Helminths Causing Unintentional Weight Loss
Enterobius vermicularis (pinworm) is the primary helminth documented to cause weight loss as a clinical manifestation, though this occurs alongside other gastrointestinal symptoms. 1, 2
Specific Helminths Associated with Weight Loss
Enterobius vermicularis (Pinworm)
- Weight loss is explicitly listed as a gastrointestinal symptom associated with enterobiasis, occurring alongside diarrhea, abdominal pain, and irritability 1, 2
- Most commonly affects children aged 5-14 years worldwide 2
- Transmitted via fecal-oral route with a prepatent period of 2-4 weeks 1, 2
- Diagnosis is made using the "sellotape test" (adhesive tape applied to perianal skin, examined microscopically for ova) 1, 2
- Treatment: Albendazole 400 mg or mebendazole 100 mg as single dose, repeated in 2 weeks 1, 2, 3
Trichinella species (Trichinellosis)
- Chronic infection can present with weight loss as part of the systemic manifestations 1
- Occurs in outbreaks, particularly in Eastern Europe, Russia, Argentina, and China 1
- Transmitted through consumption of raw or undercooked meat (usually pork) 1
- Presents with fever, periorbital edema, myalgia, and gastrointestinal symptoms (upper abdominal pain, vomiting, diarrhea) 1
Blastomyces species (Blastomycosis)
- Chronic blastomycosis presents with cough, hemoptysis, fever, and weight loss 1
- Note: This is a fungal pathogen, not a true helminth, but included in eosinophilia guidelines due to similar clinical presentations 1
Important Clinical Context
Indirect Weight Loss Mechanisms
Several helminths cause weight loss through secondary mechanisms rather than as a direct symptom:
- Hookworm (Ancylostoma duodenale/Necator americanus): Heavy infections cause severe anemia, particularly in children, which can lead to growth failure and malnutrition 1, 4, 5
- Strongyloides stercoralis: Causes abdominal bloating and diarrhea that may contribute to malnutrition 1
- Trichuris trichiura (Whipworm): Heavy infections associated with growth failure and malnutrition in endemic populations 4
Key Pathophysiologic Mechanism
Anorexia is likely the most important mechanism by which intestinal nematodes cause weight loss and inhibit growth, particularly in tropical populations on marginal diets 4. This decreased intake of all nutrients has the greatest magnitude of effect on nutritional status 4.
Clinical Pitfalls
- Most helminth infections are asymptomatic 1, so weight loss when present suggests heavy infection burden or chronic disease
- Weight loss is rarely the sole presenting symptom; look for accompanying gastrointestinal symptoms (diarrhea, abdominal pain), eosinophilia, or systemic manifestations 1
- In returning travelers or migrants with unexplained weight loss and eosinophilia, obtain concentrated stool microscopy (three samples), strongyloides serology, and schistosomiasis serology based on geographic exposure 1