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Epidemiology and Control of Zoonotic Infections Lecture 6

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Epidemiology and Control of Zoonotic Infections Lecture 6 Parasitic Diseases Mycotic Diseases Drs. Gundula Dunne & Jason Stull February 22, 2004 Parasitic diseases ... – PowerPoint PPT presentation

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Title: Epidemiology and Control of Zoonotic Infections Lecture 6


1
Epidemiology and Control of Zoonotic
Infections Lecture 6
  • Parasitic Diseases
  • Mycotic Diseases

Drs. Gundula Dunne Jason Stull February 22, 2004
2
  • Parasitic diseases
  • Giardia
  • Toxoplasmosis
  • Roundworms
  • Toxocara sp.
  • Baylisascaris sp.
  • Sarcoptes sp.
  • Mycotic Disease
  • Ringworm

3
Parasites
  • Organisms which live at the expense of another
  • Ectoparasites lives on outside of host
  • Endoparasites lives on inside of host
  • Eukaryotes
  • Single-celled (protozoa) to multicellular
    (helminthes) to arthropods (fleas)

4
Parasitism
  • Obligate parasites most parasites are obligate
    but many have free living stages
  • Facultative parasites not normally parasitic
    but wont pass up the opportunity
  • Accidental parasites attach or enter wrong
    host, may or may not survive but can be very
    pathogenic.
  • Permanent parasites - live adult lives in or on
    host
  • Temporary parasites - eat and run

5
Notifiable Parasitic Diseases
  • Reportable in CA
  • Amebiasis
  • Anisakiasis
  • Babesiosis
  • Cryptosporidiosis
  • Cysticercosis
  • Echinococcosis
  • Giardiasis
  • Malaria
  • Toxoplasmosis
  • Trichinosis
  • Not reportable in CA
  • Zoonotic ascarids
  • Baylisascaris procyonis
  • Toxocara spp.
  • Cercarial dermatitis

6
Giardia
7
Giardia
  • Protozoan flagellate
  • Global distribution
  • Two-stage life cycle - trophozoite and cyst
  • Reservoirs domestic and wild animals

8
Giardia life cycle
Sheep, goats Cattle Pigs Horses Dogs and
cats Wildlife
Giardia intestinalis G. lamblia G.
duodenalis
9
Giardia - cysts
10
Giardia in Animals
  • Symptoms asymptomatic to diarrhea
  • Transmission, diagnosis and treatment similar to
    humans
  • Contaminate surface water (e.g. beavers,
    livestock)

11
Giardia Transmission to Humans
  • Oral ingestion of cysts
  • Fecal-oral transmission
  • Contamination of water
  • Foodborne transmission
  • Zoonotic transmission from pets and livestock may
    be important

12
Direct Contact Transmission
  • Person-to-person is 2nd most commonly identified
    mode of transmission
  • Poor fecal-oral hygiene
  • Children in daycare centers
  • Cyst passage as high as 20-50
  • Spread the disease within center, homes, and
    communities
  • Men who have sex with men (MSM)
  • Cyst passage as high as 20
  • Persons in custodial institutions

13
Giardia Human Disease
  • Incubation period of 1-25 days (average 7 days)
  • Infectious dose is low (10 cysts)
  • Excreted in the stool intermittently for weeks or
    months
  • Asymptomatic infections can occur
  • Duration of illness 1 to 3 weeks

14
Giardia Human Clinical Signs
  • DIARRHEA
  • Other symptoms flatulence, bloating, weight
    loss, abdominal cramping, nausea, malabsorption,
    foul-smelling stools, steatorrhea, fatigue,
    anorexia, and chills
  • Chronic disease
  • recurrent symptoms
  • malabsorption and debilitation may occur

15
Giardia Diagnosis
  • Microscopic visualization
  • via wet mount
  • staining (trichrome or iron hematoxylin)
  • Direct fluorescent antibody detection
  • ELISA
  • Alternative - samples of duodenal fluid (e.g.,
    Enterotest) or duodenal biopsy may demonstrate
    trophozoites

