Many infectious diseases have similar signs and symptoms. Samples of body fluid can help in the diagnosis of the particular microbe that's causing the illness. These methods include blood tests, urine tests, throat swabs, stool sample, spinal tap. This helps the doctor to treat the disease. Knowing what type of germ causing the illness makes easier for the doctor to choose an appropriate treatment. Antibiotics, Antivirals, Antifungals, Anti-parasites are used for medications.