Arenaviruses are a group of viruses that primarily infect rodents and can be transmitted to humans. They are known for their unique structure, which includes a segmented RNA genome. Some arenaviruses can cause diseases in humans, such as Lassa fever and Argentine hemorrhagic fever, leading to severe symptoms and complications. These viruses are typically spread through contact with infected rodent excretions, such as urine or droppings, or through direct contact with an infected person's bodily fluids. Preventive measures include maintaining good hygiene and controlling rodent populations in areas where these viruses are prevalent.