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What caused this 95-year-old female farmer in rural Japan to develop abdominal symptoms that persisted for months?

Upon arriving at the emergency department, the patient told clinicians that she did not drink alcohol. She was taking 8 mg of prednisolone daily, as well as lansoprazole (Prevacid). Her medical history included a diagnosis of bullous pemphigoid 8 months previously; this had been treated with prednisolone at an initial dose of 15 mg daily, explained Mitsuyo Kinjo, MD, MPH, of Okinawa Chubu Hospital in Uruma City, Okinawa, Japan, and colleagues in .

The patient said her ongoing symptoms began 3 months previously with loss of appetite and intermittent abdominal bloating, diarrhea that developed 2 weeks previously, and abdominal pain for the past 24 hours. She also reported one episode of shortness of breath during physical activity about 2 weeks prior to her presentation at hospital.

She had not been feverish, and had no cough, wheeze, nausea, or vomiting; she had not passed any blood in her stool, which she said appeared to be normal in color and smell.

The patient's vital signs included a temperature of 37.7°C (99.9°F), blood pressure of 110/56 mm Hg, heart rate of 125/min, and an oxygen saturation of 95% on room air.

On physical examination, her lungs were clear to auscultation, and she had widespread abdominal tenderness on palpation, without rebound. Clinicians noted purpuric macules and small thumbprint-like patches on the skin of her upper abdomen and central chest.

Laboratory test results included:

• White blood cell count: 13,600/μL (89.9% neutrophils, 0.2% eosinophils)
• Hemoglobin: 10.9 g/dL
• Serum sodium: 130 mEq/L (reference 138-145 mEq/L)
• Creatinine: 0.82 mg/dL
• Aspartate aminotransferase: 55 U/L (reference 13-30 U/L)
• Alanine aminotransferase: 54 U/L (reference 7-23 U/L)
• Erythrocyte sedimentation rate: 31 mm/h (reference 3-15 mm/h)

Platelet count and prothrombin time were normal. Abdominal CT scan with intravenous contrast showed evidence of inflammation of the small intestine.

Clinicians admitted the patient to the hospital, where she received treatment with ampicillin/sulbactam; subsequently, her blood cultures grew Klebsiella pneumoniae.

Making the Diagnosis

The team did not order an activated protein C resistance panel for gastrointestinal pathogens, which they said would have been useful if she had acute, rather than chronic, diarrhea.

Similarly, they said they did not test her anti-neutrophil cytoplasmic antibody level since she did not have typical signs of ANCA-associated vasculitis, and did not order a fungal culture, given that purpura do not tend to occur in the setting of a fungal infection.

Based on the fact that she was immunosuppressed and worked on a farm, and her development of chronic abdominal symptoms, purpuric macules and patches on her abdomen, and bacteremia, clinicians checked her stool for ova and parasites.

Strongyloides stercoralis larvae were detected in the patient's stool and induced sputum, which led to the patient's diagnosis of disseminated strongyloidiasis. She received 9 mg of oral ivermectin daily for 14 days. Results of antibody testing for human T-cell leukemia virus type 1 (HTLV-1) were negative.

However, the patient's mental status worsened. On hospital day 10, clinicians ordered a lumbar puncture, which detected Enterococcus faecium in the cerebrospinal fluid culture. As a result, antibiotic treatment was changed to vancomycin and meropenem. She developed upper gastrointestinal bleeding and died 4 weeks after hospital admission.

Discussion

Kinjo and colleagues noted that strongyloidiasis is caused by the intestinal helminth S. stercoralis; while about 370 million people are affected worldwide, it is most common in tropical and subtropical regions, where its prevalence is between 10% and 40%.

"In the U.S., strongyloidiasis is most commonly diagnosed in people who have immigrated or in travelers returning from high-prevalence regions; however, S. stercoralis is endemic in the southeastern U.S.," they wrote.

Infection tends to be associated with walking barefoot on soil that contains filariform larvae, which then penetrate the skin, they explained. The larvae then travel through the venous circulation to the lungs, and up the trachea to the oropharynx where they are ingested.

Then, they where they produce eggs; the eggs develop into rhabditiform larvae, which are excreted in stool. Some of the larvae mature to become filariform larvae, which reinfect the host by puncturing the wall of the colon or perianal skin. This autoinfection causes persistent S. stercoralis infection.

Left untreated, acute strongyloidiasis becomes chronic, Kinjo's team explained, when the autoinfection process spreads S. stercoralis via the gastrointestinal tract, peritoneum, and lungs, organs that each play a direct role in the life cycle of S. stercoralis.

Among patients with a normal immune response, chronic strongyloidiasis may cause no symptoms or result in minor abdominal symptoms, dermatologic manifestations, and eosinophilia percentages from 5% to 15%.

Hyperinfection syndrome is characterized by an accelerated rate of autoinfection, the authors noted, and tends to occur when adaptive immunity of patients with chronic strongyloidiasis is compromised "due to corticosteroids, HTLV-1, chemotherapy, solid organ transplant, or malnutrition."

Patients with hyperinfection can develop disseminated strongyloidiasis when the S. stercoralis infection spreads to "organs outside the typical autoinfection cycle, such as the skin, brain, heart, liver, gallbladder, pancreas, kidneys, ovaries, and skeletal muscle," Kinjo and colleagues wrote.

These dually affected patients may develop small bowel obstruction due to the large volume of intestinal larvae, "and gastrointestinal bleeding from intestinal invasion," they noted. Additional gastrointestinal symptoms may occur, including abdominal pain, diarrhea, constipation, nausea, and vomiting. The lungs may also be affected, causing symptoms such as cough, wheezing, dyspnea, and hemorrhagic pneumonitis.

As in this patient, thumbprint-shaped purpura may develop around the umbilicus, if the larvae invade the umbilical vein; this is a of disseminated strongyloidiasis.

Patients with hyperinfection syndrome and disseminated strongyloidiasis may not develop eosinophilia, the authors said, but they will have abundant larvae evident "on examination of stool, sputum, and pleural or cerebrospinal fluid."

There are no evidence-based guidelines to direct treatment of severe strongyloidiasis, they noted. Daily treatment with ivermectin (200 μg/kg) is often used for at least 2 weeks "and until stool examination is negative for 2 weeks."

Even in treated patients, hyperinfection syndrome and disseminated strongyloidiasis has been associated with of 69% to 85%. Deaths are generally "due to complications such as peritonitis, respiratory failure, meningitis, and bacteremia caused by enteric bacterial translocation that accompanies larval invasion of the intestines," Kinjo and team explained.

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