Filariasis is a prominent cause of funiculoepididymitis, periorchitis and hydrocele in Puerto Rico. However, the high incidence of these lesions is related to multiple etiological factors rather than to filarial infection alone. The true proportion of filarial lesions cannot be established by the available methods.
In autopsies of Puerto Rican males over 10 years of age, filariae were found in the intrascrotal organs in 3.9 per cent and in all locations of the body in 4.4 per cent, an incidence similar to that of microfilaremia in comparable groups. For the same age groups, filariae were detected in 14.3 per cent of the surgical specimens of intrascrotal organs. The true incidence of filariasis was probably somewhat higher. Filarial lesions occurred at all ages, with predominance in the older age groups.
Endemic filarial lesions of the intrascrotal organs varied greatly in type and in severity. There were asymptomatic foci simulating a carrier state and mild chronic lesions often clinically undistinguishable from essential hydrocele except for the presence of inflammatory changes of the tunica in the operative specimens. There were also severe lesions, usually presenting mixed or complicating etiological factors such as thrombophlebitis, bacterial superinfection or testicular damage. No secondary tissue changes pathognomonic of filariasis were found. A clearing method for the diagnostic visualization of filarial worms in tissue specimens is described.
Clinical manifestations of endemic filariasis frequently occurred in the absence of diagnostic data in the history, laboratory examinations and excised tissues. In considering the relation between filarial infection and filarial disease, support was given to the three stage concept of filariasis suggested by Manson-Bahr.