A horror scenario

Could a disease arise that killed half the human population? And that inflicted horrifying neurological effects as the victims slowly died? Sure could. It’s happened in other animals. It’s happening right now in moose.

Minnesota saw a 58% decline of the moose population in the northeastern part of the state between 2006 and 2017.

If you’ve ever seen a moose, you know they’re huge and intimidating — you don’t want to tangle with one. The bulls are temperamental and cranky, the cows are fiercely protective, and you really don’t want to have to deal with a 700kg angry beast. But here’s what’s bringing them low.

A primary driver of the decline is brainworm, a parasite that affects the animal’s nervous system ultimately leading to paralysis and death. Researchers from the University of Minnesota and the Grand Portage Band of Lake Superior Chippewa recently discovered evidence that moose in Minnesota consume species of gastropods —slugs and snails—which are known hosts for the brainworm parasite (Parelaphostrongylus tenuis).

This massive die-off is a consequence of climate change: the worm is moving north as the weather warms, migrating with resistant deer populations whose range is overlapping with that of moose. When people talk about new diseases accompanying climate shifts, this is the kind of thing we’re talking about.

It can happen to us, you know.

I do sometimes wonder if Republicans have been eating snails.


  1. hemidactylus says

    I don’t eat slugs or snails. If I did I would cook them, which deer or moose usually don’t do. Would cooking render the brainworm harmless. Ironically ivermectin may help with some worm infections. I wonder if it would have prevented The Strain. Have a problem with vampire worms? Try this…

    If ivermectin or other antiparasitics were pushed by Fauci, in an alternative history, against spread of vampirism worms, the comments sections experts would tell everyone to get a tetanus shot instead. Or maybe a flu shot.

  2. hemidactylus says

    Should have done my own research first. Ivermectin may not be a magic bullet against brainworms:
    “Currently, there is no definitive treatment for P. tenuis in mammals, though research is still being conducted. The use of anthelmintics (ivermectin and fenbendazole) have been attempted in white-tailed deer. The results indicate, however, that ivermectin was ineffective against larvae that had already reached the spinal cord.[25] Fenbendazole and ivermectin, combined with anti-inflammatory therapy have been used to manage infections in goats.[15][17][16]”

  3. says

    “I do sometimes wonder if Republicans have been eating snails.” What a good idea.
    Just tell them it’ll protect them from Covid and they will.

  4. dbarkdog says

    The same thing has been happening in Maine for years. Climate change and changing land use patterns are bringing moose into increasing contact with deer resulting in the transfer of internal parasites to a non-resistant population. In addition, the warmer climate has dramatically increased the load of external parasites, especially ticks, resulting in many more deaths among moose calves. Wildlife managers are quite alarmed.

  5. hemidactylus says

    Ok I jumped the gun. Maybe prophylactic dosing: https://cwhl.vet.cornell.edu/disease/p-tenuis-brainworm
    “Administration of an anthelmintic during peak transmission months (late summer, fall) may reduce larval infections.”

    Yay ivermectin!

    And I don’t know what is meant here:
    “Humans cannot become infected with this worm, and properly cooked meat of infected animals is safe to eat.”

    If these worms are not viable in humans, maybe they are encouraging cooking in general as a safe precaution.

    And: “Nematodes need crustaceans, finfish, and marine mammals to complete various stages of their life cycle. Transference of nematodes to humans, called anisakiasis, can only occur when raw, undercooked, or improperly frozen seafood is ingested. Proper freezing and cooking are both effective controls. In Alaska, gold-standard freezing techniques are employed to ensure any parasites present are killed.”

  6. chrislawson says


    Ivermectin doesn’t cross the blood-brain barrier so it’s not going to help once the worms get inside the CNS. It might stlll be helpful if it can be administered early, but that’s probably not feasible for population-level treatment of huge wild ungulates.

  7. hemidactylus says

    @8- chrislawson
    Would hunting of deer help? I dunno if deer overpopulation is a problem in Minnesota.

  8. nomaduk says

    “Humans cannot become infected with this worm, and properly cooked meat of infected animals is safe to eat.”

    Well, if it’s not one thing, it’s another:-


    When a rat lungworm finds itself in a human, it does what it usually does in rats—it heads to the central nervous system and brain. Sometimes the migration of the worms to the central nervous system is asymptomatic or only causes mild transient symptoms. But, sometimes, they cause severe neurological dysfunction. This can start with nonspecific symptoms like headache, light sensitivity, and insomnia and develop into neck stiffness and pain, tingling or burning of the skin, double vision, bowel or bladder difficulties, and seizures. In severe cases, it can cause nerve damage, paralysis, coma, and even death.

