Heat, Not Disinfectant: Raccoon Latrines, Roundworm Eggs and Why the Attic Is the Hard Case

1. Introduction: a cleanup rule that runs backwards

This journal has written twice about cleaning up animal droppings. Our hantavirus article examined guidance that wets rodent droppings with disinfectant because the virus is inhaled and disinfectant kills it. Our pigeon droppings article examined diseases also acquired by breathing dust, and a risk public health authorities describe as rare.

1.1 Raccoon latrines are the case where that logic fails

The eggs are swallowed rather than inhaled, chemistry does not kill them, and the effective method, heat, is the one that cannot be used in the place raccoons often choose, the attic.

1.2 What this article argues

That the eggs' biology inverts several intuitions about droppings cleanup, that the inversion is sharpest indoors, and that Winnipeg has local evidence that the parasite is common in the city's raccoons but, as far as we could find, no local public guidance on what to do about it. Sections 11 to 18 are the case.

2. The parasite

A roundworm of the raccoon gut.

Baylisascaris procyonis is a small-intestinal nematode of raccoons in North and Central America, including Canada, and is also present in raccoons introduced into Europe and Japan.¹⁴

2.1 It rarely troubles the raccoon

Infection rarely causes symptoms in raccoons, so an infected animal cannot be recognised by its behaviour.¹

2.2 And it produces enormous numbers of eggs

Infected raccoons shed millions of eggs a day,¹² and a veterinary college's reference page reports female worms producing up to 250,000 eggs per gram of feces.¹⁴

2.3 None of them visible

The eggs cannot be seen with the naked eye, only under a microscope.¹

2.4 Two scales of output

One study speaks of mature worms producing thousands of eggs a day,¹⁵ another of infected raccoons shedding millions.¹² The figures describe a single worm and a whole animal carrying several, so they are not in conflict.

That reconciliation is ours.

3. The latrine

Where the eggs accumulate.

Raccoons defecate in communal places. Public health guidance lists the base or raised forks of trees, fallen logs, stumps and large rocks, and also woodpiles, decks, rooftops, attics, garages and haylofts.¹

3.1 Often where people are

A report of a Canadian case notes that raccoons tend to defecate in communal locations that are often in areas of human activity.¹²

3.2 And where eggs build up

Eggs accumulate at latrines, and a study of latrine management describes transmission to other animals occurring there when eggs are ingested with seeds in the fecal material.¹⁵

3.3 Which is why latrines are the focus

A public health journal describes latrines as recognised primary sources of transmission to humans.⁴

3.4 Eggs do not stay where they are left

A wildlife damage management centre, illustrating its page with a latrine on the roof of a house, warns that even soil near a latrine may be contaminated because rain may carry eggs.²³

3.5 A roof drains somewhere

A rooftop latrine sits above eavestroughs and downspouts, so the soil at a downspout outlet is a plausible place for washed eggs to collect, and a place children may dig.

That application to roof drainage is ours and untested.

4. How people are infected

By mouth.

Infection follows swallowing infective eggs. Federal guidance notes that inhaling roundworm eggs has not been shown to cause infection.²

4.1 Who is most exposed

Most reported cases have been in children under five with a history of pica or geophagia, eating non-food items or soil, and exposure to raccoons or their habitat.¹⁴

4.2 Very young children especially

A clinical review reports that most diagnosed patients have been children under two, though the number of older patients diagnosed has been increasing.²⁰

4.3 Why children dominate the case list

The scoping review suggests that the need for a large dose accounts for the overrepresentation of young children, particularly those with pica, since that behaviour increases the chance of high-level exposure.¹⁰

4.4 And the introduction to the Winnipeg study agrees

It describes pica or geophagia, together with exposure to infected raccoons or environments contaminated with their feces, as the most important risk factors identified in epidemiologic studies.²²

5. How rare it is

Very.

