Can One Still Have Leptospirosis Despite Negative Test Results?

my dad did a test for leptospirosis a week after exposure to contaminated water, the result is negative. I have read articles saying that incubation period of the bacteria is up to 3 weeks. Is it possible to become positive even if the first test is negative? 2 or 3 weeks after exposure, my dad got fever, headache, muscle pain, swollen ankle (I dont know if it s because of his gout. his uric acid result is at 420). He said that it is just flu. He had his urine test recently, color: yellow orange. transparency: slightly turbid. reaction: acidic ph 6.0. specific gravity: 1.030. sugar: negative. albumin: trace. RBC: 4-6/HPF. PUS CELL: 1-3/HPF. CAST: NONE FOUND. crystals: amorphous urates few. epithelial cells: rare. mucous threads: +++. bacteria: rare. Can this urine test result determine if he has leptospirosis?? Can this urine test result determine of his kidney is fine? What does 4-6 /hpf mean? thank you very much for your answer.