  9. wzrd1 says

    Another problem with cervids mixing due to habitat incursion and climate change is faster and much farther spread of chronic wasting disease. CWD is a prion disease in deer, elk and moose and it is fatal. It was first identified in the late 1960’s, first in captive deer, in 1981, found in wild deer, it’s now found in 405 counties in 29 states, two provinces in Canada, Norway, Finland and Sweden, as well as some imported cases in South Korea. Overall infection rates appear to be around 10%, however localized infection rates have been recorded to be as high as 25%. One captive herd had a 79% infection rate.

  10. hemidactylus says

    @10- nomaduk
    Rat lungworm sounds scary enough at first glance, but doesn’t seem very deadly:

    “Most people get mild or no symptoms, but the parasite can infect your brain and cause headaches, neck stiffness, vomiting and neurological (brain and nerve) issues. Meningitis can be serious. Go to the ER if you have symptoms of meningitis… Sometimes, humans eat a gastropod that’s infected with rat lungworm larvae or its slime (for instance, on vegetables a slug has crawled on). The larvae can develop into mature worms and travel to your brain, causing symptoms. It’s also possible you could get the parasite from eating infected freshwater shrimp, crabs or frogs. But this isn’t a common or well-documented way to get infected.”
    “ The best ways to prevent or reduce your risk of rat lungworm include:

    Thoroughly cooking snails, crabs and shrimp before eating.
    Thoroughly washing or cooking vegetables and checking them for slugs and snails before eating.
    Avoiding eating raw vegetables in areas where rat lungworm is common.”

    Not going to keep me awake at night.

  11. says

    How virulent would a disease have to be to kill half of all Americans? We’ve seen how the right wing responds to public safety measures, from attacking the Walmart greeter who asked you to please wear a mask, to outright bans on vaccination requirements. They’ll stage protests demanding changes to public policy without learning the first thing about a crisis.
    There could be zombies in the streets and Republicans would fight to keep the bars open.

  12. raven says

    Ivermectin won’t cross the blood brain barrier.

    Ivermectin does not readily cross the blood-brain barrier (BBB) due to the presence of P-glycoprotein drug pumps. These pumps lie on the blood side of the cells lining the BBB. Any ivermectin that crosses into the cell gets immediately pumped back out, excluding the drug from the central nervous system (CNS).

    ToxTalks – The University of Virginia
    University of Virginia School of Medicine https://med.virginia.edu › sites › Oct21-Ivermectin

    Which is a good thing.
    It also can interact with the CNS located GABA gated chloride channels. Meaning if it gets to the brain it causes CNS symptoms. Serious Neurological Adverse Events after Ivermectin—Do …

    by RE Chandler · 2018 · Cited by 127 — Ivermectin is not thought to readily cross the blood-brain barrier in humans as it is excluded by a P-glycoprotein drug pump. (mdr-1).6 Therefore, it has …This is rare but does happen. Sometimes the blood brain barrier is compromised by illness, high doses, or a defective P-glycoprotein drug pump.

  13. Matt G says


    “When a rat lungworm finds itself in a human, it does what it usually does in rats—it heads to the central nervous system and brain….”

    I knew there was a scientific explanation for Florida.

  14. raven says

    Raccoons also carry a roundworm parasite that can cause serious illness in humans.


    Baylisascaris Infection Fact Sheet
    What is Baylisascaris?
    Baylisascaris is a roundworm parasite most often found in raccoons. Infection with Baylisascaris, baylisascariasis, can lead to severe illness.

    How do people get infected?
    Raccoons infected with Baylisascaris roundworms pass parasite eggs in their feces.

    Where is Baylisascaris found?
    Raccoons carrying Baylisascaris roundworms have been found throughout the United States.

    What are the signs and symptoms of Baylisascaris infection?
    Symptoms can appear as soon as 1 week after ingesting eggs and may include:

    Nausea, tiredness, loss of coordination, vision loss
    Liver enlargement, lack of attention to people and surroundings, coma


    In the past, most human Baylisascaris infections proved fatal, but it is possible that more rapid diagnosis and treatment improved the outcomes of the recently reported cases. Regardless, raccoon roundworm can be extremely dangerous to humans, and the prognosis is typically poor.

    Raccoon roundworm infections can be fatal. Inapparent infections are more common.

  15. hemidactylus says

    @17- raven
    Raccoons usually make me think of rabies. The shots aren’t that bad now. Part of me is tempted to get my rabies shots just for the hell of it, but I dunno if the health departments is into just giving them out willy nilly. I wonder how hard they screen, like needing to be a vet or wildlife biologist.

    Another issue, besides malaria now, in Florida is leprosy which seems tied to armadillo.