A 2025 scoping review identified sixty human infections in the literature, with a median age of 2.9 years and a range from nine months to 73 years.⁹

5.1 The count has grown as recognition has

A 2012 report counted only 20 reported cases of cerebral infection,¹² and a 2016 report at least 54 human cases, adding that cases may not have been recognised or reported, especially ocular ones.¹¹

5.2 Why so few, given so many eggs

The scoping review explains that the parasite is not drawn to the nervous system, that only a small percentage of ingested larvae, around 5 to 7 per cent, reach it, and that disease probably needs a large inoculum, which could account for its rarity despite high prevalence in raccoons.¹⁰

5.3 And some infections pass unnoticed

Of 347 adult wildlife rehabilitators with no symptoms, 24 tested positive for antibodies, suggesting infection without disease.¹¹

5.4 A short history

The first recognised human case was reported in 1984, in a 10-month-old child in Pennsylvania, and around thirty further severe or fatal cases had been reported in the United States by the time of the Hamilton case report.¹³

5.5 Many other species are affected

The same report notes that approximately 130 species of wild and domesticated animals have been affected by the parasite's larvae.¹³

6. How severe it is

Of the sixty infections in the scoping review, 47 involved neurological disease, nine of them with eye disease as well, and eleven involved the eye alone. Among 42 people with neurological disease and a reported outcome, 8 (19%) died, 4 (10%) fully recovered and 30 were left with mild to significant deficits.⁹

6.1 Eye disease is lasting too

Seven of ten people with eye disease alone had permanent vision loss.⁹

6.2 Why the damage is so great

Unlike the roundworm larvae of dogs, these larvae continue to grow as they migrate, causing more inflammation and damage.¹⁰

6.3 And treatment comes late

Treatment is difficult once neurological symptoms appear,¹¹ and infection is difficult to diagnose in people.³

6.4 The early signs are vague

The scoping review describes the clinical signs of neurological disease as highly variable and progressive, with vague initial signs and symptoms, and eye disease as most often presenting with painless loss of vision.⁹

6.5 Which is part of why prevention carries the weight

A disease that is hard to recognise early, hard to diagnose and hard to treat once established leaves avoidance of exposure as the main defence.

That conclusion is ours, drawn from §§6.3 and 6.4.

7. The Canadian cases

Few, and instructive.

In 2008 a previously healthy 14-month-old boy in Hamilton, Ontario, developed fever, lost speech and could not bear weight; his family confirmed numerous raccoons in their backyard. The report's authors knew of only one earlier Canadian case, from 2009.¹³

7.1 An infection nobody noticed

A 2012 report described a 73-year-old nursing home resident in British Columbia with dementia, formerly living in a rural area, whose cerebral infection was proven at pathology and caused no apparent symptoms.¹²

7.2 Two ends of the range

A toddler with a backyard full of raccoons and an older adult with cognitive impairment illustrate the pattern the literature describes: exposure combined with a reason to put contaminated material in the mouth.

That reading is ours.

8. Winnipeg's raccoons

A study by the provincial chief veterinarian's office collected feces from active raccoon latrines in Winnipeg and examined nuisance raccoons at postmortem. Of 52 latrines, 26 were positive on one or more occasions; 33 of 89 latrine samples were positive; and 57 of 114 trapped raccoons were positive.⁷

8.1 The authors' conclusion

That carriage is widespread in the city's raccoons, and that raccoon latrines in Winnipeg should be treated as infectious sites, with access by pets and people at risk limited.⁷

8.2 Why the study was done

The paper's introduction notes that the parasite had been identified as a cause of animal loss at Assiniboine Park Zoo,²² and a veterinary blog reports that the study followed the identification of the parasite as the cause of death of several animals in the collection.⁸

8.3 Where the latrines were

The same account reports that most latrines and nuisance raccoons were found close to the two major rivers running through the city.⁸

8.4 A negative test is not a clean bill

The study found a single fecal flotation test had a sensitivity of 78.9 per cent against finding adult worms at postmortem.⁷ We read that as meaning a single negative sample from a latrine does not show the latrine is free of eggs.

8.5 And a positive test is usually right

The specificity of 92.9 per cent means a positive single test was usually confirmed at postmortem.⁷ A latrine that tests positive once has, in effect, been shown to be a source.

The second sentence is our reading.

8.6 The raccoons sampled were the ones in conflict with people

The animals examined were nuisance raccoons, trapped because they were causing problems, and then euthanised and examined.⁸ That is the population a household with a raccoon problem is dealing with, which makes the figure more relevant to this article rather than less.

That point about relevance is ours.

9. Two numbers for one result

A data note.

The study's abstract reports 57 of 114 raccoons positive.⁷ The veterinary blog describing the same study reports 61 of 114, or 53.5 per cent.⁸

9.1 We use the abstract

Because it is the authors' own statement. The difference may reflect two ways of counting, for example worms at postmortem versus eggs in feces, but we could not read the full paper to check.

10. Prevalence elsewhere

For comparison.

