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Volume 14, Number 9—September 2008

Letter

Genotyping of Orientia tsutsugamushi from Humans with Scrub Typhus, Laos

Philippe Parola, Stuart D. Blacksell, Rattanaphone Phetsouvanh, Simaly Phongmany, Jean-Marc Rolain, Nicholas P.J. Day, Paul N. Newton, and Didier RaoultComments to Author 
Author affiliations: World Health Organization Collaborative Center for Rickettsial Diseases and Other Arthropod Borne Bacterial Diseases, Marseille, France (P. Parola, J.-M. Rolain, D. Raoult); Mahosot Hospital, Vientiane, Laos (S.D. Blacksell, R. Phetsouvanh, S. Phongmany, N.P.J. Day, P.N. Newton); University of Oxford, Oxford, United Kingdom (S.D. Blacksell, N.P.J. Day, P.N. Newton); Mahidol University, Bangkok, Thailand (S.D. Blacksell, N.P.J. Day);

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Table

Serologic results for 11 patients from Laos positive by real-time quantitative PCR for the 47-kDa outer membrane protein and a PCR for a fragment of the 56-kDa protein–encoding gene of Orientia tsutsugamushi*

Patient GenBank accession no. of 56-kDa–amplified gene fragment Highest % identity with GenBank sequences (reference)
IgG/IgM titers, acute phase–late phase
Gilliam Kato Kawasaki
LaoUF74 64/1,048–64/1,048 128/256–128/256 128/256–128/256 EU168798 These 4 genotypes showed 100% identity with each other and 96.6% with strain BB23 from Thailand (5)
LaoUF317 2,048/1,024–ND 128/1,024–ND 2,048/1,024–ND EU168799
LaoUF366 2,048/512–2,048/512 128/32–128/32 2,048/512–2,048/512 EU168797
LaoUF396
256/1,024–256/1,024
128/64–128/64
256/1,024–256/1,024
EU168796
LaoUF220 2,048/512–2,048/1,024 2,048/512–2,048/512 1,024/256– 2,048/512 EU168801 These 2 genotypes showed 100% identity with UT150 and UT332, which are related to Karp serotype isolates (6), BB29 from patients in
Thailand (5), and TWyU81 from chiggers in Taiwan (7)
LaoUF244
1,024/128–ND
256/64–ND
128/64–ND
EU168800
LaoUF83
128/1,024–ND
0/1,024–ND
0/128–ND
EU168795
95.9% with BB23 from 
Thailand (5)
LaoUF136
2,048/1,024–2,048/1,024
2,048/1,024–2,048/1,024
2,048/1,024–2,048/1,024
EU168804
99.5% with UT144, UT125, and UT196 from Thailand, which are related to Gilliam serotype isolates (6)
LaoUF186
128/1,024–2,048/1,024
128/1,024–2,048/1,024
128/1,024– 2,048/1,024
EU168805
100% with BB23 from 
Thailand (5)
LaoUF187
256/1,024–256/1,024
256/0–256/0
0/0–256/1,024
EU168803
100% with UT144, UT125, and UT196 from Thailand (6)
LaoUF238 2,048/1,024–2,048/1,024 2,048/1,024–2,048/1,024 0/512–256/512 EU168802 100% with UT219, UT395, UT221, and UT213, which are related to Karp serotype–related isolates (7), and FPW2031 from Thailand (6)

*Ig, immunoglobulin; ND, not done. Specific microimunofluorescence assay (IFA) was performed in Marseille, France, by using whole-cell antigens of O. tsutsugamushi serotypes Kato, Gilliam, and Kawasaki. Serotype Karp was not available for serologic assays. An IFA result was positive if 1) titers were >128 for IgG and >64 for IgM, 2) seroconversion was observed in a convalescent-phase serum sample when an acute-phase serum sample was negative, or 3) there was a >4-fold increase in titers between acute- and convalescent-phase serum samples (0 indicates a titer <25).

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