The Spirurida

8/8/2019 The Spirurida

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A and B : The female guinea worm induces a painful blister ( A ); after rupture of the blister, the worm emerges as a whitishfilament ( B ) in the center of a painful ulcer which is often secondarily infected. (Images contributed by Global 2000/The CarterCenter, Atlanta, Georgia).

Dracunculiasis medinensisMales:

o Recovered from man and animalo Posterior is called on i tself one or more timeso Primary pairs of caudal papillae (4 pre-anal, 6 post-anal)o Copulatory spicules are subsequent (490-730)o Gubernaculums (200mm)



o Much smaller than the female and measures 12-30mm by 0.4mm in breadth

Life span: male is 6 months, female is 1 year

Female worm is viviparous so it discharges embryo until the gravid female completely empties its urine contentsEmryo:

o Coiled bodies with rounded heads and long tapering tail (650-750u)o Ony set free at the time of parturition when affected part is submerged in water.

Lab DiagnosisThe clinical presentation of dracunculiasis is so typical, and well known to the local population, that it does not needlaboratory confirmation.In addition, the disease occurs in areas where such confirmation is unlikely to be available.Examination of the fluid discharged by the worm can show rhabditiform larvae.

No serologic test is available.Other tests: detection of embryo using water, Intradermal test using Dracunculus antigen (wheal in 24 hours), xraywhen worm is calcified, eosinophilia

Gnathostoma spinigerumSeveral species of the genus, Gnathostoma are responsible for zoonotic infections in man.Gnathostoma spinigerum is a nematode found in dogs, cats, and several other carnivores.Human infections of the disease have been reported from Japan, China, Thailand, the Far East, and the Philippines,with man acquiring the infection from eating various freshwater fish.

Life CycleNatural definite host: domestic and wild felines, dogs and foxesUnnatural host: man (parasite does not develop normally)Habitat: tightly-coiled within tumors of the intestinal wallIntermediate hosts

o 1 st IH: Cyclopso 2nd IH: Fresh water fish (Philippines and Thailand), snakes (India). Crabs, crayfish and amphibians (Japan)



If the infected fish or frogs are eaten by other hosts, apartfrom the definitive hosts, (paratenic host), such as herons, pigs and man,

o They do not mature but migrate through the subcutaneous tissues causing visceral and cutaneous larva

migrans.

Lab EpidemiologyCases of human gnathostomiasis (G hispidum) attributed to consumption of the fish Misgurnus angillicaudatus

o “jojo” in Ifugao w/ c was brought as protein supplement by Japanese soldiersIn Phils. Larvae of G doloresi found in “dalag” (Ophicephalus striatus in Laguna. IH?

Morphology



The adult worms measure 25-54umo Females have a more curved tail.o Larger than males

Whereas the male measures 11-25um.o The male worms have a red tail

The anterior half of the worm is covered with lead like spines.The larval worms are 4um long.

Clinical DiseaseHumans are accidental hosts and after ingestion, the larvae do not mature but migrate throughout the body via theintestinal wall.Symptoms include epigastric pain, vomiting and anorexia.

o These symptoms subside as the larvae continue their migratory path through the cutaneous tissue.Evidence of migration appears as either lesions similar to cutaneous larva migrans or migratory swellingsaccompanied by inflammation, redness or pain.The swelling is hard and non-pitted and lasts for several days.

o These migratory lesions may be accompanied by pruritus and pain.

The clinical manifestations in human gnathostomiasis are caused by migration of the immature worms (L3s).Migration in the subcutaneous causes intermittent, migratory, painful, pruritic swellings (cutaneous larva migrans).Migration to other tissues (visceral larva migrans), can result in cough, hematuria, and ocular involvement, with themost serious manifestations eosinophilic meningitis with myeloencephalitis.

High eosinophilia is present.

There is marked eosinophilia in patients with cutaneous involvement.Ocular involvement resulting in blindness may occur in serious disease.Eosinophilic myeloencephalitis may result from migration of the worms along the nerve tracks.Symptoms may include pain, paralyses, seizures, coma and death.The CSF may be xanthochromic (yellowish discoloration) or bloody.



DiagnosisPresumptive diagnosis may be made on the basis of clinical symptoms.Definitive diagnosis is the recovery and identification of the worm since the symptoms be suggestive of Sparaganosis,

paragonimiasis and cutaneous larvae migrans and myiasis.A bloody spinal fluid or xanthrochromia may resemble infection with Angiostrongylus cantonensis.

Migrating Gnathostoma should be differentiated from hookworm larva migrans.

Nonmigrating Gnathostoma should be differentiated from furunculosis or other localized bacterial infection.

Humans serve as paratenic hosts for Gnathostoma spp.

Identification of gnathostomiasis is achieved by serology and microscopic observation of the larval worms in tissue

sections.

Diagnostic characters for Gnathostoma include the presence of large lateral chords, multinucleate intestinal cells(some species), presence of pigmented granular material in the intestinal cells, and the presence of spines on thecuticle, especially near the anterior end of the worm.

Intradermal test: use antigen extract from adult or larva of the worm.Incision of the lesion and removal of the worm.

o Surgical removal or treatment with albendazole or ivermectin is recommended.



A: Hematoxylin and eosin (H&E) stained cross-section of Gnathostoma sp., taken from a subcutaneousnodule above the right breast of a patient, showing the esophagus. Note the presence of cuticular spines(arrow). Image courtesy of Diagnostix Pathology Laboratories LTD, Canossa Hospital, Hong Kong, China.B: Another H&E-stained cross-section of Gnathostoma sp., taken of the same specimen in Figure A ,showing the intestinal cells and characteristic large lateral chords ( LC ). Note the multinucleate intestinalcells and the presence of pigmented granular material in the intestinal cells.

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The Spirurida