For which disease is close contact with an infected human host the most important means of transmission?

For which disease is close contact with an infected human host the most important means of transmission?

• A. Trichomoniasis
• B. Toxoplasmosis
• C. Trichinosis
• D. Schistosomiasis

Answer: (A)

Understanding how a disease spreads helps identify why close contact with an infected person is the main route. Trichomoniasis is caused by the protozoan Trichomonas vaginalis and is transmitted almost entirely through sexual contact. The parasite colonizes the genital tract and is spread when there is intimate contact, so the most important means of transmission is direct, close interaction with an infected human host. Toxoplasmosis, by contrast, is primarily acquired from ingesting contaminated food or handling cat litter, not from casual person-to-person contact. Trichinosis comes from eating undercooked meat containing larvae, not from transmission between people. Schistosomiasis spreads via freshwater that contains cercariae released by snails, making environmental exposure the key route rather than direct human-to-human contact.

Understanding how a disease spreads helps identify why close contact with an infected person is the main route. Trichomoniasis is caused by the protozoan Trichomonas vaginalis and is transmitted almost entirely through sexual contact. The parasite colonizes the genital tract and is spread when there is intimate contact, so the most important means of transmission is direct, close interaction with an infected human host.

Toxoplasmosis, by contrast, is primarily acquired from ingesting contaminated food or handling cat litter, not from casual person-to-person contact. Trichinosis comes from eating undercooked meat containing larvae, not from transmission between people. Schistosomiasis spreads via freshwater that contains cercariae released by snails, making environmental exposure the key route rather than direct human-to-human contact.