PRE FI: TISSUE NEMATODES Flashcards
- “rat lungworm”
- Classified under genus Angiostrongylus
- First found in Canton, China
Parastrongylus cantonensis
Parastrongylus cantonensis DEFINITIVE HOSTS?
RAT (IN THE LUNGS)
Parastrongylus cantonensis INTERMEDIATE HOST
SLUGS AND SNAILS
Parastrongylus cantonensis PARATENIC HOST
FRESHWATER PRAWN OR CRAB
Parastrongylus cantonensis MOT FOR HUMANS (ACCIDENTAL HOST)
INGESTION OF RAW MOLLUSKS, LEAFY VEGETABLES WITH MUCUS OF MOLLUSK, PRAWN OR CRAB, OR CONTAMINATED WATER
Parastrongylus cantonensis Infective Stage (humans and rats)
third stage larva (L3)
- Shape: ovoidal, elongated with hyaline shell
- Unembryonated when oviposited
- Embryonation: hatch after 6 days in the bloodstream
Parastrongylus cantonensis EGG
has a distinct SMALL KNOB near the tip of the tail
Parastrongylus cantonensis 1ST STAGE LARVA
has two well-developed CHITINOUS RODS below its buccal cavity that has EXPANDED KNOB-LIKE TIPS; penetrates stomach to reach bloodstream to access CNS
Parastrongylus cantonensis 3RD STAGE LARVA
Parastrongylus cantonensis LARVAE UNDERGO ______- MOLTS
2 MOLTS
Pale and filiform in shape
Parastrongylus cantonensis ADULT WORM
Parastrongylus cantonensis FEMALE OR MALE ADULT WORM?
- have a well-developed single lobed kidney-shaped CAUDAL BURSA
o Used to grasp into the body of the
female during copulation
MALE ADULT WORM
Parastrongylus cantonensis FEMALE OR MALE ADULT WORM?
- have uterine tubules that wound
spirally around the intestine, usually
described as “BARBER’S POLE ” pattern
o White: uterus
o Red: digestive tract
o Posterior end: blunt shaped
o Lay up to 15,000 eggs daily
FEMALE ADULT WORM
Parastrongylus cantonensis PRIMARY SITE OF INFECTION?
BRAIN
- Most common complaint: occipital or
bitemporal headache - Incubation period: 6-15 days
- Symptoms: stiffness of the neck, paresthesia, vomiting, fever, blurred vision or diplopia, body or muscle pain,
confusion, incoherence, disorientation,
memory lapses, coma - Complications: intraocular hemorrhage and retinal detachment
Primary Eosinophilic Meningoencephalitis
In Primary Eosinophilic Meningoencephalitis immature worms are seen in?
CEREBRUM AND CEREBELLUM
TREATMENT
- surgical removal of worms from the eyes
Ocular parastrongyliasis
TREATMENT
- Headaches
analgesics and lumbar puncture
TREATMENT
- Cranial nerve involvement
PREDNISONE, 30 mg daily
- “Trichina worm”, “muscle worm”, or
“great imitator” - Most important cause of trichinellosis in humans and most adapted to domestic and wild pigs
- Habitat: STRIATED MUSCLE
Trichinella spiralis
Trichinella spiralis Infective Stage and Diagnostic Stage?
ENCYSTED LARVAE
MOT OF Trichinella spiralis
ingestion of undercooked meat
- Spear-like with a burrowing anterior tip coiled in a nurse cell or a striated muscle cell to become encysted
- Undergo 4 molts
- Average lifespan: 5-10 years
Trichinella spiralis ENCYSTED LARVAE`
- Has thin anterior end, small mouth, and a long slender digestive tract
- Begin to copulate 5-7 days after
- Habitat: small intestine
Trichinella spiralis ADULT WORM
Trichinella spiralis FEMALE OR MALE ADULT WORM?
- has a SINGLE TESTIS near the posterior end joined in the mid-body by the genital tube, extending to the cloaca
o Cloaca: has a pair of caudal appendages and two pairs of papillae
o Curved posterior end
MALE ADULT WORM
Trichinella spiralis FEMALE OR MALE ADULT WORM?