The British Columbia case report gives estimated prevalence of 68 to 82 per cent in the western United States and 61 per cent in southwestern British Columbia.¹² A latrine study reports up to 82 per cent of adult and 90 per cent of juvenile raccoons infected.¹⁵

10.1 Winnipeg sits lower but not low

About half, by either measure in the Winnipeg study, which is enough for the authors' advice to treat every latrine as infectious.⁷

10.2 And raccoon numbers track people

The latrine study notes that raccoon densities have increased in response to resources available in agricultural and urban ecosystems.¹⁵

10.3 The range is wide

The Winnipeg paper notes that prevalence in North American raccoons varied between 0 and 100 per cent across 33 studies it cites from a review.²² A single local survey is therefore worth more than a borrowed national figure.

The second sentence is ours.

11. Why chemistry fails

The first inversion.

Federal guidance states that most chemicals do not kill roundworm eggs,¹ and its latrine cleanup sheet adds that they are not suitable for outdoor use.²

11.1 A hardy egg

A laboratory study describes infective eggs as remaining viable in the environment for years and resistant to most decontamination methods.⁵

11.2 So the disinfectant spray bottle is the wrong tool

Which runs against the habit, reinforced by guidance for other droppings, of reaching for disinfectant first.

That contrast is ours; §20 develops it.

11.3 And the evidence base for disinfection is thin

The 2007 study's authors wrote that no comprehensive studies had been published describing practical and effective methods for decontaminating areas where the eggs are present, although health authorities were routinely contacted about contaminated yards, pools and homes.⁵ The 2011 follow-up still described little information as available on egg survival and effective disinfection.⁶

12. What does kill the eggs

Heat.

A public health journal describes heat, in the form of boiling water, steam-cleaning or fire, as the optimal tool for killing the eggs and decontaminating areas around latrines.⁴

12.1 Instantly, at the right temperature

Federal guidance says heat kills the eggs instantly.¹

13. How much heat

A laboratory study heated infective eggs in water. All larvae remained viable up to 47 degrees, more than 75 per cent were viable at 52 and 57 degrees, and inactivation was complete at 62 degrees.⁵

13.1 Lower than boiling

The authors noted that complete inactivation at relatively low temperatures indicates approaches well short of incineration or boiling will work, and that temperatures achievable in household point-of-use water heaters could deactivate eggs.⁵

13.2 Under laboratory conditions

They added that further work was needed on heat and other methods in natural circumstances.⁵

13.3 And a warm tap is not enough

Water hot enough to be comfortable is well below the range in which most larvae survived, so hot soapy water removes eggs rather than killing them.

That inference from the temperature data is ours.

14. Cold does not help

The Manitoba point.

A follow-up study found that eggs lost viability when heated to 62 degrees or dried for seven months, but not when frozen at -15°C for 6 months.⁶

14.1 A prairie winter is not a disinfectant

A latrine that has sat under snow since autumn should be assumed to hold viable eggs in spring.

That application to this climate is ours; the study tested one temperature for one duration.⁶

15. Drying does, slowly

With a conflict.

The same study found that eggs dried for seven months lost viability.⁶

15.1 A commercial source says the opposite

A wildlife removal company states that eggs survive drying and that leaving an attic for a year is not an effective approach.¹⁹

15.2 Both could be partly right

Laboratory desiccation is controlled and complete, while material in an attic may not dry evenly, and eggs deposited across a season will be of different ages. The company also sells the remediation it recommends.¹⁹

15.3 So we would not rely on waiting

Not because drying has been shown to fail, but because no one has shown how long a real attic takes to dry every egg in it.

Sections 15.2 and 15.3 are our reasoning.

16. The timing inversion

Eggs in newly deposited feces are not infectious and take at least two to four weeks to become infective.²

16.1 So prompt removal is the cheapest control

Federal guidance says prompt removal and destruction of feces before the eggs become infectious will reduce the risk of exposure.³

16.2 And an old latrine is the dangerous one

Which inverts the intuition that fresh waste is the hazard and old, dry waste is spent.

That framing is ours; it follows from §§14 and 16.

16.3 A practical interval

Because eggs take at least two to four weeks to become infective,² removing fresh feces from a latrine still in use at least weekly, while exclusion is being arranged, would keep removal ahead of maturation.

That interval is our inference, not a figure any source gives.

17. Outdoor cleanup as guidance describes it

Federal public health advice.

