Follow-up studies on Epstein-Barr virus IgA/VCA antibody-positive persons in Zangwu County, China

Serological mass surveys were carried out in Zangwu County, China, using an immunoenzymatic test. 3,533 persons were found to have Epstein-Barr virus (EBV) IgA/VCA antibody among 148,029 persons age 30 years and older who were tested during 1978-1980. Among the IgA/VCA antibody-positive persons, 55 nasopharyngeal carcinoma (NPC) cases were detected. Follow-up studies were carried out yearly on the IgA/VCA antibody-positive persons for 1-3 years, and 32 additional NPC patients were diagnosed. IgA/VCA antibody was detected 8-30 months (average, 13 months) prior to the clinical diagnosis of stage I NPC. There was no marked difference in geometric mean titers of IgA/VCA antibody between the period before onset of NPC and after diagnosis at stage I, but antibody titers were higher during stages II-IV. The NPC detection rates for all persons tested serologically and for IgA/VCA antibody-positive persons, respectively, was 2- and 82-fold the annual incidence of NPC in the general population of the same age group. These data further indicate that serological testing is valuable for the diagnosis of NPC, especially in its early stages, and that EBV may play an important role in the development of NPC.