Case 189. Onchocercosis (45 y-o F)
         
   
Excised subcutaneous nodule in the neck of a Mexican female
   
         
   
Key words : Onchocerca volvulus, river blindness, Oncocerca gutturosa
   
     
 
     
Female adults of Onchocerca volvulus are clustered in the subcutaneous tissue (HE, low power). Onchocercosis is endemic in the highland of central America, Arabian peninsula and tropical Africa, causing "river blindness" due to microfilaria invasion into the eye balls.   The uterus is filled with numerous microfilariae. The cuticles are thick, while the muscle layer is thin. Characteristic skin lesions in onchocercosis include scrotal elephantiasis and onchocercal dermatitis.
     
 
     
Reference case 189A
Onchocerca gutturosa infection (bovine onchocercosis) in the wrist of a 57 y-o female in Oita. Within eosinophilic granulomatous reaction, a helminth with a ridge-forming thick cuticle is observed. Zoonotic onchocercosis is a very rare occasion.
  Reference case 189A
The final host of O. gutturosa is the cow, and it is transmitted by gnat. A total of six kinds of zoonotic onchocercosis are seen in Japan. The worm is featured by the ridge-forming thick cuticle and well-developed muscle layer. The gut is seen in the center.