ʻO ka maʻi hanu syncytial kahi maʻi RNA no ka genus Pneumovirus, ʻohana Pneumovirinae. Hoʻolaha nui ʻia e ka hoʻouna ʻana i ka droplet, a ʻo ka hoʻopili pololei ʻana i ka manamana lima i haumia ʻia e ka maʻi respiratory syncytial me ka nasal mucosa a me ka ocular mucous kahi ala nui o ka lawe ʻana. ʻO ka maʻi hanu syncytial ke kumu o ka pneumonia. I ka wā incubation, ʻo ka respiratory syncytial virus ka mea e hoʻoulu ai i ke kuni, ka ihu e holo ana, ka ʻū, a i kekahi manawa hoʻi. Hiki ke loaʻa ka maʻi maʻi respiratory syncytial ma waena o nā heluna kanaka o kēlā me kēia makahiki, kahi e loaʻa ai ka maʻi o ka poʻe ʻelemakule a me ka poʻe me nā māmā ʻeha, ka puʻuwai a i ʻole ka ʻōnaehana pale.