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26 Cards in this Set
- Front
- Back
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Describe Order Rhabditida, Superfamily Rhabditoidea.
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1. Mostly free living nematodes
2. Some are facultative parasites: occur in skin, CNS or small intestine 3. Very small nematodes 4. Have a RHABDITIFORM ESOPHAGUS: 3 regions - corpus, isthmus and bulb |
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Describe Rhabditis (Pelodera) strongyloides
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1. Facultative parasite: normally free-living in decaying organic matter, can invade skin and cause dermatitis, life cycle not completed in skin
2. Most often associated with wet or damp straw bedding |
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What are signs/lesions of Rhabditis (Pelodera) strongyloides?
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Lesions limited to skin areas in contact with bedding
Superficial contact dermatitis: alopecia, serum exudate, erythem, pustules, pruritus, secondary bacteria |
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What is the most useful morphological feature for differentiating Pelodera strongyloides?
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Rhabditiform esophagus in anterior end
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Describe Halicephalobus gingivalis.
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1. Most are free living nematodes
2. Very small: adults ~250 um long 3. Pathogenic facultative parasite 4. Sporadic - mainly in equine hosts |
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How are animals infected with Halicephalobus gingivalis?
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1. Route of infection is unknown: ingestion or inhalation + haematogenous spread, local skin invasion, mammary gland infection of mare --> possible lactogenic transmission to foal
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How do you diagnosis Halicephalobus gingivalis?
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ID parasite in lesions, urine, semen: Rhabditiform esophagus, adult parthenogenetic females (dorsoflexed ovaries and single egg in uterus); kidneys: ultrasound can detect lesion
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Describe Strongyloides spp.
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1. Intestinal or minute thread worm
2. Unique life cycle: alternate free-living and parasitic generations; parasitic females only (no males) - reproduce by parthenogenesis Eggs oval to elliptical, thin-shelled, contain an L1: all species shed eggs with L1 in fresh feces and except S. stercoralis: eggs hatch in intestine |
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What is the structure of Strongyloides?
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1. Very fine, tiny worms: ~1-2 mm x ~35 um
2. Parasitic adult females have a filariform esophagus: straight cylinder, > or = to 1/4 length of body |
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Life cycle of Strongyloides
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1. Parsitic (homogonic) generation; adults in SI mucosa; parthenogenetic adult females produce eggs; egg --> rhabditiform L1
2. Homogonic rhabditiform L1 develops into: infective filariform L3 --> parasitic adult female OR free living rhabditiform adult males and females |
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What does the tail of the Strongyloides infective filarifrom L3 appear to be like?
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Notched or forked.
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What is the life cycle of Strongyloides?
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Rhabditiform males + females reproduce sexually --> eggs --> rhabditiform L1 --> rhabditiform L2 --> filariform L3 --> skin penetration (blood) or ingestion (blood) --> blood carries L3 to lungs --> undergo blood-lung-tracheal migraiton or somatic migration
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What is the epidemiology of Strongyloides?
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1. Typical age group infected: foals (2 weeks - 6 months); ruminants (nursing age); pigs (more common in nursing); dogs and primates (depend on conditions than host age)
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Clinical signs and lesions of Strongyloides.
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Usually asymptomatic or mild but can be severe: depends upon host species and age, infecting dose, immune status and strain of parasite
Caused by larval migrations - possible pruritus and erythema at skin penetration sites, bronchopneumonia with petechial to ecchymotic hemorrhage in lungs |
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What are the clinical signs of Stongyloides?
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Caused by adults in small intestine: anorexia, weight loss, decreased weight gain, intermittent diarrhea with mucus, blood, dehydration
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What are the different species of Strongyloides?
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Strongyloides westeri = equine
Strongyloides ransomi = pigs Strongyloides papillosus = ruminants Strongyloides stercoralis = primates/dogs (cats) Strongyloides tumefaciens = cats |
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Describe Strongyloides westeri
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Horse
Lactogenic transmission important: usually first nematode acquired by foals --> onset 2-44 weeks of age; most self-cure by 6 months of age |
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Diagnosis of Strongyloides westeri.
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Flotation (fresh feces): detect eggs with L1; 10-14 days of age; thin-shelled egg that contains an L1
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Describe Strongyloides ransomi
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More common in warm climates: mainly SE states
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What are the clinical signs of Strongyloides ransomi?
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1. Asymptomatic to severe
2. Anorexia and acute onset of enteritis: mucoid to bloody diarrhea, rapid emaciation, stunted growth in survivors and anemia |
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Diagnosis of Strongloides ransomi.
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1. Age and clincial signs suggestive: lactogenic transmission, usually nursing pigs 2-3 weeks old
2. Flotation: fresh feces to detect eggs with L1 3. Detection of adult females |
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Describe Strongyloides papillosus.
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More common in sheep
Lactogenic transmission to nursing neonate Prepatent period ~ 7 days No usual clinical signs or treatment for ruminants |
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Describe Strongyloides stercoralis (canis)
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1. More common in humans
2. Most common: warm climates, warm weather, kennels and under unsanitary conditions |
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Unique features of Strongyloides stercoralis
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1. L1 usually hatches from egg in host gut
2. L1 develops rapidly into an infective L3: autoinfection can occur in humans and in immunosuppressed dogs; immunosuppressed can develop fatal, systemic invastion 3. Autoinfection |
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What are clinical signs of Strongyloides stercoralis?
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1. Severity of clinical signs and public health significance varies with strain
2. Cutaneous - skin penetration by larvae 3. Respiratory: bronchopneumonia 4. Mucoid to watery diarrhea |
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Describe Strongyloides tumefaciens.
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Domestic cats in SE US: uncommon
Adults, eggs and L1 in raised tumor-like nodules in large intestine: grossly visible, glistening white, raised on mucosal surface |
