How is lymphatic filariasis diagnosed?
The standard method for diagnosing active infection is the identification of microfilariae by microscopic examination. This is not always feasible because in most parts of the world, microfilariae are nocturnally periodic, which means that they only circulate in the blood at night. For this reason, the blood collection has to be done at night to coincide with the appearance of the microfilariae. Serologic techniques provide an alternative to microscopic detection of microfilariae for the diagnosis of lymphatic filariasis. Because lymphedema may develop many years after infection, lab tests are often negative with these patients.