- has a SINGLE OVARY in the posterior end of the body, an oviduct, seminal receptacle, coiled uterus, vagina, and a vulva
o Viviparous female: lives for 30 days,
can lay more than 1,500 larvae in its lifetime
o Blunt, round posterior end
FEMALE ADULT WORM
Pathogenesis of Trichinella spiralis
- asymptomatic
Light infection (>10 larvae)
Pathogenesis of Trichinella spiralis
- symptomatic
-gastroenteritis, diarrhea, abdominal pain
Moderate infection (50-500 larvae)
Pathogenesis of Trichinella spiralis
- Severe infection (how many larvae
(1,000-3,000 larvae)
Trichinellosis (what phase?)
- incubation and intestinal invasion
o Symptoms: diarrhea, constipation,
vomiting, abdominal cramps, malaise
ENTERIC PHASE
INVASION PHASE
CONVALESCENT PHASE
ENTERIC PHASE
Trichinellosis (what phase?)
- larval migration and muscle invasion
o Symptoms: eosinophilia = release of histamines, serotonin, bradykinins, prostaglandins, causing vascular permeability resulting to tissue edema
o Cardiac muscle involvement: pericardial pain, tachycardia, congestive heart failure
o Neurological complication: meningitis
and meningoencephalitis
ENTERIC PHASE
INVASION PHASE
CONVALESCENT PHASE
INVASION PHASE
Trichinellosis (what phase?)
- encystment and encapsulation
o Symptoms: fever, weakness, pain
ENTERIC PHASE
INVASION PHASE
CONVALESCENT PHASE
CONVALESCENT PHASE
Trichinellosis cardinal signs?
severe myalgia, periorbital edema, eosinophilia
Trichinella spiralis DIAGNOSIS
- Muscle biopsy using _______ of tissue
0.2-0.5 g
Skin test made from Trichinella LARVAE ANTIGEN + SALINE
BACHMAN INTRADERMAL TEST
Trichinella spiralis TREATMENT
MEBENDAZOLE AND ALBENDAZOLE
Trichinella spiralis PREVENTION AND CONTROL
COOKING OF THE MEAT
77 C (170 F)
STORAGE (freezing)
-15 C for 20 DAYS
- 30 C for 6 DAYS
SMOKING, DRYING MEAT IS
INEFFECTIVE
ANIMAL MONITORING
Meat inspection
Serological tests for animals
Rat free pens
Proper disposal of carcasses
“dog roundworm”
Toxocara canis
feline roundworm
Toxocara cati
Toxocara species
- lactation rather than transplacental (term?)
o Causes fewer cases due to their
defecation patterns
Vertical transmission
Toxocara spp. Infective Stage
EMBRYONATED EGG
Toxocara spp. Diagnostic Stage
LARVAE
Toxocara spp. MOT?
transplacental (major route) or transmammary (minor route);
ingestion of eggs from soil
Toxocara spp. Embryonation of egg
2 weeks to several months
- Penetrate the gut wall from eggs and
migrate to striated tissue muscles then
encyst - Reactivate during pregnancy in older
female dogs and infect their puppies - Development: 60-90 days after hatching
Toxocara spp. LARVAE
Toxocara spp. LARVAE
Younger dogs: larvae migrate to the
_____ and _____via circulation,
coughed out, swallowed, then develop
into adult worms
LUNGS; TRACHEA
Toxocara spp. FEMALE ADULT WORM lays how many eggs/day?
