Amanda Bruce, DVM z Ringworm in shelters
Yep, that s me snuggling kittens up against my body, no gloves on, early in my shift.
Majority of scientific info for this lecture:
Boots on the ground info for this lecture:
Dermatophytosis has importance in the shelter because: Contagious Infectious Can be transmitted to people
The dreaded zoonosis because kittens and kids with upset parents and time and money and image
Ringworm in humans Known zoonotic disease causing skin lesions that are treatable and curable Dermatophytosis is a common skin disease in humans with an unknown rate of transmission from animals to people Predominant agent in humans is non-animal-derived T. rubrum, presenting as toe nail fungus Most common complication of M. canis infection is prolonged treatment time. Most common underlying conditions associated with severe dermatophytosis are solid organ transplant, CARD9 deficiency, and HIV
Self-limiting disease Immunocompetent hosts can typically clear dermatophytosis within weeks to months.
Our villains: Most commonly: Microsporum canis Microsporum gypsum Trichophytom mentagrophytes (Arthroderma sp)
Transmission: Direct contact between animals Exposure to contaminated environment Fomites Bedding/grooming appliances Collars Ectoparasites
Microsporum canis Typically due to contact with an infected animal
Microsporum gypseum Presumed to be due to contact with contaminated soil
Trichophyton Suspected to be due to contact with infected rodents or their nests
Clinical appearance: Hair loss Papules Scales Crusts Erythema Changes in nail growth +/- pruritus Typically asymmetrical Hyperpigmentation Follicular plugging
Factors increasing risk of ringworm: Age <1 year and geriatric Species/breed CATS Yorkies/Persians Immune status Malnutrion Pregnancy/lactation STRESS Preexisting conditions Flea allergies URI
Normal grooming behavior likely decreases formation of clinic infection Clinical infection is difficult to establish in cats Experimental infection required that skin surface was abraded and kept moist (Trans St Johns Hosp Dermatol Soc 1959; 45: 19-27) Use of e-collars and prevention of self-grooming required to allow clinical infection (Vet Microbiol 1994; 42: 289-295)
Development of infection: Fungal hyphae fragment into infective spores Infective spores adhere to corneocytes within 2-6 hours of exposure Penetrate stratum corneum within 4-6 hours Fungal hyphae invade keratinized structures, including follicular unit Clinical lesions appear within 1-3 weeks post exposure
The Gold Standard of Diagnostic Testing 1. What test (s) confirm the presence of an active infection? Remove from foster? Euthanize? Quarantine? 2. What test (s) confirm the absence of an active infection? Move from isolation? Open community rooms? OK for foster? Adoptable?
Multiple complementary tests available: Wood s lamp Direct exam Dermoscopy PCR Fungal culture
Wood s lamp as a point-of-care diagnostic tool
Using the Wood s lamp: Use a plug-in model versus battery for stronger light Perform exam in dark room Hold the light within 4-10 cm of the animal Warm up light for 5 minutes
M. canis fluorescense Green fluorescence on hair shafts due to a chemical metabolite located within the cortex or medulla of the hair. What percent of M. canis fluoresce? 50, 90?
What else will fluoresce? Doxycycline Clavamox Eye ointments Sebum
Apple green on hair shafts
Direct examination of hair and scale:
In theory: Pluck or scrape suspicious area (s) Mount in mineral oil +/- stain (lactophenol cotton blue, India Ink) Microscopic confirmation of hyphae or fungal spores Rapid ID of infected cats that may be Wood s lamp negative
Dermoscopy Commonly used diagnostic tool in human medicine to examine hair and follicular abnormalities Identify opaque, curved and/or broken hairs Comma-like hairs identified Patient cooperation can be an issue
PCR testing Identify dermatophyte DNA Concordant results between culture and PCR Positive results as a result of: Active infection Fomite Nonviable fungal DNA from successful treatment Negative result: True negative Global marker not used (pathogens other than M. canis)
Fungal culture Risk assessment in exposed cats Diagnosis of suspicious lesions Confirmation of cure after treatment
For single & multifocal lesions Pluck plenty of hairs from edge of lesions using sterile hemostats Place 2 different samples on each side of the growth medium
No lesions Toothbrush sample Using a freshly open toothbrush brush animal 30 times including face, ears and feet saving suspicious areas for last Press sample firmly into medium trying not to disrupt medium
Tips for successful culture Plates are easier to inoculate than narrow jars or slants Larger plates are easier to gather tape preps Plates with combined rapid sporulation medium and dermatophyte test medium aid in identification
Sample monitoring Sample has been labeled with date and animal ID Cultures are monitored +/- daily Our experience: M. gypseum within 4 days Trichophyton within 4-7 days M. canis within 7-10 days
Color change Contaminants Red color change ph change triggered by fungal growth Not all dermatophytes turn DTM red Wide range of contaminants cause color change RW species typically white, fluffy colony. Contaminants often yellow, green, or slimy
Sample prep
Microscopic ID
