How do humans acquire infections with Diphyllobothrium latum adult worms?

Diphyllobothrium latum, commonly known as the fish tapeworm, is acquired by humans primarily through the consumption of raw or undercooked freshwater fish. The lifecycle of this parasite involves various hosts, including copepods and fish, where they develop into their infectious larval stages. When humans eat contaminated fish, the larvae can then develop into adult worms within the human intestine.

As the chosen answer highlights, the ingestion of raw freshwater fish is the primary means of infection. This method allows the larvae to bypass the initial developmental stages in other hosts, directly entering the human body where they can thrive and cause infection. Understanding this lifecycle is crucial for preventing infection, emphasizing the importance of proper fish preparation and cooking practices.