Calabar Swellings

A history of Calabar swellings, also known as fugitive swellings, is the primary tool used to diagnose loiasis. Subcutaneous injection of a small amount of Dirofilaria immitis results in formation of Calabar swelling in the area where it was injected. Calabar swellings are named after a coastal Nigerian town where they were first documented.



(Photograph from http://www.medicine.mcgill.ca/tropmed/txt/lecture4.htm)

Worms in Conjunctival Tissue

The presence of an adult worm in the conjunctivae of the eyes, or in the bridge of the nose is also a tell tale sign of the disease, and is the most painful manifestation of the disease.


Not a very reliable diagnostic tool because microfilaremia may not develop until many years after worms or their activities become apparent. However, some times microfilaremia can appear quite early in the disease, and so thick films made from blood, taken during the middle of the day, when the periodicity would create the highest concentration in the blood.

Nested Polymerase Chain Reaction

This is a new diagnostic tool being developed. The advantage is that "nested PCR amplification product is specific and that its sensitivity in detecting occult loiasis is 95%. This approach has significant promise for the screening of large human populations for active loiasis without the requirement for blotting and hybridization of the PCR products." Consult the following link for more information: http://www.ajtmh.org/cgi/content/abstract/59/1/144.

Note: all of the material above, unless specifically cited, is from Markell and Voge's Medical Parisitology, 8th Ed.

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