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Diagnostic Methods
Diagnostic methodsPros and cons
Parasitological diagnosis 
Microfilariae can be found in day blood (peak between noon and 2 p.m.). However, many infected individuals are amicrofilaraemic due to immunity to microfilariae (“occult loiasis”). Standard procedure: membrane filtration or lysis of blood (Knott’s method).
Adult worms may be seen migrating through the conjunctiva. Fugitive swellings (calabar oedema) are characteristic for loiasis.
  • Sensitivity of parasitological methods unsatisfactory due to long pre-patent period and immunity to microfilariae
Molecular diagnosis 
PCR methods detecting two repetitive DNA sequences of Loa loa in whole blood have been described but are not yet standardized. 
Antigen detection 
Attempts to develop a sensitive antigen detection assay have been unsuccessful so far 
Antibody detection 
Serological tests detect circulating antibodies in loiasis lack specificity (cross-reacting antibodies from Mansonella perstans and other filarial infections) and are unable to distinguish between past and current infection
  • No specific test so far available