Given symptoms of diarrhea and weight loss, what is the likely diagnosis?

The diagnosis of roundworms or tapeworms is supported by the symptoms of diarrhea and weight loss, which are common indicators of intestinal parasitic infections. These parasites often disrupt the normal functioning of the gastrointestinal tract, leading to malabsorption of nutrients and subsequent weight loss. Diarrhea can result from the irritation and inflammation caused by the presence of these worms in the gut.

In contrast, the other options do not align with the presented symptoms. Seizures are neurological events and would typically not cause diarrhea or weight loss directly. Aspergillosis is a fungal infection that primarily affects the respiratory system and does not usually present with gastrointestinal symptoms like those described. The "None of the above" option is invalid because the symptoms do point towards a specific diagnosis, supporting the conclusion that roundworms or tapeworms are the most likely cause.