Hedgehog dermatophytosis (Trichophyton erinacei): diagnosis, treatment and zoonotic risk

Bottom line

Treat Trichophyton erinacei as present until culture says otherwise, and treat the zoonotic risk as independent of whether the hedgehog has lesions. In 103 captive African pygmy hedgehogs (Atelerix albiventris) sampled in the Czech Republic and Romania, 24.3% (25/103) were positive for T. erinacei and 76.0% (19/25) of those positives were asymptomatic [1]. Quill loss and crusting look the same whether the cause is dermatophytosis, Caparinia tripilis, or both, so finding mites does not close the case — culture the spines anyway [6]. Systemic plus topical antifungal therapy is the working standard, the endpoint is mycological cure rather than a better-looking hedgehog, and the owner needs glove-and-handwashing advice on the day you take the sample, not on the day the culture returns.

The organism and what to call it

T. erinacei is a zoophilic dermatophyte whose primary reservoir is hedgehogs. Multigene work places it as a monophyletic species within the Trichophyton benhamiae complex, with two main subpopulations — one associated mainly with Atelerix hosts, the second with Erinaceus hosts [4]. Older clinical literature and many human case reports name it T. mentagrophytes var. erinacei; the 2005 CDC review of hedgehog zoonoses uses exactly that name for the organism most commonly isolated from hedgehog quills and underbelly [8]. Search both names or you will miss half the case series. Isolates in the Atelerix-associated cluster spread clonally between pet African hedgehogs, while the second cluster spread predominantly among wild Erinaceus hedgehogs [4]; consistent with that, all 25 isolates from the 103-hedgehog captive survey were genetically identical by multilocus microsatellite typing, indicating a single circulating clone [1].

Carriage without lesions is the load-bearing fact

Population	Prevalence	Positives without skin lesions
103 captive A. albiventris, Czech Republic and Romania [1]	24.3% (25/103)	76.0% (19/25)
412 wild E. europaeus admitted to a French rehabilitation centre, 2016 [2]	23.3% (96/412) infected at arrival	79.2% (76/96)

In the French cohort, only 8% (32/412) of admitted hedgehogs showed skin lesions at all; 62.5% (20/32) of those with lesions were culture-positive, but so were 20% (76/380) of those without. Lesions made a positive culture more likely, yet the authors state that "the high number of positive cultures coming from asymptomatic hedgehogs (79.2%) confirm that in the context of wildlife rescue, proper measures such as the use of protective gloves and continuous environmental disinfection become crucial to avoid contagion" [2]. The Merck professional hedgehog chapter says the same thing in one clause: dermatophytosis is a common clinical disease in African pygmy hedgehogs, "however, infection without notable clinical signs is also possible" [6].

Read the two rows as separate observations, not as one validating the other: different host species, different settings — captive African pygmy hedgehogs in central Europe, and wild European hedgehogs passing through a French rescue centre. Nor are the prevalences comparable as point estimates. The captive study found detection strongly method-dependent, with interdental brushes recovering 80% of positive animals against 36.0% for cotton swabs and 36.0% for toothbrushes, and spines or crusts catching cases every brush-and-swab technique missed [1] — which makes 24.3% a floor set by sampling rather than a fixed population value. What the two surveys share is a clinical consequence rather than a number: each found roughly a quarter of animals positive and roughly four in five of those positives lesion-free, and neither supports reassuring an owner on the strength of normal-looking skin. Quote either figure with its population attached, never as a general pet prevalence. Advise on handling before you have a result.

Presentation, and why it will not tell you the answer

Dermatophytosis in the hedgehog produces crusting dermatitis, especially around the face and pinnae, and quill loss may also be noted; although some animals scratch with the hindlimbs or rub against stationary objects, many do not display signs of pruritus [6]. Lesions recorded in the French wild cohort were scaly skin, loss of spines or alopecia, graded from mild to severe [2]; in pet hedgehogs, crusty skin, scaly or abnormally textured patches, and alopecia particularly prominent over the head or back [3].

