Strongyloides stercoralis

Strongyloides stercoralis or intestinal nematode is a small worm causing strongyloidosis. It belongs to Nematoda - nematodes. It usually lives in the outdoor environment - in humid tropical, subtropical areas, but also in cold areas. If the larvae encounter a human at the stage, they will attack it.

Life cycle
They are small worms with a size of 0.8–2.2 mm  with a complex evolution. Upon contact with humans, they actively penetrate the skin and enter the bloodstream. They get through the lungs through the blood, where they irritate the airways and force a person to cough. They enter the esophagus through the alveoli, bronchi and trachea. They then settle in the small intestine, where the larvae mature, copulate and begin to produce eggs. Eggs enter the stool or may hatch in the host's digestive tract.

If a person is not immunocompetent enough, the eggs hatch in the GIT and the larvae penetrate the wall into the bloodstream, where they migrate to various tissues.

Clinical signs
The patient's clinical symptoms depend on where the parasite is located.

Skin phase

 * Itching on the skin.
 * Macroscopically visible path.
 * Local edema.

Pulmonary phase
The pulmonary phase usually manifests itself as 6-9. the day after infection.


 * Cough, shortness of breath.
 * Massive infections manifest as hemorrhagic pneumonia or bronchopneumonia.

GIT phase
We already have pathogenic agents in the digestive tract that cause problems. Females settle in Lieberkühn's crypts and produce eggs. Hatched larvae can invade the mucosa again, causing multiple ulcerations and subsequent wall thickening. Clinically, this will manifest itself as:


 * abdominal pain in the epigastrium,
 * diarrhea,
 * bleeding into the GIT.

Hyperinfection syndrome is the result of disseminated strongyloidosis (dissemination of larvae throughout the body, affected liver, heart, lungs, gallbladder and intestines) in immunosuppressed individuals (AIDS). In these people, the disease is severe. Severe diarrhea, ileus and bronchopneumonia are common.

Diagnostics

 * Microscopy: detection of larvae in stool about 27 days to 1 month after infection.


 * Detection of specific antibodies.


 * Detection of parasitic DNA (not performed in the Czech Republic).


 * Laboratory tests: marked eosinophilia and leukocytosis, decrease in values ​​in the chronic phase of infection.

Therapy

 * Albendazole


 * Thiabendazole


 * Ivermectin


 * Levamisole

related articles

 * Diarrheal diseases : Viral gastroenteritis ▪ Bacterial gastroenteritis ▪ Gastrointestinal parasitosis ▪ Enterotoxicosis ▪ Drug-induced diarrhea ▪ Differential diagnosis of diarrheal diseases ▪ Treatment of diarrheal diseases

Source

 * CHANOVÁ, Marta. Diseases caused by nematodes  [lecture on the subject Parasitology, General Medicine, 1st Medical Faculty, Charles University]. Prague. 12/10/2015



Reference

 * 1) VOLF, Petr and Petr HORÁK. Parasites and their biology. 1st edition. Prague: Triton, 2007. 318 pp. 209–210. ISBN 978-80-7387-008-9.
 * 2) ↑ FÖRSTL, Miroslav, Vladimír BUCHTA and Libuše KOLÁŘOVÁ. Overview of diagnostics and therapy of intestinal parasitosis. Internal medicine for practice. 2004, vol. 6, vol. 4, pp. 209, ISSN 1803-5256.