16
Giardia Treatment
  • Many effective treatment alternatives
  • Metronidazole first choice for humans and
    animals
  • Alternatives Nitazoxanide, Furazolidone,
    Quinacrine, Tinidazole, Albendazole, and
    Paromomycin

17
Risk Factors
  • Travel
  • Backpackers/campers
  • To disease-endemic areas
  • Poor sanitation
  • Inadequate drinking water treatment facilities
  • Children in day care with prolonged diarrhea
  • Men who have sex with men
  • Persons drinking water from shallow wells

18
Prevention and Control
  • Proper handling and treatment of water
  • Travelers to developing world or wilderness
    should boil or treat surface water
  • Good personal hygiene
  • Daycare center foci are a problem
  • Some recommend only symptomatic children be
    treated
  • However, asymptomatic passers may infect others
  • If strict handwashing and treatment of
    symptomatic children does not control outbreak,
    treating all infected should be considered

19
Toxoplasmosis
20
Toxoplasmosis
  • Single-cell organism
  • Global Distribution
  • Reservoir host - Cats
  • Uncommon cause of human disease
  • Except
  • pregnant women fetus
  • Immunocompromised persons

21
Toxoplasma gondii
Tachyzoites Cyst in brain tissue
22
Toxoplasma - oocysts
  • Survives in the environment for several
  • months
  • Resistant to disinfectants, freezing, and
  • drying
  • Killed by heating to 70C for 10 minutes
  • Sporulation 1-5 days

23
Toxoplasma gondii life cycle
  • Presence of cats in environment is necessary
  • Oocyst excretion in 1 of cats in various areas
  • No T. gondii infection in areas without cats

24
Toxoplasma Animal Disease
  • Infects all animals, including birds
  • Cats
  • infected by ingestion of cyst (feces or raw meat)
  • Asymptomatic
  • Shed for 1-2 weeks
  • No treatment necessary
  • Diagnostic tests
  • Serology
  • Do NOT routinely perform serologic test of cats
  • Cannot determine whether excreting oocysts
  • Microscopic evaluation of feces

25
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26
Toxoplasma Human Transmission
  • Infection in humans typically through ingestion
  • Raw/undercooked meat
  • Estimated to occur in ½ of T. gondii infections
    in U.S.
  • Parasite isolated from 32 pork chops, 4 lamb
    chops (1960s)
  • Ingestions of oocyst from cat feces or soil
  • Water or food contaminated with oocysts
  • Also transplacental transmission
  • Mother acquires infection during gestation

27
Toxoplasma At Risk for Severe Disease
  • Congenitally infected fetuses and newborns
  • Estimated 400-4000 cases each year in the U.S.
  • Immunologically impaired individuals, most
    commonly with defects in T-cell-mediated immunity
  • Hematologic malignancies
  • Bone marrow and solid organ transplants
  • AIDS, e.g. leading to toxoplasmic encephalitis

28
Toxoplasmosis Clinical Signs
  • Usually asymptomatic (80-90)
  • Flu-like illness
  • Lymphadenopathy
  • Self-limiting
  • Toxoplasmic encephalitis (AIDS)
  • Congenital toxoplasmosis
  • Retinochoroiditis

29
Toxoplasmosis ocular lesions
30
Congenital toxoplasmosis
31
Toxoplasma Diagnosis
  • Serologic testing
  • Observation of parasites in patient specimens
  • Isolation of parasites from blood or other body
    fluids, by intraperitoneal inoculation into mice
    or tissue culture
  • PCR (for congenital infections in utero)

32
Toxoplasmosis Treatment
  • Consideration should NOT depend on cat exposure
  • Treatment may or may not be indicated based on
    presence of active disease, immune status, site
    of infection
  • Prevention most important in seronegative
    pregnant women and immunodeficient patients

33
Prevention and Control
  • Education
  • Avoid ingestion of and contact with cysts or
    sporulated oocysts
  • Cook meat to well done with no visible pink in
    center
  • Wash hands thoroughly after handling raw meat or
    vegetables
  • Avoid areas with cat feces
  • Change litter every day (before sporulation)
  • Wear disposable gloves when disposing of cat
    litter, working in garden, cleaning childs
    sandbox
  • Serologic screening for pregnant women

