmospheric I adore it. I won’t talk about how the deaths are achieved in this one as it is too fun to spoil, but I will mention that one of the main suspects is known as Mr Venables, who requires the use of wheelchair after severe polio infection. An eye witness identifies him close to a crime scene, but his legs are entirely atrophied, making it physically impossible for him to stand or walk. A lot of the discussion therefore centers around whether his has a genuine polio disability or is it a long in the planning elaborate alibi. I’ll leave discovering the answer to you.

Agatha Christie used the times in which she lived, not just as the backdrop for her novels, but as the driver for the plots within them. It is no surprise, therefore, that infectious diseases featured heavily. Living in a pre-antimicrobial, mostly pre-vaccination world must have been terrifying, especially if a loved one fell ill. Using that fear of the unknown, fear of the less understood, makes a lot of sense when setting the scene for murder and mayhem. The inclusion of a detective character, whose job it is to reduce the chaos and make the world make more sense, also explains why it may have struck a cord with those reading who also were experiencing disease within their own daily lives. This deep dive has just made me extra grateful for all the progress we have made in making these organisms much more present in books than they are in my reality, and if possible love Christie even more than I did before.

All opinions in this blog are my own

And now…for a shameless plug

If you love Halloween, or a nice outbreak thriller/zombie film, keep an eye out for my new book ‘Don’t Open That Door: A microbiologist’s guide to infection in movies and TV’ is out in early December, and available for kindle pre order now:

Have you ever wondered whether The Last of Us TV series could actually happen?

Have you ever considered what you would do if you were the one standing at the air lock door in Alien?

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The Survival Basics: Master the fundamentals of microbiology and infection control, including how pathogens spread from airborne droplets to zoonotic transmission.
The Intervention Arsenal: Learn the truth behind pandemic interventions, exploring everything from real-world isolation protocols to the mechanics of vaccines.
The Rogue’s Gallery of Pathogens: Dive into dedicated sections exploring the distinct worlds of viruses, fungi, parasites, and bacteria.
Hollywood vs. The Lab: Deep-dive into chapters exploring both your favourite cult films and TV series, as well as ones you may be less familiar with. Discover how fictional world-building and cinematic outbreaks stack up against actual scientific investigations.

Whether you are a die-hard sci-fi geek, a horror movie buff, or simply curious about the microscopic partners that share our world, this book will completely change the way you watch television.

Happy Halloween

Halloween 2025: Let’s talk all things vampirism and infection

October 31, 2025November 17, 2025 girlymicro General, Healthcare Science, Science Communication bacteria, books, fungi, halloween, horror, infection control, movies, parasites, TV, vampires, viruses, Writing

I am not a big Halloween girly, to be honest I can take it or leave it because I’m mostly excited about the build up to Christmas. That said, what I do love are movies and TV, and despite never being someone who can tolerate a lot of slasher or gore based horror movies, I love a good vampire movie.

A lot of this may be because I enjoy the world building and lore that seems to be more integral to vampire movies and series. This is because, although they share some of the same rules, depending on how the world is built they always need to explain which of the nuance comes into play in that particular setting. It felt fun this Halloween therefore, to write a blog post that talks about some of those tropes when vampirism is linked to infection, and how those rules compare to the real world.

Common vampire tropes to be aware of and to bear in mind as you read on:

Experiencing pain or physical damage in relation to sunlight
Needing to consume blood as a protein source
Inability to eat or digest food other than blood
Avoidance of animals
Ability to influence humans to undertake acts that may be against their will
Violent reactions to garlic
Inability to see themselves in mirrors or via cameras
Death only by beheading
Death by wooden stakes
Damage linked to holy water
Aversion to signs of faith
Aversion to alcohol or drug use

Not all of these are present in every piece of world building, hence why I find the variety of vampire mythos so interesting. The choice of which ones go together combined with different origin stories and creation processes enable a pretty large tapestry to be created from some similar thematic components.

Mystical, infections or something else?

The place to start I guess is by discussing whether all vampire world building includes infectious transmission? And the answer is a definitive no. Sometimes the way that the creation of new vampires works isn’t discussed. Sometimes the rules about the underlying process is unclear. That said, the fear of becoming something new is a frequently used trope for dramatic purposes and so the process by which a human is turned into or by which vampires exist is discussed pretty frequently as part of world building, and from what I can see there are three main routes:

Mystical – some form of occult/magic/cause not routed in science
Genetic – vampires are born and exist as a stand alone species
Infection – transmission via blood or other infectious transfer, even if the agent is unclear or unspecified

Now, I’m not going to cover the mystical/magically as that’s not anything based in science and the science is what I’m here for. The other two, however, are often based (sometimes loosely) in science as they are often inspired by things that actually exist and so I’m going to talk about both of those in a bit more details.

