Pulmonary Stage in Parasitic Infections

The pulmonary stage occurs when parasitic larvae migrate through the lungs as part of their life cycle.

Organism Analysis:

• Ascaris lumbricoides: Larvae migrate from the intestine to the lungs, then are swallowed back to mature in the intestine. This involves a distinct pulmonary phase, often causing Loeffler's syndrome.
• Strongyloides stercoralis: Larvae penetrate the skin, travel through circulation to the lungs, migrate into the alveoli, ascend the respiratory tree, and are swallowed to reach the intestine. This includes a pulmonary stage.
• Onchocerca volvulus: This parasite primarily affects the skin and subcutaneous tissues. Its life cycle does not typically involve a significant larval migration through the lungs.

Identifying Infections with Pulmonary Stage:

Based on the life cycle analysis:

• Ascaris lumbricoides (1) has a pulmonary stage.
• Strongyloides stercoralis (2) has a pulmonary stage.
• Onchocerca volvulus (3) does not typically have a pulmonary stage.

Therefore, infections 1 and 2 exhibit the pulmonary stage.