The organism which spread the disease from an infected to a healthy person is called

The right answer is Vector

Vectors are living organisms that can transmit infectious diseases between humans or from animals to humans. Many of these vectors are bloodsucking insects, which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later inject it into a new host during their subsequent blood meal. Mosquitoes are the best known disease vector. Others include ticks, flies, sand flies, fleas, triatomine bugs and some freshwater aquatic snails.