Genetic

I’m going to kick off by talking all things genetics. There are an increasingly large number of vampire movies and TV series where the vampires that featured were born vampires. This includes movies like Abigail, Perfect Creatures, the finale of the Twilight series, but also TV series such as A Discovery of Witches, First Kill and Vampire Academy. Sometimes within these there are vampires that are made through other means (discussed below) in the same world. Often these genetic vampires exist as a separate species to their Homo sapien neighbours either openly or in hiding.

There is often much discussion about where the vampire myth comes from, and in many way these stories of genetic vampires who are birthed through a similar route to standard human deliveries, links in most with what is considered to be a real world inspiration for many vampire myths. The origin is thought to be linked to a rare inherited condition known as Porphyria, the presentation for which may account for for some of the common components of vampire portrayals.

Porphyria is a rare, inherited blood disorder that occurs when the body can’t convert porphyrins into haeme, a vital component of haemoglobin. The resulting symptoms vary depending on the type of porphyria. Acute porphyria presentations include symptoms such as gastro intestinal pain and symptoms like nausea and vomiting – symptoms that are often portrayed linked to vampires attempting to eat normal food. Whilst cutaneous porphyria symptoms include pain, burning and swelling in response to sunlight, skin fragility and a tendency towards skin blistering – all of which are frequently included as vampire responses to exposure to sunlight.

Porphyria
D. Montgomery Bissell, M.D., Karl E. Anderson, M.D., and Herbert L. Bonkovsky,
N Engl J Med 2017;377:862-872
VOL. 377 NO. 9

Interestingly, in some of the genetic origin vampire stories, the impact of some of the limitations of the lifestyle limitation of traditional vampires are not so extreme. In some of these cases they can be seen in daylight, although not for long and don’t enjoy it, and they may be able to tolerate some, if not all, of human food. They are possibly therefore most aligned to their real world inspirations. I could write pages and pages on this, but infection is where my heart lies so I’m going to crack on.

Virus, parasitic, others?

Now we’ve covered off those born vampires, let’s move onto the most common version of vampirism outside of the traditional Dracula more mystical inspiration, that is vampires who are created linked to transfer of infection by blood or other means.

There are three main ways that this commonly comes into play:

Viral causes
Parasitic routes
Bacteria intoxication

I’m still trying to find a vampire movie where the main infectious agent is fungal, but it seems that most of the movies based on fungi are linked to zombie outbreaks. That makes a lot of sense, due to the fact that fungi are eukaryotes (like us) rather than prokaryotes (like bacteria), and so fungi tend to be linked to changing behaviour linked to interfering with the human nervous system. If you’ve seen a vampire version though please do let me know as I’m collating a list of where different organisms might come into play.

By far the most common route depicted is where the causative agent is a virus. Viruses are featured in movies such as Blade and Daybreakers and TV series such as Ultraviolet. This is because viral transmission in general is associated with transfer of bodily fluids, be that faecal-oral, respiratory via saliva, bodily fluids such as breast milk, or in the case of vampire movies via blood.

The most uncommon causative agent I’ve discovered is the parasitic cause of vampirism as shown in The Strain TV series. During the series transmission of the virus to create a full vampire is via something known as ‘The White’ that contains parasitic worms. These then lead to anatomical changes, including the growth of a proboscis that enables the biting and transmission of the parasite to others.

Bacterial coverage is mostly linked to potential methods of intoxication that supports the control over humans by vampires. Rather than being a direct cause of the vampirism, this seems to be about how transfer of the bacteria releases, or causes anatomical change, which then changes behaviour via things like hormonal or neurological changes. I’ve talked before about why bacteria may feature less in horror movies than other causes, but this can mostly be summed up by the fact that audiences tend to know more about bacteria and therefore it is less tempting for writers, but also horror tends to sit better in ‘the possible but not too close to us’.

Transmission

Obviously it’s not just the infectious agent that is important, but the mode of transmission for that agent. This being all about vampires the biggest mode of transmission is by bite, but it’s not always so straight forward. In mystical vampire movies, there’s usually a whole lot of removing of the original human blood and then transfer of the vampire blood, leading to a mystical baptism and rebirth. Infectious causes are much more one way, any bite could lead to someone turning into a vampire and the most important thing is load related. If someone is in contact for longer, if more blood is drunk and therefore more saliva and fluids exchanged, then the chances of conversion are much higher.

