A 48 y.o. recent refugee from Colombia complains of a subcutaneous nodule which has been present for two years.
He has no fever, chills or weight loss. A biopsy was done
What is the diagnosis? and what are the lesions present?
Our patient had onchocerciasis in a nodule in the skin. The image shows a stained specimen of the biopsy of the nodule. The uteri of adult worms are seen containing the immature worms, filariae.
the arrow points to the uteri in the adult worms filled with filariae
Onchocerciasis is a nematode found in Africa, Yemen, Central and South America. It is transmitted by black flies that live near rivers. The fly bite deposits larvae which mature into adults in the skin. The first published report was from Africa in 1893. They can be seen on biopsy or even snippings of skin. The filaria rather than being discharged into the blood stream are discharged into the skin and form nodules in the skin which can last 15 years. They also infiltrate the eye chambers causing blindness. The parasite migrates to the internal tissue of the eye causing inflammation.
The penetrance of the the microfilaria is variable with most people developing nodules, itchy skin or eye disease.
the nodule on our patient’s leg
In endemic areas of Africa test and treat strategies are being evaluated. Individuals are tested first for LoaLoa which can exclude them from ivermectin treatment which can cause encephalopathy. Loa loa is treated with diethylcarbamazine. The dosing should be repeated every six months since the ivermectin kills larvae but not adult worms.
Eosinophilia is present in only 2/3 of people with onchocerciasis
The parasites can sometimes be seen in the anterior chamber of the eye
Fun facts
Human parasites have been found in human coprolites in Chile dated to 5900 BC. These were paragonimus, lung flukes.
Human transmission of canine Onchocerciasis has been reported in Europe and in the desert southwest of the US .
Our patient was treated with ivermectin.
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