Feces and contaminated material should be removed carefully and burned, buried or sent to a landfill, and decks, patios and other surfaces treated with boiling water or a propane flame-gun.³

17.1 Soil is flamed in layers

The latrine sheet advises breaking up and turning over contaminated soil several times, flaming each time, and warns that flaming could cause a fire, burn injury or surface damage, so the local fire department should be called first.²

17.2 Dust is damped, not disinfected

The guidance suggests lightly misting a latrine with water from a spray bottle to reduce dust, wearing boots that can be scrubbed or disposable booties, and laundering clothes in hot water.¹

17.3 A wildlife charity's version

A Toronto wildlife centre advises steam-cleaning solid surfaces such as decks and rooftops, and turning the soil or adding topsoil where a latrine is on a lawn.¹⁷

18. The attic inversion

The latrine sheet is explicit: do not use a propane torch indoors.²

18.1 The indoor fallback

For an indoor latrine where a torch cannot be used, guidance says to wipe the area with a damp but not wet sponge and hot soapy water.¹

18.2 Which removes eggs rather than killing them

At the temperatures of hand-hot water, by §13.3.

18.3 An attic floor is not a deck

Loose insulation, joists and sheathing cannot be steamed, scrubbed or flamed like a patio, so contaminated material generally has to be taken out rather than treated in place.

18.4 And the result cannot be inspected

Because the eggs are invisible,¹ nobody can look at a cleaned attic and see that it is clean.

Sections 18.2 to 18.4 are our reasoning from the guidance and the temperature data.

19. Breathing protection and why it is there

A detail worth reading closely.

The latrine sheet recommends an N95 respirator for cleaning latrines in confined spaces, while noting that inhaling eggs has not been shown to cause infection; the respirator is for fungal spores, bacteria or viruses that may be present.²

19.1 So the mask protects against something else

The main defence against the roundworm itself is keeping hands, tools and clothing from carrying eggs to the mouth.

That emphasis is our reading of §§4 and 17.2.

19.2 Hands last

Federal guidance ends its cleanup advice by recommending washing hands well with soap and warm running water.¹

20. Against the hantavirus case

Our comparison.

In our hantavirus article, the virus is inhaled and killed by disinfectant, so guidance wets droppings with disinfectant before removal. Here the eggs are swallowed and survive most disinfectants, so guidance removes and heats the material.

20.1 One shared rule

Both sets of guidance damp the material to keep dust down: disinfectant in one case, plain water in this.¹

20.2 Why the difference matters

A homeowner who has learned the rodent routine and applies it to a raccoon latrine will feel thorough while leaving the eggs alive.

Sections 20 to 20.2, apart from the cited guidance, are our reasoning.

20.3 And against the pigeon case

Our pigeon droppings article reported authorities describing routine cleaning of a windowsill as posing no serious risk to most people, because the relevant diseases are acquired by breathing dust. A raccoon latrine differs in route, since exposure is hand to mouth, and in who is at greatest risk, since the cases are concentrated in very young children.⁹¹⁴

The comparison is ours.

21. What provincial guidance says

Next door.

Alberta's government page on raccoons notes that some of the province's raccoons may carry roundworm and advises anyone cleaning a latrine to be very cautious, wear gloves and a mask and wash their hands thoroughly.¹⁶

21.1 Without the key facts

In the portion we read, it does not mention that most chemicals fail, that heat is the effective method or that fresh feces become more dangerous with time.¹⁶

21.2 Manitoba

We found no Manitoba public guidance on raccoon latrine cleanup, despite the provincial study advising that latrines in the capital be treated as infectious.⁷

21.3 Other diseases it lists

Alberta's page also mentions canine distemper and leptospirosis in raccoons, and notes that raccoon rabies is not seen in that province.¹⁶

22. Prevention: keeping raccoons out

The measure that removes the problem.

An animal welfare organisation advises sealing entry points with 16-gauge wire mesh or metal flashing, and following federal guidance or hiring professionals where feces have accumulated.¹⁸

22.1 With care over young

It warns that one-way doors used to let raccoons out of attics are best left to professionals, who can make sure mothers are not separated from their kits.¹⁸

22.2 Exclusion and cleanup are separate jobs

Sealing an attic stops new deposits but does nothing about eggs already there, which remain viable by §§11 and 14.

That distinction is ours.

