Who is in a symbiotic relationship with a rat?

Fleas could be in a symbiotic relationship with a rat. This would be known as parasitism because the flea is drinking the blood from the rat when the rat is losing blood to survive. (: 

The truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey

Maybe haha