Now the differential. Caparinia tripilis acariasis is very common in hedgehogs and presents with excessive quill loss, loose quills, and white or brownish crusts at the base of the quills and around the eyes [6] — the same picture. The two also travel together: an earlier New Zealand survey summarised in the 2023 review found Caparinia to be the primary cause of most hedgehog "scabbiness", with T. erinacei frequently recoverable from those same lesions, and raised the possibility that mites transmit the fungus between animals [3]. The French study found mites in only two of its 412 animals and states it was not possible to confirm that hypothesis [2], so the co-transmission mechanism remains unsettled while the clinical overlap does not. Either way, a positive scrape for Caparinia does not rule out dermatophytosis and is not a reason to skip the fungal sample.

Diagnosis: sample the spines, and know what a negative means

Wood's lamp is not a rule-out here. Merck's professional dermatophytosis chapter (canine and feline) describes the Wood's lamp as a tool used to find Microsporum canis–infected hairs, which fluoresce apple green, and notes only hair shafts, not crusts, glow [7]. T. erinacei is not M. canis: a dark hedgehog under a Wood's lamp has told you nothing.

Culture of spines is the confirmatory test. Merck states that diagnosis is confirmed by culturing spines in dermatophyte test medium [6]. In the surveys above, samples were cultured on Sabouraud dextrose agar with cycloheximide and chloramphenicol, with isolates identified by ITS rDNA sequencing [1][2].

How you collect matters. Comparing three non-invasive techniques in 103 captive African pygmy hedgehogs, interdental brushes detected 80% (20/25) of positive animals, significantly outperforming cotton swabs and toothbrushes at 36.0% (9/25) each, and spines or crusts recovered cases all brush-and-swab techniques missed [1]. Sampling an asymptomatic in-contact animal with a cotton swab means missing infections.

PCR shortens turnaround but changes the question. Merck's professional dermatophytosis chapter is explicit that a PCR assay confirms the presence or absence of fungal DNA on the coat — the spines and coat, in this species — and cannot distinguish between viable and nonviable spores [7]. That makes PCR good for a first "is this dermatophytosis?" answer and treacherous as a cure test on a recently treated animal, where dead spores still amplify. Sampling adequacy sets the floor under any negative: given how much the recovery rate moved with collection technique in the captive survey [1], a negative from a single cotton swab on a spiny, balled-up hedgehog is a weaker result than the same negative from an interdental brush plus plucked spines and crusts.

Treatment

Both systemic azole and allylamine therapy work, and the published head-to-head favours terbinafine. In a trial of 165 European hedgehogs with naturally occurring dermatophytosis randomised to oral itraconazole or oral terbinafine for 28 days, mycological cure rates at day 14 and day 28 were 36.6% and 65.9% for itraconazole and 92.8% and 98.8% for terbinafine; both drugs were well tolerated and clinically effective, and the authors conclude terbinafine was more effective [5].

Doses that a source states for a hedgehog:

• Itraconazole 5–10 mg/kg PO once or twice daily, reported by the 2023 Journal of Fungi review for the African pygmy hedgehog (Atelerix albiventris) [3].
• Itraconazole 10 mg/kg PO once daily, in three cycles of one week of treatment separated by one-week intervals, as used in wild European hedgehogs (E. europaeus) at the French centre, layered on top of topical enilconazole [2].
• Topical enilconazole, applied four times at three-day intervals over one month in that same European hedgehog protocol [2].

The terbinafine trial dose is not reproduced here. The 165-hedgehog trial necessarily dosed the drug, but the mg/kg figure sits in the full trial report behind a publisher paywall rather than in the freely readable abstract, and the figure as reprinted in the 2023 review carries a unit that cannot be transcribed safely. Take the terbinafine mg/kg from a current exotic-animal formulary such as Carpenter's and record it as extra-label. None of these drugs carries a hedgehog label; every use described here is off-label in this species.

