j. jill heatley dvm ms dabvp (avian), daczm associate professor, zoological medicine college of...
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J. Jill Heatley DVM MS DABVP (Avian), DACZMAssociate Professor, Zoological Medicine
College of Veterinary Medicine & Biomedical Sciences Texas A&M University, College Station
Gray... Western - Sciurus griseus Eastern – Sciuris carolinensis Arizona ...Sciurus arizonensis
Tassel-eared...Sciurus aberti Fox
Eastern Fox....Sciurus niger Apache Fox.....Sciurus apache
Tamiascirus American Red.....Tamiasciurus hudsonicus Chickaree......Tamiasciurus douglasi
Flying Squirrels – Northern Southern and Glaucomys volans
Order Rodentia Family Sciuridae
All continents Except Antarctica, Australia 50 genera, 273 species Subfamily
Cyonomys – Prairie Dogs Spermophilus – Ground squirrels Marmota – Marmots Ammospermophilus – Antelope Squirrels Tamias – Chipmunks Tamiasciurus – Chickarees Sciurus – Tree Squirrels Glaucomys – New World flying squirrels
Expanding urban communities Parks, neighborhoods
Bird feeders Nature Vacation Exotic Pets Research Rehabilitation Hunting
Bacterial Fungal Parasitic Viral Prion
Literature review
Toxoplasma gondii Intermediate not
definitive host Cryptosporidium parvum
Eastern gray squirrel Chipmunk Red squirrel California Gray squirrel
Hymenolepis nana Dwarf tapeworm of hamsters Human enteric disease
Praziquantel Mange in squirrels is
generally notoedric or demodectic and not transmissable to humans
Zoonoses Squirrel Disease
Lyme Disease Epidemic Typhus Tularemia Plague Leptospirosis Rat Bite fever
Squirrel Bite fever Streptobaccillus
moniliformis Spirillum minus
Red legged ground squirrel
Xerus erythropus Nigeria
Campylobacter spp. Salmonellosis Pasteurella multocida
Red squirrel Yersinia pseudotuberculosis
White tailed antelope squirrel Citellus lecurus
Yersinia enterocolitica Grey squirrel
Tularemia Isolated in 1912
Plague like disease of rodents Plague foci search
Bacterium tularense Francisella tularensis Tulare county of origin, CA Ground squirrels Spermophilus beecheyii
Zoonoses Sciurus carolinensis
Infant Bite Arkansas Prairie Dog (BT Cyonomys ludovicianus)
Titer positive 3 y with bite
Fox Squirrel Skinned/dressed
Magee JS et al. Tularemia trans by Squirrel Bite. Pediatric Infect Dis J.1989Feb8(2):123-5.
Avashia SB at al Emerging Infec Dis 10(3) March 2004
Kirkwood T. Tularemia from the Fox Squirrel JAMA 1931; 96(12);941-942
Leptospirosis Multiple species
Isolations - serovars Gray squirrel - ballum Fox squirrel - grippotyphosa
Zoonosis Leptospira kirschneri
Southern Flying squirrelGlaucomys volans
Exported to Japan28 29 yo males
Borrelia burgdorferi sensu latu Spirochetal bacteria
Most common tick borne disease Debilitating chronic infection Tick intermediate
Reservoirs Western Gray squirrel Eastern chipmunk
Tamias straitus – eastern & upper midwestern US Persistent infection, no clinical signs Ixodes scapularis
European reservoir potential Gray squirrel Sciurus carolinensis European tree squirrel – S. vulgaris
Bacterium Rickettsia prowazekii
Clinical Signs Fever, Headache, Muscle
pain Rash – trunk spreads to
extremities Doesn’t involve the palms or
soles (cf RMSF) Mort ~ 40% if untreated
Primary Vector Human Body Louse
Sporadic cases in Eastern US since 1970s Most cases in winter when squirrels nest in
attics All non fatal, humans faster recovery with
antibiotics Flying squirrels
Glaucomys volans Handled, squirrels nests, pets in home
Capable reservoirs Transient inapparent infection Squirrel human transmission unknown
Sucking lice (Neohematopinus sciuropteri)
