Volume 25, Number 5—May 2019
Dispatch
Value of PCR, Serology, and Blood Smears for Human Granulocytic Anaplasmosis Diagnosis, France
, Benoit Jaulhac, Pierre Kieffer, Martin Martinot, Elisabeth Wurtz, Régis Dukic, Geneviève Boess, André Michel, Christophe Strady, Jean François Sagez, Nicolas Lefebvre, Emilie Talagrand-Reboul, Xavier Argemi, and Sylvie De Martino
Table
Anaplasma phagocytophilum diagnostic test results of patients with nonanaplasmosis and human granulocytic anaplasmosis diagnoses, France, May 2010–July 2012
| Test result | Control group, no./total | Anaplasma group, no./total |
|---|---|---|
| Positive blood smear |
0/36 |
4/19 |
| Positive by serology | 2/36 | 16/19 |
| Seroconversion* or 4-fold rise in antibody titer | 1/36† | 6/19‡§ |
| Antibody titer >1:256 at first
visit |
1/36¶ |
11/19§ |
| Positive PCR | 0/36 | 14/19 |
*Seroconversion is defined as a change in antibody titer from negative in the first sample obtained during acute illness to >1/64 in the second sample acquired >4 weeks later.
†One patient had a seroconversion with a microbiologically confirmed diagnosis of parvovirus B19 infection.
‡Only 1 patient had a 4-fold increase in antibody titer, but the titer at the first study visit was already high enough to establish the diagnosis (increase from 1:512 to 1:2,048).
§One patient had a seroconversion with an A. phagocytophilum antibody titer >1:256 at the second visit (patient counted once in both serology categories). All other patients with seroconversion had an antibody titer <1:256.
¶One patient with microbiologically confirmed leptospirosis had an A. phagocytophilum antibody titer of 1:256 at the first visit that decreased to 1:64 at the second visit.