Merck's professional hedgehog chapter lists topical enilconazole or clotrimazole in spray or shampoo formulations, oral terbinafine or itraconazole, and notes lime-sulfur dips may also be used [6]. Griseofulvin has been used historically in hedgehogs but the 2023 review states it is no longer recommended, on safety and efficacy grounds [3].

Topical alone is not enough. In the French cohort, 45.8% (44/96) of treated animals were still infected after one month of enilconazole alone. Only combined topical plus oral azole therapy eliminated the dermatophyte or reduced fungal load in 95.6% (394/412) of animals after up to three months [2]. Note the denominators differ and are not a before-and-after pair: 44/96 counts the animals that were culture-positive, while 394/412 is expressed over the entire admitted cohort, of which only 96 were ever infected.

Expect long courses, and expect recurrence. Three hedgehogs that arrived heavily contaminated needed three to four months of itraconazole treatment before dermatophyte withdrawal in order to be allowed to hibernate, and they showed a relapse after hibernation [2]. Separately, of 16 hedgehogs that entered hibernation with a negative fungal culture, 3 of 16 were culture-positive when resampled at the end of the hibernation period, with 1–5 colonies per plate [2]. The authors' own reading is that the culture may not have been sensitive enough to detect residual dermatophyte before hibernation, and that straw bedding could have preserved spores through it [2] — an under-sensitive clearance test and a contaminated substrate, both of which apply just as well to a pet hedgehog in a fabric-lined enclosure.

The endpoint is mycological, not cosmetic. Merck's professional dermatophytosis chapter (canine and feline) states that the end of treatment includes both clinical and mycological cure, and that one negative fungal culture supports mycological cure in an otherwise systemically well animal [7]. Regrowing quills on a hedgehog that still cultures positive is a treatment failure that looks like a success.

Environment and in-contact animals

The French protocol washed and disinfected cages and all reusable material daily, cleaning or immersing materials in sodium hypochlorite 4% for at least 15 minutes, with bedding replaced regularly [2]. The general principle is mechanical removal of infective material first, then disinfectant [7]. Sample in-contact hedgehogs rather than watching them, given how many positives carry no lesions [1][2]. In a single-hedgehog household the enclosure, bedding, handling gloves, exercise wheel and fabric hides are the reservoir.

Zoonosis: this is the part the owner needs

Human infection from hedgehogs is documented, not theoretical: Merck's professional hedgehog chapter states that dermatophytosis in humans, transmitted from pet hedgehogs, is well documented [6]. The CDC review notes that hedgehogs can be asymptomatic carriers of these fungi, that T. mentagrophytes var. erinacei causes an extremely inflammatory and pruritic eruption which frequently resolves spontaneously 2–3 weeks after onset, and that the disease may present as a localized rash with pustules at the edges and a thickened, intensely irritating central area; one reported patient had merely handled a hedgehog in a pet store for one to two minutes [8].

The case literature explains the commonest human error. Among eight hedgehog caretakers in and around Göttingen who developed T. erinacei dermatophytosis, the four who handled animals without gloves developed hand lesions more in keeping with hand eczema, which delayed diagnosis, while those who wore gloves presented with typical ringworm on the arms, big toe, back, abdomen and thighs, whose typical features led to early diagnosis [9]. In two Munich cases T. erinacei was cultured from the patients and, in one, from the hedgehog itself; both received oral terbinafine 250 mg daily for two weeks, one of them alongside topical ciclopirox olamine, and both healed [10]. A 29-year-old woman developed marked erosive inflammation of an entire finger from a pet African pygmy hedgehog [11], and tinea manuum has been acquired from a hedgehog café and carried across borders [12]. Human cases misread as eczema and treated with corticosteroids see the infection progress [3].

What to tell the owner: wear gloves and wash hands after handling the hedgehog, its bedding and its enclosure, whatever the culture shows [2]; assume a lesion-free hedgehog can still shed [1][2]; and take any new red, scaling, itchy or pustular patch — especially on a hand or forearm — to their own physician, naming both the hedgehog and T. erinacei. A hand lesion that looks like eczema is the presentation that gets missed [9], and a hedgehog-owning patient handed a topical steroid is the outcome you are preventing.

