 Rats that live their entire lives indoors usually are able to avoid disease @-@ causing bacteria such as Salmonella and Pseudomonas aeruginosa ; the latter is absent in treated water . They may also more easily avoid vectors like cockroaches , beetles , and fleas which are essential for the spread of endemic typhus and intestinal parasites like the Rat tapeworm . Additionally , pet or laboratory rats enjoy the intrinsic benefits of having a consistent and well @-@ balanced diet , along with access to medical care . 
