One hundred patients with PCR and/or IFA-confirmed HGE were followed by serial IFA (E. equi antigen) at six month intervals for up to 42 months between 6/1990 and 6/1996 for antibodies to E. equi. Not all patients were available at every testing interval. Patients (F=24, M=76) were separated into Untreated (U; doxycycline not given). Early (E) or Late (L) treatment groups (doxycycline given before or on/after the 8th day of symptoms, respectively). IFA tilers were expressed as the reciprocal of dilution, and IFA values ≥ 80 were considered positive. Patient groups and geometric mean IFA titer values were compared by the Wilcoxon rank sum test. 42/90 (47%) of the initial (acute phase) samples (E=16, L=17, U=9) tested IFA-positive and 96% (71/74) samples were positive at 4 weeks (mean IFA group tilers at 4 weeks: E 954, L 1613, U 880; p = NS). Group mean IFA titers were lower for E compared with L or U for the period 6 to 18 months and the relative proportion of patients with IFA ≥ 80 was lower for E than for L and U during the same time period (p = 0.05 - < 0.001). Five of 10 patients (50%) still tested positive at 30 months. No differences were observed between the group mean IFA values from 24 to 42 months. E. equi IFA titers ≥ 80 persisted in 50% of patients followed for at least 30 months after acute HGE. Institution of doxycycline treatment during the first week of illness did not influence the ability of infected patients to generate antibodies to the HGE agent. However, early doxycycline therapy may result in earlier disappearance of serum antibodies man in patients who are treated later or not at all.
|Original language||English (US)|
|Number of pages||1|
|Journal||Clinical Infectious Diseases|
|State||Published - Dec 1 1997|