  16. wzrd1 says

    @ 14, nah, the GOP would insist on inoculating the entire populace with the disease itself. Then, gripe about losing family members to some space alien and Democratic Party plot.
    Then, they’d sponsor bite a zombie party.

    hemidactylus, I’ve always wondered the vector for Hanson’s elsewhere, as armadillos aren’t exactly common outside of the US, especially in the past in the old world.
    As for the rabies vaccine, looks like it does have a good safety profile, so it’s potentially possible one could find a doctor who’d order it, sourcing the vaccine might be a bit troublesome. WHO doesn’t recommend it, largely due to some nations deriving it from neural tissue, which is likely why it’s more difficult to obtain.

    raven, @ 17, just realized, if Ivermectin could make it past the BBB, it’d likely behave similar to propofol. Makes me wonder if propofol would harm the parasites as well.

  17. birgerjohansson says

    Feralboy12 @ 14
    The diseases brought to the New World killed off far more than 50%.
    Paleo-DNA from some regions show those people have no modern descendants!
    So many fields cultivated by indians reverted to forest that ice cores showed a drop of atmospheric CO2 as carbon was sequestered in overgrown fields.
    My point is, while modern medicine has created the illusion that we have the upper hand over disease, nature has the “tools” for bringing us low. Certain deadly pathogens (I forgot which) only need a few strategic mutations to get airborne, and then it is goodbye population chrisis (unless we have Dr. McCoy’s tricorder and can get an instant cure).

    If another Trump/BoJo monster is in charge at the time, you might consider going survivalist and stay on a small island until the pandemic burns itself out.

  18. lasius says


    CWD is a prion disease in deer, elk and moose

    I had to read this sentence twice since elk are deer and moose is just another term for elk. Then I switched to American English.

  19. jrkrideau says

    @ 14 feralboy12
    How virulent would a disease have to be to kill half of all Americans?

    Very but that does not mean it cannot happen. The Plague of Justinian may have wiped out have the Eastern Roman Empire in the 500’s and the Plague (aka DLak Death) in the 1300’s probablp wiped out half the population of Europe, Nort Africa, and the Middle East.

    We have a much better understanding of biology, etc. now but if we get hit by something that stumps science for a year or two, well…..

    And then of course, if one resolutely ignore safety precautions things could get really bad really fast. See the / Great Plague of Marseille, 1720 The telling lines are:
    Powerful city merchants wanted the silk and cotton cargo of the ship for the great medieval fair at Beaucaire and pressured authorities to lift the quarantine.

    A few days later, the disease broke out in the city. Hospitals were quickly overwhelmed, and residents panicked, driving the sick from their homes and out of the city. Mass graves were dug but were quickly filled. Eventually, the number of dead overcame city public health efforts, until thousands of corpses lay scattered and in piles around the city.

  20. jrkrideau says

    That Should have read:

    The Plague of Justinian may have wiped out half the Eastern Roman Empire in the 500’s

  21. tacitus says


    How virulent would a disease have to be to kill half of all Americans?

    For the reasons you cite, perhaps the most deadly scenario, which isn’t that far fetched, would be the sudden appearance of a new Covid-19 strain that was significantly more deadly than they have been so far, across all age groups.

    I doubt it would end up being close to 50%, because seeing half the people around you dropping dead has a way of overcoming the prejudices of even the most hidebound of conspiracy theorists, but something that kills 20% or even 10% would cause far more carnage today than if it had been that bad from day one.

  22. tacitus says

    We have a much better understanding of biology, etc. now but if we get hit by something that stumps science for a year or two, well…..

    Right, but it would have to be a very specific type of disease to overwhelm the protection from masks and quarantine — something highly infectious and caused by airborne transmission and with a long incubation period for example.

    Prion disease is another possibility. I still lived in the UK in the 1990s and have been banned as a blood donor in the US until earlier this year as a result of the possibility of being a carrier for vCJD. The fear was that we’d see a major spike in cases after an incubation period of a decade or more, but fortunately it didn’t transpire, with only a few dozen cases overall.

    In general though, if Covid-19 had been a deadlier disease I doubt we would have seen as much hysteria against the measures designed to protect people, or at least the vast majority of people would have complied with the impositions of government.

    Covid may have ended up causing many more deaths than a disease with a much higher mortality rate would have done if all other aspects had been equal.

  23. wzrd1 says

    birgerjohansson @ 20, there were Native American cities all over the plains as well, by the time white settlers got there, they were only mounds, with no sign of habitation until someone had a dig.

    lasius @ 21, yeah, blame the UK, as they didn’t bother documenting the language until after 1776 and there was some sort of tiff going on. ;)

    tacitus @ 25, I’m reminded of how long HIV baked in before it was noticed, then how much longer before it was even barely understood. One nice, slow retrovirus that’s easily spread casually, things could get fugly.

