COLONIC STRONGYLOIDES STERCORALIS INFECTION

Strongyloides stercoralis is a nematode infection which predominantly involves the small bowel. Spillover infection to the colon does occur, but is uncommon and is usually associated with an immunocompromised host. Individuals with infection confined to the intestinal tract are often asymptomatic but may have abdominal pain, weight loss, diarrhea, and other nonspecific complaints. In such cases the only sign of infection is an increased peripheral blood eosinophil count but should not be relied upon.Strongyloidiasis is endemic in rural areas of tropical and subtropical regions; in these areas, the overall regional prevalence may exceed 25 percent. In addition, strongyloidiasis occurs sporadically in temperate areas such as North America, southern Europe, Japan, and Australia. An estimated 30–100 million people are infected worldwide; precise data on prevalence

Strongyloides stercoralis is a nematode infection which predominantly involves the small bowel. Spillover infection to the colon does occur, but is uncommon and is usually associated with an immunocompromised host. Individuals with infection confined to the intestinal tract are often asymptomatic but may have abdominal pain, weight loss, diarrhea, and other nonspecific complaints. In such cases the only sign of infection is an increased peripheral blood eosinophil count but should not be relied upon.Strongyloidiasis is endemic in rural areas of tropical and subtropical regions; in these areas, the overall regional prevalence may exceed 25 percent. In addition, strongyloidiasis occurs sporadically in temperate areas such as North America, southern Europe, Japan, and Australia. An estimated 30-100 million people are infected worldwide; precise data on prevalence are unknown in endemic countries (WHO) (1,2). Strongyloidiasis is transmitted through direct penetration of human skin by infective larvae when in contact with soil; walking barefoot is therefore a major risk factor for acquiring the infection. Strongyloides spp. larvae penetrate the human host and reach the intestine where they mature into adults and produce eggs; the eggs hatch in the gut lumen and yield larvae that are evacuated in faeces. The peculiarity of this worm is that some larvae are not excreted but reinvade the intestine or perianal skin to perpetuate the infection (-autoinfection cycle‖).(2) The larvae mature into adult worms that burrow into the mucosa of the duodenum and jejunum. Adult worms may live for up to five years. In the apparent absence of male adults, pathogenic adult females produce eggs, from which noninfectious larvae (rhabditiform larvae) develop within the lumen of the gastrointestinal (GI) tract. The rhabditiform larvae (picture 1) are generally passed in the stool. The duration of the cycle from dermal penetration of filariform larvae to appearance of rhabditiform larvae in the stool is approximately three to four weeks. (2,3). Her ABD USS showed Mild hepatomegaly with bright hepatic parenchyma likely representing fatty hepatomegaly, Suspected spastic colon. A CT scan of the abdomen and pelvis with contrast was unremarkable. The patient was discharged home and given appointment to Gastroenterology clinic. Gastroscopy and colonoscopy was advised. Gastroscopy showed multiple erythematous nodularities in the body of the stomach, Biopsies showed Moderate to marked chronic active gastritis and Giemsa special stain showed numerous H. pylori organisms (3+). Considered for testing prior to being initiated on any immunosuppressive therapy, particularly corticosteroids.

Screening: Physicians should be particularly diligent to consider Strongyloides in patients:
Who are on or about to begin corticosteroid therapy or other immunosuppressants Known to have HTLV-1 infection With hematologic malignancies including leukemias and lymphomas Who have had or are being considered for organ transplantation With persistent peripheral or unexplained eosinophilia With recent or remote travel histories to endemic areas.
Of note, though persons with HIV/AIDS can have disseminated strongyloidiasis or hyperinfection syndrome, observational studies have not shown an increased risk in this population.

Prevention & Control(5,6):
The best way to prevent Strongyloides infection is to wear shoes when you are walking on soil, and to avoid contact with fecal matter or sewage. Proper sewage disposal and fecal management are keys to prevention.
Furthermore, if you believe that you may be infected, the best way to prevent severe disease is to be tested and, if found to be positive for disease, treated.

You should discuss testing with your doctor if you are:
Taking steroids or other immunosuppressive therapies About to start taking steroids or other immunosuppressive therapies A veteran who served in the South Pacific or Southeast Asia Infected with Human T-cell Lymphotropic Virus-1 (HTLV-1) Diagnosed with cancer Going to donate or receive organ transplants

Conclusion:-
Stool microscopy should still be routinely performed, as it is the gold standard for diagnosis. It can take 3-4 weeks for larvae to appear in the stool after dermal penetration (we did Stool analysis twice in this patient on 16/10/2019 and 04/12/2019 post treatment with Albendazole given for 7 days and showed no more Strongyloides infection) Serological testing, which consists of an enzyme linked immunosorbent assay to detect IgG to a filariform larval antigen, is generally considered to be a superior investigation (5). Commercially available assays have a sensitivity between 83% and 89% and a specificity of 97.2%.15 In the presence of other helminthic infections there is a risk of a false positive result owing to cross reactivity. This is particularly true for filariasis, where up to 60% of patients may have false positive S stercoralis serology Repeat serological testing after treatment seems to be the best way to test for cure. If the antibody titer has decreased at 6-12 months after treatment this is indicative of eradication of the parasite.37 It has been suggested that a posttreatment to pre-treatment titre ratio of <0.6 is a good indicator of treatment success (2,4,7) Unlike most other intestinal parasite infections, strongyloidiasis may be lifelong problem.