Frequently Asked Questions

My patient's hedgehog has no lesions. Do I still need to warn the owner about ringworm? Yes. In 103 captive African pygmy hedgehogs, 76.0% (19/25) of the T. erinacei-positive animals were asymptomatic [1], and in 412 wild European hedgehogs admitted to a French rehabilitation centre, 79.2% (76/96) of positives had no skin lesions [2]. Those are two different host species in two different settings, and neither validates the other — but both point the same way. Normal skin is not evidence of a clean animal. Give glove and handwashing advice at the first visit, not after the culture returns.

I found Caparinia tripilis on the scrape. Can I stop there? No. Mites and dermatophytes produce an overlapping picture of quill loss and crusting [6], and T. erinacei has been reported as frequently recoverable from lesions whose primary cause was Caparinia [3]. Treat the mites and still submit a fungal culture.

Is a negative Wood's lamp useful? Not for this organism. The Wood's lamp is described in Merck's professional dermatophytosis chapter (canine and feline) as a tool for finding Microsporum canis–infected hairs, which fluoresce apple green [7]. T. erinacei is not M. canis, so a non-fluorescing hedgehog rules nothing out.

Culture or PCR? Culture of spines in dermatophyte test medium is the confirmatory test named for hedgehogs [6]. PCR is faster but confirms the presence or absence of fungal DNA and cannot distinguish viable from nonviable spores [7], which makes it poor at proving cure after treatment. Sampling technique also drives sensitivity: interdental brushes detected 80% (20/25) of positive animals against 36.0% (9/25) for cotton swabs and 36.0% (9/25) for toothbrushes, and spines or crusts caught cases the brushes missed [1].

Which systemic antifungal should I reach for? The only published head-to-head, in 165 European hedgehogs treated orally for 28 days, gave mycological cure rates of 92.8% at day 14 and 98.8% at day 28 for terbinafine versus 36.6% and 65.9% for itraconazole, with both drugs well tolerated [5]. For itraconazole, 5–10 mg/kg PO once or twice daily has been reported for the African pygmy hedgehog [3], and 10 mg/kg PO once daily in one-week-on, one-week-off cycles was used in wild European hedgehogs alongside topical enilconazole [2]. No terbinafine mg/kg is quoted here: the trial's dose sits in the paywalled full report rather than the abstract, so take it from a current exotics formulary. All of this is extra-label in hedgehogs.

Can I treat topically only? Topical monotherapy underperformed. After one month of enilconazole alone, 45.8% (44/96) of infected hedgehogs in the French cohort were still infected; combined topical plus oral azole therapy cleared or reduced fungal load in 95.6% (394/412) of animals over up to three months [2]. The two fractions use different denominators — 96 is the infected animals, 412 the whole admitted cohort — so read them as two separate results rather than a before-and-after pair.

When do I stop treating, and should I expect relapse? Stop on mycological cure, not on appearance. Merck's professional dermatophytosis chapter (canine and feline) states the end of treatment includes both clinical and mycological cure, with one negative fungal culture supporting mycological cure in an otherwise well animal [7]. Courses can be long: three heavily contaminated hedgehogs in the French study needed three to four months of itraconazole before dermatophyte withdrawal, and relapsed after hibernation [2]. Recurrence is not confined to hard cases — of 16 hedgehogs that entered hibernation culture-negative, 3 were culture-positive at the end of it [2].

What does hedgehog ringworm look like in a person, and what do I say? Typically a markedly inflammatory, pruritic eruption, described in the CDC review as a localized rash with pustules at the edges and a thickened, intensely irritating centre, often self-resolving 2–3 weeks after onset [8]. The trap is the hand: among eight German hedgehog caretakers, the four who handled animals bare-handed developed lesions resembling hand eczema, which delayed diagnosis [9]. Send any suspicious lesion to the owner's physician, and tell them to mention the hedgehog and name T. erinacei.