It’s not just blood as a bodily fluid that features in conversion during vampire movies. There are also films, such as Requiem for a Vampire and Trouble Every Day, where vampirism is treated more like a sexually transmitted disease, rather than transfer occurring during feeding on the blood of their victims. It seems that these films have increased since the 1980s, maybe as a result of fear processing linked to the HIV/AIDS pandemic during that time period or maybe because our knowledge about and ability to detect infections has increased and therefore there are a larger part of the collective public awareness. It will be interesting to see how the SAR CoV2 pandemic will impact this further.

The most unusual transmission, and one that aligns most highly with blood borne transmission is the presence of congenital transmission as featured in Blade. Where the main character Blade becomes a vampire hybrid by acquiring the vampire virus at birth, due to his mother being bitten and placental crossing of the virus into his blood stream. As a result, he exhibits some of the characteristics of a vampire due to the virus, but the effects are attenuated linked to his exposure route. It can often be that congenital infection presents differently to primary infection via other causes, and it appears vampirism is no different.

The other variable is linked to the time to turning once the infection has been introduced. I would speculate that this too is load related, as well as the infectious agent behind the symptoms. Viruses, for instance, are likely to reproduce and induce change at a much higher rate than anything linked to bacteria or parasites. This is partly due to their reproductive rate, but also linked to the level of dose that tends to be available. The exception to viruses resulting in the fastest change is likely to be bacterial intoxication and influencing. As the toxin acts immediately, when this is present in media and TV the change is almost instantaneous, but also time limited and therefore requires top up or re-application. Not all impacts are until beheading, some require a more time boundaried set of interventions.

Interventions

Once your characters are aware that vampires exist within their mist, then they will want to look for actions in order to protect themselves. One of the classic ones as featured in many movies, including the classic Lost Boys, is garlic.

In some ways the impact of garlic makes even more sense if you think of vampirism through an infectious transmission route, as garlic has been considered to have anti-infective properties for a long time, although warning you may have to ingest a LOT of it!

Bedir, A.S.; Almasri, R.S.; Azar, Y.O.; Elnady, R.E.; Al Raish, S.M. Exploring the Therapeutic Potential of *Allium cepa* and *Allium sativum* Extracts: Current Strategies, Emerging Applications, and Sustainability Utilization. *Biology* **2025**, 14, 1088

Another common feature in vampire movies is the roles that animals play as protectors. For instance, in 30 Days of Night, the vampires kill all of the dogs before they launch their main attack. This kind of thing also often happens in films and TV where vampires are hiding in plain sight. It could be that they are taking out animals as they don’t want to be found, and animals are easier than humans, but I have another proposition. There are a number of infections where animals can be used to sniff out and identify infected individuals. Therefore, if animals could detect vampires they are much more likely to be a risk and warrant removal. Animals could therefore act as a front line of diagnostic defence to enable you to tell friend from foe.

Volume 26, Issue 4, April 2020, Pages 431-435

Having determine that a common weakness of vampires is their damage response to ultraviolet light (UV), films such as Underworld weaponise light against the vampire protagonists. Light, and especially UV-C (200 – 280nm), has been known to impact viruses and bacteria for well over 100 years. When light is in this frequency is can damage both RNA and DNA, resulting in cell death, and it is possible that if the infectious agent is the only thing that is keeping your body moving the damage would be more pronounced. We’ve also discussed how the lack of some biochemical pathways can lead to UV-C causing much larger amounts of pain an damage.

Normally, penetration of the light to cause damage might be an issue, but if you are using bullets or other means this may not impact. The most important thing I have to say here is, that despite what is shown in Blade 2, light does not bend around corners. This is also important for when you are considering using UV-C in hospitals to support cleaning, it doesn’t have good penetration and doesn’t go around corners of work in shadows. Using UV-C may work against your vampires but you are going to need to think carefully about where you use it so it does what you think it can.

Vampire movies have amazing world building and are often my favourite genera in terms of their string internal logic. I love the fact that so many types of infection and route of transmission that reflect real world cases are present as part of these pieces of entertainment. They can actually teach us a lot, even when we don’t realise it, and so much of it has origins in real world knowledge, even if only loosely. So, this Halloween evening find one you haven’t seen before and let me know which intervention you would use to stop your town being turned into creatures of the night!

