Note: Apologies for any grammatical errors.

I have been working on a story of mine for quite a while now. A part of that story is a viral pathogen that turns people infected with it into what is basically analogous to 'fast zombies'

The following is a quick rundown of the details I have come up with:

1. Types of immunity:

A) Cannot be infected through inhalation of virus aerosols. Can only be infected by getting bitten or spat in the face (high virus concentration; entering through mucous membranes). Will be referred to as Group A or Alpha for simplicity's sake from now on.

B) Can be infected through inhalation of virus aerosols as well as the other vectors mentioned above. Will be referred to as Group B or Beta for simplicity's sake from now on.

2. Modes of Transmission:

When the virus is introduced into the body through a bite from an infected, it travels from the site of the bite to the brain by moving within the nervous system. As mentioned, exposure can also occur through inhalation of aerosolized virus at high concentrations through mucous membranes (Group B). As the virus is not bloodborne, it cannot be transmitted via blood spatter.

3. Stages of infection:

Airborne infection:

1. Subject is infected.
2. After virus has moved past mucosal epithelial barriers, it establishes infection in oropharyngeal or small bowel lymphoid tissues. Virus then travels through the body until it reaches the brain. This process can last approximately 1 to 2 weeks. During this period the subjects has no outwardly noticeable symptoms. However, infection of other Beta subjects is already possible.`
3. Subject can develop a cough associated with a sore throat. Headaches can also manifest during this time. Subject also becomes irritable during this time.
4. Subject starts to present further noticeable symptoms. Symptoms can include: Unusually heavy discharge of nasal mucus fluid; red, irritated, and bloodshot eyes.
5. Overproduction of saliva from salivary glands (Week 2 - 3)
6. Subject begins to show extreme aggression toward uninfected persons

Infection through bite:

1. Virus is introduced into the body through a bite from an infected,
2. Virus travels from the site of the bite to the brain by moving within the nervous system
3. Stages 3 - 6 are largely the same, with the biggest difference being shorter incubation period

Overall average incubation period from infection to to full onset of the disease:

• Airborne: 3 - 4 Weeks:
• Bitten: 6 - 20 Days
• Sounds interesting, similar to David Weber's Under a Graveyard Sky. However, do you have any suggested mechanism for the extreme aggression being limited to uninfected persons only? Also, you may want to check your formatting - I needed to paste the "Stages of Infection" information into another program to read the lines that extend past the edge of the text window. Aug 19 '21 at 5:06
• Aren't you describing the rabies virus? Aug 19 '21 at 5:15
• Is the "types of immunity" supposed to refer to different groups of people? It's difficult to imagine how a virus could infect some people through the air but others only through saliva. If someone's immune to a virus it's something to do with how their body reacts to the virus once it's inside, which doesn't normally depend on how they are exposed. Aug 19 '21 at 10:15
• the separate incubation periods seems strange as well Aug 19 '21 at 11:53
• @KerrAvon2055 I have started to try and think of mechanisms to limit the aggression to uninfected persons only. The basic gist of it is that I could see them recognizing each other from a mix of recognizing each others scent to recognizing their behavior in other infected. I also forgot to mention this in the OP, but in my story the infected retain part of their intelligence. Also this is what the formatting looked like for me (prnt.sc/1qcetj1), how come it's so different on your end? Aug 19 '21 at 19:18

## Para-Rabies:

It is rare to have a virus have significantly different modes of transmission based on host immunity (not impossible). If the virus transmits through a bite, it's likely bloodborne as well. The more things you ask a virus (very simple thing) to do, the less plausible. Bacteria can exhibit more complex behaviors, but you clearly want a virus. I'd research rabies, make your virus a variant of the rabies virus (does much of what you want, has established patterns, neurological, transmissible via bite, causes behavioral abnormality.

To get the combination of infective pathways you want, consider using two related viruses. So as a scenario, imagine someone makes a super-rabies virus in a lab for terror purposes. Outbreaks would be horrifying but not globally disastrous. But sloppy work means the virus merges with an influenza strain in a coinfected individual and a hybrid virus emerges that is slow-incubating, looks like the flu for most of its early infection pattern, and doesn't affect anyone who had that strain of the flu previously. Developing a vaccine is only partly effective (and if no one ever made a vaccine against this flu strain prior, it could take a long time to do so).One is transmitted airborne, but a substantial percent of the populous is immune.

The other is transmitted via bite, but the zombies extensively bite each other to the point that coinfection with the two virus strains is widely prevalent. A gentle breaking of the skin could even be the socializing element that ties your zombies together. If zombies accept biting from other zombies, and look for the presence of bite marks and aggressive biting behavior as the indicator of who is or isn't a zombie, you have a way the zombies know who is or isn't to be attacked. The bites physically mark them to each other (and the more a person is bit up, the faster the infection). A person who was "captured" by zombies would get repeatedly bitten (increasing the chance of the bite-transmissible strain being spread) and the zombies would keep biting until the person started biting back. The constant in-biting makes "faking it" by covering yourself in false bites possible but extremely risky behavior. The fact that not all zombies are guaranteed to have the bite-transmissible form also means people can get bitten and still convince themselves they might not be infected, increasing the likelihood they might hide the fact they were bitten to avoid being killed/locked up/ostracized.

