Trichuris trichiura

Whip Worm

• Geographical distribution -Parasite of warm climates • Morphology - 3 - 5 cm. Posterior 2/5th of the body is

thick (whip handle). Anterior 3/5th thin and is threaded into the mucosa of the large intestine. Posterior end of male is curved.

• Disease: Trichuriasis, trichocephaliasis • Habitat: Large intestine Disease • Infective stage: Embryonated egg • Diagnostic stage: Eggs • Transmission: By fecal pollution of soil. A person is

infected by ingestion of the infective eggs in food from contaminated fingers.

Life Cycle:

Pathogenesis and Clinical features

• Few worms – little damage

• Heavy infection- spread throughout the colon to the rectum causing Haemorrhages

• Muco-purulent stools, dysentery and rectal prolapse

• Mild infections are asymptomatic

• Children may get ‘Trichuris dysentery syndrome’ resulting in severe diarrhoea, malnutrition, growth retardation and impairment of cognitive functions

Diagnosis

• Finding the characteristic eggs in stool by direct smear or by concentration methods

• Proctoscopy – in cases of dysentery, show numerous worms attach to the mucosa which is redden and ulcerated

Treatment and prevention

• Mebendazole and Flubendazole

• Prevention: As Ascaris

Strongyloides stercoralis

Dwarf Thread Worm

Strongyloides stercoralis

• Disease: Strongyloidiasis

• Distribution - Worldwide but more common in warm climates. Major opportunistic infection among immunocompromised persons.

• Morphology - Male: The male measures1 mm in length with curved posterior end and carries two spicules

Female: The female measures 2.5 mm in length with straight posterior end.

• Habitat: Small intestine

• Infective stage: Filariform larva

• Diagnostic stage: Larva (Rhabditiform larvae- Filariform larva)

• Transmission: Penetration of skin

Life Cycle: Two life cycles –

Parasitic cycle ( if the external conditions are unfavorable) Free living cycle( if conditions are favorable )

Clinical Features

Disease: Strongyloidiasis

Vast majority of infections in endemic areas are symptomless

Primary infection

• A pruritic erythematous eruption ‘Ground itch’ at the site of entry to larvae, last about 3 weeks

• Pneumonitis due to lung migration not common

Chronic uncomplicated strongyloidiasis

• Epigastric pain, anorexia, chronic diarrhoea due to mucosal damage, weight loss

• Skin rashes: Two types:

• Larva currens: Occur around the anus and anywhere on the trunk.

• larvae migrate under the skin :causes itchy rash which is not indurate & has a red flare at the edge

Clinical Features

• Urticaria – Allergy to larval penetration in already sensitized patient. Occur in the buttocks with pruritus ani& around the waist. Last 1-2 days and can recurs at regular intervals

Severe complicated strongyloidiasis

• Severe disease with hyper-infection in persons with immunosupression.

• severe watery diarrhoea, often with malabsorption, hypoalbuminaemia causing Generalized oedema and Fever.

• Lungs hypereosinophilia, pneuminitis, diffuse crepitation, pulmonary abscess and gross respiratory failure.

Diagnosis

• Microscopic identification of larvae (rhabditiform and occasionally filariform) in the stool or duodenal:

• Differentiate from hookworm 1st stage larvae: Ss 1st stage rhab larva has a short buccal capsule compared to that of Hw

• ELISA – to detect

parasite specific IgG

Treatment and Prevention

• Thiabendazole

• Mebendazole and albendazole

• Pyrvinium pamoate

• Prevention like Ancylostomiasis