| Abstract|| |
Infection with Strongyloides stercoralis, a human pathogenic roundworm, is common in tropical countries like India. Owing to its variable clinical presentation and irregular larval output in stool, it often remains neglected and underdiagnosed. Signs and symptoms are largely dependent on the immune status of the infected individual. Alteration in the host immunity due to chronic use of steroids can surge the number of parasites and cause hyperinfection syndrome. This can be catastrophic with a fatal outcome. Focus on early detection and treatment of the parasite in at-risk patients is imperative to reduce mortality. We summarize here an interesting case of hyper infection syndrome of strongyloidiasis with gangrenous bowel changes later progressing to burst abdomen.
Keywords: Acute abdomen, burst abdomen, hyperinfection, Strongyloides stercoralis
|How to cite this article:|
Singh K, Ganorkar S, Bhalekar S, Rao R. Hyperinfection with Strongyloides stercoralis presenting as acute abdomen in a patient on corticosteroid therapy: A case report. Indian J Pathol Microbiol 2021;64:831-3
|How to cite this URL:|
Singh K, Ganorkar S, Bhalekar S, Rao R. Hyperinfection with Strongyloides stercoralis presenting as acute abdomen in a patient on corticosteroid therapy: A case report. Indian J Pathol Microbiol [serial online] 2021 [cited 2022 Nov 28];64:831-3. Available from: https://www.ijpmonline.org/text.asp?2021/64/4/831/328686
| Introduction|| |
Strongyloides stercoralis (S. stercoralis) is a gastro-intestinal nematode parasite, prevalent in tropical and sub-tropical regions of Southeast Asia, Africa and South America. Immunocompetent individuals can host this helminth for many years without developing any significant clinical symptoms andmore than half of the infected patients remain asymptomatic. Although in a host with debilitated immunity, it can manifest as acute gastrointestinal discomfort, hyperinfection syndrome, or disseminated disease. This can be accompanied by pneumonia or Loffler's syndrome. Owing to the large rate of subclinical infection, the exact prevalence of strongyloidiasis worldwide remains underestimated. Incidence as less than 1% has been reported in the Indian population with a heavy parasitic infestation.
Hyperinfection syndrome, characterized by increased proliferation of the larvae and worsening of abdominal symptoms, has been seen in patients who are immunocompromised or on immunosuppressive therapy. This may lead to mortality if left undiagnosed and untreated.
Here, we report a case of a patient on corticosteroid therapy for mixed connective tissue disorder, who presented with acute abdomen and eventually succumbed to hyperinfection by S. stercoralis.
| Case Report|| |
A 36-year-old male, known case of mixed connective tissue disorder, on corticosteroid for over a year, presented to the surgery department with complaints of abdominal pain and distension for 8 days. On examination, the patient had digital gangrene. The serological test for HIV was negative. A computed tomography scan showed dilation of the jejunum and proximal bowel loops. Clinical diagnosis of acute small intestinal obstruction was rendered. He underwent exploratory laparotomy with resection anastomosis about 15 cm from duodenojejunal flexure and an 8-cm segment of jejunum was removed [Figure 1] which showed gangrenous changes on histology. However, there was no evidence of any parasite in the paraffin sections studied.
|Figure 1: Gross photograph of resected small bowel segment showing edematous and congested mucosal surface with blood tinged mucus|
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On post-operative day 7, the patient complained of pain at surgical site with signs of wound dehiscence of anterior abdominal wall (burst abdomen). Blood examination showed neutrophilic leukocytosis. Re-exploration laparotomy with ileostomy was performed in which anastomotic leak was detected and the anastomotic edges were sent for histopathology examination.
Hematoxylin-Eosin (H and E)-stained sections showed eggs and larvae of S. stercoralis located within the crypts of small intestinal mucosa [Figure 2]a and [Figure 2]b which were Periodic acid–Schiff (PAS) positive [Figure 2]c. The lamina propria showed dense mixed inflammatory infiltrate comprising lymphocytes, plasma cells, eosinophils and neutrophils. Superficial ulceration and cryptitis was also noted. Histopathological diagnosis of chronic inflammatory bowel disease secondary to parasitic infection by S. stercoralis was given. Subsequent stool examination for parasite was negative.