• So are you advising me to use bacteria or a variant of the rabies virus? Also could you elaborate on the socializing element convincing people to hide a bite? Aug 23 '21 at 21:42
• @Wurzel I edited the question; does that make it clearer? I based the biting behaviors on social interactions between Tasmanian Devils (and also non-related mice). The Devils are being wiped out due to a transmissible tumor they spread via bite. I would go with a rabies base for the bitten virus, and a hybrid rabies/influenza for the airborne strain. Aug 23 '21 at 22:47
• thanks for making your post clearer! I do wonder about 3 things though: 1) being that you wrote that the more a person is bit up, the faster they would turn. Is it actually realistic for it to work that way? And 2), wouldn't zombies repeatedly biting each other cause them to die off rather quickly/if they tested if their opponent is a zombie, would that not give people ample opportunity to fight them off, reducing their threat significantly? 3) So do you mean that people who had that strain of the flu previously would be immune to the airborne version, or did I misunderstand what you wrote? Aug 23 '21 at 23:18
• @Wurzel Rabies spreads along nerves, and symptoms develop once the virus reaches the CNS. Bites nearer the head mean shorter distances for the virus to spread; and depending on how it works it also means more viral lode. If the zombies nipped each other frequently, it would certainly risk shortening their lives, but they're zombies. Are they supposed to be cautious? Aug 23 '21 at 23:42
• @Wurzel Finally, if the rabies/flu hybrid strain doesn't affect many people, then the logical way to explain this is that they were previously exposed to a flu antigen (like a surface protein) in the influenza virus part and already have an immune response. It explains why you'd have an immune part of your population to a novel virus - it isn't entirely novel. One year with a poorly matched-up flu vaccine, and you can name the % of your population who are resistant to the airborne strain - how many people got the H3N4 strain last year? Aug 23 '21 at 23:45

Most of it is ok

Most of what you are saying is ok.

Viruses are mostly highly specific where they grow. Most often only a few cells with a certain type of DNA will be able to be affected. That means sickness can have difficulties to spread to many different species. You don't have to be afraid of most dog diseases thanks to this, although there are exceptions like rabies.

Infecting multiple cells can help with spreading through the body. Growing first in the belly before going to the brain. Though it can make more sense for the airborne virus to start in the lungs. That way it'll be easier to develop the cough and have large enough concentrations of viruses to infect others thanks to the cough. It also explains the further development of cold like symptoms. Growing in the gut is highly unlikely to give the effects you want. Outward noticeable symptoms often develop thanks to the body as it responds to the sickness and not the virus itself, so you're clear there as well.

The other category can house itself in other tissue to not become airborne, or have a defect that they near instantly die if expelled from the body.

If I remember correctly, viruses (and bacteria) can have multistage behaviour. First they simply grow and spread a little throughout the body. Then, if the concentration is high enough, some hormonal triggers can make them change their behaviour and spread aggressively. Then they can primarily focus on the brain for both reproduction, but also control. Viruses like rabies already try to control you in some ways, like making you avoid water. The virus can do the same. The reasons can be multiple why it does this, but self preservation, resource gathering or ability to spread more efficiently are all good reasons.

Travelling through the nervous system doesn't make sense however. It would generally be slow, as viruses have little in transport capabilities themselves. So why not use the blood (+ lymph nodes)? It is used by most viruses to get around, incredibly fast and spreads to literally everywhere in the body. The brain will be difficult thanks to the blood brain barrier, but as this is weakest at the olfactory bulb (smell) they always have an in (likely a reason you lose/change smell during Corona!). During the second stage they might also release things that can weaken this barrier throughout the brain, or move through the few other transport systems after infecting the olfactory bulb.

Other methods of infection can help greatly with the spread of the virus. That way it can shorten incubation times and such.

• Thank you very much for your reply! > Growing in the gut is highly unlikely to give the effects you want. I'll be honest, that was a part from a very early draft that somehow managed to evade my eyes until now. But thanks for pointing it out. > Other methods of infection can help greatly with the spread of the virus. That way it can shorten incubation times and such. I actually made the incubation period deliberately long, because that way to me it seems more believable that the outbreak of the virus could actually result in the collapse of society. 1/2 Aug 19 '21 at 19:04
• > Travelling through the nervous system doesn't make sense, however. It would generally be slow, as viruses have little in transport capabilities themselves. So why not use the blood (+ lymph nodes)? I mainly added this bit for balancing reasons in the sense that, if the blood is infectious, I would find it hard to believe for anyone to survive any kind of armed confrontation with an infected person without getting infected themselves. 2/2 Aug 19 '21 at 19:06
• I just noticed that the comment function seems to eat my formatting. I hope it's readable nonetheless. Aug 19 '21 at 19:07
• @Wurzel it can be approached differently. The virus is in the lungs, mouth and nose, going through the nose to the olfactory bulb and the rest of the brain after some time (and possibly already a bit before). Aug 20 '21 at 8:07
• Thank your for that suggestion. Since other commenters also took issue with the types of immunity and the separate incubation periods, could those also be approached differently to achieve the desired effect (That being a believable collapse of society while also leaving a chance of survival for my characters)? Aug 21 '21 at 11:42