In this week’s Case Record of the Massachusetts General Hospital, a 59-year-old man was admitted to the hospital because of 9 months of abdominal pain, vomiting, and weight loss. He was born in a Caribbean country and had been treated for intestinal strongyloidiasis years earlier. A diagnosis of celiac disease had recently been made.
S. stercoralis is endemic in the tropics and subtropics; in the United States, it is often diagnosed in recent immigrants or U.S. military personnel who have recently returned to the United States.
• How does celiac disease present and how is it diagnosed?
Symptoms of celiac disease may range from fatigue and no gastrointestinal symptoms to profuse diarrhea with metabolic disturbances. Classic gastrointestinal symptoms of celiac disease include those of malabsorption, such as steatorrhea, flatulence, and abdominal discomfort. Dermatologic manifestations include eczema and dermatitis herpetiformis. Serologic testing is important in the diagnosis of celiac disease; the sensitivity and specificity of IgA antibodies to tissue transglutaminase are greater than 94% in the absence of IgA deficiency, which can occur in up to 2% of persons with celiac disease. HLA testing could be considered if clinical suspicion for celiac disease is high despite negative serologic testing. A biopsy specimen of the small bowel is a cornerstone of the diagnosis of celiac disease and typically reveals villous atrophy, crypt hyperplasia, increased intraepithelial lymphocytes, or a combination of these.
• What is the means of transmission and usual presentation of Strongyloides infection?
S. stercoralis is endemic in the tropics and subtropics. The life cycle starts in the soil, where rhabditiform larvae develop into infectious filariform larvae that penetrate the skin, enter the systemic circulation, penetrate the alveolar spaces, are coughed up and swallowed, and enter the gastrointestinal tract. Most cases of strongyloidiasis are asymptomatic or cause only mild symptoms. An acute manifestation is duodenitis, which causes abdominal pain, nausea, vomiting, diarrhea, or a combination of these. Ground itch is a severely pruritic cutaneous manifestation of the disease. Dermal migration of the larvae may result in urticaria and areas of serpiginous erythema, known as larva currens. Pulmonary manifestations include dry cough and asthmalike symptoms.
Morning Report Questions
Q: What are the manifestations of Strongyloides hyperinfection syndrome?
A: Hyperinfection with S. stercoralis is the accumulation of a large burden of parasites during the autoinfection cycle. Autoinfection typically occurs in immunocompromised patients, where rhabditiform larvae mature into filariform larvae in the gut and penetrate through the wall of the large intestine or the perianal skin into the systemic circulation. Parasites accumulate primarily in the colon. Eosinophilia may be absent. Mortality associated with strongyloides hyperinfection is estimated to exceed 10%. Localization in the colon and association with severe inflammation, ulceration, and burrowing beyond the mucosa are uncommon in uncomplicated infection and suggest autoinfection and hyperinfection. The presence of filariform larvae and rhabditiform larvae in the stool is a clue that autoinfection has occurred, and a high parasite burden suggests hyperinfection.
Q: Why is hyperinfection with strongyloides less common in patients infected with HIV than in those infected with HTLV-I?
A: In patients infected with HTLV-I, the Th1 program is enhanced, and the Th2 response is blunted, resulting in impaired ability to defend against helminths. In HIV infection, loss of CD4+ T cells can affect both the Th1 and the Th2 responses, and in some patients a Th2 response may even predominate. As a result, the Th2 response is not as disproportionately blunted in patients with advanced HIV infection as it is in patients with HTLV-I infection.