Virus serology in familial Crohn disease

Background: Recent findings that early-in-life virus infections represent a risk factor for Crohn disease, that exacerbations of disease sometimes appear associated with common viral infections, and, in particular, suggestions that Crohn disease may be the result of persistent infection with measles virus prompted serologic studies for antibody to 19 common viruses, Chlamydia psittaci, and Mycoplasma pneumoniae. Methods: Sera from 14 affected members of 2 French families with a high frequency of Crohn disease and from age- and sex-matched controls, taken in 1990 and 1992, and from unaffected family members were tested. Complement fixation, enzyme immunoassay, and indirect immunofluorescent tests were used. Results: There were no significant differences between patients and controls or between affected and unaffected family members of family 2, with the exception that affected siblings carried higher antibody titers for mycoplasma one year and for varicella another year. There were no differences in measles IgM and IgG or mumps IgG antibody levels between patients and controls, or between patients and unaffected family members. Conclusions: Serology failed to find evidence of participation by 19 common viruses, C. psittaci, and M. pneumoniae in Crohn disease. The data do not support the hypothesis that persistent measles virus infection causes Crohn disease.