I thought I'd post this question here rather than just ask a friend because someone else may need this information as well.
How do you determine the correct classifier/measure word (量词) for a compound noun?
For example, I work in computer security, so I need to talk about various forms of malicious software including what we call "worms", which in Chinese is 蠕虫病毒. 蠕虫 is just the animal, a worm, and 病毒 means "virus" both in the biological and computer senses. The classifier for the animal is 条 because it is something long and skinny, like a rope. The classifier for a virus is 种, but I am not sure which classifier to use with 蠕虫病毒. I would think it would be 种, because 蠕虫病毒 is a type of 病毒, but I wanted to ask a native speaker just to be sure.
Can you give a general rule for determining the correct classifier for a compound noun? It is always based on the last word?