Complex sentence: The CDC had found that eight of the people sickened had eaten cantaloupes purchased from a warehouse club and they used the purchase records to figure out that the food in common was cantaloupes, and they had come from the same Guatemalan farm.
Split into simpler sentences: The CDC had found that eight of the people who got sick had eaten cantaloupes purchased from a warehouse club. Agency officials said they used data drawn from membership card records, in part, to figure out that the cantaloupes had come from the same Guatemalan farm.