P.G. Koehler and J.L. Castner 2 Fleas and ticks are the most important external parasites of pets, livestock and humans. Both fleas and ticks are very abundant, have irritating bites and can transmit disease.
Fleas can transmit tapeworms.
Ticks can transmit Lyme disease, Rocky Mountain spotted fever and relapsing fever. Lyme disease is transmitted in the Northern United States by the deer tick and in the Southern United States by the black legged, Gulf coast, American dog, lone star and relapsing fever tick. Lone star and American dog ticks can cause tick paralysis. The cat flea is the most important flea species in the United States and attacks both cats and dogs. The flea inserts its mouthparts in the skin, injects saliva and sucks blood.