22.3 Prevention as the stated priority

The same organisation describes prevention as the key, and advises keeping raccoons out of attics and crawl spaces and supervising young children and pets outdoors so they do not come into contact with raccoon feces.¹⁸

23. Breaking the latrine habit

Outdoors.

The Toronto wildlife centre reports that a raccoon's commitment to a latrine site is not strong, and suggests moving furniture or a planter onto the spot, or taping a double layer of plastic over it for a couple of weeks.¹⁷

23.1 Protecting the people most at risk

The same centre advises covering sandboxes and not letting very young children play unsupervised where raccoon feces may be, such as woodpiles and under porches.²¹

23.2 And not inviting raccoons in

Federal guidance advises against keeping, feeding or adopting raccoons.³

24. Pets, rodents and birds

Other hosts.

Dogs can carry patent infections, though this has been reported rarely, and a veterinary college notes that the eggs are hard to distinguish from those of the common dog roundworm, so the infection may be more common in dogs than believed.¹⁴

24.1 Rodents and birds

Rodents and birds that swallow eggs at latrines become intermediate hosts, and larvae entering the central nervous system can kill them.¹⁵

24.2 In a Winnipeg zoo, too

Which is how the parasite came to notice locally, through deaths in the zoo's collection.⁸

24.3 Moving raccoons may move the parasite

Our wildlife translocation article reported, as an attributed claim we had not verified, that translocated raccoons spread raccoon roundworm to uninfected populations. We have still not read that study.

24.4 Why small animals are hit hardest

The Winnipeg paper's introduction explains that small rodents and birds are considered most susceptible, mainly because the mass of the larvae is large relative to the brain in low-dose infections.²²

24.5 So mice in a contaminated attic are themselves exposed

A rodent problem and a raccoon latrine in the same attic are linked: mice feeding on seeds in the latrine are the intermediate hosts the life cycle describes.¹⁵

The application to a shared attic is ours.

25. What this means for a household

Our suggestions.

Treat any raccoon latrine as infectious, as the Winnipeg authors advise;⁷ remove fresh feces promptly, before eggs mature; keep young children and pets away; do not rely on disinfectant or on winter; and on hard outdoor surfaces use heat as federal guidance describes.¹³

25.1 Indoors, think removal

An attic latrine means taking out contaminated material and damp-wiping what remains, and accepting that the result cannot be checked by eye.

25.2 And close the entry first

Cleaning an attic that raccoons can still reach invites a new latrine on top of the old one.

Sections 25.1 and 25.2 are our reasoning.

26. What this means for operators

Also ours.

A quote for raccoon work should say plainly whether it covers exclusion, latrine cleanup or both, because they are separate jobs with separate methods, and a customer who pays for one may reasonably assume the other.

26.1 Method should be named

Given §11, a cleanup that consists of spraying disinfectant on a latrine does not address the roundworm, and a customer should be told what method is being used and why.

26.2 Technicians are the exposed group

Among wildlife rehabilitators with no symptoms, about 7 per cent had antibodies,¹¹ which suggests that people who handle raccoons and their material regularly do become exposed. Gloves, scrubbable or disposable footwear and hot laundering, as the guidance describes, are the practical defences.¹

The inference from rehabilitators to pest control technicians is ours.

26.3 And the propane torch is a fire risk in its own right

Federal guidance warns that flaming can cause a fire, burn injury or surface damage, and advises consulting the local fire department first.² An operator offering heat treatment of a latrine outdoors takes on that risk explicitly.

The second sentence is ours.

27. Our own position

The disclosure.

This company performs exclusion work, which this article discusses as prevention. We make no claim here about whether it offers raccoon removal or latrine cleanup, and nothing in the article should be read as a description of its services.

28. The Manitoba position

28.1 Local evidence exists

Winnipeg is one of the few cities with a published study of the parasite in its own raccoons, which found about half the latrines and half the nuisance raccoons positive.⁷

28.2 But it is old

The study was published in 2009, and we found no later survey of Winnipeg or other Manitoba raccoons.

28.3 Local guidance does not

We found no Manitoba public guidance on latrine cleanup, and the nearest provincial guidance we read omits the facts that matter most (§21).¹⁶

28.4 And the climate does not help

Winter does not kill the eggs, by §14.⁶

28.5 Where to look first

The Winnipeg latrines and nuisance raccoons were concentrated near the city's two major rivers,⁸ so riverside properties are where a household is most likely to find a latrine.

That practical inference is ours, from a study now more than fifteen years old.

