Ownership of cats or dogs does not increase exposure to Rickettsia typhi

In the United States, murine typhus (Rickettsia typhi) is endemic in southern California and South Texas. Evidence indicates the natural host/vector system is the opossum and cat flea, the most common flea on both cats and dogs, and speculation suggests that pet contact may pose a risk for R typhi exposure. Serum from 140 subjects was tested for rickettsial antibodies by an enzyme-linked immunosorbent assay that used an R typhi antigen. Each subject was asked about pet contact status and placed in one of the following groups: owners, non-owners but with regular contact (more than 3 times per week), non-owners with irregular contact (fewer than 3 times per week), or non-owners with no contact. Overall, 15.7% of sera were positive for antirickettsia IgG. Of owners or those with regular contact, 14 of 96 (14.6%) were seropositive, while 8 of 44 (18.2%) of non-owners or those with irregular contact were seropositive. A chi-square test showed no significant difference among these groups (P > .5). We conclude that pet ownership or regular contact with pets is not a risk factor for exposure to Rickettsia typhi.