Patient and sample-related factors that effect the success of in vitro isolation of Orientia tsutsugamushi.

Orientia tsutsugamushi is the causative agent of scrub typhus infection, a major cause of human disease in rural areas of Southeast Asia. Twenty-six blood samples collected from patients with serologically proven scrub typhus during a six month period were sent to Bangkok (535 km from the clinical site) by road at ambient temperature (average daily temperature range: 27.1-29.1 degrees C) for attempted in vitro isolation in Vero cells. O. tsutsugamushi was isolated from 12 samples (sensitivity 46.7%) with the time to isolation ranging from 16 to 37 days [median 27 days, inter-quartile range (IQR) 22.5-33.5 days]. Patient factors such as days of fever and O. tsutsugamushi IgM antibody titer, transport factors such as transit time, and isolate genotype (Karp and Gilliam/Kawasaki) were assessed to determine their influence on the outcome of in vitro isolation. None of the factors significantly influenced the isolation outcome. This study demonstrates that O. tsutsugamushi can often be isolated in vitro from the blood of scrub typhus patients when transported at ambient tropical temperatures for many days.

Elevation of serum transcobalamin II in patients with scrub typhus.

Serum transcobalamin II levels were measured in scrub typhus patients. Eighteen out of fifty-two patients admitted to Maharat Nakhon Ratchasima Hospital were diagnosed with scrub typhus infection. The serum unsaturated vitamin B12 binding protein (UBBC) and total vitamin B12 binding protein (TBBC) levels in these patients were significantly higher than in normal subjects (p < 0.001). The mean serum transcobalamin II level in the typhus patients was also significantly higher than in the normal subjects (p=0.004). There was a significant correlation between serum TCII levels and typhus IgM or IgG titers (p < 0.05), but not to total IgM levels. These findings indicate that patients with scrub typhus had stimulation of the recticuloendothelial system as a result of a considerable increase in transcobalamin II levels.

Septic shock secondary to scrub typhus: characteristics and complications.

Scrub typhus is an acute febrile illness caused by infection with Orientia tsutsugamushi transmitted by the bite of larval trombiculid mites (chiggers). A prospective study was conducted in septic shock patients in Maharat Hospital, Nakhon Ratchasima Province, Thailand, from 12 November 2001 to 5 January 2002. Of the 51 septic shock patients studied during the 7 week period, 18 (35.3%) were found to have evidence of scrub typhus infection; 3 patients (16.7%) died. In this study, septic shock caused by Orientia tsutsugamushi is the most prominent (35.3%) in endemic area of scrub typhus. Scrub typhus with septic shock patients results in organ failure: respiratory failure, DIC were predominant, followed by renal and hepatic involvement. Two deaths were due to respiratory failure and one death was as a result of combined respiratory and renal failure. Fever was the most common symptom, followed by headache, myalgia and dyspnea; lymphadenophathy and eschar are common signs. Laboratory findings revealed that almost all of the patients had a mild leukocytosis, reduced hematocrit and thrombocytopenia; SGOT, ALP, direct bilirubin (DB), total billirubin (TB), BUN, Cr were elevated; hypoalbuminemia was noted. Urinalysis showed that 88.9% of the patients had albuminuria. 77.8% of patients had abnormal chest X-rays.

Antibodies to Orientia tsutsugamushi in soldiers in northeastern Thailand.

The prevalence and incidence of antibodies to Orientia tsutsugamushi, the etiologic agent of scrub typhus, in Thai soldiers living and working near the Thai-Cambodian border in Si Sa Ket Province was investigated. The point prevalence of antibodies varied from 0 to 4.1%. The incidence of antibodies, calculated from individuals who seroconverted following a negative result in a previous bleeding 3 to 5 months earlier, was 4.21% (9/214) in January 1992, 0 in April 1992 and 3.76% (8/213) in September 1992. An annual infection rate of 2.66% was estimated.