A lymphatic virus was a type of virus that attacked the lymphatic system.
In 2152, Dr. Phlox detected a lymphatic virus aboard Enterprise that he determined likely came aboard with the deuterium canisters from the mining colony of Tessic's species. Phlox recommended to Acting Captain Tucker that he begin inoculating the entire crew, though it would cause side effects such as nausea and diarrhea. (ENT: "The Seventh")