Strongyloidiasis

Article Author:
Daphne Joyce Gonzales
Article Editor:
Antonette Climaco
Updated:
4/2/2019 2:54:58 PM
PubMed Link:
Strongyloidiasis

Introduction

Strongyloidiasis is a disease caused by the intestinal nematodes Strongyloides stercoralis or Strongyloides fuelleborni. The more common agent, Stercoralis stercoralis, is a helminth transmitted by soil and can cause severe disease in immunocompromised individuals.[1][2][3]

Etiology

Strongyloides stercoralis is a nematode with a complicated life cycle that involves parasitic and free-living forms. It can cause autoinfection, which is the ability to complete a full life cycle within humans and therefore multiplies. Multiple migratory cycles can lead to recurrent infection. Only complete cure can eliminate the risk of complications, so accurate diagnostic methods must be employed.[4][5][6]

Epidemiology

Endemic to the Caribbean, Latin America, Europe, Asia, and sub-Saharan Africa, strongyloidiasis mainly affects tropical and sub-tropical regions. It is estimated that S. stercoralis affects 30 to 100 million people worldwide. It is often underdiagnosed and more appropriate and sensitive diagnostic tests would yield a higher global incidence.[7]

Pathophysiology

The life cycle of S. stercoralis has three components: direct, indirect, and autoinfection. In the direct cycle, the rhabditiform larva from stool matures into filariform larvae in the soil and penetrates the skin to travel to the lungs and eventually the gastrointestinal system. The indirect cycle follows, where eggs are excreted and returned to the soil to live as free-living adults or develop into filariform larvae or reinvade the host through the perianal skin. This reinvasion characterizes the autoinfection cycle, where the infective filariform larva completes its formation in the host’s intestines.

History and Physical

Minor and chronic Strongyloides infection is commonly clinically unapparent in healthy individuals. Some experience gastrointestinal symptoms such as nausea, vomiting, constipation, and abdominal pain, skin problems including pruritis or dermatitis, or respiratory symptoms such as a cough, apnea, or dyspnea. Others can have malabsorption which can mimic tropical sprue clinically and radiographically. Immunocompromised or patients on immunosuppressive treatment are at risk for more severe complications such as disseminated infection and enterococcal meningitis.

Evaluation

The gold standard for diagnosis is based on identifying rhabditiform larvae on direct stool examination under microscopy, or by culturing on agar plates. Serial and repeat stool examination is necessary because the parasitic output is often limited and dependent on the occurrence of larvae in the stool. Therefore, examining multiple stool samples is recommended to identify uncomplicated strongyloidiasis. Hyperinfection is readily diagnosed as filariform larvae in high numbers can be visualized. Other serologic tests using recombinant antigen and enzyme-linked immunosorbent assay are more sensitive and specific, but available only in special laboratories.

Treatment / Management

Many studies show that the best treatment for uncomplicated strongyloidiasis is a drug called Ivermectin. The recommended treatment regimen consists of 200 mg/kg for 2 consecutive days. For uncomplicated strongyloidiasis, the treatment is ivermectin daily until larvae can no longer be detected in stool, urine, or sputum for two weeks.[8][9][10]

  • Ivermectin does not kill the Strongyloides larvae, only the adult worms. As a result, repeat dosing is necessary.
  • There is an auto-infective cycle of about 2 weeks in which Ivermectin must be re-administered and additional dosing will be necessary as it will not kill Strongyloides in the blood or larvae deep within the bowels.
  • Albendazole and thiabendazole (25 mg/kg twice daily for 5 days, a 400 mg maximum are also effective.
  • The optimal duration of treatment is not clear.
  • Treatment can be difficult as Strongyloides has been known to live in individuals for decades even after treatment.
  • Continued treatment is often necessary even if symptoms resolve.
  • Clothes and sheets should be washed with enzyme washing powder and dried on hot days.

