Echinococcus is a genus of tapeworms that can infect humans and animals, primarily through contact with infected dogs or wild canines. The most common species, Echinococcus granulosus, causes hydatid disease, where cysts form in organs like the liver and lungs. Transmission occurs when eggs are ingested, often through contaminated food or water. Symptoms may not appear for years, but can include abdominal pain and organ dysfunction. Treatment typically involves surgery or medication to remove or shrink the cysts, highlighting the importance of proper hygiene and animal control to prevent infection.