Rating systems Positive/negative Inadequate for interpreting infection Worse or better in subsequent weeks? Colony forming units (CFUs) Pathogen scores P1, P2, P3 based on number of CFUs present
We consider cure 2 consecutive negative cultures
Literature: Samples should be held for 21 days for certain strains of Trichophyton What we do: Samples are rarely held for more than 2 weeks
Treatment Topical antifungals Systemic treatment
Lime sulfur: 8% or 8oz per gallon warm water (2x bottle recommendation)
Dipping process Done on Tues and Saturday Done on pregnant, nursing animals and kittens > 2-3 weeks old Kittens are dipped Older cats poured over Reports of crosscontamination, not our experience
A rag is used to get those areas that can t be dipped: face, nose, ears No eye lube No e-collar No pre-wetting Air dry in a room with heaters on Use a hot pot to warm water Garden sprayers would be ideal for this
Side effect of dipping Ears and feet can become irritated with hair loss Staff report animals for worsening hairloss even though fungal cultures are showing resolution/clear What we ve found helps: Duoxo Calm spray
Other topical therapies Other effective topical therapies include: 2x weekly use of enilconazole or a miconazole/chlorhexidine shampoo Accelerated hydrogen peroxide products show some promise Miconazole or chlorhexidine monotherapies are not effective, do best when combined Localized treatment with topicals such as clotrimazole, miconazole cremes show some effectiveness, but not recommended as sole therapy
Oral therapies Systemic treatment targets the active site of infection. Until the active site is treated risk exists for more lesions, seeding of haircoat with infective spores, and spread to other animals and the environment Itraconazole Ketoconazole Terbinafine Fluconazole Griseofulvin (last mention of this)
Remember those cultures? We only treat M. canis with oral meds M. gypseum and Trichophyton Dips 2x/week M. canis Dip 2x/week Oral Itrafungol week on/week off at 5mg/kg Until recently Sporonox at 10mg/kg
Consensus guideline conclusions regarding systemics Noncompounded itraconazole and terbinafine are most effective and safe treatments for dermatophytosis In our shelter we ve decided to stop using terbinafine in cats due to perceived poor response N of 2: Itrafungal cat cleared faster than Sporonox cat Ketoconazole and fluconazole are less effective with ketoconazole having potential for more adverse events
Environmental control goals Minimize risk of disease transmission to people and other animals Minimize fomite transfer Begin new disease outbreaks Complicate monitoring of disease
Other things we keep in mind: Provide mental and physical stimulation to cats in our care Adopt out socialized kittens Don t turn this into high security prison
Basics of disinfecting nonporous surfaces 1. Mechanical removal of organic debris 2. Washing the area with a detergent until visibly clean 3. Application of a disinfectant to kill any residual spores
Mechanical removal is important Clear clutter and places dust bunnies can accumulate Electrostatic cleaning product like a Swiffer Vacuuming all accessible areas Cleaning of duct work is likely overkill
Detergent/Disinfectant Rescue Detergent activity Kennels cleaned 3x Disinfectant
If it can be washed, it can be decontaminated In home cleaning/disinfection Fosters should use towels/blankets that can be washed Toys should be plastic Feeding containers should be nonporous Daily removal of pet hair from areas pet is confined 2x weekly cleaning/disinfection Formula 409 Clorox Clean-Up
Let s do some pathway planning
Ward terminology in our shelter Our C ward houses cats with URI Often getting nebulized Daily weighing, recording of inputs/outputs Our I ward houses cats with suspicious hairloss Negative Wood s lamp, suspicious hairloss Culture pending Our G ward houses cats with confirmed ringworm lesions Wood s lamp positive Culture positive
Things you can t unsee
4 kittens no lesions, the runt has hair loss on his head Just finishing URI treatment in our C ward, looking to be released to public kennels Runt has hair loss on his head, no erythema or crusts noted Has had treatment for ectoparasites Wood s lamp negative Plucked hair from edges of lesion for culture
Layover in I while culture pending Culture + for Trichophyton One more of this litter developed a lesion on its nose during its week in I increasing our suspicion of dermatophytosis Move to G to start dipping entire litter
Our thoughts We like to keep litters together or pair up singlets with kittens with the same type of dermatophytosis whenever possible In this case, we could have separated the 2 lesional kittens and the 3 non-lesional kittens Dip non-lesionals, culture 4 days later and potentially release non-lesionals to general population following second dip prior to release
The glowing kitten Immediate move to G Start 2x weekly dipping Start Itrafungol week on/week off We don t start recheck culturing M. canis until no longer glowing (contradicts literature)
Lesions noted on an animal in group room, gulp!?! Lesional animal moved to I or G depending on Wood s lamp results All other animals examined by vet for lesions All animals in room are dipped. While room is empty for dipping it is deep cleaned and disinfected Remove and replace all scratching posts, toys, blankets, etc Animals returned to group room Culture in 4 days, room stays closed until results back