34
The Zoonotic Ascarids Toxocara canis/cati
Baylisascaris procyonis
  • Jason Stull, VMD, MPVM
  • CDHS, Veterinary Public Health Section
  • jstull_at_dhs.ca.gov
  • 916-552-9782

35
Outline
  • Background
  • Toxocara sp.
  • Lifecycle
  • Infection in dogs/cats
  • Infection in humans
  • Baylisascaris procyonis
  • Lifecycle
  • Infection in raccoons
  • Infection in humans

36
Ascarids Background (1)
  • Biology
  • adult size lt1 mm to gt1 m
  • complete digestive system with anterior mouth and
    posterior anus
  • Reproduction
  • separate male and female
  • eggs shed in environment

Toxocara canis
37
Ascarids Background (2)
  • Humans definitive host
  • Ascaris lumbricoides
  • Humans aberrant host
  • Toxocara canis/cati
  • Baylisascaris procyonis
  • Ascaris suum

38
Toxocara canis / cati
  • Definitive host Dogs and cats
  • Transmission
  • Transplacental
  • Transmammary
  • Environmental
  • Prevalence
  • Neonate 100 (puppies)
  • Adult 20-40

39
Toxocara Life cycle
40
Toxocara - Life cycle
  • Key concepts
  • Adult worms live in small intestines of
    dogs/cats, with eggs shed in feces
  • Eggs shed into the environment require 2-5 weeks
    to become infectious
  • Animals/humans are infected when ingesting
    infectious eggs
  • Eggs are very resistant and may survive in
    environment for months - years
  • Infected dogs contaminate the environment with
    1.4 million eggs / day

41
Toxocara Dogs and Cats
  • Clinical signs
  • None
  • Diarrhea
  • Weight loss
  • Cough
  • Diagnosis fecal examination
  • Outcome
  • Most asymptomatic with occasional death in the
    young

Toxocara canis
42
Toxocara - Humans
  • Larva Migrans
  • Migration / presence of nematode larvae of
    animals within the tissues of a human
  • Named by location
  • Visceral larval migrans (VLM)
  • Ocular larval migrans (OLM)
  • Neural larval migrans (NLM)

43
Toxocara - Humans
  • Infected after ingestion of an infectious egg
  • Visceral, ocular, or neurological larval migrans
  • Tissue trauma, inflammation, necrosis
  • Granulomatous immune response (eosinophils)
  • Abscesses (?)

44
Toxocara - Visceral Larval Migrans
  • Larvae lodged in liver, lungs, heart, muscle
  • Clinical manifestations depend on number of
    larvae and location
  • Most cases mild or asymptomatic
  • Symptoms are variable including
  • Fever, GI / respiratory signs, lymphadenopathy,
    persistent eosinophilia
  • Majority of patients lt 3 yrs of age

45
Toxocara - Ocular Larval Migrans
  • Larvae lodged in eye
  • Inflammation and retinal scarring
  • Vision loss (progressive or sudden blindness) -
    unilateral without systemic signs
  • May be misdiagnosed as retinoblastoma
  • Majority of patients older children

46
Toxocara - Neurological Larval Migrans
  • Larvae lodged in CNS
  • Meningitis, encephalitis, convulsions, motor
    deficiencies

47
Toxocara Human
  • Diagnosis
  • Fecal not useful
  • Larvae do not develop into adults in humans
  • Antibody detection (blood, aqueous/vitreous
    humor)
  • EIA indicates previous exposure
  • Clinical signs, fecal exposure, laboratory
    results, Toxocara antibodies
  • Treatment antiparasitics, antiinflammatories

48
Toxocara Public Health (1)
  • Estimate 10,000 human cases/yr in U.S.
  • 700 cases of OLM/yr
  • Risk factors
  • Children
  • Pica (dirt consumption)
  • Dog/cat ownership

49
Toxocara Public Health (2)
  • Prevention
  • Regularly treat dogs/cats for worms (especially
    young)
  • Hygiene
  • Limit contact with feces
  • Clean pets area regularly
  • Dissuade pica
  • Education

50
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51
Baylisascaris procyonis
52
B. procyonis Background (1)
  • Definitive host raccoons
  • Transmission
  • Environmental (consumption of eggs or infected
    animals)
  • Prevalence common in raccoons
  • Geographic distribution
  • Widespread throughout the U.S.