Before I go, I thought I would share a few of the previous years Halloween blog posts in case you are looking for some more spooky season and infection reading:

Saturday Morning Zombies: how infection is portrayed in the genre

Infection Representation in Popular Culture: Why infection and infection risks, as discussed in movies and TV, may matter more than you think

Would You Let Them In? Celebrating Halloween by discussing what not to do in infection control as modelled in the Alien movies

Let me know your favourite vampire movies and if there are any other infection related Halloween topics I should cover.

All opinions in this blog are my own

Would You Let Them In? Celebrating Halloween by discussing what not to do in infection control as modelled in the Alien movies

November 3, 2024 girlymicro General, Healthcare Science, Microbiology (Clinical), Science Communication alien, alien movies, alien-romulus, Aliens, halloween, horror movies, infection, infection control, movie science, movies, parasites, public engagement, science-fiction

It’s Halloween weekend, and in previous years I’ve talked about all things Zombie and infection transmission. This year, though, I thought we talked about something a little different, infection control precautions through the lens of the Alien movie series. Most importantly, I’m going to talk about those initial interactions with the unknown that we frequently see in both these movies and in infection prevention and control (IPC), and whether we too would open the door when someone presents at the air lock?

Spoiler warning! This post is going to mention things that happen in various Alien movies. If you haven’t seen them it may, therefore, contain spoilers – the best way to deal with this oversight in your viewing (if you are concerned) is to just get out there and watch them as Alien is the same age as me 😁

This post was inspired by watching Alien Romulus again this weekend, which, if you haven’t seen it is the best Alien movie in forever.

In preparation for the cinema release I also did a re-watch of a number of the movies in the franchise. Just in case you are less familiar, and inspired to do the same, the list includes a variety of films in different sub-genres as listed below:

Original series:
Alien (1979)
Aliens (1986)
Alien 3 (1992)
Alien Resurrection (1997)
Alien vs. Predator movies:
Alien vs. Predator (2004)
Aliens vs. Predator: Requiem (2007)
Prometheus movies:
Prometheus (2012)
Alien: Covenant (2017)
Alien: Romulus (2024)

So the big question is…..does life imitate art?

Whilst watching these I was struck by a number of moments that made me think about behaviours during the pandemic, but also tales of heard of some activities that occurred during the response to the Ebola pandemic and other high risk clinical settings. Not all of these moments would have been massively out of place, in terms of parallels with these films, and demonstrate that both risk assessment and clarity of thinking can be impacted and lead to responses outside of what would be normally expected.

The thing to remember is that there are usually protocols for just about everything, so most of the decision-making should occur and have been thought out long before the situation ever arises. The problems are almost always linked to human factors in the way we respond to stress and unexpected situations, and when the protocols appear to go out the window. So, just like every character and every space ship in the Alien franchise has a protocol for how to behave when they encounter new life, strange situations or sick crew members, every healthcare facility also has protocols to help deal with illnesses we see less often or that get issued when new diseases are encountered. Healthcare facilities may not have air locks, but they do have labs and isolation facilities, so the parallels may be more present than you’d imagine.

Infection is not always obvious

One of the first themes that recurs throughout all the movies is that infection is not always obvious, either to those on the other side of the air lock, or to the individuals outside waiting to come in. Infection with the parasite sometimes occurs when the stars of our show are unconscious, be that due to trauma or medical interventions, and so they are unaware of the Facehugger on character action that has occurred.

In terms of IPC the same if frequently true, both for viruses and bacteria. Some viruses have what is known as a pre-symptomatic phase, where you are infectious to others before you even know you are sick. This was a big problem in the early stages of the SARS CoV2 pandemic. Even for bacteria, when we talk about antibiotic resistant bacteria, most people are colonised and have the potential to act as silent sources without even knowing it, with only small numbers going on to develop infections.

The truth is not always apparent

Even when an individual knows that something has happened, and are aware of their close encounter with Alien kind, the truth of their scenario may still not be apparent to either them or to others. If you look at the Facehugger situation, surely once the terrifying creature has dropped off without apparent poor consequences, then everyone breaths a sign of relief and is grateful for the near miss, not knowing that this is only the beginning. When you combine this with the fact that some people will determine this to be a low risk event and therefore not want to disclose, as they are aware of the inconvenience that will result, you end up in situations where not all the information is available.

