Of all the individuals with lymphatic filariasis less than half appear clinically asymptomatic, though they have microfilariae circulating in their blood and yet all have hidden damage to their lymphatic (as evidenced by lymphoscintigraphy) and/or renal systems (microscopic heamaturia and/or proteinuria). It is clear that this state of asymptomatic microfilaraemia is associated with a highly down-regulated immune system, but it is as yet unclear how, when or even whether these individuals will progress to develop one of the more overt clinical manifestations of filarial disease.

A second asymptomatic 'presentation' exists in individuals previously termed 'endemic normals'; their infections are defined not by microfilaraemia but by the presence of parasite antigen in the blood (which will disappear after appropriate treatment). It has only recently been possible to recognize this group of patients, and both their clinical features and sequelae of infection remain to be defined.