29. Limitations and open questions

Human infection is rare. Sixty infections in the literature is a very small number, and nothing here should be read as saying a latrine is likely to cause disease; the case for care rests on severity and on how easy the precautions are.⁹

The Winnipeg study is old and read as an abstract. It was published in 2009, the archive page with the full text did not load for us, and we could not resolve the difference between its figure and the blog's (§9).⁷⁸

The heat and cold data are laboratory results. Eggs were heated in water and frozen at one temperature, and the authors themselves called for work under natural conditions.⁵⁶

Some sources have interests. The wildlife removal company sells remediation, and the animal welfare organisation and wildlife centre advocate particular approaches to raccoons; each is flagged in the references.¹⁷¹⁸¹⁹

The zoo and river details are second-hand. They come from a veterinary blog, not the paper itself.⁸

Absence of Manitoba guidance is a search result. We did not find any, which is not proof that none exists.

Sections 2.4, 6.5, 7.2, 8.4 to 8.6, 10.3, 11.2, 13.3, 14.1, 15.2, 15.3, 16.2, 16.3, 18.2 to 18.4, 19.1, 20, 22.2, 3.5, 24.5, 25, 26 and 28.5 are our reasoning, apart from the sources cited within them. The attic argument, the timing and climate applications, the hantavirus comparison and the suggestions for households and operators are ours rather than sourced positions.

30. Conclusion

Raccoon roundworm is rare in people and severe when it occurs. The scoping review of the literature found sixty infections, most in very young children; of 42 people with neurological disease and a known outcome, eight died and thirty were left with lasting deficits.⁹ The parasite is common in the animals: in Winnipeg, half the latrines and half the nuisance raccoons sampled were positive, and the provincial authors advised treating the city's latrines as infectious sites.⁷

The eggs invert the rules a household may have learned from other droppings. They are swallowed rather than breathed; most chemicals do not kill them; they are harmless for two to four weeks and dangerous for years afterwards; and six months frozen did not kill them.¹²⁶ Heat does, with complete inactivation at 62 degrees in the laboratory, and guidance recommends boiling water, steam or flame outdoors.⁵⁴

That guidance also bars the torch indoors, which leaves the attic, one of the places raccoons choose, to be handled by removing material and wiping what remains, with no way to see whether the eggs are gone. Keeping raccoons out is therefore worth more than any cleanup, and cleanup, where needed, should be understood as removal rather than disinfection. Manitoba has a local study showing the parasite is common and, as far as we could find, no local guidance on what to do about it.