Female: lays 200,000 eggs per day
Toxocariasis
- migration of and subsequent death of larvae in the different TISSUES and ORGANS
o Produces intense inflammatory response: eosinophilic granulomas
o Most sensitive areas: liver, lungs CNS, eyes
o Most common sign: wheezing
o Complications: eosinophilic pneumonia, respiratory failure, liver enlargement, necrosis, diffused non cavitating pulmonary nodules and
pleural effusions, granulomatous hepatitis, and Loeffler endomyocarditis
A. Visceral larva migrants
B. Ocular larva migrants
C. Covert toxocariasis
D. Neurological toxocariasis
A. Visceral larva migrants
Toxocariasis
- LARVAL INVASION OF THE EYES
o Common manifestation: unilateral
visual impairment, sometimes with
strabismus; also, blindness
o Most serious consequence:
invasion of the retina
o Other ocular lesions: posterior pole
granuloma, peripheral granuloma, or
a condition similar to chronic
endophthalmitis
A. Visceral larva migrants
B. Ocular larva migrants
C. Covert toxocariasis
D. Neurological toxocariasis
B. Ocular larva migrants
Toxocariasis
- ASYMPTOMATIC with less frequent eosinophilia
o Symptoms: coughing, wheezing,
chronic or recurrent abdominal pain,
hepatomegaly, sleep disturbances,
headache, malaise, anorexia
o Manifestations: polyarthralgia,
monoarthritis, migratory cutaneous
lesions, small-vessel vasculitis
A. Visceral larva migrants
B. Ocular larva migrants
C. Covert toxocariasis
D. Neurological toxocariasis
C. Covert toxocariasis
Toxocariasis
- arval migration to the brain, meninges, and can be found in the CSF
o One of the causes of encephalitis
o Solitary mass lesions: cause seizure, static encephalopathy, arachnoiditis, spinal cord lesions, optic neuritis, eosinophilic meningitis
A. Visceral larva migrants
B. Ocular larva migrants
C. Covert toxocariasis
D. Neurological toxocariasis
D. Neurological toxocariasis
DISADVANTAGE OF USING WESTERN BLOT IN THE DIAGNOSIS OF TOXOCARIASIS
CANNOT DIFFERENTIATE BETWEEN NEW AND OLD INFECTIONS
Toxocariasis Diagnosis
- Definitive diagnosis: tissue biopsy
- IgG ELISA kits: Toxocara excretory secretory antigens detect IgG antibodies
o Western blot: used for confirmation
▪ Disadvantage: cannot differentiate between new and old infections - PCR
- Abdominal ultrasound
- CT scan: detect hepatic lesions as low density areas
- MRI scan: reveal granulomas as hyperintense area
TOXOCARIASIS TREATMENT
- Albendazole or mebendazole
- Allergic reaction with high doses: steroids
- OLM infections: removal of worms
- “Guinea worm”
- Suspected being the “fiery serpents” that caused a plague affecting the Israelites living by the Red Sea
LONGEST NEMATODE OF MAN
Dracunculus medinensis
Dracunculus medinensis INFECTIVE STAGE?
L3
DIAGNOSTIC STAGE OF Dracunculus medinensis
ADULT WORMS
DEFINITIVE HOST OF Dracunculus medinensis
HUMANS
Via ingestion of water contaminated
with infected copepods (FRESHWATER
FLEAS)
INTERMEDIATE HOST OF Dracunculus medinensis?
(Harbors 3rd stage larvae)
COPEPODS
- Tail: 1/3 of body length
- DIAGNOSTIC STAGE
- Ruptured ulcers immersed in cool
water reveals this larvae - Consumed by intermediate hosts
(L1 OR L3?)
L1
- In the intermediate host
- INFECTIVE STAGE
(L1 OR L3?)
L3
Dracunculus medinensis MALE OR ADULT WORM?
- has a prominent blunt, rounded
anterior end
FEMALE ADULT WORM
Dracunculus medinensis MALE OR ADULT WORM?
- coiled anterior end at least once
- smaller and rare
MALE ADULT WORM
Dracunculus medinensis ADULT WORM migrates to ________ after mating
subcutaneous tissue (skin of extremities)
Symptoms associated with allergic reactions
Painful ulcer develops at the site of larvae release
Unsuccessful attempts to remove an entire worm may result to partial worm being left – additional allergic reaction and nodule formation
DRACUNCULOSIS/ DRACUNCULIASIS
TREATMENT FOR DRACUNCULOSIS/ DRACUNCULIASIS
Total worm removal (winding of
stick)
DIAGNOSIS OF DRACUNCULOSIS/ DRACUNCULIASIS
o RECOVERY OF ADULT WORMS
- Observing ulcers for emergence of
worms
o RUPTURE OF ULCERS BY COOL WATER
- Reveals 1st stage larva
