What is Strongyloidiasis?

On a recent episode of House, a young man who is bound to a wheelchair with Spinal Muscular Atrophy suddenly loses consciousness while crossing the street.. Thanks to Hoover, his English Shepard service dog, the young man barely misses being hit by a car. He is then brought to Dr. House to see what is wrong with him. Of course, there is a myriad of incorrect diagnoses and plenty of twists and turns before the correct diagnosis is figured out: strongyloidiasis. For most people, strongyloidiasis can be treated, but unfortunately for the patient, the diagnosis came too late. So what is strongyloidiasis?

Strongyloidiasis is an infection caused by the parasitic roundworm Strongyloides stercoralis. S. stercoralis is a nematode that can affect humans, other primates, and dogs. The parasite has a rather complex life cycle. It has both free-living and parasitic life cycles. S. stercoralis has the ability of autoinfection, a unique feature in which the organism can establish a life cycle using only one host. There are only three organism that have this ability. S. stercoralis is common in warm, moist areas. However, it can be found in other habitats. The parasite is extremely small, barely visible to the naked eye. S. stercoralis infects people when they come into contact with contaminated soil or ingest the larvae. Through circulation, the larvae makes its way to the lungs and airways. Eventually, the larvae makes its way to the intestines where they burry themselves. The females produce eggs which can either be passed with stool or can autoinfect, thereby starting the cycle over again. Strongyloidiasis is relatively uncommon in the United States. It is more common internationally, however. Certain areas have a prevalence rates as high as forty percent. It is estimated that strongyloidiasis affects approximately 70 million people worldwide.

Symptoms of strongyloidiasis can vary greatly from patient to patient. People with normal immune systems usually exhibit little or no symptoms. These patients are not greatly affected by the infection and generally do not know they even have it. Untreated, the infection usually does not "go away." Instead, it becomes a chronic infection and asymptomatic. Diagnosis at this point is extremely hard. On the other hand, patients who are immunocompromised usually exhibit more symptoms and can be greatly affected by the infection. It is important to note that should a person with a normal immune system become immunocompromised, then they would also experience more severe infection. In order to help with the diagnosis of strongyloidiasis, the infection is broken down into three categories: acute, chronic, and severe. Symptoms of acute strongyloidiasis include itch or rash at site of larval penetration, cough, difficulty breathing, wheezing, low-grade fever, abdominal pain or discomfort, diarrhea, occasional nausea, and vomiting. Symptoms of chronic strongyloidiasis include abdominal discomfort which is usually worse after eating, diarrhea, constipation, nausea, vomiting, weight loss, and recurrent rashes. Symptoms of severe strongyloidiasis include bloody diarrhea, severe abdominal pain, extreme respiratory problems, stiff neck, headache, confusion, syncope, rash, fever, and chills.

Diagnosis of strongyloidiasis can be particularly difficult. In order to diagnose the infection, a doctor will listen to a patient's symptoms and will also look for observable signs of the infection. There are many tests that can be performed to aid in diagnosis. These include a CBC, stool sample, a duodenal fluid culture, sputum culture, and a blood antigen test for S. stercoralis. Imaging tests and a gastrointestinal endoscopy may also be helpful. Once the diagnosis is confirmed, prompt treatment is very important. Treatment of strongyloidiasis is aimed at eliminating all the worms and larvae with antiparasitic medications such as ivermectin, albendazole, mebendazole, or thiabendazole. The length of treatment varies from patient to patient. It is important to get rid of all worms or larvae because autoinfection can occur. Because of autoinfection, once someone has been infected with S. stercoralis, infection is life-long unless treatment eliminates all adult parasites and larvae. Prognosis varies from patient to patient. Severe strongyloidiasis has a mortality rate of up to eighty percent. This is usually because diagnosis is delayed. However, assuming all worms and larvae are killed through treatment, prognosis for individuals with strongyloidiasis is extremely good.

Strongyloidiasis is an infection caused by the parasitic roundworm Strongyloides stercoralis. The infection can be quite serious, especially in the immunocompromised. For most people, strongyloidiasis can be treated. In those patients, prognosis is usually good. Unfortunately for some, however, the diagnosis comes to late.

Sources

Wikipedia

eMedicine