Intensive Care

  • Immunocompromised patients may require intensive care in disseminated infection.
  • Contact isolation should be considered because sputum, stool, and vomitus may contain infective larvae.
  • Patients with hyperinfection syndrome often have sepsis, shock, and acute respiratory distress syndrome (ARDS).

Differential Diagnosis

The differential diagnoses include:

  • ARDS
  • Asthma
  • Cholera
  • Chronic Obstructive Pulmonary Disease
  • Diverticulitis
  • Ileus
  • Inflammatory Bowel Disease
  • Loffler Syndrome
  • Peritonitis
  • Pneumonia, especially in the immunocompromised

Prognosis

The prognosis in Strongyloidiasis depends on if complications develop. Strongyloidiasis can result in dermatologic, gastrointestinal, renal, pulmonary, and neurologic complications and even death.

Gastrointestinal

  • Appendicitis
  • Eosinophilic oophoritis
  • Hemorrhage
  • Ileus
  • Infarction
  • Intestinal obstruction
  • Malabsorption
  • Obstructive jaundice
  • Perforation
  • Peritonitis
  • Pneumatosis intestinalis 

Pulmonary

  • Alveolar hemorrhage
  • Asthma
  • ARDS
  • Granulomatous lung disease
  • Pneumonitis
  • Respiratory failure
  • Pleural effusion

Dermatologic

  • Chronic urticaria
  • Larva currens
  • Purpura of the trunk and proximal extremities

Neurologic

  • Brain abscess
  • Meningitis
  • Vascular Complications
  • Hyperinfection syndrome presenting as bacteremia

Renal Complications

  • Nephrotic syndrome
  • Syndrome of inappropriate antidiuretic hormone (SIADH)

Pearls and Other Issues

The goal in strongyloidiasis is to eradicate the infection, decrease morbidity, and prevent complications.

  • Albendazole and mebendazole are sometimes used in Strongyloides stercoralis infection, but results are varied.
  • Ivermectin is more effective than albendazole.
  • The disseminated disease should be treated with ivermectin. For those too sick to tolerate oral ivermectin, subcutaneous or rectal dosing may be effective.
  • Ivermectin should be administered daily until symptoms have resolved and larvae have not been detected for at least 2 weeks.

Parasite pathways are different from the human host and allow selective interference by chemotherapeutic agents. The effectiveness of anthelmintic agents against larvae is poor; they are more effective in established infection.

Ivermectin

  • Ivermectin is the drug of choice for both acute and chronic strongyloidiasis in intestinal stages, hyperinfection syndrome, and disseminated strongyloidiasis.
  • This drug has not been studied extensively in children, and it has been used as an adjuvant in patients with hyperinflation not responding to thiabendazole.
  • Ivermectin is a semisynthetic macrolide mold avermectin that binds selectively to glutamate-gated chloride ion channels in nerve and muscle cells, increasing cell membrane permeability with hyperpolarization and causing paralysis and cell death.
  • Ivermectins half-life is 16 hours, and it is metabolized in the liver.
  • The cure rate is close to 100% with a 2-day course.

Albendazole

  • Albendazole is an alternative to ivermectin for acute and chronic strongyloidiasis.
  • Albendazole has a high-affinity for binding free beta-tubulin in the parasite's cells and inhibiting tubulin polymerization, resulting in loss of cytoplasmic microtubules and decreasing ATP production in the worm which results in energy depletion by inhibiting glucose uptake, immobilization, then causing death.
  • Albendazole should be administered with high-dose glucocorticoids and anticonvulsants to avoid a central nervous system inflammatory response.

Mebendazole

  • Mebendazole has variable efficacy against strongyloidiasis.
  • This agent inhibits microtubule formation and causes worm glucose depletion and is available in the chewable form for pediatric use.

