This is the definitive, direct test for diagnosing filariasis (the parasitic infection that can lead to lymphedema). This test involves an expert microscopic examination of your blood smear to look for the actual microfilariae (larval worms). Because these parasites are most active in the blood at night, your sample is ideally collected between 10 PM and 2 AM. A simple blood draw at the right time provides the direct, visual evidence your doctor needs to confirm this specific parasitic infection and get you the correct anti-parasitic treatment.