    Thankfully, prion disease isn’t easily transmitted in humans. Well, save for one variant I recall, which was spread by ritual cannibalism.

    COVID-19 was bad, the 1918 influenza pandemic was worse and still there were antimask protests in San Francisco and other cities. That, despite it being well established that masks were highly effective in 1890 during a pneumonic plague outbreak in Mongolia (a French physician made an ethnic slur comment about the doctor using the masks, refused to use a mask and died within 3 days of pneumonic plague).

    COVID ended up called by myself, “the now what?! virus”, because every time I turned around, it was doing something else odd, all of which I predicted would be rooted in cytokine storms. Early research fouling up and proclaiming initially, “no cytokine storm activity”, only to be proved wrong later. That also happened with the 1918 influenza pandemic, when one leading researcher claimed to have isolated h. influenzae from patients, which later was shown to be false, diverting study away from that long haired theory of viruses.
    Yet another illustration of why replication of research is important.
    One factor that lowered morbidity and mortality was starting patients suspected of having COVID on a steroid. By that March, I ended up hospitalized with difficulty breathing and the first thing done was shoot me full of dexamethasone. Helped with some of the symptoms, but I was in heart failure, due to a thyroid storm. I remember the hospital configuration well, rooms with warning tape and seals, beds lining the hallways and beds in the elevator landings. The worst hotspot hospitals converted parking structures into wards.

  24. hemidactylus says

    @25- tacitus
    Your: “In general though, if Covid-19 had been a deadlier disease I doubt we would have seen as much hysteria against the measures designed to protect people, or at least the vast majority of people would have complied with the impositions of government.”

    I’m in far much less fear now with SARS-CoV-2 still amongst us. Just got my XBB shot, maybe amongst the first and still few.

    As for more severe viruses I’m for a coercive public health reaction to an extent. I have my boundaries though. The Operation Cobalt thing from The Walking Dead universe which extended across three main shows haunts the shit out of me and involves National Guard doing fucked up things to civilians. World Beyond gave one of the most horrific depictions of the three series. If that went down, I would be anti gov’t to the core.

  25. asclepias says

    wzrd @ 11 Chronic wasting disease was my first thought. Many years ago, I got a job the last 3 weeks of hunting season dissecting retropharyngeal lymph nodes out of harvested elk and getting them ready to send to the lab at the University of Wyoming for testing. The big deal was that a moose over in the Star Valley area had tested positive, and up to that point managers had thought moose couldn’t get it. (I have no idea why–they are ungulates after all.) Just before that job, I had spent the summer in the Washington, DC metroparks monitoring deer populations. The wildlife biologist on staff at the Center for Urban Ecology knew it was just a matter of time before CWD got to that area, and lo and behold, it’s now there.

  26. John Morales says

    I suggest that people would have much more incentive to address the problem were it occurring in people instead of in moose.
    So, comparing wild animal morbidity with potential human morbidity is a bit misleading.

    “Albendazole, ivermectin, fenbendazole, diethylcarbamazine, levamisole, and moxidectin administered alone or in combination have been reported to successfully treat P. tenuis infection in captive animals. However, controlled studies of the efficacy of such treatment protocols are lacking. ”


  27. wzrd1 says

    asclepias @ 29, necropsy on a moose, nearly as bad as harvesting one. That’s a lot of animal to work on! Pretty much the same with elk.
    Hence, why I never hunted, or will hunt either. These days, even a white-tailed deer is a bit more meat than I’d consume before it’d freezer burn. Probably end up donating half to a homeless shelter.
    But, yeah, I’ve been tracking the spread via PROMED and a few other lists. I’m fairly surprised at the distance that prion has traveled, including crossing major rivers. Although, it does seem to follow major highways for the most part through major terrain obstructions. But then, there is a very real world version of walking dead, minus zombies. Hopefully, some mutation will allow them to adapt, as happened despite some early predictions, with WNV.

    John, it’s easier to treat such illnesses in people, than with wild animals. One doesn’t have to chase people that much in order to treat them. And well, the people that run off into the forest, well they’re not spreading the illness about anyway. With a pandemic, one need not treat each and every victim, which would be logistically impossible anyway, one need only introduce an effective firebreak in transmission. That’s typically done via vaccines. Which wasn’t extremely effective, largely due to a misleadership campaign by a national misleader.
    Like every other effective mitigation campaign, one needs to have the full support from the top for it to be effective.

  28. says

    I do sometimes wonder if Republicans have been eating snails.

    I’ve wondered often if it is some kind of virus of the mind doing the rounds, when I see seemingly smart people suddenly spout stupid nonsense. Not necessarily Republicans, though they may turn Republican (or the local equivalent) once infected.