|Figure 2: (a) Photomicrograph showing small intestinal tissue with the presence of parasite within mucosal crypts (H and E stain, 100×).(b) Eggs (black arrow) and larvae with pointed tail (blue arrow) of S. stercoralis seen (H and E stain, 400×).(c) Parasitic larva showing PAS positivity (PAS special stain, 400×)|
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His wound swab culture showed growth of Klebsiella pneumoniae. Unfortunately, the patient went into sepsis with multiorgan failure and expired.
| Discussion|| |
S. stercoralis was first identified in 1876 by Normand, in feces of French soldiers suffering from diarrhea in Vietnam. Distributed worldwide, its occurrence is frequently linked to poor hygiene and sanitation. It is a soil-transmitted helminth with a unique yet intricate life cycle characterized by transdermal entry of the infective filariform larvae in humans which reach lungs, are coughed up and swallowed to arrive in the gut where it matures to its adult form. Eggs are laid by females, which yield rhabditiform larvae. These are either passed in stools or can metamorphose into filariform larvae and lead to an internal auto-infective cycle, causing persistence of the organism in the body.
Normal individuals are often asymptomatic or have vague pulmonary and gastrointestinal (GI) complaints. They often stay unevaluated. However, immuno compromised and immunosuppressed individuals including those who are malnourished, having underlying autoimmune disease, malignancy, HIV/human T-lymphotropic virus type 1 infected, or on steroid treatment are at increased risk of developing severe disease manifesting as hyperinfection and dissemination of the parasite to various organs.
Hyperinfection syndrome (HS) is attributed to the excess worm burden as a result of accelerated reproduction. The larvae disrupt the GI mucosa and enter the bloodstream, carrying with them the gut flora which can cause septicemia. Complications like infarction and intestinal perforation due to local venous thrombosis as well as GI bleeding from micro aneurysms in the mesenteric vessels have also been noted, similar to our case with gangrenous changes and anastomotic leakage being related to the presence of parasite in a small bowel. Hemorrhagic necrosis and vascular changes in intestine are attributed to mesenteric vein thrombosis or obliterative enteritis caused by the involvement of the intestinal vessels by the parasite., In our case, though we did not find any evidence of microthrombi or presence of parasites within vessels, the larval forms were found close to the mucosal capillaries. Underlying infection in the adjacent unresected bowel could have resulted in leakage at the anastomotic site along with wound dehiscence. Most patients with HS have disastrous clinical manifestations such as shock, disseminated intravascular coagulation, meningitis, renal failure and respiratory failure. Sometimes, patients present with an acute abdomen as in our case.
Mortality rates due to HS is found to be as high as 87%. A multicenter study of Strongyloides HS cases (n = 133) conducted by Geri et al. showed that 83.5% of the patients were receiving corticosteroid therapy with a median of 42 days of therapy before the onset of symptoms. In addition, though eosinophilia was seen in 70% of patients overall but was present in only 20% of the patients with HS. In our case too, the patient was on steroids and did not show peripheral eosinophilia.
Existing lab diagnosis is mainly stool examination for larvae but this has low sensitivity probably due to low larval output. In up to 70% of cases, single stool examination fails to detect larvae by use of conventional techniques. ELISA, though more sensitive, is available only at specialized centers and can show cross-reactivity with other helminths. Our patient also showed negative stool microscopy and definitive diagnosis was possible only on histopathology.
| Conclusion|| |
A high index of suspicion is required in patients belonging to endemic areas and especially those on long-term immunosuppressive medications. Emphasis on parasitic investigation prior to initiating steroid treatment may be useful in averting life-threatening HS.
It is imperative to note that the absence of eosinophilia and failure to detect larvae in a stool examination does not necessarily indicate the absence of the infection and serial stool examination should be considered in clinically suspicious cases. The nonspecific nature of clinical and radiological presentation along with the unrewarding diagnostic rate of single stool examination highlights the urgent need for new and improved diagnostic tools and biomarkers for early detection.
Clinicians and histopathologists need to be aware about this parasite with its different stages of development and its characteristic histological features to avoid missing the diagnosis.
Department of Surgery under Dr. S. Deolekar, Dr. D.Y. Patil Medical College and Hospital.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Department of Pathology, Dr. D.Y. Patil Medical College and Hospital, Sector 5, Nerul, Navi Mumbai - 400 706, Maharashtra
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]