Serologic and molecular evidence of coinfection with multiple vector-bornepathogens in dogs from Thailand

Forty-nine dogs from Thailand were evaluated for serologic evidence of expo sure or polymerase chain reaction (PCR) evidence of infection with vectorbo rne pathogens, including Ehrlichia sp. (Ehrlichia canis, Ehrlichia chaffeen sis, Ehrlichia equi, and Ehrlichia risticii). Bartonella vinsonii subsp. be rkhoffi (Bvb), spotted fever group (SFG) rickettsiae (Rickettsia rickettsii ), Typhus group (TG) rickettsiae (Rickettsia canada, Rickettsia prowazekii. and Rickettsia typhi). and Babesia sp. (Bahesia canis and Babesia gibsonii ). All study dogs had at least I of 3 entry criteria: fever, anemia, or thr ombocytopenia, By immunofluorescence antibody (IFA) testing, seroreactivity was most prevalent to E chaffeensis (74%) and E cams (71%) antigens, follo wed by E equi (.58%), Bvb (38%), E risticii (38%). R prowazekii (24%), B ca nis (20%). R rickettsii (12%), R canada (4%), and B gibsonii (4%) antigens. There was 100% concordance between E canis IFA and western blot immunoassa y (WI) for 35 of 35 samples 2 samples were IFA and WI reactive only to E eq ui antigens. By PCR amplification, 10 dogs were found to be infected with E canis, 5 with Ehrlichia platys, and 3 with B canis. Sequencing of PCR prod ucts was undertaken to compare Ehrlichia strains from Thailand to strains o riginating from the United States. Partial DNA sequence analysis confirmed infection with E canis and E platys, with identical 16S rRNA sequence align ment to E canis (U26740) and to E platys (M83801), as reported in GenBank. Partial E canis P28.1 and P28.2 amino acid sequences from Thai dogs were di vergent from analogous sequences derived from North American E canis (AF082 744) strains, suggesting that the Thai dogs were infected with a geographic ally distinct strain of E canis compared to North American strains. The res ults of this study indicate that dogs in Thailand have substantial exposure to vectorborne diseases and that coinfection with these pathogens may be c ommon.