Elephantiasis

An absolutely sure diagnosis (called a definitive diagnosis) of filarial disease requires that the actual nematode be identified within body tissue or fluid from an individual experiencing symptoms of infection. This is not actually easy to accomplish, as the lymph nodes and vessels in which the nematodes dwell are not easy to access. Sometimes, blood samples can be examined to reveal the presence of the microfilariae. Interestingly enough, because of the nocturnal periodicity of these microfilariae, the patient's blood must be drawn at night to increase the likelihood of the sample actually containing the parasite.

Many times, however, diagnosis is less sure, and relies on the patient's history of having been in an area where exposure to the nematode could have occurred, along with the appropriate symptoms, and the presence in the patient's blood of certain immune cells which could support the diagnosis of filarial disease.