Most patients with rebound fever have an increased total white blood cell count, up to 1.5-2×1010/L, and increased neutrophils. Platelets and clotting time are mostly normal, but may be abnormal in severe cases. Serum alanine aminotransferase is often elevated, and serum bilirubin may be increased. There is a small amount of protein, tubular type and red and white blood cells in the urine. Cerebrospinal fluid pressure is slightly increased, and protein and lymphocytes are mildly increased. Spirochetes may be found in blood or bone marrow smear stained for microscopy or dark field examination during the febrile period. What are the prevention methods for regression fever? 1. Focus on cutting off the transmission route and controlling the source of infection. 2.Rational diet. More intake of high fiber and fresh vegetables and fruits, balanced nutrition, including protein, sugar, fat, vitamins, trace elements and dietary fiber and other essential nutrients, meat and vegetables, food variety diversification, give full play to the complementary role of nutrients between foods. 3, the prevention of tick-borne regression fever should pay attention to the isolation of patients, and thorough extermination of lice. 4, tick-borne regression fever should be exterminated ticks, rodents. Tick can be sprayed with malathion or dichlorvos, and rodent can be poisoned with drugs and trapped and beaten. 5, in the epidemic area when carrying out tasks should pay attention to personal protection, if necessary, oral doxycycline or tetracycline to prevent morbidity. 6.After the fever has subsided, observation should continue for 15 days. Contact person should also be thoroughly exterminated lice, if necessary, oral doxycycline 100mg to prevent disease.