Antibody Detection
Pulmonary paragonimiasis is the most common presentation of patients infected with Paragonimus spp., although extrapulmonary (cerebral, abdominal) paragonimiasis may occur.  Detection of eggs in sputum or feces of patients with paragonimiasis is often very difficult; therefore, serodiagnosis may be very helpful in confirming infections and for monitoring the results of individual chemotherapy.  In the United States, detection of antibodies to Paragonimus westermani has helped physicians differentiate paragonimiasis from tuberculosis in Indochinese immigrants.  The complement fixation (CF) test has been the standard test for paragonimiasis; it is highly sensitive for diagnosis and for assessing cure after therapy.  Because of the technical difficulties of CF, enzyme immunoassay (EIA) tests were developed as a replacement.  The immunoblot (IB) assay performed with a crude antigen extract of P. westermani has been in use at CDC since 1988.  Positive reactions, based on demonstration of an 8-kDa antigen-antibody band were obtained with serum samples of 96% of patients with parasitologically confirmed P. westermani infection.  Specificity was >99%; of 210 serum specimens from patients with other parasitic and nonparasitic infections, only 1 serum sample from a patient with Schistosoma haematobium reacted.  Antibody levels detected by EIA and IB do decline after chemotherapeutic cure but not as rapidly as those detected by the CF test.  Most published literature deals with pulmonary paragonimiasis due to P. westermani although in some geographic areas other Paragonimus species cause similar or distinct clinical manifestations in human infections.  Cross-reactivity between species does occur but at varying levels for different species.  Thus, use of a test for P. westermani may not allow detection of antibodies to other Paragonimus species.

Reference:

Slemenda SB, Maddison SE, Jong EC, Moore DD. Diagnosis of paragonimiasis by immunoblot. Am J Trop Med Hyg 1988;39:469-471.