Fleas transmit to squirrels in lab Direct contact, inhalation of dried
squirrel excretions bites of squirrel ectoparasites
Sucking lice Flea
Bacterium - Yersinia pestis Complex flea rodent cycle
Sylvatic reservoir Human clinical signs
Severe disease Fatality rate > 50% if untreated Rare - Dozen cases / year
Semiarid West New Mexico Arizona Colorado California
Periodic plague outbreaks Flea vector (Flea control!!!) CS: nonspecific: lethargy, depression, respiratory
distress, lymphadenopathy, anorexia Serologic testing
More susceptible rodent hosts Prairie dogs
Known reservoir Ground squirrels Fox squirrels
Human exposure occurs during outbreaks Flea bites Direct contact w nonrodent hosts
Trend of eastward expansion Epizootic fox squirrels central Texas
Dermatophytosis Sporotrichosis
Sporothrix schenckii Unknown Sciurid, not captured
Bite 1.5 months earlier in the park Severe arm lesion responded to 3 months of
antibiotic and antifungal therapy
Lymphocutaneous Sporotrichosis Associated with a Squirrel Bite: Case Report and Review PS Saravanakumar, P Eslami FA Zar Clinical Infectious Diseases, 23(3)3 Sep 1996) 647-648.
Dermatomycoses, Tinea, “Ringworm”
May accompany parapox fibromas
Systemic Phycomycosis Circular shape, scaly raised
border Patchy hair loss
Neck , head ,armpits, abdomen
Skin reddening, thin layer serous exudate, crusts, skin nodules
Hair broken off at skin surface,
Fine stubble broken hair
Lesions Etiologies
Lewis et al. JWD
Oct 1975 Urban
Gray squirrel
mycology
Trichophyton mentagrophytes Mucor Candida albicans Microsporum gypseum, Scopulaiopsis brevicaulis Microsporum cookei Systemic Phycomycosis Dermatiaceous Fungi –
pigmented Phaeoannellomyces wernecklii
Damp weather conditions Prevalence > 50%
Rule out Alopecia Sciurus carolinensis Glaucomys volans
Dietary, heritable? Congenital Alopecia Dermatophytosis Louse Bite Lesions Notoedric Mange Larval Harvest Mite Lesions
Histology Fungal organisms in superficial
skin, in and around hairs History, Lesions Direct examination Culture
Identify specific fungus Zoonotic
Young animals more commonly affected
One researcher developed lesions after handling squirrels
Use gloves, wash with soap after handling
White et al. Micro Study of Urban Gray squirrel 1975 JAVMA 167
Lymphocytic Choriomeningitis Virus Gray squirrels serologically positive UK 4/19
Snowshoe hare virus (SSHV) Arboviruses
West Nile Virus Western Equine Encephalitis
Lacross Virus Eastern Equine Encephalitis
Rabies Gray squirrel No human cases associated with squirrel bite
Monkeypox Virus Encephalomyocarditis virus
Alphaviruses, Togaviridae WEE rare disease in people
Lacrosse Virus, EEE (mort 50%), VEE rare serious disease Mosquito vector
Hosts (Black tailed jack rabbit, White footed mouse?, ?) Lacrosse Encephalitis –
Tree squirrels and chipmunks primary amplifying hosts WEE Viremia –
Gray squirrels (Sciurus carolinensis), California ground squirrels, San Joachin antelope ground squirrels, Aggressive, bite people, Usu fatal, may survive overwinter
Richardson’s ground squirrels (Spermophilus richardsonii) contaminated urine, cannibalism Experimental Infection
Weak, depressed, ataxic, limb paralysis prior to death Some became hyperexcitable Brain, brainstem Necrosis & edema
EEE - Gray squirrels Peripheral inoculation: Encephalitis & death
VEE – Significant viremia, > 50% mort Mexican ground squirrel - Spermophilus mexicanus Gray squirrel
Bunyaviridae Variant of the La Crosse virus Encephalitis occasional - NY, Eastern Canada
Antibodies Experimental infection ground squirrels