Enhancing Healthcare Team Outcomes

The diagnosis and management of Strongyloides infection is done with a multidisciplinary team that includes an infectious disease expert, gastroenterologist, emergency department physician and pharmacist. The key is to get rid of all larvae with ivermectin. Once discharged, the patients need to follow up by the nurse practitioner and primary physician to ensure that all body fluids have no larvae. Patients also need to be educated about hand washing and maintaining personal hygiene. For those with a simple infection of the GI tract, the outcomes are good but in patients with multiple organ infestation, the prognosis guarded.[11][12]


References

[1] Barroso M,Salvador F,Sánchez-Montalvá A,Bosch-Nicolau P,Molina I, Strongyloides stercoralis infection: A systematic review of endemic cases in Spain. PLoS neglected tropical diseases. 2019 Mar;     [PubMed PMID: 30860995]
[2] Bourée P,Usubillaga R,Viard JP,Slama L,Salmon D, [Strongyloidiasis, a sexually transmitted disease]. Presse medicale (Paris, France : 1983). 2019 Mar 7;     [PubMed PMID: 30853289]
[3] Camargo JF,Simkins J,Anjan S,Guerra G,Vianna R,Salama S,Albright C,Shipman E,Montoya J,Morris MI,Abbo LM, Implementation of a Strongyloides screening strategy in solid organ transplant donors and recipients. Clinical transplantation. 2019 Feb 17;     [PubMed PMID: 30773692]
[4] Kaya F,İnkaya AÇ,Ertenli Aİ,Abbasoğlu O,Aksoy S,Akyön Yılmaz Y,Ergüven S, The investigation of Strongyloides stercoralis seroprevalence in immunosupressed patients in Turkey Turkish journal of medical sciences. 2019 Feb 11;     [PubMed PMID: 30761833]
[5] Greenaway C,Castelli F, Migration Medicine. Infectious disease clinics of North America. 2019 Mar;     [PubMed PMID: 30712766]
[6] Krolewiecki A,Nutman TB, Strongyloidiasis: A Neglected Tropical Disease. Infectious disease clinics of North America. 2019 Mar;     [PubMed PMID: 30712758]
[7] Mazigo HD, Strongyloidiasis and schistosomiasis: lessons from migrants' data. The Lancet. Global health. 2019 Feb;     [PubMed PMID: 30683227]
[8] Asundi A,Beliavsky A,Liu XJ,Akaberi A,Schwarzer G,Bisoffi Z,Requena-Méndez A,Shrier I,Greenaway C, Prevalence of strongyloidiasis and schistosomiasis among migrants: a systematic review and meta-analysis. The Lancet. Global health. 2019 Feb;     [PubMed PMID: 30683241]
[9] Agbata EN,Morton RL,Bisoffi Z,Bottieau E,Greenaway C,Biggs BA,Montero N,Tran A,Rowbotham N,Arevalo-Rodriguez I,Myran DT,Noori T,Alonso-Coello P,Pottie K,Requena-Méndez A, Effectiveness of Screening and Treatment Approaches for Schistosomiasis and Strongyloidiasis in Newly-Arrived Migrants from Endemic Countries in the EU/EEA: A Systematic Review. International journal of environmental research and public health. 2018 Dec 20;     [PubMed PMID: 30577567]
[10] Page W,Judd JA,Bradbury RS, The Unique Life Cycle of Strongyloides stercoralis and Implications for Public Health Action. Tropical medicine and infectious disease. 2018 May 25;     [PubMed PMID: 30274449]
[11] Wołyniec W,Sulima M,Renke M,Dębska-Ślizień A, Parasitic Infections Associated with Unfavourable Outcomes in Transplant Recipients. Medicina (Kaunas, Lithuania). 2018 May 1;     [PubMed PMID: 30344258]
[12] Mileo Bacelar Guerreiro F,Tavares Sodré C,Brandão Pavan L,Feijó Barroso P,Carvalho Quintella D,Cuzzi T,Ramos-E-Silva M, Disseminated Strongyloidiasis. Acta dermatovenerologica Croatica : ADC. 2018 Dec;     [PubMed PMID: 30665485]