53
B. procyonis Background (2)
  • Can infect numerous animals (including humans)
  • Similar epidemiology to Toxocara
  • Eggs only passed by definitive host
  • Eggs require 2-4 weeks to become infectious
  • Eggs resistant to environmental conditions
  • Humans ingestion of infective eggs ? larval
    migrans

Baylisascaris procyonis
54
Baylisascaris Life cycle
55
B. procyonis Background (3)
  • Raccoon behavior influences epidemiology
  • Habitually defecate in latrines
  • Latrines associated with natural and human-made
    structures
  • Rooftops, attics, decks, stumps, woodpiles, lawns
    (especially near trees)
  • Where raccoon densities are high, substantial
    amounts of feces and B. procyonis eggs accumulate

56
B. procyonis Raccoons
  • Diagnosis
  • fecal examination
  • Outcome
  • most asymptomatic with occasional death in the
    young

57
B. procyonis - Humans
  • Clinical features
  • May be asymptomatic
  • Often severe disease (VLM, OLM, NLM)
  • Larvae
  • larger than Toxocara
  • extensive migration
  • neurotropic

58
B. procyonis - Humans
  • Diagnosis
  • Clinical findings
  • Limited diagnostic tests
  • No commercially available serologic test
  • Diagnosis requires biopsy specimen with adequate
    cross-section

59
B. procyonis - Humans
  • Treatment
  • No drugs have been demonstrated to be completely
    effective
  • Antiparasitics
  • If suspect ingestion of eggs, consult a physician
    immediately

60
B. procyonis Public Health
  • lt 25 cases diagnosed in US (5 in CA)
  • 5 deaths
  • Many cases undiagnosed, misdiagnosed
  • Risk factors
  • Children
  • Pica (dirt consumption)
  • Raccoon contact

61
Latrines and B. procyonis in CA
  • 3 communities
  • Pacific Grove
  • Carmel
  • San Jose
  • Latrines found on
  • 73 of Pacific Grove,
  • 72 of Carmel, and
  • 46 of San Jose
  • properties
  • 244 latrines identified on 164 properties

Percentage of properties that contained at least
one raccoon latrine positive for B. procyonis eggs
Roussere G, et al. Raccoon Roundworm Eggs near
Homes and Risk for Larva Migrans Disease,
California Communities. Emerg Infect Dis. 2003
Dec.
62
B. procyonis - Prevention Control (1)
  • Prevent human exposure to eggs
  • Dissuade pica
  • Periodic inspection of home for latrines
  • Weekly removal of latrines and feces
  • Personal protective equipment
  • Removal of underlying soil 5-7.5 cm deep
  • Burn, bury, landfill
  • Boiling water
  • Cover sand boxes

63
B. procyonis - Prevention Control (2)
  • Avoid or limit contact with raccoons
  • When handling raccoons/potentially contaminated
    items
  • Wear coveralls, rubber boots, gloves, facemask
  • Vigorously wash hands
  • Wash clothing in hot (200 F) water with bleach
  • Reduce enticements for raccoon activity
  • Do not keep, feed, or adopt raccoons as pets

64
Take Home Points
65
Ectoparasites
  • Mange Sarcoptes
  • Ringworm - Dermatophytes

Courtesy of William D. James, MD
66
Scabies
  • An arthropod skin mite
  • Sarcoptes sp.
  • Obligate parasite
  • Species specific (different for humans and
    animals)
  • AKA Mange, Sarcoptes, Norwegian mites

67
Life cycle 17-21 days
68
Human scabies
  • Mites burrows and breeds on man
  • Norwegian Scabies more severe clinical
    manifestation
  • Does not infect animals

