Eating food from a street vendor with dry cough, fever, weakness, and malnutrition. Which helminth infection is likely?

• A. Hookworm infection
• B. Trichinellosis
• C. Giardiasis
• D. Ascariasis

Answer: (D)

Ascaris lumbricoides infection is acquired by swallowing eggs that contaminate food or hands in areas with poor sanitation. Once the eggs hatch in the intestine, larvae travel through the bloodstream to the lungs, where they cause a transient pneumonitis that brings about dry cough and fever (the migratory lung phase). The larvae then migrate back to the gut to mature into adults, which can lead to a high parasite load and interfere with nutrient absorption, producing weakness and malnutrition. In a person with exposure to street-vended food in settings with inadequate sanitation, this fecal-oral transmission is a common route, and the combination of respiratory symptoms during the life cycle and consequent nutritional impact fits ascariasis well.

Other helminths don’t fit as neatly. Hookworms also migrate through the lungs and can cause a cough, but they primarily cause chronic iron-deficiency anemia from intestinal blood loss rather than prominent malnutrition. Trichinellosis comes from undercooked meat and presents with fever and muscle pain rather than a pulmonary phase leading to malnutrition. Giardiasis is a protozoan infection causing diarrhea and malabsorption, not a helminth and not associated with a pulmonary migratory phase.