References

1. Preventing raccoon roundworm, published by the American federal public health agency. Official government material. Source for latrine locations including woodpiles, decks, rooftops, attics, garages and haylofts; the statement that most chemicals do not kill roundworm eggs but heat kills them instantly; the advice to treat surfaces with boiling water or a propane torch after consulting the fire department; misting latrines with water to reduce dust, wearing scrubbable boots or disposable booties, and laundering clothes in hot water; wiping indoor latrines with a damp but not wet sponge and hot soapy water where a torch cannot be used; and the statements that infection rarely causes symptoms in raccoons and that eggs are visible only under a microscope. https://www.cdc.gov/baylisascaris/prevention/index.html
2. Raccoon latrines: identification and clean-up, a fact sheet published by the same agency. Official government material. Source for the statements that eggs in fresh feces are not infectious and take at least two to four weeks to become infective; that inhaling roundworm eggs has not been shown to cause infection and that an N95 respirator is recommended in confined spaces for fungal spores, bacteria or viruses; that a propane torch should not be used indoors; that most chemicals do not kill the eggs and are not suitable outdoors; and for the advice to turn and flame soil several times after consulting the fire department. https://www.cdc.gov/parasites/baylisascaris/resources/raccoonlatrines.pdf
3. About raccoon roundworm, published by the same agency. Official government material. Source for the advice to remove feces and contaminated material and burn, bury or landfill it, to treat decks and patios with boiling water or a propane flame-gun, and to remove feces promptly before eggs become infectious; the advice not to keep, feed or adopt raccoons; and the statement that infection is difficult to diagnose in humans. https://www.cdc.gov/baylisascaris/about/index.html
4. Letter on the parasite in raccoons in China, published in a public health agency's infectious disease journal in 2014. Peer-reviewed material. Source for the statements that eggs remain viable and infective for years, that latrines are recognised as primary sources of transmission to humans, and that heat in the form of boiling water, steam-cleaning or fire is the optimal tool for killing the eggs. https://wwwnc.cdc.gov/eid/article/20/12/14-0970_article
5. Thermal death point of Baylisascaris procyonis eggs, a letter published in the same journal in 2007. Peer-reviewed material. Source for the finding that all larvae remained viable in water up to 47 degrees, more than 75 per cent at 52 and 57 degrees, with complete inactivation at 62 degrees; the statements that infective eggs remain viable for years and resist most decontamination methods; the authors' conclusion that approaches well short of incineration or boiling will be effective and that temperatures achievable in household point-of-use water heaters can deactivate eggs; and their call for work under natural circumstances. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2725829/
6. Follow-up study of heat, desiccation and freezing effects on the eggs, published in the same journal in 2011 and read as its summary. Peer-reviewed material. Source for the finding that eggs lost viability when heated to 62 degrees or desiccated for seven months, but not when frozen at minus 15 degrees for six months. https://wwwnc.cdc.gov/eid/article/17/7/10-1774_article
7. Prevalence and distribution of Baylisascaris procyonis in urban raccoons in Winnipeg, Manitoba, published in a Canadian veterinary journal in 2009 by authors from the provincial chief veterinarian's office, and read as its abstract. Peer-reviewed material. Source for 26 of 52 latrines positive on one or more occasions, 33 of 89 latrine samples positive, 57 of 114 trapped raccoons positive at postmortem; a single fecal flotation sensitivity of 78.9 per cent and specificity of 92.9 per cent against postmortem; and the conclusions that carriage is widespread and that latrines in Winnipeg should be treated as infectious sites with access by pets and people at risk limited. https://pubmed.ncbi.nlm.nih.gov/19881923/
8. Blog post describing the Winnipeg study, published by a veterinary infection control blog in 2010. Commentary material, flagged. Source for the statements that the study followed identification of the parasite as the cause of death of several animals at Assiniboine Park Zoo, that most latrines and nuisance raccoons were found close to the city's two major rivers, and for its figure of 61 of 114 raccoons positive, which differs from the abstract. https://www.wormsandgermsblog.com/2010/01/articles/diseases/parasites/baylisascaris-in-winnipeg/
9. Human infections with the raccoon roundworm: a scoping review, published in a Canadian veterinary journal in 2025 and read as its abstract. Peer-reviewed review material. Source for sixty infections identified, a median age of 2.9 years with a range from nine months to 73 years; 47 with neurological disease, nine with concurrent eye disease, and eleven with eye disease alone; outcomes for 42 people with neurological disease of 8 deaths, 4 full recoveries and 30 with residual deficits; and seven of ten with eye disease alone having permanent vision loss. https://pubmed.ncbi.nlm.nih.gov/40671903/
10. The same scoping review, read in its full text through a public biomedical archive. Peer-reviewed review material. Source for the statements that the parasite is not neurotropic, that around 5 to 7 per cent of ingested larvae reach the central nervous system, that disease probably requires a large inoculum, which could explain its rarity despite high prevalence in raccoons, and that unlike dog roundworm larvae these larvae continue to grow as they migrate. https://pmc.ncbi.nlm.nih.gov/articles/PMC12261942/
11. Seroprevalence study among wildlife rehabilitators in the United States and Canada, 2012 to 2015, published in a public health agency's infectious disease journal in 2016. Peer-reviewed material. Source for at least 54 reported human cases, the note that cases may not have been recognised or reported, especially ocular cases; that most diagnosed cases were in children and severe or fatal; that treatment is difficult after neurological symptoms begin; and that 24 of 347 asymptomatic adult rehabilitators had antibodies. https://wwwnc.cdc.gov/eid/article/22/12/16-0467_article
