What is Strongyloidiasis?
Strongyloidiasis is a human parasitic infection caused by Strongyloides stercoralis, which is a roundworm or nematode. Strongyloidiasis is found in warm climates and this infection is seen in subtropical and tropical countries. Strongyloidiasis is one of the neglected tropical diseases and efforts are being made all over the world to eradicate this infection. This infection also commonly occurs in rural areas. In many cases, strongyloidiasis produces no symptoms. Symptoms commonly experienced due to this intestinal worm include primarily skin symptoms, diarrhea, abdominal pain and weight loss. In patients who require certain medications, such as immunosuppressants or corticosteroids, strongyloidiasis can lead to hyperinfection syndrome, which if left untreated, can cause death of the patient. Blood and stool tests can confirm the diagnosis of strongyloidiasis. Treatment of strongyloidiasis consists of the medication Ivermectin.
Symptoms of Strongyloidiasis
Many patients having strongyloidiasis may not experience any symptoms. Symptoms when present consist of:
- Pain or burning in the upper abdomen.
- Patient can have diarrhea or it can alternate with constipation and diarrhea.
- Development of red hives near the anus.
- Weight loss.
There are 5 forms of Strongyloidiasis. When the patient initially acquires this infection, he/she may experience respiratory symptoms (Löffler's syndrome). Strongyloidiasis then becomes chronic where the patient will primarily experience mainly digestive symptoms. If the patient has re-infection where there is migration of the larvae through the body, then the patient will have skin, respiratory and digestive symptoms. Lastly, if the patient has the hyperinfection syndrome, then symptoms will be of multiple organ systems.
Causes of Strongyloidiasis
The cause of Strongyloidiasis is a parasitic roundworm, Strongyloides stercoralis, which mainly infects human beings. Strongyloides stercoralis is commonly found in subtropical and tropical climates; however, sometimes it can also be found in more temperate climates including Appalachia and parts of the southern United States. After the patient has come in contact with Strongyloides stercoralis, then the infection follows the life cycle of the worm, which consists of the following stages:
In the first stage, these tiny worms penetrate the patient's skin and enter the bloodstream. Next, the worms then migrate through the bloodstream after which they pass through the right side of the heart and move to the lungs. The parasites then migrate from the lungs to the windpipe and up into the patient's mouth. The patient can unknowingly swallow these worms from where they reach the stomach and move into the small intestine. They then lay eggs which hatch and produce larvae. These larvae then get expelled from the body through the patient's feces. These larvae can cause infection in the body by penetrating the skin surrounding the anus where they develop into mature worms and can infect some other person. In rare cases, the worms, instead of passing from the body through feces, can penetrate the intestine of the patient as larvae.
Risk Factors for Strongyloidiasis
- Individuals living in or traveling to Africa, South America and other tropical regions are at a higher risk to contract Strongyloidiasis.
- People who don't practice good personal hygiene are more prone to contract Strongyloidiasis.
- Individuals living in or traveling to rural regions and areas with poor sanitary conditions without proper public health services are at an increased risk for having Strongyloidiasis.
- Individuals with weakened immune system such as those patients who are suffering from AIDS or HIV, are at a higher risk for contracting Strongyloidiasis.
Diagnosis of Strongyloidiasis
The following tests may be performed to diagnose an infection with Strongyloides stercoralis:
- Stool tests are done to look for Strongyloides stercoralis larvae in the feces. This test may need to be repeated for accurate diagnosis of Strongyloides.
- Microscopic examinations of stool and duodenal samples are the commonest methods for diagnosis of Strongyloidiasis. In a duodenal aspiration, fluid is taken from the first section of the small intestine, which is then sent to laboratory to examine it under the microscope for Strongyloides stercoralis.
- Fluid from the airways or lungs can be taken and sputum culture can be done to look for Strongyloides stercoralis.
- Blood test, which includes Complete Blood Count (CBC) with differential helps in excluding other causes of symptoms or other infections.
- A blood antigen test can also be done to check for antigens to Strongyloides stercoralis. This test is done when the doctors cannot find the parasite in stool samples or in a duodenal aspiration, but suspect that the patient has this infection.
Treatment for Strongyloidiasis
- Treatment for Strongyloidiasis primarily consists of elimination of the worms. Ivermectin is the medicine of choice for treating strongyloidiasis. This medicine is given in single dose and it works by killing the worms in the small intestine.
- Two courses of albendazole can also be taken about 10 days apart. Alternatively, albendazole can also be taken twice a day for two or three days.
- If the patient has widespread Strongyloidiasis then the medication needs to be taken for a longer duration or will be repeated.
Prevention of Strongyloidiasis
It is not possible to always prevent Strongyloidiasis; however, using sanitary facilities and maintaining good personal hygiene when traveling to tropical or warm areas will cut down the risk of contracting Strongyloidiasis.
Complications of Strongyloidiasis
Patient can have the following complications from Strongyloidiasis:
- Malnutrition: Patient suffers from malnutrition when the intestines are not able to properly absorb nutrients from the food due to Strongyloidiasis.
- Eosinophilic Pneumonia: Patient develops Eosinophilic Pneumonia when there is swelling of the lungs due to increased eosinophils. Increase in the eosinophils occurs when the worms enter the lungs and the body produces more eosinophils as a result.
- Disseminated Strongyloidiasis: There is widespread distribution of the parasite in the body involving multiple organs. This happens when the patient is taking immunosuppressive medicines or if the patient has a weak immune system due to a virus. Disseminated Strongyloidiasis can also occur when the Strongyloides stercoralis changes its life cycle by entering the intestines and re-entering the blood circulation. Patient experiences the following symptoms: Pain and swelling in the abdomen, shock, septicemia, neurological and pulmonary complications.
Prognosis of Strongyloidiasis
Prognosis for strongyloidiasis is good, provided proper treatment of the patient is started. With appropriate treatment, the patient can have a full recovery after the parasites have been completely eliminated. In some patients, the treatment may need to be repeated.
However, the prognosis is not good if the patient has a weak immune system with widespread or severe infection. If the diagnosis and treatment is delayed in such patients, then Strongyloidiasis can cause death of the patient.