Symptomless viremia Artic ground squirrels
Spermophilus parryii Golden mantled ground squirrels
Spermophilus lateralis Yellow-pine chipmunks
Eutamias amoenus Red squirrels
Encephalitis virus Fox squirrel (Sciurus niger)
Seroconversion late summer early fall None in urine, fleas Exp: feces and oral cavity
Experimental infection suggests amplifying host High seroprevalence
Western gray squirrel (S. griseus) Eastern gray squirrel (S. carolinensis)
3/36 live neurologic tree squirrels viremia similar to WNV-infected birds. Most squirrels no virus in serum S. carolinensis
not amplifying hosts low viremias, lack of mortality Low seroprevalence 2% Useful as sentinels High seroprevalence
Tick borne encephalitis flavivirus complex 1956 epidemic of people and monkeys
Fever, hypotension hepatomegaly,
hemorrhage/neuro/bronchopneumonia recovery/late fever
Southern india - 2500 m radius Striped palm squirrels
Funambulus tristriatus Antibodies Viremic infective for Ticks
Orthopox virus Broad primate host range includes humans
Fever rash resembles small pox Low mortality high morbidity
Infection via direct contact Main host African tree squirrels
Tree squirrels Heliosciurus rufobrachium H. gambianus
Rope Squirrels Funisciuris anerythrus F. lemniscatus
Prairie dogs Poorly competent host Effective transmitters for veterinary staff
Diseases Infectious Monkey Pox
Humans 1-10% mortality Contact, respiratory droplets CS: fever, cough, conjunctivitis,
lymphadenopathy, nodular rash No treatment Strict biosecurity, humane
euthanasia CDC website
www.cdc.gov/ncidod/monkeypox Final rule prohibits
capture, offers to capture, transport, sale, barter, exchange, distribution, or release of a listed animal into the environment. Prairie dogs (Cynomys sp.) African Tree squirrels (Heliosciurus
sp.), Rope squirrels (Funisciurus sp.), Gambian giant pouched rats
Cricetomys sp.
Squirrel brains Creutzfeldt-Jakob disease (CJD)
“burgoo” Squirrel brain stew
5 patients 56-78y Unrelated, Different towns
Rural Kentucky Don’t eat brain unless you want
be a zombie
Summary Squirrels are harbor a plethora of zoonoses
Sentinel Is it the cute factor? Thanks for your attention
Field Manual of Wildlife Diseases in the Southeastern United States, 3rd ed Davidson, WR
Zoo & Wild Animal Medicine 5th edSainsbury, Rodent Chapter
Infectious Diseases of Wild Mammals ES Wiliams, IK Barker
Smithsonian Museum of Natural History North American Mammals http://www.mnh.si.edu/mna/main.cfm
Clostridium botulinum Saravanakuma PS Eslami P Zar FA Lymphocutaneous sporotrichosis associated with
a squirrel bite: case report and review. Clin Infect Dise 1996 sep 23(3) 647-8
Squirrel Fibroma AKA Squirrel Pox
Squirrel Pox Virus 1953
Leporipoxvirus Related to Shope’s Fibroma of rabbits
Range Range: Maryland, New York, Virginia,
Michigan, North Carolina, Ontario Host
Gray squirrel Fox Squirrel Red squirrel
Significant cause of decline Experimental infections
Woodchucks, rabbits
Squirrel Fibroma Lesions
Limited to skin Metastasis to the lungs, liver, kidney, and lymph nodes has
been reported. Secondary infection Vision obstruction
Raised flattened nodules Light colored, little fur 1/16- 1 inch diameter Single or wide dissemination Epizootic
Lesions on the eyelid Swelling, discoloration, necrosis of leg or foot
Clinical Signs Most infections self limiting, spontaneously regress Debilitation, emaciation, death Rare epizootics
Morbidity, mortality many squirrels Florida
www.michigan.gov/dnr
Parasite-mediated competition Parapoxvirus: Grey
& Red Squirrels Mosquito
spread
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