This can also be true in real life clinical situations. Patients may not know they have been exposed. Patients may also present with symptoms that they haven’t recognised as significant, or that they have risk assessed themselves and decided they aren’t concerned about and so don’t disclose. This can happen more easily they you think, especially at the start of something, where patients don’t feel particularly unwell, or they just have a couple of vesicles/small rash. In the latter stages, when patients are presenting because they feel unwell, they may be confused or not always able to accurately disclose what’s happened. Occasionally, this may be a deliberate attempt to withhold personal details, but most often it’s because they are rightly focussed on how they are feeling in the moment. Plus, if you asked me to accurately recall everyone I met and everything I ate a week ago, I’m not sure I could, even when well.

By the time you realise the condition is a threat it may already be a risk/out of control

One of the consistent themes across all of the movies is that situations get out of control before anyone truly understands the situation and the risks. It’s only when the person that you breached protocol for suddenly starts to writhe and the horror stands before you in all its glory do you truly understand the implications of the decisions you’ve made. At that point you are trapped in your glass med bay with a growing Alien and your self recriminations are not going to save your life.

This one is a rather more dramatic version of some of the conversations that happen amongst healthcare workers when you phone to give results and have conversations about whether patients had been in the right precautions and the staff member was wearing the right personal protective equipment (PPE). There have definitely been times when staff have made a risk assessment and not followed the protocols about what PPE to wear and have then responded to these phone calls with ‘what can you do?’ in relation to the exposure. Sadly, in some cases there is nothing that can be done once the guidance has been bypassed but to wait and see, which is the reason for the guidance in the first place. Fortunately, for most scenario’s in the real world, the consequence isn’t bloody horror, death and an alien threat to mankind.

Risk assessment is linked to risk management

One of the reasons that protocols are in place in the Alien movies is that someone, somewhere, has obviously recognised the risk of infection in a small contained community where everyone interacts and lives on top of each other. Even in Aliens, when you’re talking about somewhere the size of a colony, this principle stands. This is because you are unlikely to be able to access a clinical trial on a mining ship, or develop a novel antiviral on terraforming mission, even if what you’re importing is a more traditional style of infection, versus an Alien parasite. The extent of the risk mitigations needed will always align to the risk itself. If you are concerned about an introducing something that is untreatable, then your measures are going to be much more extreme than if your infection is likely to just mean someone goes to bed and takes paracetamol for a weekend. If you can’t treat, then prevention is your only option. After 9 movies there doesn’t appear to be a Xenomorph (Alien) cure and so measures taken to prevent allowing one into your space need to match the risk they present.

This approach is definitely seen in response to infection in IPC. If you have a condition that spreads easily, rapidly and can be incapacitating for a period (i.e. norovirus) then you will use a different set of precautions to those that you use to manage something which may not be as transmittable but is untreatable or has life threatening consequences such as a haemorrhagic fever. Having conversations and being open with people about the risks of getting things wrong and ensuring that individuals understand why responses are different in different circumstances are a key requirement for people working in IPC, and something I think we should all endeavour to do better at. I think the days of asking people to blindly follow protocols should probably be behind us, as I think the Alien movies demonstrate that if people don’t get the why, they often ignore some of the core components based on external drivers

So, what lessons can we learn?

Beware of acting on incomplete information

Decisions are consistently made in these movies based on incomplete information, which leads them to underestimate both risk and consequences. A great example of this is the way people use information related to the black goo, especially in Alien Romulus, maybe don’t inject yourself with a substance that doesn’t have a proper name let alone a full data set for you to understand what it does. The other thing is that information is often treated as static, and so there is very little rapid inclusion of new info, rather than being mindful of an iterative response to new data, so help constantly inform and improve your risk assessment. It’s always worth being conscious of when is enough is enough when it comes to information and decision making.

Emotions get in the way of logic

During the movie Covenant, the entire crew is made up of couples. I get this in terms of colonisation, but in terms of good decision making, and in relation to risk this is just a one way route to bad outcomes. There’s a reason that in a certain Zombie series husbands have kept their zombie wives locked in basements rather than removing the risk to them and others. There’s a reason medical professionals should not manage their loved ones. Emotions interfere with logic, and there is no way under this setting you are managing to make decisions without your emotions getting in the way. It’s a reminder that if we become aware that we are in an emotive place, it may be the time to step away and take a deep breath, before making that judgement call or even tap out entirely and allow someone more removed to take our place.

The contrast between human emotional decision making and evidence based decision making, usually undertaken by the android cast, is beautifully explored during Romulus via Andys story arch and is one of the highlights for me in terms of enjoyment.

