Page 95 - Medical Parasitology_ A Textbook ( PDFDrive )

88 10 Nematodes: Roundworms

There may be dermatitis, with erythema and itching at the site of penetration of
the filariform larva, particularly when large numbers of larvae enter the skin. Larva
currens has been used to describe the rapidly progressing linear or serpigenous urti-
carial tracks caused by migrating filariform larvae which are seen following exter-
nal autoinfection around the perianal region.
In heavy infection, patient may present with Loeffler’s syndrome during the lar-
val lung migration phase of the parasite.
Intestinal manifestations may present as malabsorption syndrome. Diarrhoea is
often present. In heavy infection, there may be extensive sloughing of the intestinal
mucosa. Other manifestations include protein losing enteropathy and paralytic ileus.
In immunocompromised patients, internal autoinfection takes place, resulting in
a large number of worms in the intestine and lungs. This is known as hyperinfection.
In disseminated strongyloidiasis, the filariform larvae may enter blood circulation
and lodge in various organs, e.g. heart, lungs, brain, kidneys, pancreas, liver and
lymph nodes. Clinical manifestations depend on the sites affected. Brain abscess,
meningitis and peritonitis are major fatal complications.

Diagnosis
1. Microscopic examination
Detection of the rhabditiform larvae in freshly passed stools. Larvae found in old
stools have to be differentiated from larvae hatched from hookworm eggs by doing
stool culture. Baermann’s funnel gauze is a method used for larval examination.
2. Stool culture
When larvae are scanty in stools, diagnosis may be facilitated by stool culture.
Culture techniques used include agar plate culture. Serial examinations of faecal
samples and the use of agar plate culture improve the sensitivity of stool diagnosis.
3. Serodiagnosis
4. Molecular diagnosis
PCR on stool sample.

Note: Patients who are infected with Strongyloides and are prescribed corticoste-
roids or immunosuppressive drugs can develop disseminated strongyloidiasis or
hyperinfection syndrome. These conditions are potentially fatal. Thus, it is
important to rule out the presence of strongyloidiasis prior to starting steroids or
other immunosuppressive therapy.

Treatment
All cases of strongyloidiasis, symptomatic and asymptomatic, should be treated to pre-
vent severe invasive disease. Ivermectin (200 μg/kg/day orally for 1–2 days) is more
effective than albendazole (400 mg orally twice/day for 7 days). For disseminated
strongyloidiasis, treatment with ivermectin should be extended for at least 5–7 days.

Prevention and Control
1. Proper faecal disposal
2. Use of footwear and gloves to prevent skin penetration by filariform larva
3. Treatment of patients