12. Case report of infection in an elderly person in British Columbia, published in the same journal in 2012. Peer-reviewed material. Source for the count of 20 reported cases of cerebral infection at that time; the case of a 73-year-old nursing home resident with dementia whose pathologically proven infection caused no apparent symptoms; estimated prevalence of 68 to 82 per cent in the western United States and 61 per cent in southwestern British Columbia; and the statements that infected raccoons shed millions of eggs daily and defecate in communal locations often in areas of human activity. https://wwwnc.cdc.gov/eid/article/18/2/11-1046_article
13. Case report of possible pet-associated infection in a child in Canada, published in the same journal in 2012. Peer-reviewed material. Source for the case of a 14-month-old boy in Hamilton, Ontario, in 2008 whose family confirmed numerous raccoons in their backyard, and the authors' statement that only one earlier human case had been reported in Canada, in 2009. https://wwwnc.cdc.gov/eid/article/18/2/11-0674_article
14. Reference page on the parasite in people, published by a Canadian veterinary college in 2021. Educational institutional material. Source for the parasite's distribution in North and Central America including Canada and in introduced raccoons in Europe and Japan; female worms producing up to 250,000 eggs per gram; most human cases being children under five with pica or geophagia and exposure to raccoons or their habitat; and the statements that patent infections in dogs are rarely reported and that the eggs are hard to distinguish from those of the common dog roundworm. https://wcvm.usask.ca/learnaboutparasites/parasites/baylisascaris-procyonis-people.php
15. Study of reducing roundworm larvae in raccoon latrines, published in a public health agency's infectious disease journal in 2011. Peer-reviewed material. Source for up to 82 per cent of adult and 90 per cent of juvenile raccoons infected; eggs accumulating at latrines and infecting rodents and birds that ingest them, with larvae able to enter the central nervous system and cause death; transmission at latrines when eggs are ingested with seeds; and raccoon densities increasing in response to agricultural and urban resources. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204634/
16. Human-wildlife conflict page on raccoons, published by the Alberta provincial government. Official government material. Source for the statements that some raccoons in the province may be infected with raccoon roundworm, that raccoons use a designated latrine outside the den, and the advice to be very cautious when cleaning a latrine, wear gloves and a mask and wash hands thoroughly. https://www.alberta.ca/raccoons
17. Page on raccoons defecating on decks or roofs, published by a Toronto wildlife rehabilitation charity. Charity and advocacy material, flagged. Source for the advice to steam-clean solid latrine surfaces, turn the soil or add topsoil on lawns, and to discourage latrine use by moving furniture or a planter or taping a double layer of plastic over the site, and for the statement that a raccoon's commitment to a latrine site is not strong. https://www.torontowildlifecentre.com/wildlife-emergency-rescue-hotline/conflicts-with-wildlife/common-raccoon-problems/raccoons-feces-on-your-property/
18. Guidance on dealing with raccoons, published by an animal welfare organisation. Advocacy material, flagged. Source for the advice to seal entry points with 16-gauge wire mesh or metal flashing, to follow federal guidance or hire professionals where feces have accumulated, and that one-way doors are best left to professionals who can ensure mothers are not isolated from their kits. https://www.humaneworld.org/en/resources/what-do-about-raccoons
19. Blog post on raccoon feces in attics, published by a wildlife removal company in 2026. Commercial material from a firm that sells remediation, flagged. Source for its claims that eggs survive drying and that leaving an attic for a year is not an effective approach. https://drcritter.com/blog/is-raccoon-poop-dangerous-health-risks-in-florida-attics/
20. Update on baylisascariasis, a clinical review published in a microbiology review journal and read as its summary. Peer-reviewed review material. Source for the statement that most diagnosed patients have been children under two, with the number of older patients diagnosed increasing. https://journals.asm.org/doi/10.1128/cmr.00044-15
21. Page on raccoon roundworm published by the same Toronto wildlife rehabilitation charity as reference 17. Charity and advocacy material, flagged. Source for the advice to keep sandboxes covered and not to let very young children play unsupervised where raccoon feces may be, such as woodpiles and under porches. https://www.torontowildlifecentre.com/wildlife-emergency-rescue-hotline/answers-to-your-wildlife-questions/wild-animals-and-disease/raccoon-roundworm/
22. The same Winnipeg study as reference 7, read as an extract of its introduction in a public biomedical archive, since the full page did not load for us. Peer-reviewed material. Source for the statements that prevalence in North American raccoons varied between 0 and 100 per cent in 33 studies recently reviewed; that the parasite had been identified as a cause of animal loss at Assiniboine Park Zoo; that small rodents and birds are considered most susceptible because of the larger ratio of larval mass to brain mass in low-dose infections; and that pica or geophagia and exposure to infected raccoons or contaminated environments are the most important risk factors for human infection. https://pmc.ncbi.nlm.nih.gov/articles/PMC2711470/
23. Page on raccoon roundworm published by a wildlife damage management information centre. Educational material from an organisation serving the wildlife control trade, flagged. Source for the warning that soil near a latrine may be contaminated because rain may carry eggs, and for its illustration of a latrine on the roof of a house. https://icwdm.org/raccoon-roundworm/