69
Animal Scabies
  • Dogs Sarcoptic Mange
  • Hair loss and pruritis
  • Distribution to ears, face, and feet
  • Demodex vs. Sarcoptes
  • Sarcoptes scabiei canis infestation is a highly
    contagious disease of dogs found worldwide
  • Dog scabies can produce an unpleasant
    papulovesicular eruption in humans

70
Animal Mites
  • rat mite Ornithonyssus bacoti fowl mite
    Ornithonyssus sylviarum dog mite Cheyletiella
    yasguri cat mite Cheyletiella blakei rabbit mite
    Cheyletiella parasitovorax sparrow mite
    Pellonyssus passeri bat mite Chiroptonyssus
    robustipes

71
Mycotic Disease
  • Ringworm - Dermatophytosis

72
Ringworm
  • Fungus not a worm
  • Global Distribution
  • Skin infection
  • Infections are self-limiting

73
Ringworm the Fungus
  • Several different species of fungi
  • Epidermophyton
  • Microsporum
  • Trichophyton
  • Grow only in keratinized tissue
  • Stops at living tissue
  • Infects the hair shaft
  • Can live in humans, animals, and soil
  • Not always a zoonotic disease

74
Ringworm in Animals
  • All animals can be infected cats, dogs, cows,
    goats, pigs, and horses
  • Transmitted from direct contact from an infected
    animal's skin or hair to susceptible animal
  • Hair loss, rash/red skin, /- pruritis
  • Infections are self-limiting
  • Rare chronic or generalized diseases

75
Ringworm Transmission
  • Direct skin-to-skin contact with an infected
    person or pet
  • Indirect/Fomite contact
  • Contaminated from infected person or animal
  • hats, combs, brushes, bed linens, stuffed
    animals, telephones, gym mats, and shower stalls
  • Rarely, by contact with soil

76
Ringworm Human Clinical Signs
  • A skin and scalp disease
  • Incubation 4 to 10 days after contact
  • Dry and scaly or wet and crusty
  • Duration weeks, months
  • Chronic infections

77
Ringworm Clinical Signs
  • RASH
  • a flat, round patch anywhere on the skin
  • Ringworm of the scalp usually begins as a small
    pimple that becomes larger, leaving scaly patches
    of temporary baldness.
  • Infected hairs become brittle and break off
    easily
  • As the rash gradually expands, its center clears
    to produce a ring
  • More than one patch might appear, and the patches
    can overlap.
  • Sometimes itchy
  • Ringworm of the foot (athlete's foot), groin
    (Jock itch), and the nails not typically from
    animals

78
Ringworm Diagnosis
  • Wood's lamp
  • Direct microscopical examination of hair or skin
    scale
  • Fungal culture (gold standard)

79
Ringworm Treatment
  • Ringworm usually responds well to self-care
    within 4 weeks without having to see a doctor
  • Keep your skin clean and dry
  • Over-the-counter antifungal or drying powders,
    lotions, or creams
  • Wash sheets and nightclothes every day while
    infected.
  • Antifungals
  • Prescription and OTC
  • Miconazole, clotrimazole, etc.

80
Ringworm Prevention
  • Difficult
  • Very common
  • Contagious before symptoms appear
  • Steps to prevent infection include the following
  • Educate the public, especially parents, about the
    risk of Ringworm from infected persons and pets.
  • Clean common-use areas (including disinfect
    sleeping mats and gym mats)
  • Do not share personal items

81
Ringworm Prevention
  • Infected persons and animals should follow these
    steps to keep the infection from spreading
  • Complete treatment as instructed, even after
    symptoms disappear
  • Do not share towels, hats, clothing, or other
    personal items with others
  • Minimize close contact with others until treated
  • Make sure the person or animal that was the
    source of infection gets treated

82
Webcast Students
  • Paper due next week March 1
  • Email to gdunne_at_dhs.ca.gov

83
Questions?
Acknowledgements CDC, Dr. Ben Sun, and Dr.
Katherine Feldman
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