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We investigated the prevalence of Bartonella species in 10 rodent and one shrew species in Thailand. From February 2008 to May 2010, a total of 375 small animals were captured in 9 provinces in Thailand. Bartonella strains were isolated from 57 rodents (54 from Rattus species and 3 from Bandicota indica) and one shrew (Suncus murinus) in 7 of the 9 provinces, and identified to the species level. Sequence analysis of the citrate synthase and RNA polymerase β subunit genes identified the 58 isolates from each Bartonella-positive animal as B. tribocorum in 27 (46.6%) animals, B. rattimassiliensis in 17 (29.3%) animals, B. elizabethae in 10 (17.2%) animals and B. queenslandensis in 4 (6.9%) animals. R. norvegicus, R. rattus, and Suncus murinus carried B. elizabethae, which causes endocarditis in humans. The prevalence of Bartonella bacteremic animals by province was 42.9% of the animals collected in Phang Nga, 26.8% in Chiang Rai, 20.4% in Sa Kaeo, 16.7% in Nakhon Si Thammarat, 12.0% in Surat Thani, 9.1% in Mae Hong Son and Loei Provinces. These results indicate that Bartonella organisms are widely distributed in small mammals in Thailand and some animal species may serve as important reservoirs of zoonotic Bartonella species in the country.

Bartonella henselae is an emerging gram-negative facultative intracellular pathogen transmitted via Ctenocephalides felis (cat fleas) or cat scratches. Bartonellosis is present mainly in the form of cat scratch disease (CSD), bacillary angiomatosis and infective endocarditis (IE). The methods used to diagnose B. henselae rely on culturing, immunofluorescent assays and molecular techniques. The objective of the present study was to identify candidate proteins for the serodiagnosis of bartonellosis with the differential discrimination of both clinical scenarios: CSD and IE. For this, an immunoproteomic approach combined with 2-DE, immunoblotting and matrix-assisted laser desorption/ionization time-of-flight MS has been developed. Immunoproteomic profiles of sera collected from patients with CSD and IE were compared with those of blood donors. We identified several candidate proteins as phage-encoding Pap31 protein and an outer membrane protein of BH11510 that, in our view, might be useful for the serodiagnosis of bartonellosis.

The adult patients who, between July 2001 and June 2002, presented at any of five hospitals in Thailand with acute febrile illness in the absence of an obvious focus of infection were prospectively investigated. Blood samples were taken from all of the patients and checked for aerobic bacteria and leptospires by culture. In addition, at least two samples of serum were collected at different times (on admission and 2-4 weeks post-discharge) from each patient and tested, in serological tests, for evidence of leptospirosis, rickettsioses, dengue and influenza. The 845 patients investigated, of whom 661 were male, had a median age of 38 years and a median duration of fever, on presentation, of 3.5 days. Most (76.5%) were agricultural workers and most (68.3%) had the cause of their fever identified, as leptospirosis (36.9%), scrub typhus (19.9%), dengue infection or influenza (10.7%), murine typhus (2.8%), Rickettsia helvetica infection (1.3%), Q fever (1%), or other bacterial infection (1.2%). The serological results indicated that 103 (12.2%) and nine (1%) of the patients may have had double and triple infections, respectively. Leptospirosis and rickettsioses, especially scrub typhus, were thus found to be major causes of acute, undifferentiated fever in Thai agricultural workers.

Leptospirosis and scrub typhus are important causes of acute fever in Southeast Asia. Options for empirical therapy include doxycycline and azithromycin, but it is unclear whether their efficacies are equivalent. We conducted a multicenter, open, randomized controlled trial with adult patients presenting with acute fever (P = 0.02). In conclusion, doxycycline is an affordable and effective choice for the treatment of both leptospirosis and scrub typhus. Azithromycin was better tolerated than doxycycline but is more expensive and less readily available.

A nested PCR technique was performed to detect a specific 483 bp DNA fragment of Orientia tsutsugamushi, the aetiological agent of scrub typhus, in 53 blood samples from 36 patients with acute pyrexia of unknown origin in southern Thailand. The specific primers could amplify the specific DNA from all 10 prototype strains of O. tsutsugamushi and all nine seropositive patients and three seronegative patients, while no DNA amplification was obtained with DNAs from other rickettsiae or from healthy persons or from patients with murine typhus. The specific PCR product was detectable in the blood for as long as 22 days after the onset of disease in patients without specific treatment and 27 days after receiving a single dose of doxycycline. Thus, nested PCR may be more sensitive than the serological test for diagnosis of scrub typhus and prolonged persistence of O. tsutsugamushi DNA in patients' blood was demonstrated despite clinical recovery of the patients.