Science doesn’t change based on how much you wish the outcome to be different

One of the reasons that emotional involvement in decision making can be so challenging is that it can interfere with perspective and accurate interpretation of risk, thus impacting risk perception. Sadly the truth that wishing does not impact outcomes is hard to argue with, but it is human to try to persuade ourselves we have more control and ability to influence the outcome than we do. Under stress, our natural tendencies towards pessimism or optimism are definitely amplified. All of this means that when there is someone at the door banging and begging to be admitted, it is easy to persuade ourselves there is a) enough time to manage to open the door safely and b) the consequences of opening said door will not be as bad as we fear. Emotions don’t change outcomes but we are almost programmed to hope that they can.

An individual will always want to be the 1 in a million

The reason someone opens the door is the same reason that when one character looks at another and utters the fateful and true words ‘it’s too late’, and it almost definitely is, neither one acts before everything gets out of control. Humans are not good at dealing with numbers and risk when they are actively involved in the situation. One of the reasons we aren’t in that we throw sentences around saying it is a 1/million chance. We, as humans, have a tendency to focus the fact that, although it is a long shot, there is a chance that things can go your way. Sadly, as someone who has experienced the opposite, where my sister died in a 1/10,000 pregnancy, someone always need to be the one. The stats work both ways, whereas most of us survive in the world by only focussing on one side of the equation. This therefore impacts our capacity to evaluate any risk in situations we are involved with. Somebody always bears the cost and few of us can bear the vulnerability of acknowledging that that somebody could be us.

The people with the most experience are not always the ones making the decisions

One of the other main themes in these movies is that decisions, when not being made by friend and loved ones, are often being made by people in positions of power, not necessarily based on knowledge or even accepting of prior experience. This works well or not so well based on how well they listen to those who do have the information to help improve their decision making. Chains of command, especially in high stakes scenarios, are not necessarily bad, as we’ve already talked about the risks linked to emotional decision making, but so much depends on how well they work and how they place value on evidence based choices rather than hierarchy.

The other theme here is the trusting of unknown sources, especially ones with no evidence of expertise, over those who have either lived experience or expertise. I think this one resonates a lot right now, when there are so many sources of misinformation out there, and so many conspiracy theories that rely on speculation and rumour. Fact checking is key, be that on a space ship or deciding on your vaccination options.

Not everyone has the same thought processes

One of the other reasons decision making goes astray in these movies is because those involved in that decision making often have undisclosed values, beliefs or drivers that are impacting their choices, and this process is not always obvious to those others involved. This is true from androids that may or may not be obviously androids and who will have programmed ‘primary directive’, as well those working for the corporation. This is interesting as they often have more complete information than the others involved, as well as seeing the situation through a different lens because of how they view the world. This means that they can see others as disposable or views risks different, as they have a set of criteria that they wish to achieve which is more than just survival. Although in clinical life the juxtaposition is rarely so extreme, the challenge of reaching alignment when people come with different world views can definitely impact shared decision making.

Smart people can do stupid things

Having said all of that, smart people can in general do stupid things, even without all of these complications. Even when the experts are the ones making the decisions they can still make the wrong ones, especially when tired, stressed, or lacking all the information. This is the reason why protocols are key, drawn up and decided upon when all of the confounders to good decision making are not present.

You need to follow the standard operation procedures

In the end this entire post has been a very very long way of saying ‘JUST FOLLOW THE SOP!’

Many of these movies but have been much shorter with a much reduced body count, if those involved had just followed the pre-established procedures laid down for their safety. Obviously, we don’t have so many Xenomorphs as a daily risk factor in healthcare, but the same is true for us. SOPs are rarely there for the sake of it, they are there to support decision making so that in times of stress or information overload, you are not having to seek extra information to support good decision making, you have it freely pre-digested and available to you. So the next time you think twice about donning that PPE or the closing that isolation room door, ask yourself ‘would you open the airlock door?’, think twice and do the right thing.

And now for something completely different

Finally, because this is something that has amused me whilst watching these films and is probably not something that I can talk about in general down the pub. The computer in the Alien movies is usually referred to as Muthur, pronounced Mother. I just want to share my joy that the analysis software that is used to help analyse 16S rDNA runs, to give you microbiome analysis i.e. tell you what bacteria are present in your sample, is called Mothur, and also pronounced Mother. I’m sure the two things have nothing to do with each other, but allow me my scientific joy that something which was so ‘other world’ when it came out to me as a scientist has the same name as something imagined from ‘another world’.

Also, if anyone needs a science advisor on their next project, give me a shout as this post has brought me much joy and I think I may have missed my calling 🙂

All opinions in this blog are my own