Strongyloides

Strongyloides is a nematode helminth (same class as pinworm, filariasis, oncho).

Tremadtoes, such as schisto, are flukes.

Cestaodes (tapeworm).

 

Clinical Manifestations of Strongyloides:

Most patients don't have prominent symptoms and eosinophilia is not universally present.

 

- Three main organ systems involved

a) Skin: "ground itch" = inflammation, edema, petechiae, serpiginous or urticarial tracts, severe pruritis

   other manifestations: periumbilical purpura, angioedema, non-palpable purpura 

   larva currens aka "running larva"- when you see the parasite moving under the skin before your eyes

b) GI: duodenitis--> upper abdominal pain

   diarrhea, constipation, nausea, vomiting

   malabsorption if high burden of worms

c) Pulmonary: dry cough, throat irritation, dyspnea, wheezing, hemoptysis

   fever and mild pneumonitis

 

LIFE CYCLE:

   The parasite enters your body through the feet, traveling hematogenously to the lungs. They penetrate the alveolar sac and crawl up the tracheobronchial tree to be coughed and then swallowed in the gut. In the GI tract these larvae mature to worms, which burrow into the mucosa of the duodenum and jejunum. They can live there for 5 years.

They can complete their entire life cycle within the human host, in contrast to other helminthic parasites. Autoinfection occurs and can increase the human burden. Larval transformation in the GI can be accelerated in setting of constipation, diverticula, steroid use, decreased motility.

 

Why test for strongyloides:

1. unexplained eosinophilia with epidemiologic exposure + clinical manifestations

2. Immunosuppressed patient with eosinophila/epi exposure/skin lesions

3. Asymptomatic patients who are immigrants, refugees, travelers, military exposure to endemic areas

4. In endemic regions- check in patients with invasive infections (because they can get superinfected)

 

How do you diagnosis Strongyloides?

- O+ P-- low yield: sensitivity 50%

- serology ELISA IgG 83-86% sensitive, 97% specific

 

Lastly, hyperinfection syndrome is from massive dissemination to lungs, liver, CNS and endocrine systems. It can lead to multiple organ failure and septic shock (from superinfection). You would not want to give these patients steroids. They are typically febrile, with nausea/vomiting, abdominal pain, SOB and cough. Patients with impaired CMI are at increased risk.

 

(Katharine Cheung MD, 1/27/11)